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31.
投料顺序对动态硫化PP/EPDM性能影响及其机理的研究 总被引:12,自引:0,他引:12
针对PP降解在PP/EPDM动态硫化中对体系产生的不利影响。考察了四种不同投料顺序对PP/EPDM动态硫化物的冲击韧性,加工流动性,交联程度和断面形貌等宏观和微观性能,并进行了不同EPDM含量的动态硫化和非硫化PP/EPDM的性能比较。结果表明,优化投料顺序能实现对动态硫化体系中化学反应对象和化学反应程度的有效干预。 相似文献
32.
Jean Calbrix 《Transactions of the American Mathematical Society》1996,348(5):2085-2090
We say that a countable, Hausdorff, topological space with one and only one accumulation point is a point-space. For such a space, we give several properties which are equivalent to the property of being a k-space. We study some free filters on the set of integers and we determine if the associated point-spaces are k-spaces or not. We show that the filters of Lutzer-van Mill-Pol are k-filters. We deduce that, for each countable ordinal , there exists a free filter of true additive class (Baire's classification) and a free filter of true multiplicative class for which the associated point-spaces are k-spaces but not , the existence being true in the additive case for . In particular, we answer negatively a question raised in J. Calbrix, C. R. Acad. Sci. Paris 305 (1987), 109--111.
33.
This paper summarizes our research in the preparation of chain end functionalized isotactic polypropylene (PP) having a terminal functional group, such as Cl, OH, and NH2. The chemistry involves metallocene-mediated propylene polymerization using rac-Me2Si[2-Me-4-Ph(Ind)]2ZrCl2/MAO complex in the presence of styrene derivatives (St-f) and hydrogen, which serve as the chain transfer agents. The molecular weight of the resulting PP polymers with a terminal Cl, OH and NH2 group (i.e., PP-t-Cl, PP-t-OH and PP-t-NH2) are inversely proportional to the molar ratio of [St-f]/[propylene]. Despite the extremely low concentration of functional group, the high molecular weight chain end functionalized PP-t-OH and exhibit a distinctive advantage over other functional PP polymers containing side chain functional groups or long functional blocks. The terminal hydrophilic OH and cations, with good mobility and reactivity, effectively hydrogen bond and ion-exchange the cations (Li+, Na+, etc.) located between the clay interlayers, respectively. Such interactions anchor the PP chain to the clay surfaces. On the other hand, the remaining rest of the unperturbed end-tethered high molecular weight PP tail exfoliates the clay layers. This exfoliated structure is maintained even after further mixing of the PP-bearing platelets with pure neat PP polymers. 相似文献
34.
离聚物Surlyn对PBT/PP共混体系的力学性能及形态结构的影响 总被引:2,自引:0,他引:2
用力学性能测试、DMA、SEM等方法研究了离聚物Surlyn对PBT/PP共混体系的力学性能及形态结构的影响。结果表明,在PBT/PP共混体系中引入少量Surlyn可以改善界面的粘接性,从而改善其力学性能。当共混体系中PBT/PP的组份比不变(90/10)且Surlyn的含量为6phr左右时,共混物的冲击强度出现极大值;而弯曲强度在Surlyn含量为1-2phr左右时有最大值。当共混体系中Surlyn的含量不变(6phr)时,其力学性能随PP含量的增加而下降。用玻璃纤维增强共混体系,可显著提高力学性能。 相似文献
35.
In this paper we have presented the results of acoustic emission (AE) during non-isothemal crystallization of polypropylene (PP) melt with mean cooling rate 4℃/min, and discussed the effects of molecular weight (MW) on AE activity. It is shown that the amount of AE ring-down counts during whole crystallization of PP depends on the MW strongly.The copious AE bursts have been observed at the late stage of PPcrystallization. AE bursts are caused by cracking, crazing and cavitation between spherulites and inside spherulites. 相似文献
36.
Supermolecular structure and phase morphology of the ternary isotactic polypropylene/atactic polystyrene/poly(styrene-b-ethylene-co-propylene) (iPP/aPS/SEP) compression molded blends with 100/0, 90/10, 70/30, and 50/50 iPP/aPS weight ratios and with different amounts of added SEP compatibilizer were studied by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD). SEP significantly reduced the size of dispersed aPS particles that enabled better spherulitization in the iPP matrix. Furthermore, iPP spherulites in ternary blends with 90/10 iPP/aPS weight ratio became larger in comparison with the pure iPP. TEM revealed that the SEP formed continuous interface layer around the dispersed aPS particles even when only 2.5 wt.% of SEP was added. Particle size distribution was distinctly bimodal. When the SEP content was increased to 10 wt.%, joining together smaller and bigger aPS and SEP particles formed dispersed aggregates. Additionally, both amorphous components (aPS and SEP) influenced crystallization process of iPP matrix and so modified, to some extent, its final supermolecular structure. SEP compatibilizer did not significantly affect crystallite orientation. The increase of crystallite sizes, which was more affected by the addition of aPS than by the addition of SEP, seemed to be influenced by the solidification effect rather than by the phase morphology of the blends. 相似文献
37.
Summary Methods for the determination of specific migration of polymer additives from polypropylene to aqueous acetic acid and isooctane have been studied. The migrants were extracted from aqueous acetic acid and characterized by supercritical fluid chromatography (SFC) with flame ionization detection (FID) and mass spectrometry (MS). The isooctane simulant was concentrated and injected directly into the SFC. Injection of extracts after incubation, using the solvent venting injection technique in the SFC, enabled additive concentrations as low as 10 ppb in 150 ml simulant to be determined, corresponding to a specific migration level of approximately 1 g additive/dm2 polymer. 相似文献
38.
采用齐格勒-钠塔催化剂使丙烯催化聚合得到聚丙烯。聚丙烯树脂本身具有优良的性能,如机械强度好,易加工成型,质量轻,成本低等,但也存在一些缺陷,如由于聚丙烯结构中存在叔碳原子,在造粒加工、贮存和使用过程中,易受热、光、氧等的作用而降解,导致材料的性能降低。为了抑制和延缓聚丙烯的氧化降解,需要在造粒阶段加入抗氧剂。本文以一种聚丙烯树脂样品为研究对象,采用溶剂抽提法提取有机添加剂,并用柱层析法对添加剂进行了分离;利用EI-MS分析了添加剂的组成,其中通过谱图解析,鉴定出添加剂中含有硫酯类抗氧剂-硫代二丙酸二(十四)酯(DMTP),并用此类常用化合物进行了验证,分析结果对树脂牌号的开发具有指导意义。 相似文献
39.
LING Daren LIU Bing WU Guoqi Department of Applied Chemistry Jiangsu Institute of Petrochemical Technology Changzhou China 《Chinese Journal of Reactive Polymers》2002,(1)
1. INTRODUCTION When investigating contaminated sites it is often essential to determine specific pollutants in a large number of ambient air samples. Amongst these sites, polycylic aromatic hydrocarbons (PAHs) are a major class of compounds that hav… 相似文献
40.
Z. Bartczak 《European Polymer Journal》2006,42(8):1819-1829
Blends of isotactic propylene-ran-ethylene (EP) and propylene-ran-(1-butene) (BP) copolymers with various comonomer content (2-3.1 wt.% ethylene, 9.9 wt.% 1-butene), were prepared in Brabender internal mixer at various compositions (25/75, 50/50, 75/25). Static, impact and dynamic mechanical behavior of copolymers and their blends was investigated. The crystalline structure was studied by DSC and SAXS analysis. For all copolymers the lamellar thickness, crystallinity degree and glass transition temperature are lower than those of iPP homopolymer, depending on the comonomer content. It was found that the copolymers exhibit improved impact strength as compared to plain iPP, due to lower crystallinity and higher mobility of chains within amorphous component. Moreover, the elastic modulus as well as the yield behavior of the examined samples resulted to depend primarily on the amount of the crystalline phase and the thickness of the lamellar crystals, respectively. A linear dependence of yield stress on the logarithm of reciprocal lamellar thickness was observed for blends and copolymers, supporting the concept of thermal nucleation of dislocations which control the crystallographic slip processes initiated at the yield point. The blends of BPS with either EPS or EP2 display complete miscibility in the entire range of composition and their mechanical properties are intermediate between those of plain components, changing gradually with the composition. 相似文献