摘要:

AbstractLa photo‐oxydation d'élastomères de type poly[éthylène‐co‐propène‐co‐(1,4‐hexadiène)] (EPDM) et de type poly(éthylène‐co‐propène) (EPM) photosensibilisés avec différents dérivés alcoxylés de phényl acétophénone: 2,3 diméthoxy (DMPA), 2‐méthoxy (MPA), 2‐éthoxy (EPA), à l'état de mélange a été étudiée dans le but de préciser la nature des mécanismes primaires de transfert d'énergie et d'amorçage radicalaire ainsi que le mode de développement des principales réactions d'oxydation dans un milieu hétérogène où les valeurs des rendements quantiques sont difficilement accessibles. Par analogie avec des systèmes modèles précédemment étudiés, l'importance du rôle joué par les fonctions hydroperoxydes et les photoproduits issus de la dégradation du photo‐amorceur, a été mise en valeur. La photoréticulation des échantillons irradiés apparaît faire partie intégrante du processus général de photooxyda

ISSN:0003-3146    

DOI:10.1002/apmc.1987.051490101

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractUne étude de la photo‐oxydation d'élastomères de type poly[éthyléne‐co‐propéne‐co‐(1,4‐hexadiéne)] (EPDM) et poly(éthyléne‐co‐propéne) (EPM) amorçée dans le proche UV‐visible par la benzophénone (BP) et quelquns de ses dérivés parasubstitués (4‐méthoxy‐BP, 4‐chloro‐BP) a permis l'élaboration d'un schéma réactionnel détaillé. Le comportement photochimique des photo‐amorçeurs dans les milieux élastomère est décrit avec précision (nature et quantité des photoproduits formés) grâce à l'emploi d'une méthode originale de dosage spectrométrique IR. Les processus réactionnels prépondérants sont mis en valeur ainsi que leur dépendance vis à vis d'une part, des propriétés spécifiques du photo‐amorçeur et d'au

ISSN:0003-3146    

DOI:10.1002/apmc.1987.051490102

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractLa photo‐oxydation à λ = 313 nm d'un poly[éthyléne‐co‐propéne‐co‐(1,4‐hexadiéne)] (EPDM) greffé contenant en faible quantité des motifs benzophénone, a été étudiée en calculant les rendements quantiques des réactions observées. Il ressort de la comparaison avec les systèmes mélangés que le greffage du photosensibilisateur favorise plus nettement la formation des produits d'oxydation et des coupures de chaînes que la réticulation. Une deuxième comparaison avec un autre système greffé — un EPDM phénylé — permet de montrer que la propagation des hydroperoxydes inactifs dépend fortement de la nature

ISSN:0003-3146    

DOI:10.1002/apmc.1987.051490103

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractThe morphology of polybutadiene grafted in emulsion with vinylchloride, methylmethacrylate, styrene, was examined by transmission electron microscopy. The morphology depends on synthesis conditions. Solubility of initiators in the monomers or in water, diffusivity of monomers in the rubber and transfer mechanism during the polymerization were found to be important factors in determining the morphology. New experimental data of diffusion coefficients of the monomers in polybutadiene are given. A special technique was used for liquid VC diffusivity measurements.

ISSN:0003-3146    

DOI:10.1002/apmc.1987.051490104

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractX‐ray diffraction, thermomechanical and thermogravimetric studies on polyacrylonitrile (PAN), poly(acrylonitrile‐co‐vinyl‐tris(methoxyethoxy)silane) (poly(AN‐co‐VTMES)), poly(acrylonitrile‐co‐vinyltriethoxysilane) (poly(AN‐co‐VTES)), and poly(acrylonitrile‐co‐methylmethacryloyloxypropyltrimethoxysilane) (poly(AN‐co‐MPTMS)) have been made for investigating their structure. The thermomechanical analysis results revealed that the glass transition temperature (Tg) for the copolymers are lower than for PAN. The lowering of Tgin poly(AN‐co‐MPTMS) is more significant than those of poly(AN‐co‐VTES) and poly(AN‐co‐VTMES). The incorporation of silane comonomers in the copolymer resulted in the reduction of crystallinity but the crystalline lattice was not disturbed, what is suggested to be due to the location of the silane containing segments in the amorphous region. Thermal stabi

ISSN:0003-3146    

DOI:10.1002/apmc.1987.051490105

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractRadiation grafting of acrylic acid (AAc) onto poly(4‐methylpentene‐1) (TPX) with different crystallinity has been investigated under various conditions. Free radicals formed by pre‐irradiation of TPX in vacuum were more stable than those in the presence of air and might initiate the grafting reaction if come in contact with the AAc. Grafting yields increased with increasing preirradiation dose, grafting temperature, and concentration of AAc. Lower crystalline TPX (24%) showed a higher initial grafting rate compared with higher crystalline one. The distribution of grafting was observed by X‐ray microanalyzer. The grafting reaction proceeded gradually with time from the surface of the film to the inner part. In high crystalline TPX (34%) the grafting distribution in the final stage depended on the film thickness, while in lower crystalline TPX it was homogeneous regardless the film th

ISSN:0003-3146    

DOI:10.1002/apmc.1987.051490106

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractA method of enzyme immobilization by graft copolymerization onto alginic acid is reported. Glycidylmethacrylate along with methyl methacrylate was used as a vinylating reagent. The enzyme trypsin has been chosen for our studies. The effects of various parameters such as pH optima, temperature optima, pH stability, thermal stability, storage stability, and re‐usability were studie

ISSN:0003-3146    

DOI:10.1002/apmc.1987.051490107

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractLiquid prepolyurethanes (PPU) were obtained from castor oil and toluene‐2,4‐diisocyanate under different experimental conditions varying NCO/OH ratio. All these prepolyurethanes were subsequently interpenetrating with poly(methyl methacrylate) made by radical polymerization initiated with benzoyl peroxide. The novel PPU/PMMA interpenetrating polymer networks were obtained as though films by transfer moulding. They were characterized by thermal studies (DSC and TGA) and mechanical properties viz., tensile strength, modulus of elasticity, and percent elongation at break. The morphological behaviour was analyzed by scanning electron microsc

ISSN:0003-3146    

DOI:10.1002/apmc.1987.051490108

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractIn various samples of the industrially used antiozonant N‐isopropyl‐N′‐phenyl‐1,4‐phenylenediamine (IPPD, Ib), a typical, intensively coloured impurity was detected, and its structure was determined (IIb). The same compound IIb was prepared independently by an acid catalyzed reaction of 4‐aminodiphenylamine (IV) with N‐isopropyl‐N′‐phenyl‐1,4‐benzoquinonediimine (IIIb). IIb is formed by the same route also in technical IPPD, both in the production process and during storage. In the autoxidation of squalene (rubber model) IIb behaves as an effective antioxidant. The simultaneous presence of IPPD does not produce any antagonistic effect. IIa, which is an analogous impurity of technical N‐(1,3‐dimethylbutyl)‐N′‐phenyl‐1,4‐phenylene‐diamine (HPPD, Ia), behaves as an antioxidant similar to IIb. Thus, with respect to the antioxidant effect, the presence of impurities IIa or IIb

ISSN:0003-3146    

DOI:10.1002/apmc.1987.051490109

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractEpoxy resins from epichlorohydrin and bisphenol A have been fractionated in various binary solvent/nonsolvent systems. Low molecular weight (M ⋍ 400) and higher molecular weight (M ⋍ 1000) resins were fractionated using solvent/nonsolvent pairs in a wide range of polarities. Two solvent‐derived parameters: total solubility parameter δTand polarity index P′ have been applied to correlated experimental data. An empirical solubility diagram in coordinates P′ = f(δT) prepared on the basis of phase separation experiments, makes it possible to predict whether other solvent/nonsolvent pairs will work as efficient systems for epoxy resin fractionation. Two areas of solvent/nonsolvent parameters have been found for efficient epoxy resin fractionation: the first δT⋍ 15.4–19.0 MPa1/2; P′ ⋍ 0.4−2.8 and the second of δT∼ 19.5, P′ ∼ 6.0. In addition, the fractional precipitation of epoxy resins permits an evaluation of δTand P′ range of the resin for

ISSN:0003-3146    

DOI:10.1002/apmc.1987.051490110

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY