摘要:

AbstractSynthesis and properties of urethane elastomer‐modified epoxy resins were studied. The urethane elastomer‐modified epoxy resins were synthesized by the reaction of a 4‐cresol type epoxy compound having hydroxymethyl groups (EPCDA) with isocyanate prepolymer. The structure was identified by IR,1H NMR and GPC. These epoxy resins (EPCDATDI) were mixed with a commercial epoxy resin (DGEBA) in various ratios. The mixed epoxy resins were cured with a mixture of 4,4′‐diaminodiphenylmethane and 3‐phenylenediamine (molar ratio 6:4) as a hardener. The curing behaviour of these epoxy resins was studied by DSC. The higher the concentration of EPCDATDI, the higher the onset temperature and the smaller the rate constant (k) of the exothermic cure reaction were. It was considered that the ratio of hydroxymethyl group to epoxide group was very small and the molecular weight of EPCDATDI was large. Therefore, the accelerating effect of the hydroxymethyl group on the epoxide–amine reaction was cancelled by the retardant effect of increased molecular weight and viscosity, and decreased molecular motion. Toughness was estimated by Izod impact strength and fracture toughness (K1C). On addition of 10 wt% EPCDATDI with low molecular weight (M̄n6710, estimated by GPC using polystyrene standard samples), Izod impact strength andK1Cincreased by 70% and 60%, respectively, compared with unmodified epoxy resin. Glass transition temperatures (Tg) for the cured epoxy resins mixed with EPCDATDI measured by dynamic mechanical spectrometry were the same as those of unmodified epoxy resin. The storage modulus (E′) at room temperature decreased with increasing concentration of EPCDATDI. Toughness and dynamic mechnical behaviour of cured epoxy resin systems were studied based o

ISSN:0959-8103    

DOI:10.1002/pi.1994.210330111

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractNatural rubber materials reinforced with cellulose fibres have been studied with respect to crosslink density, tensile strength and stress relaxation. The fibres have been grafted with butadiene or divinylbenzene by plasma treatment. Chemiluminescence analysis was used to indicate the grafting on the surface of the cellulose fibres and also to estimate the effect of the plasma on the cellulose fibres. The results indicate the possibility of obtaining a surface layer on the fibres, which is a conceivable way of improving the mechanical properties of rubber composites.

ISSN:0959-8103    

DOI:10.1002/pi.1994.210330112

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractCopolymers of ethylene with propylene, butene‐1 and hexene‐1 were prepared using a titanium–magnesium (TMC) or a vanadium–magnesium catalyst (VMC). The copolymers were examined for thermal stability by TGA, melting and crystallization behaviour by DSC and crystallinity by XRD. Fractionated samples of ethylene–hexene‐1 copolymers were also similarly characterized. Results indicate that VMC produces copolymers with a higher degree of crystallinity and greater compositional homogenei

ISSN:0959-8103    

DOI:10.1002/pi.1994.210330113

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

ISSN:0959-8103    

DOI:10.1002/pi.1994.210330116

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

ISSN:0959-8103    

DOI:10.1002/pi.1994.210330117

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

ISSN:0959-8103    

DOI:10.1002/pi.1994.210330121

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

ISSN:0959-8103    

DOI:10.1002/pi.1994.210330122

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY