共查询到17条相似文献,搜索用时 109 毫秒
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非弹性体增韧—聚合物增韧的新途径 总被引:20,自引:0,他引:20
本文是一篇关于非弹性增韧方法的综述。文章首先简要回顾了传统的橡胶增韧韧性聚合物材料的机理,然后着重介绍了最近在国外出现的刚性有机填料(ROF)增韧的基本概念、分析方法和增韧的冷拉机理,列举了脆性塑料粒子和韧性基体组成的合金体系的大量实验结果来说明以上内容,最后通过与传统橡胶增韧机理的对比指出非弹性体增韧是不同于后者的一种新增韧方法,并有可能成为制备高强度、高韧性工程塑料的一种新途径。 相似文献
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刚性有机粒子对聚氯乙烯/氯化聚乙烯共混体系形态和增韧机理的研究 总被引:14,自引:0,他引:14
刚性有机粒子对聚氯乙烯/氯化聚乙烯共混体系形态和增韧机理的研究周丽玲,吴其晔,杨文君,刘士龙,张漫(青岛化工学院橡胶系青岛266042)关键词刚性有机填料,聚氯乙烯PVC,氯化聚乙烯(CPE)形态,增韧机理在共混改性中,弹性体增韧硬质聚氯乙烯(nyV... 相似文献
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三聚氰胺甲醛树脂具有良好的耐热性和胶接强度大等特点,因此被广泛应用于木材加工用的胶粘剂、涂料的固化剂、纸张湿强剂中。但是三聚氰胺的刚性三嗪环结构会导致三聚氰胺甲醛树脂存在硬脆、力学性能差、强度低、拉伸和弯曲性能差等缺陷。上述缺陷限制了三聚氰胺甲醛树脂在某些领域中的应用。为了扩大其应用范围,三聚氰胺甲醛树脂的增韧问题得到了越来越多的关注。本文主要综述了小分子增韧和高分子增韧两种主要方法,其中小分子增韧又包括异氰脲酸酯增韧、二元醇增韧、二元醛增韧、胺类增韧以及多种小分子协同增韧。高分子增韧包括聚多元醇增韧和聚氨酯增韧。此外,还介绍了生物质增韧、硅烷增韧等其他几种方法,并阐述了上述方法的增韧机理。 相似文献
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CaSO_4晶须补强增韧聚氨酯弹性体机理的研究 总被引:13,自引:0,他引:13
提高聚氨酯弹性体的力学性能是聚氨酯研究领域里普遍关心的课题之一,一般采用刚性粒子和纤维类无机填料增强聚氨酯弹性体,但上述填料在提高强度的同时,会导致韧性降低,空易造成脆性断裂,因此填料能否同时补强增韧聚氨酯弹性体具有重要的实际应用价值,晶须是一种单晶纤维状材料,其直径极小,几乎不存在任何缺陷,由于内在的完整性,高度有序的原子排列,使其强度接近晶体理论--原子间价键的强度,晶须凭借微细的直径、较短的长度、极高的强度,成为一种新型补强增韧剂,目前晶须的复合基体多为陶瓷基、金属基和树脂基,有关复合基体多为陶瓷基、金属基和树脂基,有关复合聚氨酯弹性体的理论及应用研究报道很少,本文制备了具有较高强度和韧性的CaSO4晶须/聚氨酯弹性体复合材料,通过微观分析揭示了CaSO4晶须对聚氨酯弹性体补强增韧的机理,并对其影响因素进行了讨论。 相似文献
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MMA接枝改性PVC/CaCO3纳米复合材料的力学性能 总被引:13,自引:0,他引:13
采用熔融共混法制备PMMA接枝改性纳米CaCO3增韧PVC(PVC/CaCO3)复合材料,并研究了复合材料的力学性能.结果表明,通过表面PMMA的接枝改性,可以显著提高纳米CaCO3增韧聚氯乙烯复合材料的拉伸强度和拉伸模量,在纳米CaCO3颗粒表面PMMA包覆层厚度为2nm时,复合材料的拉伸强度和拉伸模量达到极大值.对比于未处理纳米CaCO3和钛酸酯偶联剂处理纳米CaCO3,PMMA接枝改性纳米CaCO3增韧PVC复合材料的拉伸强度得到较大幅度提高.SEM显示,经过PMMA接枝改性后的碳酸钙在PVC基体中分散均匀,与基体界面结合良好. 相似文献
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界面粘结对聚氯乙烯/丁腈橡胶共混物脆韧转变的影响 总被引:6,自引:1,他引:6
应用丙烯腈(AN)含量不同的丁腈橡胶(NBR)与聚氯乙烯(PVC)共混,研究了界面粘结对PVC/NBR共混物脆韧转变的影响.结果表明:当基体层度T相等时,过强的界面粘结,使PVC/NBR共混物的冲击强度降低,并且其产生脆韧转变的临界基体层厚度Tc减小.界面粘结对于聚合物共混物的增韧行为具有直接的影响.损伤区分析给出:随着界面粘结强度增大,空洞化过程受阻,减弱能量的耗散,并且不利于诱导剪切屈服损伤的产生,因而不利于增韧;但是界面粘强度过小,意味着共混物的相容性太差,致使分散相粒径过大,也不利于增韧.所以对增韧来讲,共混物的界面粘结强度存在一个最佳范围. 相似文献
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ChaoYingWAN YongZHANG YinXiZHANG 《中国化学快报》2004,15(1):77-78
Poly (vinyl chloride)/ethylene-vinyl acetate/montmorillonite (PVC/EVA/OMMT) composites were prepared by melt blending method. Two kinds of montmorillonites were organically modified by trimethyloctadecyl ammonium and dimethyl bis (hydrogenated tallow) ammonium, respectively. The morphology and tensile properties of the resultant composites were discussed in terms of the modifier type and OMMT content. The PVC/EVA/OMMT composites have intercalated structure, which is independent of the polarity of the modifiers, while the tensile properties show strong dependence on the modifier type. The OMMT modified by polar modifier gives higher tensile ductile and strength of PVC/EVA/OMMT composites. 相似文献
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A. M. Pourrahimi N. Mohammadi A. Javadi 《Journal of Polymer Science.Polymer Physics》2011,49(5):327-332
Toughening amplification of the neat poly(vinyl chloride) (PVC) and its reinforced version containing 25 phr of the cellulose acetate (CA)‐compatibilized starch using methyl methacrylate‐butadiene‐styrene (MBS) core–shell particles was studied. The room temperature measured impact strength of the PVC showed mild increase up to 10 wt % with the addition of MBS particles. Then, the toughness enhanced discontinuously to super‐tough plateau regime. The room temperature measured impact strength of PVC containing 20 phr of MBS particles, however, was reduced by as much as 95% when it was filled with 25 phr of the CA‐compatibilized starch. In addition, the brittle–ductile transition (BDT) of the toughened PVC increased from 0 to 60 °C because of its reinforcement, even though the matrix number density of the core/shell particles remained almost constant. The decline in the impact strength and the rise in the BDT of the hybrid PVC system were attributed to the decrease in the shear deformable matrix and shear deformation propagation rate despite the increase in the process zone size. Maximum impact strength of the hybrid system at 60 °C (its BDT) increased to about 25% of the toughened PVC at its BDT (0 °C). The toughness amplification correlation of the toughened and hybrid PVC systems with their process zones fractional stress volumes under the impact load showed three regimes: quasi‐tough, transition, and super‐tough, which were superimposable on literature data regarding hybrid nylon 66 systems. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010 相似文献
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Chengzhe Zhao Guangfeng Wu Chao Zhou Haidong Yang Huixuan Zhang 《Journal of Polymer Science.Polymer Physics》2006,44(4):696-702
A series of acrylic impact modifiers (AIMs) with different particle sizes ranging from 55.2 to 927.0 nm were synthesized by seeded emulsion polymerization, and the effect of the particle size on the brittle–ductile transition of impact‐modified poly(vinyl chloride) (PVC) was investigated. For each AIM, a series of PVC/AIM blends with compositions of 6, 8, 10, 12, and 15 phr AIM in 100 phr PVC were prepared, and the Izod impact strengths of these blends were tested at 23 °C. For AIMs with particle sizes of 55.2, 59.8, 125.2, 243.2, and 341.1 nm, the blends fractured in the brittle mode when the concentration of AIM was lower than 10 phr, whereas the blends showed ductile fracture when the AIM concentration reached 10 phr. It was concluded that the brittle–ductile transition of the PVC/AIM blends was independent of the particle size in the range of 55.2–341.1 nm. When the particle size was greater than 341.1 nm, however, the brittle–ductile transition shifted to a higher AIM concentration with an increase in the particle size. Furthermore, the critical interparticle distance was found not to be the criterion of the brittle–ductile transition for the PVC/AIM blends. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 696–702, 2006 相似文献
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In this study, tough and high heat‐resistant poly (vinyl chloride) (PVC)/poly (α‐methylstyrene–acrylonitrile) (α‐MSAN) blends (70/30) containing acrylic resin (ACR) as a toughening modifier was prepared. With the addition of ACR, heat distortion temperature increased slightly, which corresponded with the increase in glass transition temperature measured by differential scanning calorimetry and dynamic mechanical thermal analysis. Thermogravimetric analysis showed that addition of ACR improved the thermal stability. With regard to mechanical properties, tough behavior was observed combined with the decrease in tensile strength and flexural strength. A brittle‐ductile transition (BDT) in impact strength was found when ACR content increased from 8 to 10 phr. The impact strength was increased by 34.8 times with the addition of 15 phr ACR. The morphology correlated well with BDT in impact strength. It was also suggested from the morphology that microvoids and shear yielding were the major toughening mechanisms for the ternary blends. Our present study offers insight on the modification of PVC, since combination of α‐MSAN and ACR improves the toughness and heat resistance of pure PVC simultaneously. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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根据作者已建立的准网络形态模型和推导出的基体层厚度计算公式,从实验上研究了橡胶粒子的分布对聚氯乙烯(PVC)/丁氰橡胶(NBR)共混物脆韧转变的影响.结果表明,不仅无规形态PVC/NBR共混物存在脆韧转变主曲线,而且准网络形态PVC/NBR共混物也存在脆韧转变主曲线.但是两条主曲线明显不重合,表明橡胶粒子的分布对PVC/NBR共混物脆韧转变有显著影响.而且准网络形态PVC/NBR共混物的临界基体层厚度比无规形态PVC/NBR共混物的临界基体层厚度大得多,表明准网络形态比无规形态明显有利于增韧.因此临界基体层厚度不仅是基体的特征参数,还是界面粘结和橡胶粒子分布的函数. 相似文献
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Morsy MA Shwehdi MH 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,63(3):624-630
Electron spin resonance (ESR) study is carried out to characterize thermal endurance of insulating materials used in power cable industry. The presented work provides ESR investigation and evaluation of widely used cable insulation materials, namely polyvinyl chloride (PVC) and cross-linked polyethylene (XLPE). The results confirm the fact that PVC is rapidly degrades than XLPE. The study also indicates that colorants and cable's manufacturing processes enhance the thermal resistance of the PVC. It also verifies the powerfulness and the importance of the ESR-testing of insulation materials compared to other tests assumed by International Electrotechnical Commission (IEC) Standard 216-procedure, e.g. weight loss (WL), electric strength (ES) or tensile strength (TS). The estimated thermal endurance parameters by ESR-method show that the other standard methods overestimate these parameters and produce less accurate thermal life time curves of cable insulation materials. 相似文献
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Seung Hyeon Yeon Sung Hoon Ahn Jong Hak Kim Ki Bong Lee Yujin Jeong Seong Uk Hong 《先进技术聚合物》2012,23(3):516-521
A series of amphiphilic graft copolymers consisting of poly(vinyl chloride) (PVC) main chains and poly(vinyl pyrrolidone) (PVP) side chains, i.e. PVC‐g‐PVP, was synthesized via atom transfer radical polymerization (ATRP), as confirmed by 1H NMR, FT‐IR spectroscopy, and gel permeation chromatography (GPC). Transmission electron microscope (TEM) and small angle X‐ray scattering (SAXS) analysis revealed the microphase‐separated structure of PVC‐g‐PVP and the domain spacing increased from 21.4 to 23.9 nm with increasing grafting degree. All the membranes exhibited completely amorphous structure and high Young's modulus and tensile strength, as revealed by wide angle X‐ray scattering (WAXS) and universal testing machine (UTM). Permeation experimental results using a CO2/N2 (50/50) mixture indicated that as an amount of PVP in a copolymer increased, CO2 permeability increased without the sacrifice of selectivity. For example, the CO2 permeability of PVC‐g‐PVP with 36 wt% of PVP at 35°C was about four times higher than that of the pristine PVC membrane. This improvement resulted from the increase of diffusivity due to the disruption of chain packing in PVC by the grafting of PVP, as confirmed by WAXS analysis. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献