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  • Polymer and Materials Science  (47)
  • Physics  (6)
  • Photoinitated lamination  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Materials research innovations 2 (1998), S. 64-71 
    ISSN: 1433-075X
    Keywords: Key words Photocrosslinking ; Surface photografting ; Photoinitated lamination ; Polymer sheets ; films ; filament and yarns ; Polyolefins ; polyesters and polyamides ; Functional vinyl monomers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Based on extensive studies of photoinitiated reactions of synthetic polymers, processes for modification of sheets, films, filaments and yarn have been invented and developed. Using ultra violet irradiation, photocrosslinking of polyethylene melts as a continuous process on line with an extruder has been invented. Effective photocrosslinking has also been obtained for ethylene-propylene-diene (EPDM) elastomers and ultra high strength fibers of high density polyethylene (HDPE). A continuous process for surface modification of polymers by surface photografting has been invented and applied to strips of film, filaments and yarns. The inert surface of polyolefins, polyesters and polyamids, grafted with functional vinyl monomers, show decreased contact angle with water, increased adsorption of dyes and increased adhesion to other polymers. Photoinitiated lamination of polymer films and sheets has been invented and developed as a ”bulk surface photografting process”. Two or more films and sheets are interdispersed with reactive layers of monomer and initiator and then bonded together by photoinitiated grafting with ultraviolet irradiation. The crosslinked network formed is grafted to two adjacent polymer surfaces. This gives laminates of high lamination strength, high barrier properties, and promising commercial applications.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 199 (1992), S. 33-44 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Hochfeste Polyethylen- (HSPE), Polypropylen- (PP), Polyethylenterephthalat-(PET) und Polyvinylalkohol-(PVA) Textilgarne wurden unter Anwendung des entwickelten kontinuierlichen Einweichprozesses mit verschiedenen funktionellen Monomeren, wie beispielsweise Acrylsäure (AA), Acrylamid (AM), Glycidylacrylat (GA) und 4-Vinylpyridin (VP) oberflächenfotogepfropft. Die Einfärbbarkeit der oberflächenmodifizierten Garne mit verschiedenen Textilfarbstoffen wurde untersucht. Im allgemeinen wurde eine erhebliche Verbesserung der Einfärbbarkeit beobachtet. Die Farbstoffaufnahme der oberflächenfotogepfropften Fasern wird von vielen Faktoren beeinflußt, beispielsweise von der Art der Faser, der Menge und den Eigenschaften des auf die Oberfläche der Fasern gepfropften funktionellen Monomeren, der Art des Textilfarbstoffs usw. Die Faseroberflächen, auf die ein Monomeres mit basischen Gruppen wie Acrylamid und 4-Vinylpyridin gepfropft wurde, lassen sich mit einem sauren Farbstoff wirkungsvoll einfärben. Dagegen läßt sich eine Faseroberfläche, auf die ein saures funktionelles Monomeres gepfropft wurde, leicht mit basischen Farbstoffen in tiefen Farbtönen einfärben. Die Farbstoffaufnahme steigt stetig mit zunehmender Pfropfung, in ESCA-Spectren als relative Intensitaten relevanter Linien gemessen. Die nicht gepfropften HSPE-, PP-, und PET-Fasern können mit bestimmten Farbstoffen in gewissem Maße eingefärbt werden. Bei der vorliegenden Arbeit erhöhte sich die Farbstoffaufnahme bei HSPE-Fasern, die mit GA gepfropft und mit dem Metallkomplexfarbstoff IO eingefärbt wurden, um das 3,4fache, bei PP-Fasern, die mit AA gepfropft und mit dem basischen Farbstoff MB eingefärbt wurden, um das 7,9fache, bei PET mit AM und dem Direktfarbstoff SL um das 6,1fache, bei PVA mit VP und dem sauren Farbstoff TE um das 15,3fache.
    Notes: High-strength polyethylene (HSPE), polypropylene (PP), poly(ethylene terephthalate) (PET), and poly(vinyl alcohol) (PVA) textile yarns have been surface-photografted with various functional monomers, such as acrylic acid (AA), acrylamide (AM), glycidyl acrylate (GA) and 4-vinyl pyridine (VP), by means of the continuous presoaking process developed. The dyeing of these surface-modified yarns with various textile dyes has been investigated. In general, considerable improvements of dyeability have been observed. The dye adsorption of the surface-photografted fibers is influenced by many factors, such as type of fiber, amount and properties of the functional monomer grafted on the surface of the fibers, type of textile dye, etc. The fibers surface-grafted with a monomer containing basic groups, such as acrylamide and 4-vinyl pyridine, are efficiently dyed with an acid dye. Conversely, a fiber surface-grafted with acidic functional monomer is easily dyed to deep shades with basic dyes. The dye adsorption increases monotonically with increasing grafting measured in ESCA spectra as relative intensities of relevant lines. The ungrafted HSPE, PP and PET fibers can be dyed to some extent with certain dyes. In the present work, the dye adsorption increased by 3.4 times for HSPE fiber grafted with GA and dyed with the metal complex dye IO, by 7.9 times for PP fiber grafted with AA and dyed with the basic dye MB, by 6.1 times for PET with AM and with the direct dye SL, and by about 15.3 times for PVA with VP and with the acid dye TE.
    Additional Material: 1 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 195 (1992), S. 17-33 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die photoinitiierte Oberflächen-Pfropfung von Acrylmonomeren auf hochfeste Polyethylen-Fasern (HSPE-Fasern) wurde in einem kontinuierlichen Prozeß durchgeführt. Die Pfropfreaktion wurde durch UV-Bestrahlung der Fasern initiiert, nachdem diese mit einer Lösung des Photoinitiators und des Monomeren in Aceton vorimprägniert worden waren. Es wurden vier Initiatoren, Benzophenon (BP), 4-Chlorbenzophenon (CCBP), 2-Cyclohexyl-2-hydroxyacetophenon (HHA) und 2,2-Dimethoxy-2-phenylacetophenon (DMPA), sowie die zwei Monomeren Acrylsäure (AA) und Acrylamid (AM) untersucht. Bereits nach kurzer Bestrahlungszeit (10 bis 20 s) konnte eine erfolgreiche Pfropfung mittels ESCA und IR-ATR sowie anhand von Farbstoffadsorption aus wäßriger Lösung und Adhäsions-Versuchen an Epoxidharz mit Einzelfasern nachgewiesen werden. Mit AA als Monomerem konnte eine Pfropfausbeute von 74% erreicht werden (26% Homopolymer). Zugfestigkeit und Modul der HSPE-Fasern wurden durch die Pfropfung nicht verändert. Der Oberflächen-Pfropfungsgrad hängt im wesentlichen von Struktur und Reaktivität des Monomeren und des Photoinitiators in der Vorimprägnierungslösung und von den Bestrahlungsbedingungen ab. Durch Verlängerung der Bestrahlungszeit konnte die Menge an aufgepfropftem Polymerem bis zu einem bestimmten Grenzwert gesteigert werden. Der Vergleich der vier untersuchten Photoinitiatoren zeigte die größte Pfropfausbeute von AA mit BP und von AM mit 4-CBP. Mit AA gepfropfte HSPE-Fasern konnten durch Eintauchen in eine wäßrige Kristallviolett-Lösung um bis zu siebenfach stärker eingefärbt werden, als dies ohne Pfropfung möglich ist. Auch die Adhäsion an Epoxidharz konnte durch die Pfropfung um das fünffache gesteigert werden.
    Notes: Photoinitiated surface grafting of acrylic monomers has been carried out onto high strength polyethylene (HSPE) yarn by means of a continuous process. The grafting reaction is initiated by UV irradiation of the yarn after presoaking in an acetone solution of initiator and monomer. Four initiators, benzophenone (BP), 4-chlorobenzophenone (4-CBP), 2-hydroxy-2-cyclohexylacetophenone (HHA), and 2,2-dimethoxy-2-phenylacetophenone (DMPA), and two monomers, acrylic acid (AA) and acrylamide (AM), have been used. After short irradiation time (10 to 20 s) successful grafting is obtained, as shown by ESCA and IR-ATR spectra, dye adsorpotion from aqueous solution, and measurements of adhesion of single filaments to epoxy resin. Grafting efficiency of 74% has been reached for AA as monomer (26% is homopolymer). The tensile strength and modulus of the HSPE yarn are retained in the grafting process. The degree of surface grafting is mainly a function of structure and concentration of monomer and photoinitiator in the presoaking solution and of the irradiation conditions used. Increasing irradiation time gives increasing amounts of grafted polymer up to a certain limiting value. The reactivities of the four initiators have been compared showing the highest grafting yields of AA with BP and of AM with 4-CBP as photoinitiator. AA grafted HSPE yarn can be dyed to rather deep color by dipping in an aqueous solution of Crystal Violet. Increased dye absorption by a factor of up to seven has been measured for yarn grafted with AA to the maximum level obtained. The filaments of the grafted yarn show increased adhesion to epoxy resin by a factor of up to five compared with the ungrafted filaments.
    Additional Material: 11 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 196 (1992), S. 113-125 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die lichtinduzierte Oberflächenpfropfung von Acrylsäure (AA), Acrylamid (AM) und 4-Vinylpyridin (VP) auf Polyethylenterephthalatfasern (PET) (handelsübliches Garn) mit Benzophenon (BP) als Initiator nach einem bereits beschriebenen, kontinuierlichen Verfahren, bestehend aus der Imprägnierung der Fasern mit einer Lösung aus Initiator und Monomerem in Aceton und anschließender UV-Belichtung, wurde untersucht. Die auf der Faseroberfläche gebildeten Pfropfcopolymeren wurden mittels ESCA, Titration der Carboxygruppen (gepfropfte AA) und Farbstoffadsorption charakterisiert. Dabei dienten die relativen ESCA-Intensitäten (RI) O1s/C1s und N1s/C1s als Maß für die Pfropfung von AA, AM und VP, unter Berücksichtigung der Intensitäten der ungepfropften Fasern. Für AA stiegen die RI-Werte von 32,8% (Blindprobe) auf 48,6% nach 20 h Bestrahlung. Die titrimetrisch bestimmte Konzentration der Carboxygruppen stieg von 0,045 auf 0,106 mmol/m2. Unter der Annahme einer gleichmäßigen Pfropfcopolymerschicht ergibt sich daraus eine Beschichtungsdicke von 4,8 nm. Nach der Pfropfung stieg die Adsorption von Kristallviolett (CV) aus wäßriger Lösung um etwa das Dreifache. Für AM stiegen die RI-Werte von 2,6 (Blindprobe) auf 14,8% und die Adsorption des Direktfarbstoffs Sirius Lichtbordo B-LL um etwa das Sechsfache. Für VP stiegen die RI-Werte von 2,6 (Blindprobe) auf 5,1% und die Adsorption des Direktfarbstoffs um etwa das Vierfache.
    Notes: Photoinitiated surface grafting of acrylic acid (AA), acrylamide (AM) and 4-vinyl pyridine (VP) onto poly(ethylene terephthalate) (PET) fibers (a commercial textile yarn) has been studied using benzophenone (BP) as photoinitiator. A continuous process as previously described has been applied, which involves presoaking of the PET yarn in a solution of initiator and monomer in acetone and UV irradiation in nitrogen atmosphere. The resulting grafted polymer on the fiber surface has been analyzed by ESCA, titration of carboxy groups (grafted AA), and dye absorption. The relative ESCA intensities (RI) of O1s/C1s and N1s/C1s are used as measure for grafted AA, AM and VP, respectively, after recording the RI-values for ungrafted fibers. For grafting with AA, the RI-values increased from 32.8% (background) to 48.6% after 20 s irradiation time. The amount of carboxy groups measured by titration increased from 0.045 to 0.106 mmol/m2. Assuming an even coverage of grafted AA polymer, this means a grafted layer of 4.8 nm thickness. After grafting, the adsorption of the dye Crystal Violet (CV) from aqueous solution increased by about 3 times. With AM as monomer, the RI-values increased from 2.6 (background) to 14.8% and the adsorption of a direct dye Sirius Lichtbordo B-LL increased by about 6 times. With VP as grafted monomer, the RI-values increased from about 2.6 (background) to 5.1% and the adsorption of the direct dye increased by about 4 times.
    Additional Material: 10 Ill.
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  • 5
    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 effect of reaction conditions on the composition of native potato starch-polyacrylonitrile graft copolymers initiated by manganic pyrophosphate onto starch slurries at 30°C has been examined. In general, when the Mn3+ ion concentration was increased from 0.15 × 10-3M to 3.0 × 10-3M (other conditions kept constant), an increase in conversion of monomer to polymer and % add-on was observed, whereas frequency of grafts (anhydroglucose units, AGU, per grafted chain) decreased. Also, the average molecular weights of grafts showed a decrease from 2.2 × 105 to 1.5 × 105. Increasing the concentration ratio of starch to monomer during polymerization by a factor of 3 produced an increase in the conversion of monomer to polymer, whereas an increase in frequency of grafts (AGU/chain) was obtained. Values of % add-on and average molecular weights of the grafts showed, however, a decreasing tendency. It was observed that grafting onto starch took place readily even at acid additions as low as 10 × 10-3M H2SO4 (pH ≃1.8). Selective solvent extraction of homopolymer and extremely low conversions of monomer to polymer (0.1%-1.5%) in duplicate runs without addition of starch indicated that grafting efficiencies were high in all cases. An attempt has been made to interpret the results in terms of variations in factors such as initial ratio of (Mn3+)/(AGU), termination rate of acrylonitrile chain radicals by oxidation by Mn3+ ions, oxidation rate of radicals formed on anhydroglucose units by Mn3+ ions, and physical factors such as diffusion rate of Mn3+ ions through the polyacrylonitrile-grafted starch granules for terminating the radicals.
    Additional Material: 4 Ill.
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  • 6
    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: A new sulfonation method using phase transfer catalysts was applied to sulfonate a number of polymer matrices in an aqueous two-phase system. The polymer matrices included in this study are (1) styrene (Sty) and acrylonitrile (AN) copolymers with glycidyl methacrylate (GMA), (2) graft copolymers of cellulose with GMA, and (3) polystyrene and polyacrylate gels containing GMA as comonomer. The presence of polar groups such as AN in the polymer matrix makes the sulfonation easier. For cellulose graft copolymers, the extent of sulfonation was not much affected by the phase transfer catalysts, presumably due to the high polarity and high water uptake capacity of the cellulose base. For other polymer gels, the following factors influence the extent of sulfonation: (1) the method of gel synthesis, i.e., gels synthesized by delayed addition of GMA give a higher degree of sulfonation; (2) the nature of the crosslinking agent, i.e., gels with ethylene glycol diacrylate (EGDA) gives a higher degree of sulfonation than gels with divinylbenzene (DVB); (3) the pore size of the gels, i.e., gels with larger pore sizes gave higher degree of sulfonation; (4) increasing polarity of the backbone structure of gels favors increased sulfonation, e.g., MMA-GMA-EGDA gels give 54% sulfonation, whereas Sty-GME-EGDA gives only 38%.
    Additional Material: 6 Tab.
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  • 7
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 4077-4086 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some properties of photocrosslinked high density polyethylene (2 mm thick sheets) have been studied. The homogeneity of the network is greatly improved by the application of triallylcyanurate (TAC) as crosslinking agent. The role of TAC in promoting the crosslinking is discussed. The crosslinked PE is found to be durable towards immersion in boiling water. Oxygen permeability increases while density and melting point decrease with increasing degree of crosslinking. The network chain density is obtained using conventional swelling method in boiling xylene, which together with data from melting point depression show that contribution of chain entanglement is insignificant to the gel formation of PE in this work.
    Additional Material: 6 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 4051-4075 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High density polyethylene has been photocrosslinked in the melt by using 4-chlorobenzophenone (4-CBP) as photoinitiator and triallylcyanurate (TAC) as crosslinking agent. Various factors affecting the crosslinking process (photoinitiator used and its concentration, irradiation temperature and time, atmosphere, UV light source, light intensity) were examined. By optimizing the irradiation conditions, it was found that samples up to 2 mm thick could readily be crosslinked to high gel content (≈ 90%) with satisfactory homogeneity within very short irradiation times (≈ 15 s). The kinetic analysis of the crosslinking process showed a linear relation between log S and log t (S is the sol fraction t is the irradiation time). An induction period was observed, the length of which decreased with increasing concentration of 4-CBP and increasing light intensity. An upper limit of gel content was also found for long irradiation times at a level depending on the concentration of 4-CBP. The crosslinking rate was proportional to the second order of light intensity at lower intensity and changed to first order at higher light intensity. A mechanism based on the recombination of chain radicals through both allyl and alkyl type radicals of TAC was proposed.
    Additional Material: 22 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 1847-1859 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal oxidative stability of photocrosslinked high density polyethylene was studied. The relative effectiveness of various antioxidants (hindered phenols and amines, aromatic amine, organic sulfides, and phosphites) was examined by comparing the oxidation induction time (OIT) which was measured using differential scanning calorimetry. Hindered phenol antioxidants were found to be most effective. At an antioxidant concentration of 0.20 wt % which gave an OIT value of 20 min at 200°C, the photocrosslinking rate was decreased only to a limited extent as evidenced by a small drop in gel content. However, the efficiency of the antioxidants as stabilizers decreased to a considerable extent after the photocrosslinking process. Serious surface deterioration was found which was ascribed to depletion of antioxidant at the surface mainly due to high rate of oxidation and evaporation.
    Additional Material: 4 Ill.
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  • 10
    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: A process has been developed for continuous photoinitiated graft copolymerization of acrylamide (AM) and acrylic acid (AA) onto the surface of high-density polyethylene (HDPE) tape film, presoaked in a solution containing monomer and initiator under nitrogen atmosphere. As photoinitiator we have used benzophenone, which is efficient for photografting of polyolefins with acrylic monomers. The presoaking procedure of the tape film is very important for efficient photografting within short irradiation times. In ESCA spectra of the grafted tape film the relative intensity of the nitrogen over carbon peaks of film grafted with acrylamide is about 5-10% after 6 s irradiation time. The relative intensity of oxygen over carbon peaks in ESCA spectra of film grafted with acrylic acid is about 10-20% after 8 s irradiation time. The effects of varying the monomer concentration in presoaking solution and the different irradiation conditions on the grafting yield have been investigated. This technique has the advantages of being a continuous process with short irradiation times without requirements of vacuum conditions and appears to be promising for practical applications.
    Additional Material: 11 Ill.
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