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Notes: The effect of polymerization temperature on the melt flow behavior of PVC of varying molecular weights has been studied over a wide shear rate range. For the same molecular weight, higher melt viscosities are observed for polymers prepared at lower temperatures. The shear rate dependence of the viscosity vs molecular weight plot is shown to be nonlinear over the shear rates examined. The inability to achieve a limiting zero-shear viscosity is discussed.

Notes: A high-frequency alpha transition of some plasticized poly (vinyl chloride) compositions was measured at 4 MHz employing an ultrasonic pulse technique. The material property used to determine the transition region was the intrinsic loss, which is indicative of changes in both the storage and loss moduli. Four dicarboxylic esters were used as plasticizing agents. These were (1) butyl benzyl phthalate, (2) di-(2-ethylhexyl) phthalate, (3) dibenzyl sebacate, and (4) di-(2-ethylhexyl) sebacate. Compositions were prepared using 10, 20, and 30 parts by weight of plasticizer per hundred of polymer. A small quantity of thermal stabilizer was added to prevent degradation. Samples were produced by an extrusion process to promote a high degree of fusion and consolidation. Comparison of the data showed the usual decrease in the transition temperature with increasing concentration of the plasticizing agent. However, it was shown that the controlling factor of the transition response was the molecular structure of the plasticizer. Both the structure of the parent dicarboxylic acid and the ester side groups were controlling factors. This relationship was supported when a high-frequency storage and loss modulus (dilatational) was compared at 25°C to the molecular weight of the side chain. The dimethyl ester was included for both series for comparative purposes. These data showed that the storage modulus increased and the loss modulus decreased with increasing chain length and complexity. However, the factor contributing most was the complexity (steric hindrance) of the plasticizing molecule.

Notes: Crack velocity measurements and fracture toughness tests have been carried out on extruded sheets of bisphenol-A polycarbonate. Slow bend tests provided quasi-static K1c data while dynamic initiation values were obtained from instrumented Charpy impact tests. In both types of tests high-speed crack velocity measurements were made using conductive silver grids applied to the specimens. The variation of K1c with strain rate and temperature was found to be small and in general agreement with expectations from the relaxation properties of polycarbonate. Notch acuity was found to have little effect in that values of K1c and crack velocity from specimens having the standard Charpy notch were similar to values obtained from sharp-cracked specimens. Some anisotropy was present in the material and gave rise to a small variation in K1c values with direction of crack propagation. Crack velocity and also the fracture mode transition temperature showed considerable dependence upon orientation. It was thought that dynamic toughness Kd, was influenced more than K1c by partial orientation of amorphous regions in the material and that the relaxation time for re-orientation was probably significant here.

Notes: Poly(methyl methacrylate) prepared under special circumstances exhibits a substantial increase in refractive index after irradiation with ultraviolet light. The essential step in the preparation is peroxidation of the monomer prior to polymerization. This increase in refractive index results from a photo-induced polymerization of unreacted monomer (1-2 percent) within the film which produces an increase in density (and hence refractive index) in the irradiated region. It is believed that peroxides, both polymeric and monomeric, act as photoinitiators. Sensitivity depends on the concentration of photoinitiator but the absolute value of Δn depends on the amount of unreacted monomer.

Notes: A class of negative electron-beam resists is described which have excellent lithographic characteristics. The resists are copolymers of glycidyl methacrylate and ethyl acrylate. Their molecular weights, epoxy contents, and polydispersivities can be controlled to give an adjustable range of electron sensitivity and contrast. The copolymers are compared to other epoxy containing, negative electron-beam resists.Micrography of resist profiles generated from a single line scan of the electron beam have been used to illustrate the complex interaction of accelerating voltage of the electron beam and resist contrast on resolution. Optical gratings made from single line scans of the beam have feature sizes less than 300 nm in the resist, etched metals, and dielectrics.

Notes: A recently proposed method for predicting the strains resulting from the application of uniaxial cyclic stresses is developed for application to polymer systems. Experimental results obtained from rectangular cyclic loading tests on prismatic beams and circular plates are compared with theoretical predictions using two sources of basic data, (a) uniaxial isochronous and creep data and (b) deformation data resulting from constant load creep tests conducted on the components. It is concluded that the method would require considerably less computation, to obtain satisfactory accuracy, than the alternative integral superposition methods even for rectangular cyclic loading and would prove much more tractable when applied to other forms of cyclic loading.

Notes: Creep tests at constant values of tensile stress, temperature, and relative humidity for two thermoplastics were conducted for approximately 132,000 hr. The strains, ∊, for the first 2000 hr of time, t, were described by an equation of the form ∊ = ∊o + ∊+tn where all other symbols are constants. This equation was found to predict the creep of poly(vinyl chloride) for approximately 132,000 hr with reasonable accuracy. The predicted strains for polyethylene (density 0.924) were somewhat low. Strains during unloading and reloading after 90,000 hr of creep were predicted reasonably well by the Boltzmann superposition principle.

Notes: The generation of pressure in the feed section of an extruder is analyzed. It is concluded that body forces must be considered since they provide the necessary conditions for pressure initiation. Solutions are given which take into account gravity forces in both vertical and horizontal screws together with centrifugal force. Some numerical results are also given which illustrate the practical importance of these effects.

Notes: Solid state processing of polyethylene (SS60-050) by hydrostatic extrusion is investigated. Measurements are also reported for the tensile properties of polyethylene 60-050 under superposed hydrostatic pressure. With the latter data an estimate is made of the pressure required for extrusion of polyethylene in the absence of losses due to friction and redundant work. The limiting conditions for successful extrusion are discussed.

Notes: Fybex is a newly available potassium titanate whisker. Its usefulness as a reinforcement for a thermosetting epoxy resin is examined. The effect of surface treatment on the mechanical properties of the composite system is also considered.

Notes: The origin of the discrepancy between the Bagley method and the modified method suggested by Han in obtaining the end correction data is traced to the effect of a deviatoric stress contribution in the pressure measurement at the capillary wall. The end correction factors for polystyrene melt were obtained by the Bagley method. The effects of temperature, die entry angle, contraction ratio or reservoir diameter-to-die diameter ratio are discussed.

Notes: Measurements have been made of the electrical conductivity of water-saturated heterogeneous anion-exchange pyridinium membranes in their carbonate and hydroxyl ionic forms as a function of temperature. The pyridinium membranes were prepared from quaternized poly-4-vinylmethyl-pyridinium resin electrolyte incorporated in a polyvinylidene fluoride matrix; the ratio of the pyridinium electrolyte to polyvinylidene fluoride was 4 to 1 by weight.The ion-exchange capacity and water content of these anion-exchange pyridinium membranes were measured. Corresponding Arrhenius activation energies of ion transport of carbonate and hydroxyl counter-ions have been calculated. Self-diffusion coefficients and the equivalent conductances of these pyridinium membranes in their carbonate and hydroxyl counter-ion forms have also been determined over a wide temperature range and compared to the reported values for present quaternary ammonium anion-exchange membranes.

Notes: Zirconium compounds dispersed in polymers often bond the polymer molecules together, increasing their stability. This can generally be attributed to the formation of covalent bonds between zirconium atoms and small atoms of high electronegativity of the polymer molecule, to overlapping of pi orbitals of unsaturated moieties of the organic compound with sigma orbitals of the zirconium atoms, to fractional bond formation between zirconium and organic hydrogen, and to combinations of these. Bonding and its effects on physical properties have been achieved by molecular dispersions of zirconium compounds in the polymer, by dispersion of insoluble particles of zirconium compounds, and through residues from zirconium catalysts used in polymer preparation. Coatings and plastic components have been improved in strength and in durability by the dispersions. Compounds of other metals often perform similarly. The totality of relevant properties of zirconium compounds often leads to their preferential use.

Notes: The steady shear viscosities of high density polyethylene disolved in highly branched isoparaffin solvents have been measured with a high-pressure autoclave viscometer at temperatures ranging from 150 to 250°C and over a range of shear rates from 0.02 to 170 sec-1. Laboratory measurements on solutions ranging from 15 to 67 wt percent polymer were used to develop and calibrate a mathematical model for solution viscosity intended for a range of from 10 to 100 wt percent polymer. The foundation for the model consists fo two equations: the modified Martin equation is used to describe the effect of concentration, and the Sabia equation is used to describe pseudoplastic behavior. The model correlates viscosities that can range over nine orders of magnitude with sufficient accuracy for most process design work, averaging less than 10 percent error. Both the data and the model indicate that at constant stress the activation energies (EA) for the effect of temperature on viscosity are higher for solutions in the midrange of composition than for either of the pure components. This peak in EA is related to the density difference between polymer and solvent.

Notes: Several types of amorphous polymers have been cold-rolled to various thickness reductions and the notched Izod impact behavior has then been studied. It has been determined that whereas some polymers exhibit large increases in impact strength with modest reductions in thickness other polymers only exhibit small increases in impact strength. For example, PVC, ABS, poly (phenylene oxide), and polysulfones show large increases in impact strength whereas rubber-toughened acrylics show only a small increase in impact strength.

Notes: In a reciprocating-screw injection-molding machine, the screw or plunger forces the plastic into the mold. It remains in the forward position under pressure for a fixed time during which plastic flow into the mold or ‘packing’ takes place. After the timer runs out, the screw moves back while rotating thus releasing the pressure on the plastic in the mold. At this time, if the gate has not frozen, flow of plastic out of the mold or ‘discharge’ takes place. In this study, clear rigid PVC, poly (vinyl chloride), was molded with varying amounts of packing and discharge. Photoelastic stress patterns for parts observed between cross-polaroids suggested that packing and discharge give rise to high frozen stresses due to molecular orientation in the gate area. Mechanical strength tests on the molded parts show that these high stresses are a source of weakness. Short forward times for the plunger significantly improve the mechanical properties of the parts in the gate area and at the same time have a significant influence on part dimensions, especially in the gate vicinity. Laminations observed at the gate interface can also be reduced by controlling the extent of molecular orientation introduced by packing and discharge.

Notes: The spiral mold method (moldability test) was used in a study of phase separation occurring in glass-containing polyethylene and polyamide melts. Pronounced separation effects were recorded for low density polyethylene containing 25 percent glass spheres with diameters ranging approximately from 50 to 100 μm, the glass concentration at the tip of the spiral exceeding 40 percent by weight. For melts containing smaller spheres or fibers the effect was of the order of a few percent. There was a decrease in glass concentration near the center of the spiral.

Notes: Scanning electron microscopy revealed spores of Nosema apis and Thelohania fibrata to be egg-shaped, but only the mature spore of T. fibrata was shown to possess a horseshoe-like concavity at the posterior pole. Freezeetched preparations indicated that this concavity was due to a thin area of the spore coat. Freeze-etching studies also show spores of N. apis do possess an umbrella-shaped polaroplast, and a polar filament which is arranged in a double layer with over 30 coils. The spore of T. fibrata contains a pear-shaped arrangement of the polaroplast membrane, and a polar filament arranged in a single layer of 22 coils.

Notes: The fiber constituents and connections of the calyces  -  the input-receiving regions  -  of the corpora pedunculata (“mushroom bodies”) were studied in reduced silver preparations from the American cockroach, Periplaneta americana (L.). In the outer synaptic layer of the calyces five fiber classes were distinguished, the first three of which arise outside the mushroom body. (1) Four highly similar neurons with somata near the optic lobe branch into different parts of the ipsiateral protocerebrum, including both calyces. Their fibers are highly constant in arrangement and position and contain small nucleus-like bodies. (2) The tractus olfactorio-globularis (sensu lato) emits fiber groups which course along the calycal walls as “calycal tracts” before ultimately dissipating into the synaptic layer. Variability within these tracts is described. (3) Fibers of undertermined origin outside the mushroom body radiate from the calycal center outwards through the synaptic layer. (4) From the inner calycal layer of neurites belonging to intrinsic mushroom-body neurons, perpendicular collaterals enter the synaptic layer. (5) Intrinsic-neuron somata near the calycal rim emit fibers which course tangentially within the synaptic layer from calycal rim to center. These fibers form a special peripheral zone in the pedunculus.The predominant presumably afferent calycal fiber class is that derived from the tractus olfactorio-globularis. No evidence was found for tracts from optic lobe to calyces. On this basis, and in light of the experimental and comparative anatomical literature, it is suggested that the corpora pedunculata of P. americana and other pterygotes are fundamentally second-order antennal sensory processing centers.Conflicting observations in earlier reports are critically discussed.

Notes: The epidermis of Eisenia is covered by a cuticle and rests on a basement lamella. The cuticle, which is resistant to a variety of enzymes, is composed of non-striated, bundles of probable collagen fibers that are orthogonally oriented and are embedded in a proteoglycan matrix. The basement lamella consists of striated collagen fibers with a 560 Å major periodicity. Proximity and morphology suggest that the epidermis may contribute to both the cuticle and the basement lamella  -  that is, the single tissue may synthesize at least two types of collagen. The epidermis is a pseudostratified epithelium containing three major cell types (columnar, basal and gland) and a rare fourth type with apical cilia. The esophagus is lined by a simple cuticulated epithelium composed predominantly of a single cell type, which resembles the epidermal columnar cell. Rare gland cells occur in the esophageal epithelium, but basal cells are lacking.

Notes: Gill development begins on the sixth day of incubation at 10°C and is complete by 31 days (hatching). Gill arches are formed by fusion and perforation of ectoderm and endoderm across the pharyngeal wall. A primary branchial artery forms within each arch and a second branchial artery forms as a branch from its ventral end. A series of filament loop vessels forms connecting the two arteries and when several are patent a unidirectional blood flow is established via afferent (second) branchial artery, filament loop vessels to efferent (primary) branchial artery. Part of the efferent branchial artery just above its junction with the afferent branchial artery constricts and occludes. It is suggested that this change in the pattern of blood flow is dependent on differences in resistance of the two branchial arteries. A later extension of the gill ventrally is thought not to be homologous with similar regions in elasmobranchs and Acipenser.

Notes: Scanning and transmission electron microscopy studies were conducted on the antennal sensory sensilla of the hymenopteran parasitoid, Cardiochiles nigriceps Viereck, of the family Braconidae. Distinct morphological differences were found between the chemoreceptors of the male and female. Curved, non-fluted, thin-walled sensilla were found to be very abundant on the male and restricted in location and number on the female. Trichoid, placoid and fluted basiconic sensilla were numerous on the antennal flagella of both sexes. Smooth basiconic sensilla were restricted in number to one per flagellar segment in both sexes. Behavioral data suggest that bent-tipped, thick-walled sensilla unique to the female are involved in detecting a chemical(s) emitted from the host, Heliothis virescens (Fab.).

Notes: The biomechanical role of the mammalian clavicle and the functional significance of the aclaviculate condition were investigated. Shoulder movements in rats (Rattus norvegicus) with excised clavicles were compared to those of normal rats by biplanar plate radiography. Shoulder movements during walking of the claviculate American opossum (Didelphis marsupialis), and aclaviculate raccoons (Procyon lotor) and cats (Felis domestica) were compared by biplanar cineradiography.The mammalian clavicle, where present in its complete form, exerts both a “spoke” and a “strut” effect on shoulder movement. By maintaining a fixed distance between the acromion and manubrium, the clavicle ensures that relative movement between these structures is arcuate. Aclaviculate mammals, in contrast, have linear shoulder excursions that are nearly parallel or slightly oblique to the median plane, depending on the conformation of the thorax. Medial collapse of the shoulder in aclaviculate rats demonstrates that the clavicle is under compression, and thus acts as a strut.Reduction or loss of the clavicle, which has occurred independently in numerous mammalian phylogenies, has been regarded as an adaptation for greater shoulder movement and hence increased stride. However, on present evidence clavicular reduction in cursorial mammals appears to be more directly related to a linear excursion of the shoulder joint and a restriction of limb movements to a sagittal plane.

Notes: The tail of Teratoscincus scincus has dorsal scales that have tubercles on their dorsal and ventral surfaces. Sounds are produced when these rub past each other as the excited animal moves its tail. The relative movement of scales is intensified by caudal torsion. The frequencies of the sounds cover a range from 9 to 25 kops and thus, differ from those produced during vocalizations.

Notes: The locomotor function of the caudal muscle cells of ascidian larvae is identical with that of lower vertebrate somatic striated (skeletal) muscle fibers, but other features, including the presence of transverse myomuscular junctions, an active Golgi apparatus, a single nucleus, and partial innervation, are characteristic of vertebrate myocardial cells.Seven stages in the development of the compound ascidian Distaplia occidentalis were selected for an ultrastructural study of caudal myogenesis. A timetable of development and differentiation was obtained from cultures of isolated embryos in vitro.The myoblasts of the neurulating embryo are yolky, undifferentiated cells. They are arranged in two bands between the epidermis and the notochord in the caudal rudiment and are actively engaged in mitosis.Myoblasts of the caudate embryo continue to divide and rearrange themselves into longitudinal rows so that each cell simultaneously adjoins the epidermis and the notochord. The formation of secretory granules by the Golgi apparatus coincides with the onset of proteid-yolk degradation and the accumulation of glycogen in the ground cytoplasm.Randomly oriented networks of thick and thin myofilaments appear in the peripheral sarcoplasm of the muscle cells of the comma embryo. Bridges interconnect the thick and thin myofilaments (actomyosin bridges) and the thick myofilaments (H-bridges), but no banding patterns are evident. The sarcoplasmic reticulum (SR), derived from evaginations of the nuclear envelope, forms intimate associations (peripheral couplings) with the sarcolemma.Precursory Z-lines are interposed between the networks of myofilaments in the vesiculate embryo, and the nascent myofibrils become predominantly oriented parallel to the long axis of the muscle cell.Muscle cells of the papillate embryo contain a single row of cortical myofibrils. Myofibrils, already spanning the length of the cell, grow only in diameter by the apposition of myofilaments. The formation of transverse myomuscular junctions begins at this stage, but the differentiating junctions are frequently oriented obliquely rather than orthogonally to the primary axes of the myofibrils.With the appearance of H-bands and M-lines, a single perforated sheet of sarcoplasmic reticulum is found centered on the Z-line and embracing the I-band. The sheet of SR establishes peripheral couplings with the sarcolemma.In the prehatching tadpole, a second collar of SR, centered on the M-line and extending laterally to the boundaries with the A-bands, is formed. A single perforated sheet surrounds the myofibril but is discontinuous at the side of the myofibril most distant from the sarcolemma. To produce the intricate architecture of the fully differentiated collar in the swimming tadpole (J. Morph., 138: 349, 1972). the free ends of the sheet must elevate from the surface of the myofibril, recurve, and extend peripherally toward the sarcolemma to establish peripheral couplings.Morphological changes in the nucleus, nucleolus, mitochondria, and Golgi bodies are described, as well as changes in the ground cytoplasmic content of yolk, glycogen, and ribosomes.The volume of the differentiating cells, calculated from the mean cellular dimensions, and analyses of cellular shape are presented, along with schematic diagrams of cells in each stage of caudal myogenesis. In an attempt to quantify the differences observed ultrastructurally, calculations of the cytoplasmic volume occupied by the mqjor classes of organelles are included.Comparison is made with published accounts on differentiating vertebrate somatic striated and cardiac muscles.

Notes: Anolis embryos have limb buds at the time eggs are laid and require about 39 days to complete development at 28°C. Rathke's pouch is present at five days, and the subdivisions of the adenohypophysis are differentiated by ten days after oviposition. The cells of the rostral half of the pars distalis (PD) are derived from the anterior face of Rathke's pouch; cells of the caudal half from the posterior face. Lateral lobe cells differentiate on the lateral margins of the developing caudal PD, and knob-like outgrowths of this tissue attach to the walls of the diencephalon to form the pars tuberalis (PT). Subsequently, the cells of the PT lose their connection with the PD and become a pair of flattened oblong plaques. They reach maximal size in midincubation, and are gradually invaded by nervous elements and incorporated into the walls of the hypothalamus. Electron micrographs demonstrate that the embryonic PT is secretory.Ultrastructurally the pars intermedia (PI) and PD are composed of parenchymous secretory cells in a framework of stellate cells. Stellate cells surround the lumen of Rathke's pouch and are connected laterally by complex junctions that exclude the secretory cells from the luminal surface. They extend in sheet-like processes among the secretory cells to the outer margin of the gland where they form a partial sheath within the basal lamina around the secretory tissue. As development proceeds, the lumen becomes subdivided and the resulting reduced lumina are recognizable as the forerunners of the follicles of the adult adenohypophysis.The cells of the PI are differentiated into secretory or stellate cells halfway through incubation. At this time only half of the cells of the PD can be so classified. Four of the five granulated cell types described in the adult are recognizable by mid-incubation; the fifth cell type (prolactin cell) becomes distinguishable within ten days thereafter, and at hatching appears to be actively synthesizing secretory products.

Notes: The hydranth of the gymnoblastic hydroid Syncoryne tenella is invested by a cuticle approximately 530 mμ thick which is continuous with the periderm of the hydrocaulus. The ectodermal cells of the hydranth possess regularly spaced microvilli orientated with their long axis perpendicular to the ectodermal surface. The microvilli project into the cuticle, and probably serve to anchor the cuticle to the ectoderm. In the hydrocaulus the periderm is loosely applied to the ectoderm: in this region microvilli are absent from ectodermal cells. The periderm is a layered structure composed of finely filamentous material. No structural basis is found for the previously reported differential staining of peridermal layers in the hydrocaulus.

Notes: The nuchal organs of polychaetes from four different families (Nereidae, Nephtyidae, Phyllodocidae and Glyceridae) were examined with the light and electron microscopes. In each case, the organ consists of ciliated cells and primary sensory elements. The ciliated cells are similar to the cells of the adjacent epidermis but bear motile cilia. Primary sensory neurons are situated within the organs in Nephtyidae and Phyllodocidae, but are located within the brain in Nereidae and Glyceridae. Each sensory cell gives rise to a distal process which penetrates between the ciliated cells to form an apical sensory bulb bearing modified cilia. Apically these processes are lined with juxtamembranous plaques. The ciliated cells are innervated by efferent axons from the brain, and in Nereis the axons appear to be peptidergic. The elements comprising the nuchal organs closely resemble those of the vertebrate olfactory mucosa.

Notes: The cuticle of five species of Oligochaeta, chosen to represent differences in size and a variety of biotopes, was studied electron microscopically after fixation with the acrolein-TAPO-osmium tetroxide method. Five distinct layers in the cuticle of all studied species were found. Staining with lead and uranyl ions or with silver proteinate visualized basically the same structural components of the cuticle, but the degree of electron opacity and the distribution of the electron-opaque stain in these components differed according to the staining method used. Since the acrolein-TAPO-osmium tetroxide method visualized the cuticular zones preferentially stained by Thiéry's silver proteinate method, it was concluded that the TAPO method may be considered suitable for the visualization of polysaccharides. Staining with phosphotungstic acid provided some information on the composition of the cuticle of Oligochaeta not obtained by staining ultrathin sections with lead and uranyl ions nor with silver proteinate. The conclusion is that phosphotungstic acid binds to polysaccharides which do not contain vicglycol groups nor active sites responsible for the positive reaction with lead and uranyl salts. Structural components in the cuticle of the oligochaetes studied were characteristic for each species. The taxonomic value of such components, however, must be confirmed by examination of a larger number of species of oligochaetes.

Notes: Laboratory-reared outgrowths of the freshwater sponge Corvomeyenia carolinensis Harrison were examined using histological and histochemical techniques, supplemented by phase contrast observations of cellular behavior. The tissue and cellular components of the spongillid outgrowth region were defined in terms of function and morphogenic state. Archeocytes differ considderably, in both histochemical and morphological characteristics, from other cell types of the adult sponge, being histochemically similar to stem cells reported from a variety of developmental series. Archeocytes exhibit cytological characteristics of unspecialized cells capable of high levels of synthetic activity while other cell types of C. carolinensis, for the most part, can be characterized as fully differentiated cells displaying more restricted synthetic capabilities but often accumulating neutral mucoproteins. The presence of aggregates of amebocytes, not identifiable as archeocytes and possibly engaged in gemmule formation, is discussed in terms of current concepts of gemmulation and cellular developmental capabilities in sponges.

Notes: The long antennal flagellum of Neoconocephalus ensiger is covered with many sharp-tipped hairs that appear to be non-innervated; thick-walled chemoreceptors, that may also have a tactile function; thin-walled chemoreceptors of several kinds and coeloconic chemoreceptors. All of the chemoreceptors are innervated by small groups of neurons. The first flagellar subsegment is unusual in that it bears a small protuberance on its latero-ventral surface. This marks the site of the attachment, internally, of a scoloparium containing about eleven scolopales in which the dendrites of some 23 sensory neurons terminate. The most distal subsegment lacks the scoloparium reported earlier for the grasshopper. No conspicuous difference between the antennae of males and of females was found.

Notes: The antennae of two species of thrips, Bagnalliella yuccae (Hinds) and Frankliniella tritici (Fitch), have been examined with the light and electron microscopes. The antennal flagellum of both species is provided with tactile hairs, thick-walled chemoreceptors and thin-walled chemoreceptors. In addition, B. yuccae, but not F. tritici, has a single coeloconic chemoreceptor on the dorsal surface of the pedicel. Observations were made on the fluids in the lumen of the antennae of E. yuccae in the living insect. The movement of the fluids probably has an important physiological significance.

Notes: The cervicothoracic muscles of nymphal and adult Euborellia annulipes (Lucas) are described, the former for the first time. In the adult, eight new muscles are identified, while the nymphs possess a further seven muscles that disappear at maturation or before. Otherwise the same muscles occur in nymphs as in adults, though some nymphal muscles are less clearly separated from one another than their adult homologs. The attachment sites of certain muscles show a number of slight differences between nymphs and adults. The work emphasizes the necessity of taking the immature musculature into account in assessing the muscular pattern represented in an insect order.

Notes: Some of the cytological characteristics of the hemocytes of the scorpion, Palamnaeus swammerdami, were studied. The morphological features of the arachnid hemocytes were observed to be similar to those of hemocytes of insects, millipedes and isopods. Jones' system of hemocyte classification was extended to the arachnid hemocytes. The six classes of hemocytes indentified in the scorpion correspond to prohemocytes, plasmatocytes, granular hemoocytes, cystocytes, spherule cells and adipohemocytes of insects. A cell type comparable to oenocytoids of insects and crustaceans is absent. The prohemocytes can be subdivided into four categories that probably represent the precursors of the major cell types. The cytological characteristics of the major cell classes and the occurrence of the miniatures of some of these major cell types support the concept of Jones (62) that these cell types might have different cell lineages and might not be capable of transforming into one another. Some of the prohemocytes, plasmatocytes and granular hemocytes were amoeboid. The nature of the granules and the vacuoles of plasmatocytes and granular hemocytes were compared with the granules and vacuoles of corresponding hemocytes of other arthropods. Cystocytes did not bring about any visible coagulation similar to their counterparts in millipedes and crustaceans. Plasmatocytes, granular hemocytes and spherule cells were observed to occur in conglomerates. The cell types noted in the present study were compared with the hemocytes of other arachnids.

Notes: The morphological features of the hemocytes of the crustacean Ligia exotica are similar to hemocytes of insects and millipedes. Jones system of hemocyte classification is extended to crustacean hemocytes. As in insects, seven classes of hemocytes, identified as prohemocytes, plasmatocytes, granular hemocytes, cystocytes, oenocytoids, spherule cells and adipohemocytes, occur. The prohemocytes can be subdivided into five categories that probably represent the precursor of major cell types. The structural and chemical features of other major cell classes are distinct and support the concept of Jones ('62) that these types might have different lineages and might not be capable of transforming into one another. Some of the prohemocytes, plasmatocytes and granular hemocytes are amoeboid. Cystocytes do not bring about any visible plasma coagulation similar to their counterpart in millipedes. Oneocytoids and adipohemocytes are rare. Plasmatocytes, cystocytes and oenocytoids occur in conglomerates, the significance of which is discussed. The cell types are compared with those of the hemocytes of other crustaceans. It is suggested that the nomenclature based on morphological characters is more suited for crustacean hemocytes than a nomenclature based on behavioural and physiological characters.

Notes: Well preserved transitional cells were found between differentiated cells and horny cells of the frog epidermis, thus facilitating the study of the sequential events involved in horny cell formation. Autolysosomes appear to play an important role in the formation of horny cells. These structures preferentially digest those cytoplasmic components which are not necessary constituents of the terminal horny cell. The release of the contents of the small mucous granules into the intercellular spaces is one of the initial events in horny cell formation. Filaments and large mucous granules seem to be resistant to the lytic digestion and contribute to the bulk of the horny cell. Loss of fluids through the plasma membrane and consolidation of the remaining constituents, results in a flattened horny cell. The appearance of a thickened membrane around the horny cell signifies the completion of the transformation process.

Notes: The three dorsal ocelli of worker honeybees have been studied by light and electron microscopy. Each ocellus has a single flattened spheroidal lens and about 800 elongated retinular cells. Retinular cells are paired and form a two-part plate-like rhabdom between their distal processes. Each rhabdomere comprises parallel microvilli projecting laterally from the apposed retinular cells. Primary receptor cell axons synapse within the ocellus with ocellar nerve fibers of two different calibers. Each ocellus has eight thick fibers ca 10 m̈m in diameter and several thinner ones less than 3 m̈m in diameter. Fine structural evidence suggests that retinular axons end presynaptically on both types of ocellar nerve fibers. Since all retinular cells apparently synapse repeatedly with the thick fibers this involves a convergence of about 100:1. Thick fibers always terminate postsynaptically within the ocellus while thin fibers terminate presynaptically on other thin fibers, thick fibers or retinular axons. Structural evidence for synaptic polarization indicates that retinular cells and thick fibers are afferent, thin fibers efferent. Thus complex processing of the ocellar visual input can occur before the secondary neurons of the three ocelli converge to form the single short ocellar nerve which runs to the posterior forebrain.

Notes: The functional morphology of the forelimbs of the following African Viverridae was studied, Atilax paludinosus, Bdeogale crassicauda, Civettictis civetta, Genetta genetta, G. tigrina, Helogale parvula, Herpestes ichneumon, H. sanguineus, Ichneumia albicauda, Mungos mungo, Nandinia binotata. Their locomotory behaviour has been previously studied and described and is related to morphological differences. The osteology of all the species and the myology of three species is described. The species have been assigned to primary locomotor categories on the basis of their locomotion. These are 1, climbing, arboreal walking; 2, arboreal and terrestrial walking and jumping; 3, general terrestrial walking and scrambling; and 4, trotting. In the climbing arboreal walking category the most distinctive morphological adaptations are powerful flexors and extensors as well as a flexible plantigrade manus with retractile claws. In the arboreal and terrestrial walking category the shoulder, elbow and carpal joints are flexible and the manus has retractile claws, though the flexor and extensor musculature is insufficiently developed for controlled climbing. The trotting category is characterised by a high humero-radial index and a rigid antibrachium. The foot is digitigrade with the claws short and stout. Species in the general walking and scrambling category show many differences in the morphology of their feet, even though the proximal parts of the forelimb appear similar. Due to the restricted nature of the adaptations, these species have been assigned to secondary locomotor categories. Morphological characters typical of the locomotor categories are summarized in the discussion.

Notes: The temperature dependence of the mechanical properties of a 50/50 blend of PVAC and lightly crosslinked PMMA has been examined using the data of Kawai et al. The shift distances, log aT, were generated by bringing the experimental data into coincidence on master curves calculated from a Takayanagi model whose parameters were varied in different regions of temperature. This method allows one to construct a master curve for a thermorheologically complex two-phase material if the model and the mechanical properties of the constituent phases and their temperature dependence is known. The shift distances then provide insight into the intricate relations between the time and temperature dependence of the mechanical properties of the composite.

Notes: Within a normal operating range of extruders, it has been well established that the output increases nearly proportionally to the screw speed but the screw horsepower increases more than proportionally to the screw speed, making the screw HP difficult to predict. It has been also known in scale-up of extruders that the output may be predicted with reasonable accuracy but the screw HP is difficult to predict. No sound theoretical or empirical method predicting screw HP in a scale-up calculation has been offered heretofore. Since a screw performs solid conveying, melting and pumping (or metering) functions simultaneously, any theoretical analysis of screw HP has to consider all three extrusion theories; solid conveying theory, melting theory and pumping theory. In this paper, semi-theoretical equations for predicting screw HP as a function of screw speed and size are developed. Experiments are conducted to test the utility of these equations and the implications of the experimental results on extrusion theories are discussed.

Notes: A series of rigid polyurethane foams of densities varying from 65 kg/m-3 to 400 kg/m-3 have been tested in compression as a function of rate and temperature. It has been found that a linear relation exists between density and modulus if the data is referred to a constant thermodynamic temperature.

Notes: A simple theoretical model for flow in nonintermeshing twin screw extruders has been derived. The assumptions which in single screw extruders result in the “two parallel plates” model, in twin screw extruders result in the “three parallel plates” model. The flow rate equation can be expressed, for Newtonian fluids, in terms of drag and pressure flow terms, as in single screw extrusion theory, but each term is multiplied by a geometrical factor. This factor incorporates the effect of one screw on the drag and pressure flow terms of the other. The theoretical model was experimentally verified on a 1 inch diameter Bausano twin screw extruder.

Notes: This study is devoted to the mechanical properties of impregnated asbestos-cements. We studied the influence of the degree of impregnation and of the nature of the resin on the modulus of elasticity and on the strength of the materials. The impregnation of asbestos-cement by polymeric resins produces composites of outstanding mechanical properties. The relative increase in flexural and tensile strength is much higher for mortar and concrete but the improvement produced by the polymer on asbestos-cement is especially significant if one takes into consideration the already high absolute strengths of the materials.

Notes: The equilibrium sorption of n-hexane vapor and n-hexane liquid in solution cast films of polystyrene, poly(phenylene oxide), and blends of these homopolymers was studied over a significant range of penetrant activity and temperature. These equilibrium sorption measurements were supplemented by density determinations, refractive index measurements, differential scanning calorimetry and differential thermal analysis. A seemingly complicated pattern of results emerged when the equilibrium penetrant content was plotted as a function of blend composition. At relatively low activity and temperature the equilibrium concentration of n-hexane in these films monotonically increased with poly(phenylene oxide) content in the blend. Conversely, at high activities and in unit activity liquid, the equilibrium penetrant concentration exhibited a distinct minimum when plotted as a function of blend composition. At higher activities, solvent induced crazing accompanied the sorption of penetrant. These results were explained consistently by considering the nature of the sorption isotherm over an activity range sufficient to lower the glass transition temperature, of the equilibrated and swollen blend, below the temperature of the sorption experiment. Most importantly, the interpretation and explanation of these data are based upon phenomena common to all glassy polymer-organic penetrant systems and no special properties of this blend system were included in the analysis. The results, therefore, reflect the apparent homogeneity of polystyrene-poly (phenylene oxide) blends and are useful in considering the equilibrium of penetrant sorption in glassy polymers as a general class of materials.

Notes: In the process of transforming from liquid to crystal, a polymer molecule must assume conformations which cause it to have a higher free energy than either the liquid or the crystal. This free energy barrier to crystallization is minimized if the molecule folds, thus providing both the driving force for folding as well as the assurance that the crystallization behaves as a classical kinetically-controlled process. This free energy barrier exists equally well for the melting of extended chain crystals accounting for their observed super-heating. Finally these ideas can be extrapolated to predict some rather unconventional conclusions with regard to polymer conformation in the melt.

Notes: The kinetics of n-hexane vapor and n-hexane liquid sorption in solution cast films of polystyrene, poly(phenylene oxide), and blends of these homopolymers were studied over a significant range of temperature and penetrant activity. The kinetics of concomitant solvent crazing, apparent at high penetrant activities, were also monitored. In all cases the kinetics of sorption and crazing obeyed predominantly Case II or relaxation-controlled behavior. Although the rates of crazing and sorption at high activities was much more rapid in the homopolymers than in the blends, the sorption rate at lower penetrant activities increased monotonically with increasing poly(phenylene oxide) content.These kinetic results qualitatively superimpose upon the equilibrium relationships reported in Part I of this series. Specifically, at a fixed temperature, the rate of crazing was virtually a unique function of equilibrium n-hexane content independent of polymer composition and largely independent of penetrant activity. The coupling between rate of sorption and equilibrium penetrant content was dramatic. In limiting cases, the sorption rate increased by a factor of 10,000 apparently due to a twofold increase in equilibrium penetrant concentration. This seemingly complicated kinetic behavior is explained rather simply in terms of the equilibrium relationships between organic penetrants and polymeric glasses developed and interpreted in the first part of this series.

Notes: Investigations of chemically-blown vinyl foam systems, based on electrical grade plasticizers, have shown that the inclusion of 2,2′-bis (4-hydroxyphenyl) propane (BPA) as an antioxidant results in color formation in the finished foam. Color formation appears to be due to interactions between BPA and the azodicarbonamide blowing agent. Metal ion(s) present in vinyl stabilizer/kickers are also shown to have an effect on color hue though not on color development per se. Mechanisms for the development of quinoidal and diazo color bodies, based on the reaction of BPA and azodicarbonamide are postulated. Based on these reaction mechanisms, it is shown that it is possible to choose an antioxidant that will not interact with azodicarbonamide. A rudimentary screening procedure is described for evaluating these systems.

Notes: The resistance of various linear condensation polymers to acid or base hydrolysis is dependent upon the nature of the linkages in the polymer chain. Aryl polysulfonates having a styrylketone sensitizing group have been shown to be particularly resistant to attack by strong bases. Similar phosphorouscontaining polymers have been prepared and those with the arylphosphonate, thiophosphonate, and phosphate linkages have been found resistant to attack by such acids as ferric chloride. Using a solution polymerization method, these phosphorous polymers and also those containing the phosphite, phosphonite, and phosphorane linkages may readily be prepared. A comparison has been made of the resistance of these polymers and of the corresponding polycarbonates, polysulfonates, and polyesters to various bases and to ferric chloride solutions.

Notes: The formation of an image in a photoresist during photolithographic processing requires the exposure of the photoresist through a mask to a light source in the spectral region to which the photoresist is sensitive. The functional advantage of the flash exposure of photoresist is presented, which includes the elimination of oxygen effects, the reduction of diffraction and standing wave effects, and the enhancement of pattern-edge acuity. The effects of both broad and narrow band sources are also shown with emphasis on proximity printing techniques. Finally, the optical, electrical and physical design parameters for a practical flash exposure system are discussed.

Notes: Based on the assumption of a constant critical shear strain, an expression for the critical stress at the onset of entrance fracture as a function of polymer concentration has been developed. Experimental results with 10-25 percent narrow distribution, high molecular weight polystyrene-benzene solutions show the critical stress to be much lower than that for the polymer melt and in agreement with predicted values. This result is all the more impressive when the contrast in flow behavior at the capillary entrance for melts and solutions is observed. Instead of the rotating toroidal vortices surrounding a 90-deg material entrance cone observed with polystyrene melt, cine movies of the solution flow birefringence patterns in the capillary entrance region reveal only a stagnant zone surrounding a narrow cone less than 20 deg. At fracture, the cone axis moves in a rotary path circulating about the capillary axis without undergoing the flow discontinuities typical of melt behavior.

Notes: A theoretical analysis using finite element methods has been applied to oriented short-fiber composites and spherical particle composites in order to predict the influence of a finite layer at the interface on mechanical properties. In this study the interfacial layer has been modeled by assuming that a layer surrounds the interface and that this layer has a modulus of elasticity different than both the fiber and the matrix. The stress distribution near the interface has been determined as a function of the elastic constants of the interface layer and the interface layer volume fraction. This analysis has also been performed for two volume fractions of fibers and two fiber length to diameter ratios. From this stress distribution, the composite modulus and toughness have been determined as a function of interface modulus. It is theoretically shown that the toughness, measured by amount of strain energy absorbed, can be maximized by controlling the interface modulus. Furthermore, recent experimental results appear to verify the theory.

Notes: Particulate-filled thermosetting composites are widely used, yet little systematic work has been done on their long-term strength characteristics. In this study short-term tensile, flexural, and impact tests as well as tensile creep-rupture tests were made for unfilled and filled epoxy to clarify the effects of filler size, filler content, and temperature. Fillers used were silica, alumina particles, and glass beads. Test temperatures were varied from 25 to 110°C. As a result of short-term testing, it was found that the Petch relation held between strength and filler size if brittle fracture occurred, while a strength and filler size if brittle fracture occurred, while a strengthening effect existed when ductile fracture occurred. On creeprupture testing, a strengthening is observed with filler size and content for silica and glass beads. The Arrhenius plot of rupture time for various filler sizes and contents converges to a characteristic point corresponding to the glass transition temperature of the material. Using this relation, a modified Larson-Miller master rupture curve is proposed which can predict the long-term strength of particulate-filled thermosetting composites as functions of rupture time, temperature, filler size, and content.

Notes: Detailed studies have been carried out on the anisotropy of creep and creep rupture behavior of thermoplastics oriented by the imposition of a large permanent deformation. This deformation is usually such as to produce simple fiber symmetry within the specimen. Experimental techniques have been devised for the accurate measurement of all three principal strains during tensile creep on small samples which are cut from the oriented specimens at various angles to the symmetry axis. In this way a full characterization of the creep behavior up to strains of 5 percent has been obtained at room temperature.Results are presented for work on rigid poly (vinyl chloride), poly(methyl methacrylate), and low density polyethylene. The results are discussed in terms of the time dependence and nonlinearity of the anisotropy. Creep rupture results on similar specimens are also presented and discussed. Anisotropy due to orientation is shown to be important in determining engineering properties and in understanding structure-properties relationships.

Notes: During extrusion the main deformation and orientation of macromolecules is achieved by the flow component with longitudinal gradient. The orientation increases drastically if some solidification occurs during flow, yielding row-nucleated cylindrites and even fully oriented hard elastomers. In all cases the basic elements are stacks of very thin (∼100Å) folded-chain lamellae connected by very few tie molecules. The plastic deformation of the solid transforms the original lamellar material into the extremely well oriented fibrous structure with high anisotropy of physical properties. The basic element are the highly aligned, very long and thin microfibrils bundled into fibrils. The axial strength of microfibrils is caused by the great many taut tie molecules connecting as almost crystalline bridges the crystalline blocks across the interposed amorphous layers. In plastic deformation of fibrous material the fibrils are sheared and longitudinally displaced. The latter mode is responsible for almost all the observed elongation. It smooths the structural defects on the surface of fibrils caused by the ends of microfibrils and thus produces a better lateral fit of fibrils resulting in rapidly increasing resistance to plastic deformation. The former mode extends the interfibrillar tie molecules and hence drastically increases their fraction per amorphous layer.

Notes: Processing involves complex polymer flow problems, either in the melt or in solution. Rheologists have developed many studies with the aim of correlating polymer structure with flow properties and polymer processing. Most of these studies, however, have had relatively little impact on practical processing because of the difficulty in solving the mathematical equations involved. Recently, a relatively few papers have been published with the aim of bridging the gap between theoretical rheology and technology. The first part of the paper presents an account of works which have dealt with the process of filling a mold cavity. The second part discusses briefly some experimental results which provide a correlation between moldability and rheological properties. By analogy with the terms “electrology” and “electrotechnics,” the term “rheotechnics” is suggested for this new area of study.

Notes: A new kind of acetal fiber has been discovered which has a tensile strength of 1.7 GPa (250,000 psi) and an elastic modulus of 35 GPa (5 × 106 psi). This fiber is produced by a special two-stage drawing process in the solid state which requires careful control of deformation rate and temperature. Previously known drawn fibers are reported to consist of folded-chain blocks joined by a limited number of tie-molecules. It is hypothesized that the second stage of the novel drawing process eliminates the lamella (block) surfaces which act as strength-limiting stress concentrators. A new type of fiber is created in which any remaining chain-folds are distributed as defects in a continuous crystal matrix. It is the continuity of the crystal matrix which is believed responsible for the remarkable properties of the fiber.

Notes: The unperturbed radii of gyration, S02/M, of vinyl chloride-propylene copolymers at different propylene levels have been determined by a GPC method. When the percent propylene of an unknown sample is evaluated by density measurements, the molecular weights can be calculated from GPC data through the use of S02/M. It is believed, in most cases, that the percent propylene and degree of polymerization are enough to characterize commercial samples of such a copolymer system. The effects of these two variables on intrinsic viscosity have been isolated.

Notes: The influence of surface properties on the flow of fluids, including epoxy resin, through aligned glass and other fiber beds has been examined. The observed flow rates were higher than those predicted from the Kozeny-Carman equation, and were influenced by the surface properties of the fluid used. This is attributed to variations in the distribution of porosities and to the presence of air bubbles trapped during the initial wetting of the bed. The implications of these findings to the preparation of composites are discussed.

Notes: Techniques have been developed for measuring the strain and thermal histories of fluid elements as they move from the die lips to the freeze line. Motion pictures were analyzed to determine the rates of extension in the machine and transverse directions. A radiation pyrometer was used to measure the temperature of the film. These techniques were used to study the film blowing of polyethylene; a 2.5-in. diameter die was used, and blow-up ratios in the range of 1.8 to 3.4 were employed. Film thickness ranged from 2 to 4 mils. The maximum measured extensional strain rates in both the transverse and machine direction were in the range of 0.15 to 0.6 sec-1. Standard shrinkage and impact tests were performed on the finished films, and an attempt was made to correlate the results with several simple empirical norms of the strain history. No correlation could be discerned. The results of this study are inconsistent with some popular ideas about the origin of orientation in blow films, but they are consistent with some recently published data on the influence of deformation on orientation in melt-drawn capillary extrudate.

Notes: Poly(2-methyl pentene-1) sulfone undergoes scission followed by rapid chain depolymerization when irradiated with 5-20 kV electrons. Several parameters which affect the rate of this process, termed vapor development, were evaluated, viz., molecular weight, dose rate, temperature, accelerating voltage and film thickness. While it was never really possible to remove 100 percent of the film, it was possible to remove 〉 99 percent at reasonably low doses (∼ 10-6 coul/cm-2) using high temperatures (∼ 100°C) and low accelerating voltage (5 kV). Some lithographic details of this process are also described.

Notes: Poly(methyl isopropenyl ketone) (PMIPK) degrades upon exposure to 5 keV electrons. Using a scanning electron microscope to expose fine-line raster patterns in thin films of this polymer and subsequently solvent-developing the thus-degraded regions, sharp walled troughs are observed, the width of which is a measure of the sensitivity to degradation. Copolymers with several vinyl monomers were prepared and the sensitivities of these were similarly determined. Information relevant to the mechanism of depolymerization was obtained by comparing homopolymers with copolymers and by the use of additives in the irradiated polymer films. Examples of potential device-fabrication techniques using PMIPK resist are given.

Notes: The morphology of isotactic polypropylene in molded plaques containing a knit line is described in detail. The effects of mold temperature and flow on the size and orientation of spherulitic and transcrystalline regions are discussed. Deformation at the weld line under uniaxial tensile stress is analyzed by optical microscopy.

Notes: Strain recovery of polyester and nylon 66 monofilaments, following stress relaxation at constant strain, has been measured under two types of temperature history. In the first (experiments here called type A), the monofilament, extended at an elevated temperature, was held at constant strain at that temperature, and then air-quenched to room temperature while still under stress. The stress was later removed with the fiber at ambient temperature, and the recovery from strain determined. In the second (experiments of type B), the monofilament was also extended at an elevated temperature, but it was then allowed to recover, under zero load, at the same temperature, prior to quenching. A cylindrical heater is described which surrounded the fiber specimen and which could be removed suddenly to permit rapid air quenching of the specimen. Recovery was characterized by the percent of applied strain which was recovered 100 sec after load removal. The percent recovery, in type A experiments, decreased to low values with increasing stretch temperature. Recovery in type B experiments, however, was markedly different, and showed a minimum value at stretch temperatures in the vicinity of the glass transition. At higher temperatures, recovery was high, but it decreased rapidly as TM was approached due to the onset of viscous flow. There was thus a discontinuity in recovery behavior as the time of quenching increased through the time of unloading (transition between type A and type B conditions). The results were interpreted to show that the achievement of good heat setting (poor recovery) is critically dependent on the temperature of the fiber during both stretching and recovery periods.

Notes: Two component topologically-interpenetrating polymer networks were made of the SIN type (simultaneous interpenetrating network) composed of two polyurethanes (a polyether-based and a polyester-based) in combination with an epoxy resin, a polyacrylate and two unsaturated polyesters. The linear polymers and/or prepolymers were combined in solution and in bulk together with the necessary crosslinking agents and catalysts. Films were cast and chains extended and crosslinked in situ. All of the IPN's exhibited one glass transition (Tg) intermediate in temperature to the Tg's of the component networks, and as sharp as the Tg's of the components. This suggests that phase separation may not occur and thus some chain entanglement (interpenetration) of the two networks is involved. The observed Tg's are always several degrees lower than the arithmetic means of the component Tg's. A theory based on interpenetration is developed to account for this.

Notes: A finite element method is proposed for solving two dimensional flow problems in complex geometrical configurations commonly encountered in polymer processing. The method is applicable to flow in relatively narrow gaps of variable thickness and any desired shape. It was developed for analyzing flow in injection molding dies and certain extrusion dies. The fluid can be any non-Newtonian fluid which is incompressible, inelastic, and time independent. The flow field is divided into an Eulerian mesh of cells. Around each node, located at the center of the cell, a local flow analysis is made. The analysis around all nodes results in a set of linear algebraic equations with the pressures at the nodes as unknowns. The simultaneous solution of these equations results in the required pressure distribution, from which the flow rate distribution is obtained. Solution for the isothermal Newtonian flow problem is obtained by a one-time solution of the equations, whereas solution of a non-Newtonian problem requires iterative solution of the equations.

Notes: The yield stress is a simple function of the deformation ratio in the direction of testing for specimens oriented by uniaxial or biaxial stretching or rolling. Unless the yield stress increases more rapidly than in proportion to the deformation ratio, there will be instability during tensile creep under high loads. The relative merit of various polymers differs for creep and stress relaxation. Fatigue and bend recovery are also related to the molecular structure.

Notes: Specific volume change and stress-strain data were obtained simultaneously during tensile deformation on several plastics known to be resistant to impact loading. Tensile deformation rates of 20 percent/minute and 106 percent/minute and temperatures of -190° to 55°C were employed. A common sequence of deformation modes was observed in all materials studied (rubber modified acrylics and styrene, ABS materials, polycarbonate, impact grade polypropylenes, and high density polyethylene). In all cases the major mode of deformation to failure at low rates and/or higher temperatures is volume conserving and primarily a shear flow process. At higher rates of deformation or lower temperatures, a transition occurs and the specific volume of the material increases in direct proportionality to the tensile strain above the apparent yield point. Volume increases of 17 to 50% were observed and these were equal to 85 percent or more of the observed tensile strain at failure. These observations indicate that microcavitation may be the major process available for the absorption of mechanical energy at impact rates in plastic materials.

Notes: Formulas relating the rate of filtrate flow in a sectioned disk filter to the process variables are derived. It is demonstrated that an optimum inner radius which yields a maximum flow of filtrate can be chosen. Flow rates for drum and disk filters operating under similar conditions are compared.

Notes: A theoretical and experimental investigation of the pumping characteristics of the normal stress extruder was made. The theoretical model requires only material property data and extruder dimensions and rotation speed to evaluate the main velocity field, flow rate, and pressure. The flow from the extruder was measured for two viscoelastic polymer solutions and a polymer melt as a function of gap setting and angular velocity. These measurements were in reasonable agreement with the proposed model.

Notes: Experimental data are presented for five systems, each consisting of water, an alcohol (methanol or ethanol), and an inorganic salt dissolved to saturation in the boiling liquid phase. The data confirm and extend knowledge of recently discovered anomalies to the general theory of salt effect in vapor-liquid equilibrium. A partial accounting for the observed anomalies is attempted based on recent advances in the understanding of the structural nature of alcohol-water mixtures.

Notes: This is a study of a photochemical reactor consisting of a vortex-stabilized arc and an annular, triple-walled, fused silica reaction chamber. An argon arc plasma provides the light. For power inputs of 3-12 kw, the spectral output of the light source was characterized as a function of wavelength, arc-gas flow rate, power input to the arc, and position along the arc. For power inputs of 3.84 and 8.45 kw, there were, respectively, 0.314 and 0.862 einsteins emitted per hour in the 2500 to 5000Å wavelength region. Selective filter solutions of 1.5N KNO3 and 0.05N KI were investigated. A reactor analysis is presented, based on mass and energy balances, and the geometrical properties of the system.

Notes: An experimental procedure based on continuous crystal seeding was developed which can explicitly determine the fundamental relationship between collision breeding and the leading moments of the crystal size distribution. For the aqueous, cooling crystallization of potassium dichromate, the analysis determined that only the mass moment was successful in correlating observations subject to crystal seeding.It was also observed that mixing may have a pronounced effect on the nucleation rate but that kinetic orders for collision breeding and growth rate were independent of mixing.

Notes: Temperature and concentration profiles are obtained by solution of the coupled nonlinear differential equations which describe transient operation of an adiabatic fixed bed reactor. The unreacted-shrinking core mechanism describes the multiple, irreversible, exothermic gas-solid reactions. Numerical integration is accomplished by a predictor-corrector scheme which is programmed in Fortran IV language. The influence of kinetic parameters, heat and mass diffusivities within pellets, temperature variation of properties, gas velocity, bed and particle dimensions, inlet gas temperature and composition, and initial bed temperature on reactor performance are studied for sulfur dioxide removal from flue gases by fixed beds of copper oxide. Comparison with commercial reactors is in qualitative agreement.

Notes: Both polymeric solutions and fiber suspensions have separately been known to exhibit drag reduction under turbulent flow conditions. It has recently been shown that the mechanisms of drag reduction differ appreciably in these two kinds of systems.The objective of this study was to show that both mechanisms may be exploited concomitantly to achieve unusually low friction factors. Drag reductions in excess of 95% have been obtained in a 2.4-cm tube and there is no evidence that even more dramatic results could not be obtained under optimal conditions.

Notes: Based on new experimental data presented for the boiling point elevation of natural sea water solutions, smoothed tabular values are presented for boiling point elevation (BPE), osmotic coefficient, water activity, osmotic pressure, and minimum separation energy to 200°C and 12% sea salt.The concentration of sodium chloride solutions having the same water activities as sea salt solutions is also presented.Rigorous thermodynamics and the equations for strong electrolytes by Bromley (1973) were used for the correlation together with previously obtained heat capacity and enthalpy data and equations. A simplified equation is presented for boiling point elevation.

Notes: Liquid composition-total pressure and liquid composition-liquid density data for the carbon dioxide-ethane system were measured at -31.7°, -17.8°, -3.9°, and 10.0°C (-25°, 0°, 25°, and 50°F ± 0.02°F), from 0 to 80 mole % CO2 at 10°C and 0 to 100% CO2 for the other isotherms. The Benedict-Webb-Rubin equation of state with a modified A0 mixing rule was used to correlate the composition-pressure data, with deviations in predicted pressures of only 0.8% average and 2% maximum. Vapor-liquid equilibrium compositions and component K values y/x were then predicted for this minimum boiling azeotrope system from 10° down to -56.7°C (50° to -70°F).

Notes: This paper outlines the concepts for a systematic approach to the safety analysis of chemical processing systems. A procedure for automatically generating fault trees is presented. The fault trees describe nearly all the failure modes for the system under analysis. The fault tree generation procedure uses information on (1) the description of the system (detailed flowsheet), (2) physical and chemical properties of materials in and around the system, and (3) unit models which describe the behavior of the units within the system and which are assembled to describe the behavior of the complete system. The unit models are connected to form an information flow structure for the complete processing system. Unit failure models are also defined for common chemical units. By systematically defining hazard states and searching the information flow structure for the system, it is possible to generate fault trees for the complete process. An analysis of the fault trees can reveal the important failure modes for the process.