摘要:

AbstractThe plastic deformation mechanism operating in polymer glasses is analyzed. The whole process consists of two main stages: nucleation of special shear defects, called PSTs (plastic shear transformations), and their disappearance. The important feature of plastic deformation of glasses is the storage of a large amount of internal energy ΔUdefupon straining. Such energy storage is the critical issue for mechanical performance of polymeric material: if the amount of stored energy is high, the appearance of macroscopic failure is very probable while glassy materials collecting a small amount of stored deformation energy are quite ductile. It is proposed that the rate of disappearance of PSTs is a key factor in dissipation of stored deformation energy. A parameter describing the dissipation ability of material upon deformation is introduced

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060101

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractPolymers have been in use for a long time as passive materials for components in electronics and electrooptics. They combine the possibility of easy processing with an infinite potential of functionalization. They can be conductors or semiconductors, ferroelectrics and can exhibit interesting properties such as photoconductivity, piezo, pyroelectricity or nonlinear optical properties. As a consequence they are now used for merging active components in the field of electrooptics such as displays, sensors or modulators for optical signal treatment.This paper describes the properties and applications of some recent polymers in the field of electroptics.In the first part of this paper the properties of amorphous copolymers with a pending group with large hyperpolarizability are described. These amorphous copolymers show high optical nonlinear coefficients after poling under an electric field. We have used these copolymers for the manufacture of an electrooptic modulator working at 1.3 μm at a frequency of 1 GHz.The second part deals with ferroelectric polymers and their pyroelectric properties. The realization and performance of an IR pyroelectric sensor using copolymers of polyvinylidene fluoride–ethylene trifluride are described. Some new results concerning polymersdispersed liquid crystals are also describ

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060102

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper describes reviews about the characterization of optical and electronic (opto‐electronic) organic materials including polymers, and their applications for advanced key devices used for computers and communications technologies. On the basis of the author's recent investigations, discussions are made on organic electroluminescent thin film materials for emissive display devices, polymer‐dispersed liquid crystal materials for passive display devices, organic photo‐conductive materials for electrophotographic printer devices, and highly electroconductive polymers for solid tantalum capacitors. Finally, technical issues and development prospects for the opto‐electronic organic materials in the 21st century are su

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060103

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractA series of copolymer blends have been prepared using a poly(ether urethane) and a poly(siloxane–urea–urethane). The copolymers were prepared by a hardsegment first, two‐step polymerization method. The hard segments of the copolymers were derived from isophorone diisocyanate (IP) and 1,4‐benzenedimethanol (B), and the soft segments were based on polytetrahydrofuran (PTMO, Mw= 2000), and polydimethylsiloxane (PDMS, Mw=27,000), respectively. The siloxanecontaining copolymer, PDMS27K‐IP‐B2 (2 moles diol chain extender/mole PDMS27K), was used as the minor component (1.6, 2.5 and 6.0 wt%) in a series of blends. These blends were found to preserve the mechanical properties of the poly(ether–urethane) as well as the surface properties of the poly(siloxane

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060104

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractIn this review paper the photoresponsiveness of photochromic macromolecules under different structural and environmental conditions is discussed with reference to results from the authors' laboratories. Polypeptides, in particular poly(L‐glutamic acid) and poly(L‐lysine), with spirobenzopyrane side chains show photoinduced conformational variations which are amplified by addition of organic acids or bases to hexafluoro‐2‐propanol (HFP) solutions. Thus combination of light and environment effects allows modulation of order–disorder conformational transitions.Such photoindiced conformational changes are not observed in the case of macromolecules with a hydrocarbon main chain and azobenzene or stilbene side chains, obtained by polymerization of acrylic monomers. However, even in these systems structural variations affect the dependence of optical properties on irradiation. Moreover, the combination of organic solvents and water shows that polymer solubility can be modulated

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060105

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractMorphology and electro‐optic properties of composite films composed of phenoxy and nematic liquid crystal (LC) have been studied at a film composition of 40/60 (polymer/LC by weight). Effects of temperature, frequency and voltage of applied a. c. electric field on the transmittance and response time of the films were measure

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060106

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractPolystyrene with different degrees of sulfonation was empolyed as a polymeric dopant for polyaniline. The purpose of using a polymeric dopant is to avoid the migration of a small molecule dopant to increase stability of the doped complex. We applied the polymeric dopant to polyaniline in three different ways: in solid state, in solution and in gel state. In solid state, the conducting form was achieved only through a novel thermal doping method with the increase in temperature and pressure. In solution, the doping process was shown to be dependent on the nature of the solution and also on the molecular weight of the polymer. In the gel form of polyaniline, a polymeric dopant with a surprising low degree of sulfonation was found to be successful in the doping process.

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060107

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY