摘要:

AbstractThe synthesis is reported of a new photochromic monomer,trans‐4‐(2‐methacryloxyethyloxy) azobenzene (MEAB), where the azobenzene chromophore is separated from the ester group by an ethylenoxy spacer arm. Comparative experiments show thattrans‐4‐methacryloxyazobenzene (MAB), having the azobenzene group directly attached to the ester functionality, does not homopolymerize or copolymerize with (−)‐menthyl methacrylate (MnMA) in the presence of different anionic initiators, whereas isotactic homopolymers and copolymers of MEAB can be obtained: the microstructure is described with reference to analogous atactic m

ISSN:1042-7147    

DOI:10.1002/pat.1991.220020101

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe radiation resistance of a series of aromatic polysulfones comprising alternating units of diphenyl sulfone and various aromatic diols has been investigated by measuring volatile products, soluble fractions and electron spin resonance (ESR) spectra. The yields of radicals at 77 K observed by ESR and of SO2at 423 K have indicated that biphenol gives enhanced resistance to Y radiation, and tetramethyl bisphenol‐A decreased resistance, relative to bisphenol‐A, bisphenol‐S and hydroquinone. The protective effect of bisphenol was confirmed by lower scission and crosslinking yields determined from the soluble fractions after high

ISSN:1042-7147    

DOI:10.1002/pat.1991.220020102

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractPhotopolymerization of multifunctional acrylic monomers using excimer and Nd: YAG lasers operated at five different UV wavelengths is reported. The effects of different wavelengths on the surface and bulk cure both in air and under argon are investigated and discussed.

ISSN:1042-7147    

DOI:10.1002/pat.1991.220020103

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractBlends containing two, wholly aromatic, naphthalene‐based liquid crystalline polymers (LCPs) are studied. Experimental results show that the viscosities of the resulting blends are lower than the parent LCPs over the entire shear‐rate range investigated. The orientation development following capillary flow demonstrates, that over a defined blend composition range, some blends have higher orientability than the constituent polymers. This is further manifested in the tensile and flexural properties of injection‐molded specimens. A detailed analysis indicates that in the composition range where synergistic effects are observed in orientation development as well as in mechanical properties, only one glass transition temperature is detected. This suggests that “miscibility” is desirable for obtaining maximum properties in these blen

ISSN:1042-7147    

DOI:10.1002/pat.1991.220020104

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe structure and properties of dynamically cured ethylene‐propylene‐diene terpolymer (EPDM) and ionomer blends have been studied. The blends were prepared in a laboratory internal mixer, where EPDM was cured under shear in the presence of ionomer with dicumyl peroxide (DCP) under different shear conditions. The effects of EPDM/ionomer compositions, DCP concentration and the intensity of shear mixing were investigated using capillary rheometer, differential scanning calorimeter (DSC) and scanning electron microscopy (SEM) techniques. Two kinds of poly(ethylene‐co‐methacrylic acid) ionomers containing different metal ions(Na+and Zn++) were compared and the effect of the metal ion type for neutralization was considered. The Zn‐neutralized ionomer showed better miscibility with EPDM than the Na‐neutralized ionomer. It is concluded from the rheological properties, crystallization behavior and morphology that the dynamically cured EPDM and Zn‐ion ionomer blends show the behavior of a thermoplastic interpenetrating polymer

ISSN:1042-7147    

DOI:10.1002/pat.1991.220020105

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractIn order to study the tensile properties of solvolysis lignin polyurethanes, polyurethane (PU) films were prepared from the solvolysis lignin (SL)–polyethylene glycol (PEG)–diphenylmethane diisocyanate (MDI) system, and in addition to this further PU films were also prepared from the SL–MDI system. In the SL–PEG‐MDI system, the SL content, the molecular weight of PEG and the NCO:OH ratio were varied in order to control the physical properties. The tensile stress and Young's modulus of the PUs of the SL–PEG–MDI type increased with increasing SL content and NCO:OH ratio. The tensile properties of the PUs from the SL–MDI system showed no NCO:OH ratio dependency; i.e. the mechanical properties of PUs are not influenced by the change in crosslinking. It is possible to control the tensile properties of PUs of the SL–PEG–MDI type by changing the content of PEG and SL at a co

ISSN:1042-7147    

DOI:10.1002/pat.1991.220020106

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe shape of the glass transition plays a critical role in the engineering performance of polymers in sound and vibration damping, as well as other applications. The transition may be affected by fillers, plasticizers, blending, IPN formation, etc. A collection of data, both original and literature, is presented which illustrates how the phenomenon works. Emphasis is placed on the role of the area under the linear loss modulus–temperature curve, which may be evaluated in a fashion similar to other spectroscopic techniques. In addition, the loss area can be significantly affected by morphological factor

ISSN:1042-7147    

DOI:10.1002/pat.1991.220020107

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY