Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 633-642 
    ISSN: 0887-624X
    Keywords: free radicals ; grafting ; kinetics ; methacrylate ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of grafting a basic monomer, 2-(dimethylamino)-ethyl methacrylate (DMAEMA) to hydrocarbon substrates have been investigated. These systems were chosen as models for the grafting of a homopolymerizable monomer to polyolefins such as polyethylene. The reactions with squalane and n-eicosane were initiated by an organic peroxide, 2,5-dimethyl 2,5 dit-butylperoxy)-3-hexyne; grafting yields become significant at high reaction temperatures and low monomer concentrations. In squalane, the order of reaction with respect to monomer increased from about 1.1 for 0.22-0.44M DMAEMA to almost 2 at 0.69M DMAEMA; the order with respect to initiator was 0.56. The overall activation energy in the 130-160°C temperature range was, however, surprisingly low, 42±5 kJ mol-1. When analytical data were used to separate the overall rate into those for grafting and homopolymerization, different kinetic paths were observed for the competing reactions. These results are interpreted in terms of two different mechanisms; intramolecular chain transfer plays an important role in grafting, while depropagation becomes a major factor in homopolymerization at temperatures above 150°C. © 1995 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 3517-3525 
    ISSN: 0887-624X
    Keywords: peroxide ; vinylsilane ; grafting ; polymers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The peroxide-initiated grafting of vinyltrimethoxysilane (VTMS) onto dodecane has been examined as a model for grafting onto polyethylene. At 160°C, 2% v/v VTMS and 0.08% v/v initiator, the monomer was grafted onto dodecane with a 59% conversion and an average of 2.37 VTMS grafts per dodecane. These values were obtained by separation of the grafted material through reduced pressure distillation then characterization with FTIR and NMR spectroscopy, mass spectrometry, and gel permeation chromatography. NMR studies strongly indicate that the multiple grafts consist predominantly of multiple single grafts rather than homopolymer grafts. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3517-3525, 1997
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 1691-1702 
    ISSN: 0887-624X
    Keywords: grafting ; basic functionalization ; free radical polymerization ; methacrylate ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The grafting of 2-(dimethylamino)ethyl methacrylate (DMAEMA) onto two model hydrocarbons, squalane and n-eicosane, and to linear low density polyethylene (LLDPE) has been investigated. The results of the study indicate that a high reaction temperature, 160°C, and a low concentration of monomer, less than 0.3 M, are optimum conditions for the grafting reaction. Reaction products, which consisted of grafted hydrocarbons and poly(DMAEMA), were separated by solvent extraction and vacuum distillation; samples were then analyzed by NMR and FTIR spectroscopy and size exclusion chromatography. 1H-NMR spectroscopy indicates that grafted squalane contained approximately 6 DMAEMA units per squalane residue. 1H- and 13C-NMR and molecular weight studies strongly suggest that the grafts onto the model hydrocarbons consist of single DMAEMA units. Results of the melt grafting of DMAEMA onto LLDPE show that the grafting efficiency and degree of grafting are substantially lower than were expected from the model system. © 1994 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 1347-1362 
    ISSN: 0887-6266
    Keywords: polyethylene/polymethyl methacrylate blends ; reactive polymer blends ; ductile matrix/brittle dispersed phase blend ; instrumented impact testing ; toughening mechanism ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Blends of t-butylaminoethyl methacrylate grafted polyethylene (PE-g-tBAEMA) with methyl methacrylate-methacrylic acid copolymer (PMMA-MAA) and polymethyl methacrylate (PMMA) were prepared in a Banbury type batch mixer. The effects of component proportions and processing conditions on the melt flow index, morphology, impact, and tensile properties of the resulting polymer blends were investigated. The interfacial chemical reaction was studied using Fourier transform infrared (FTIR) technique. It was observed that the melt index of the blends was reduced with increasing melt processing temperature and mixing time, indicating the formation of PE-g-PMMA block copolymer. New IR bands at 1554, 1628, 1800, and 1019 cm-1 were observed only for PE-g-tBAEMA/PMMA-MAA, the reactive blends, but not for PE-g-tBAEMA/PMMA, the nonreactive blend. These IR bands were attributed to the amide, carboxylate anion and methacrylimide formation resulting from the chemical reaction between the secondary amine on the PE-g-tBAEMA/PMMA moiety and the carboxylic acid on PMMA-MAA segment. The morphology of the blends in various compositions was examined using scanning electron microscopy (SEM) and related to their mechanical properties. All of the blends have a domain structure whose morphology is strongly dependent on the concentration of the dispersed phase. Furthermore, the PE-g-tBAEMA/PMMA-MAA reactive blends were shown to have much finer morphology than the corresponding nonreactive blends. For the reactive polymer blends consisting of brittle particles dispersed in the ductile matrices, the PE-g-tBAEMA/PMMA-MAA, impact and tensile result higher than predicted by the additivity rule were observed. The toughening of polyethylene by PMMA was explained by a “cold-drawing” mechanism. The Young's modulus of the blends and the extent of interfacial adhesion were analyzed with Takayanagi and Sato-Furukawa's theories. © 1993 John Wiley & Sons, Inc.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 62 (1996), S. 1807-1818 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Very few polymeric systems are suitable for preparing engineering parts using reaction injection molding (RIM) processing. A new two-component metallocene catalyst, which is able to polymerize bulk styrene at high rates to the syndiotactic form, was studied. The catalyst used in this work was based on monocyclopentadienyl analogs of titanium (Cp*TiMe3), which was used in conjunction with a boron cocatalyst [B(C6F5)3]. When separate streams of the catalyst and cocatalyst, dissolved in either styrone or styrene/toluene solutions, met in a mixhead, the styrene polymerized rapidly to form crystalline, syndiotactic polystyrene (s-PS). Using a bench scale RIM device, the monomer conversion during polymerization was monitored through the quasi-adiabatic temperature rise, recorded by a rapid data acquisition system. The rate equation was found to be second order with respect to the monomer concentration and first order with respect to the catalyst concentration, given some assumptions. The s-PS was brittle and attempts were made to incorporate elastomer toughening into the reacting system. Several potential problems associated with using this system for RIM process discussed. © 1996 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 39 (1990), S. 655-678 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polystyrene (PS) and polyethylene (PE), along with their reactive counterparts, i.e., polystyrene having oxazoline reactive groups (OPS) and polyethylene with carboxylic acid groups (CPE), were melt blended in a Rheomix mixer. These blends were prepared by mixing these polymers in various proportions under a variety of conditions. In an alternate procedure the OPS, CPE graft polymer (OPS-g-CPE) was prepared by melt blending these two polymers beforehand, and subsequently this grafted polymer was used as a compatibilizer for PS-PE blends. The effects of the addition of OPS and CPE, on the one hand, and OPS-g-CPE, on the other hand, on the compatibility of PS-PE blends were investigated. The morphology of these blends was examined with a scanning electron microscope (SEM) and related to their tensile properties. The PS-PE blends are found to have the typical coarse morphology of incompatible blends and poor tensile properties while their reactive counterparts, OPS-CPE blends, have fine grain microstructure and show improved tensile strength throughout the range and improved elongation in the PE-rich blends. Relatively low concentrations of the reactive pair, oxazoline and carboxylic acid, are shown to be necessary to produce improved compatibility. The preblended graft copolymer OPS-g-CPE imparts compatibility to PS-PE blends also but not as effectively. This suggests that the addition of OPS and CPE during melt mixing of PS and PE forms OPS-g-CPE polymer at the interface and that these ingredients act as “in situ reactive compatibilizers” which improve physical properties.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 2285-2300 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The grafting of maleic anhydride (MAn) to low density polyethylenes (PEs) dissolved in 1,2-dichlorobenzene (DCB) has been studied. Grafting was successful at temperatures of about 160°C both in air without initiator and under nitrogen with the radical initiator 2,5-di(t-butylperoxy)-2,5-dimethyl-3-hexyne (LPO). The presence of succinic anhydride grafts was shown by FTIR spectroscopy of the product; 1H-NMR spectroscopy indicates that the grafts consist of single succinic anhydride units. The graft content was determined by nonaqueous titration, and the extent of crosslinking inferred from the melt flow rates (MFR) of the products. The effects of concentration of initiator, MAn, and PE on the graft content were determined; the influence of PE structure, reaction time, and temperature was also studied. Melt blending of the grafted PE with polystyrene containing oxazoline functional groups (OPS) was investigated using a Rheomix mixer. The interpolymer reaction which occurs during blending was studied by means of FTIR, and the morphology of the blends by scanning electron microscopy (SEM). Information was also gained from the change in torque viscosity during the blending process.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 0730-6679
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Blending of immiscible polymers offers attractive opportunities for developing new materials with useful combinations of properties. However, simple blends often have poor mechanical properties and unstable morphologies. Compatibilization of such blends is necessary. Preformed graft or block copolymers have been traditionally added to act as compatibilizers. Another route, however, is to generate these copolymer compatibilizers in situ during melt blending using functionalized polymers. In this review, a variety of reactive polymers that have been utilized in the reactive compatibilization of polymer blends is examined. They are classified into six major categories according to the types of reactive groups they have, namely, maleic anhydride, carboxylic acids, carboxylic acid derivatives, primary and secondary amines, hydroxyl and epoxide, and reactive groups capable of ionic bonding. Their preparation methods and applications and the chemical reactions they undergo during melt blending are presented. © 1992 John Wiley & Sons, Inc.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...