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11.
交联壳聚糖/聚醚半互穿聚合物网络水凝胶中水的状态 总被引:5,自引:0,他引:5
合成了一种由戊二醛交联的壳聚糖与聚醚形成的半互穿聚合物网络的水凝胶,用DSC法并结合IR光谱研究了该水凝胶中水的状态及水与聚合网络间的相互作用。 相似文献
12.
Interpenetrating polymer networks (IPNs) of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) were prepared by simultaneous network formation. The PEO network was produced by acid-catlayzed self-condensation of α,ω-bis(triethoxysilane)-terminated PEO in the presence of small amounts of water. The PMMA network was formed by free radical polymerization of MAA in the presence of divinylbenzene as crosslinker. The reaction conditions were adjusted to obtain similar crosslinking kinetics for both reactions. An attempt was made to construct a phase diagram of the IPNs by measuring the composition of the IPNs at the moment of the appearance of the phase separation, as indicated by the onset of turbidity. This composition could be determined because the siloxane crosslinks of the PEO network could be hydrolyzed in aqueous NaOH with the formation of linear, soluble PEO chains. The phase diagram was compared with phase diagrams of blends of linear polymers and of semi-IPNs (crosslinked PMMA and linear PEO), obtained under similar conditions, i.e. polymerization of MMA in the presence of varying amounts of PEO. It was observed that the form of the phase diagrams of the linear polymers is similar to that of the IPNs, but is quite different from that of the semi-IPNs. Thus, homogeneous transparent materials containing up to 60% of PEO could be prepared in the blends and the IPNs, but in the semi-IPNs, phase separation occurred with PEO contents as low as 10%. 相似文献
13.
Chonghui Wang Toshio Takayama Shigeo Nakamura 《Journal of polymer science. Part A, Polymer chemistry》1997,35(16):3561-3569
Polyester having amino sulfonic acid moieties (TBES) was prepared by a liquid/solid biphase polycondensation of terephthaloyl chloride (TPC) and N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid (BES) in trimethyl phosphate (TMP) using triethylamine (TEA) as an acid acceptor. Blends of TBES with PVA and their metal complexes with Ni2+ and Co2+ ions were prepared. A strong interaction was observed between TBES and PVA. An electric conductivity of 10−6 S cm−1 was attained for the blend films containing about 5 wt % water. A coordination structure with two chelate rings is proposed for the metal complex with Ni2+ and Co2+ ions when the molar ratio of amino sulfonic acid groups in TBES to metal ions is larger than 2. Polymer blends complexed with Ni2+ or Co2+ ions result in semi-interpenetrating polymer networks from chelate formation. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3561–3569, 1997 相似文献
14.
Summary A series of semi-interpenetrating polymer networks (semi-IPN) of polyurethane (PU) and poly(vinyl chloride) (PVC) has been obtained by prepolymer method and characterised by FTIR; morphological features were examined by SEM-EDS. It has been found that PVC spherical aggregates are dispersed in the PU matrix, but Cl atoms location indicates partial miscibility of both polymers at the interphase which is probably due to hydrogen bonding and/or dipole-dipole interactions. The PVC component influences the phase behaviour of PUs hard segments, as evidenced by DSC results. Thermogravimetric analysis (TG) reveals a complex, multi-step decomposition process with the main mass loss at 503-693 K, while the DTG maxima are located between 540 and 602 K. 相似文献
15.
Thermal properties of poly(siloxane)–poly(tetrafluoroethylene) (SIL–PTFE) system were investigated, using Perkin Elmer DSC-7
differential scanning calorimeter and TGA-7 thermogravimetric analyzer. For SIL–PTFE compositions, one glass transition temperature
T
g has been found, in accordance with the reciprocal rule up to about 40 mass% of PTFE. However, for higher PTFE contents, T
g values about –118 to –112°C were observed that can be ascribed to motions of cross-linked SIL structures. Endo- and exothermic
transitions, found in the range from 70 to 290°C, not observed for pure SIL and PTFE components, are considered as specific
ones for the SIL–PTFE semi-IPN structures.
The SIL–PTFE system, as well as its components, is thermally stable, if degradation reactions are considered; the temperatures
of decomposition at the maximum decomposition rate were above 530°C. It has been found that the thermal stability of the SIL–PTFE
system is increasing with the increase of the PTFE content.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献