ISSN:0022-233X    

DOI:10.1080/00222339009351501

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0022-233X    

DOI:10.1080/00222339009351502

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0022-233X    

DOI:10.1080/00222339009351503

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Poly(N-acetylethylenimine) (polyoxazoline) (POZO) with a terminal triethoxysilyl group was successfully synthesized by the ring-opening polymerization of 2-methyl-2-oxazoline followed by termination with 3-aminopropyltriethoxysilane. Triethoxysilyl-terminated telechelic POZO was prepared by using a bifunctional initiator. These silane coupling POZOs were subjected to acid-catalyzed cohydrolysis polymerization with tetraethoxysilane by the so-called “sol-gel” method to produce a novel organic/inorganic hybrid polymer (block copolymer), which was a homogeneous transparent/glassy composite material. The obtained hybrid showed higher hydrophilic properties compared with silica gel without POZO segments. On the other hand, a hybrid polymer consisting of poly(2-ethyl-2-oxazoline) and silica gel, which absorbed both water and organic solvents, showed amphiphilic properties. POZO segments were eliminated by pyrolysis of the present hybrid polymer to produce a silica with micropores.

ISSN:0022-233X    

DOI:10.1080/00222339009351504

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

IPNs based on polyethylene and vinyl polymers were prepared according to a new procedure. We studied the dynamic mechanical behavior of two series of IPNs: polystyrene (PS)-polyethylene (PE) and poly(butyl methacrylate) (PBMA)-PE at the frequency ω = 1 Hz and in the temperature region from −50 to 200°C. Temperature dependences of the components of the dynamic modulus of elasticity G' and G" of the networks PS and PBMA have shapes typical of amorphous networks; the corresponding dependences of pure PE show, however, features typical of a semicrystalline polymer. IPNs of the system PS/PE show two-phase behavior. AtT< 110°C, PE functions as a plasticizer. In the system PBMA/PE, better miscibility of components is seen, and PE exerts a reinforcing effect on the mechanical behavior over the whole temperature region. In both systems, network density increases with increasing PE content in IPNs. Better homogeneity and a slight increase in the network density of IPNs with PBMA/PE in comparison to PS/PE networks are probably caused by a greater number of grafted PBMA chains in the PE network compared to the PS network.

ISSN:0022-233X    

DOI:10.1080/00222339009351505

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

High conversion copolymerization of α-methylstyrene (α-MeSt) with N-methylmaleimide (NMeMl) or VV phenylmaleimide (NPhM1) was performed in a Calvet differential microcalorimeter under different ratios of monomer-to-monomer in the feed by using 2,2-azobis(isobutyronitrile) (AIBN) as the initiator. From a tracing of the electric signal of the calorimeter it was observed that in the presence of an excess of NMeMl or NPhMl, alternating copolymerization was the first reaction, and homopolymerization started only after the copolymerization was finished. The calorimetric method is therefore a convenient procedure for the preparation of blends of alternating copolymers with homopolymers of NMeM1 or NPhM1 of predetermined composition. Preliminary experiments indicate that based on a singleTgcriterion, blends prepared within this work are miscible.

ISSN:0022-233X    

DOI:10.1080/00222339009351506

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0022-233X    

DOI:10.1080/00222339009351507

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0022-233X    

DOI:10.1080/00222339009351508

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Polymers with electrically charged groups exhibit a zeta potential when in contact with electrolyte solutions in water. This can be measured with solid polymers as fibers, foils, or granulates. The method of streaming potential/streaming current allows the determination of the carboxyl content of cellulose grafted with poly-(acrylic acid). Since zeta-potential measurements concern the surface of the sample, the method yields information on the type of grafting; i.e., whether it takes place mainly on the surface or throughout the bulk. By measuring the pH dependence of the zeta potential it is possible to obtain the pKvalue of the charged groups. The significance of zeta potential as an analytical tool is emphasized.

ISSN:0022-233X    

DOI:10.1080/00222339009351509

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Critical miscibility phenomena in binary blends of chlorinated polyethylenes (CPEs) with a wide range of degree of chlorination (37 to 69 wt 970 CI) were studied by measuring the glass transition behavior. At a given temperature the miscibility of the blends was principally dependent on the difference in chlorine content between the two component CPEs and also on the mean degree of chlorination. The miscibility of these systems at 150°C was maximal around an average mole fraction chlorination, β, of 0.5. The systems displayed upper critical solution temperatures when β was below 0.5, while lower critical solution temperatures were observed when β | was above 0.5. At a given β, | the consolute points converged as the difference in chlorine content of the blend constituents increased. It appears that this double consolute point temperature decreases with increasing average degree of chlorination. A more refined analysis, taking into account the possible presence of CCl2units and the microstructure of the CPEs, is also presented.

ISSN:0022-233X    

DOI:10.1080/00222339009351510

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor