SAXS measurements of the interface in polyacrylate and epoxy interpenetrating networks with fractal geometry

The interface thickness in two-component interpenetrating polymer networks (IPN) system based on polyacrylate and epoxy were determined using small-angle X-ray scattering (SAXS) in terms of the theory proposed by Ruland. The thickness was found to be nonexistent for the samples at various compositions and synthesized at variable conditions-temperature and initiator concentration. By viewing the system as a two-phase system with a sharp boundary, the roughness of the interface was described by fractal dimension, D, which slightly varies with composition and synthesis condition. Length scales in which surface fractals are proved to be correct exist for each sample and range from 0.02 to 0.4 Angstrom(-1). The interface in the present IPN system was treated as fractal, which reasonably explained the differences between Pored's law and experimental data, and gained an insight into the interaction between different segments on the interface. (C) 1997 Elsevier Science Ltd.

Dynamic mechanical properties of interpenetrating polymer networks based on polyacrylates and epoxy

Interpenetrating polymer networks (IPNs) based on polyacrylate (poly(polyethylene glycol diacrylate), PEGDA) and epoxy(diglycidyl ether of bisphenol A, DGEBA) were prepared simultaneously Dynamic mechanical properties of the SINs (simultaneous interpenetrating networks) with various compositions were studied. Enhanced mechanical properties were found in this case. From the point of view of pre-swollen networks, all of the PEGDA/DGEBA IPNs were composed of the individual pre-swollen networks. A micro-phase segregation system was produced in the SIN. Glass transition temperatures shifted inward, which was attributed to molecular packing effects or mutual-entanglements of molecular segments among the individual pre-swollen networks. In accordance with the additivity of properties, namely the parallel model, the entanglement density between the two polymer networks reached its maximum at 50/50 PEGDA/DGEBA IPN.

Miscibility, crystallization, and morphology studies of thermosetting polyimide PMR-15/PEK-C blends

Miscibility, crystallization, and mechanical properties of blends of thermosetting polyimide PMR-15 and phenolphthalein poly(ether ketone) (PEK-C) were examined. With the exception of the 90/10 blend, which has two glass transition peaks, all the blends with PMR-15 less than 90 wt % are miscible in the amorphous state according to DMA results. Addition of PEK-C hindered significantly the crystallization of PMR-15, indicating that there must exist some kind of interaction between molecular chains of PMR-15 and those of PEK-C. The semi-IPN system of PMR-15/PEK-C blends exhibits good toughness. Two distinct microphases, interweaving at the phase boundaries, were found in the PMR-15/PEK-C 60/40 blend. The toughness effect of the blends is discussed in terms of the interface adhesion between the two distinct phases and the domain sizes of the phases. The relation between miscibility and toughness of the blends was investigated. (C) 1996 John Wiley & Sons, Inc.

Miscibility and crystallization behavior of thermosetting polyimide thermoplastic polyimide blends

Compatibility, morphology, crystalline structure and mechanical properties of the blends of a thermosetting polyimide with thermoplastic polyimides consisting of dianhydrides of different lengths have been studied by the use of dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and small-angle X-ray scattering (SAXS) techniques. The results of our research show that the blends change from compatible to semi-compatible when the difference between the length of the dianhydrides of the two components increases. Addition of a thermoplastic polyimide inhibits the crystallization of the thermosetting component. However, this effect decreases with increasing length of the dianhydrides and the distribution of the molecules of the thermoplastic polyimide component changes from interlamellar to interfibrillar. Impact strength and morphology of the fractured surfaces indicate that among the semiinterpenetrating polymer networks (semi-IPN) obtained the toughening effect of the partially compatible one is the best. The results are discussed in terms of charge transfer interaction between imide group and p-phenylene group.

聚酰亚胺及其共混物

本文综述了聚酰亚胺及其共混物的研究进展，讨论了聚酰亚胺的分子结构对其共混物的相容性，结晶行为及力学性能的影响。

聚环氧氯丙烷聚氨酯／聚甲基丙烯酸甲酯互穿网络聚合物的相容性与力学性能

用同步法合成了聚环氧氯丙烷聚氨酯／聚甲基丙烯酸甲酯互穿网络聚合物［ＰＵ（ＰＥＣＨ）／ＰＭＭＡＩＰＮ］，调节ＩＰＮ中两组分组成比制备出由完全弹性体、增强弹性体、增韧塑料到脆性塑料多种高聚物合金材料．用ＤＳＣ、动态力学谱、ＴＥＭ对ＩＰＮ的研究结果表明，ＰＵ（ＰＥＣＨ）／ＰＭＭＡＩＰＮ的两组分是完全相容的；同时对各种组成比的ＩＰＮ材料进行力学性能测试，用相容性ＩＰＮ中互穿、缠结结构解释其力学行为，并用ＳＥＭ对断面形貌进行了观察解释．

Studies on polyepichlorohydrin-based polyurethane/poly(MMA-co-St) IPNs

Interpenetrating polymer networks of polyepichlorohydrin-based polyurethane/poly(MMA-co-St) have been prepared with simultaneous mettled by changing the weight fraction of MMA(W-MMA) in copolymer of MMA with styrene. The IPNs have been studied by DSC, TEM and dynamic mechanical spectroscopy(DMS). The results show that the IPNs have only one T-g, when W-MMA is greater than 0. 6. But when W-MMA IMA is less than 0. 4, the IPNs have two T(g)s, and phase separation is observed on TEM. The phenomenon is explained according to the solubility parameters(delta) and the fraction of hydrogen bond(delta(h)) of P (MMA-co-St). The study reveals that there is a close correlation among the delta, domain size and mechanical properties of PU (PECH)/P(MMA-co-St) IPN.

MORPHOLOGY AND DYNAMIC MECHANICAL-PROPERTIES OF AB CROSS-LINKED POLYMERS BASED ON POLYURETHANES

Polyoxypropylene glycol (PPG) (or castor oil) and toluene diisocyanate (TDI) were mixed, and the prepolymer polyurethane (PU) (I) was formed. Vinyl-terminated polyurethane (II) was prepared from (I), and hydroxyethyl acrylate, AB crosslinked polymers (ABCPs) were synthesized from (II) and vinyl monomers such as styrene, methyl methacrylate, vinyl acetate, etc. The dynamic mechanical properties and morphology of ABCPs were measured. The ABCPs based on PPG have double glass transition temperatures (T(g)) on the sigma-vs. temperature curves. They display a two-phase morphology with plastic components forming the continous phase and PU-rich domains forming the separated phase on the electron micrographs. Irregular shapes and a highly polydisperse distribution of PU-rich domain sizes were observed. The crosslink density of ABCPs has a notable effect on the morphology and properties. The average diameter of the PU-rich domains depends on the molecular weight of prepolymer PPG. The highly crosslinked structures will produce large numbers of very small domains. ABCPs based on castor oil show a single T(g) relaxation on the dynamic mechanical spectra. The compatibility between the two components is much better in ABCPs based on castor oil than in those based on PPG, because there is a high crosslink density in the former. Comparison of the dynamic mechanical spectra of ABCP and interpenetrating networks (IPN) based on castor oil with similar crosslink density and composition imply that the two components in ABCP are compatible whereas microphase separation occurs in IPN. An improvement in the compatibility is achieved by the crosslinking between the two networks.

网间交联型增韧环氧树脂/蓖麻油聚氨酯互穿网络聚合物的动态力学性能和形态结构

以增韧环氧树脂(TEP)和蓖麻油聚氨酯[PU(CO)]形成的互穿网络聚合物(IPN),两网络间具有一定数量的交联点,在一定组成下,该IPN的tanδ-T曲线半峰宽达100℃,tanδ最大值接近1,阻尼性能良好。形态研究表明,该IPN既有增韧环氧树脂本身的两相结构,又有IPN的两相结构。

COPU/PMMA AB交联聚合物的性能

AB交联聚合物(ABCP)是由聚合物A链与化学组成不同的聚合物B链交联构成。它的网络结构不同于IPN。IPN是由两个独立的网络构成,而在ABCP中仅存在一个聚合物网络。目前人们对它远不及对IPN了解得多。 本文选用蓖麻油为原料,与甲基丙烯酸甲酯共聚,合成了一种ABCP。研究了它的力学性能,转变与松弛,相容性及形态结构与组成及交联密度的关系。

交联对聚己二酸乙二醇酯聚氨酯/甲基丙烯酸甲酯交联聚合物的力学阻尼、相容性及形态的影响

用紫外光聚合方法制备出一系列端乙烯基聚己二酸乙二醇酯聚氨酯(PEAPU)和甲基丙烯酸甲酯(MMA)AB交联聚合物(ABCP)。用粘弹谱仪、透射电子显微镜(TEM)和平衡溶胀法研究了AB交联聚合物的动态力学性能、玻璃化转变温度、形态和交联密度、观察到相应于聚氨酯和PMMA相两个玻璃化转变温度,TEM照片中的微相分离是更明显的,ABCP中的两个T_g内移表明,两种成分的化学交联增加了相互的可混性、与ABCP具有相同组成的IPN有比ABCP大得多的相区。氢键能够影响ABCP的相容性、形态和动态力学性能。

蓖麻油聚氨酯/甲基丙烯酸甲酯交联共聚物的合成与表征

AB交联共聚物(ABCP)和互穿网络聚合物(IPN)都属交联网状聚合物,只是前者形成一个网络,后者构成两个独立网络(图1),因此两者的性能有明显差别,特别是相容性。目前对ABCP的研究主要是聚酯,聚醚体系,本工作选用便宜的蓖麻油聚氨酯(COPU)和MMA为原料,合成ABCP,得到具有阻尼性能的材料。

聚醋酸乙烯酯/聚丙烯酸甲酯互穿网络聚合物的平衡溶胀行为及网络间的互穿缠结

本文在Thiele-Cohen模型的基础上,引入聚合物Ⅰ/聚合物Ⅱ/溶剂三元体系的作用参数,推导了一般均相互穿网络聚合物(IPN)体系的溶胀方程,将聚醋酸乙烯酯/聚丙烯酸甲酯(PVAc/PMA)IPN在丙酮中平衡溶胀度λ的理论计算值与实验值做了比较,方程经Siegfried修正后,能较好地描述一般均相IPN体系的溶胀行为,并观察到在IPN的网络之间存在着明显的互穿缠结效应。

聚氯乙烯-低分子量聚异丁烯共混物的阻尼性质

聚氯乙烯(PVC)用作阻尼材料时多作成与高聚物的共混物,也有采用IPN的方法改善PVC的阻尼性能,前巳报导PVC-丁腈羟低聚物共混物有较佳的阻尼性质。本工作考察了PVC-PIB(聚异丁烯)组成及添加剂对共混物力学性能和动态力学性质的影响。

聚醋酸乙烯酯/聚丙烯酸甲酯互穿网络聚合物的研究——1.聚合条件对体系相容性的影响

用分步法合成了聚醋酸乙烯酯/聚丙烯酸甲酯互穿网络聚合物(PVAc/PMA-IPN),PVAc和PMA的交联剂分别是丁二酸二烯丙酯(DAS),和二乙烯基苯(DVB)。当DAS用量较小时,VAc聚合时的接枝反应较明显,PVAc网络的交联密度高于化学当量的计算值。动态力学的实验结果表明,丙烯酸甲酯的聚合温度和聚合过程中的溶胶-凝胶转变对PVAc/PMA-IPN体系的相容性有很大影响。