弹性体对HDPE/E-TMB共混物性能的影响

用自制增韧母料（E-TMB）与高密度聚乙烯（HDPE）热机械共混分别制得HDPE／E-TMB的J系列共混物和S系列共混物，研究了E—TMB中乙丙弹性体M与丁苯弹性体N质量比对共混物力学性能及熔体质量流动速率（MFR）的影响。结果表明，共混物熔体的MFR随母料中N用量的增加逐渐减小；当E-TMB中m（M）／m（N）=80／20时，J类共混物的综合力学性能最好；当m（M）／m（N）=0／100时，s类共混物的力学性能最好。     

E-TMB中弹性体含量对HDPE/E-TMB共混物性能的影响

以高密度聚乙烯(HDPE)为基体树脂,(乙烯/丙烯)共聚物和(苯乙烯/丁二烯)共聚物为增韧剂研制出5种弹性体含量不同的聚乙烯增韧母料(E-TMB),将E-TMB与HDPE热机械共混制得弹性体总含量均为6.3%的5种HDPE/E-TMB共混物,研究了E-TMB中弹性体含量对共混物力学性能和热性能的影响。结果表明,当E-TMB中弹性体含量为44%时,共混物的综合力学性能最好,悬臂梁缺口冲击强度是HDPE的5.65倍,拉伸屈服强度和弯曲弹性模量保留率分别为90.8%和73.7%;共混物的熔点和热分解温度随E-TMB中弹性体含量的增加而升高,结晶温度随E-TMB中弹性体含量的增加而降低。     

母料配方对PE-HD/E-TMB共混物结晶行为的影响

用增韧母料(E-TMB)分别与高密度聚乙烯(PE-HD)2200J(HE1)、5000S(HE2)热机械共混制得HE1/E-TMB和HE2/E-TMB共混物,研究了E-TMB中弹性体配比(M/N)、基体树脂和弹性体配比(H/E)对共混物结晶行为的影响,并将其和简单共混对照样对比。结果表明,与纯PE-HD和简单共混物对照样相比,HE1/E-TMB和HE2/E-TMB的结晶起始温度升高,且随M/N比值的减小而增大,随H/E比值的减小而减小;HE1/E-TMB的结晶焓减小而成核速率和结晶速度增大,HE2/E-TMB的结晶焓增大而成核速率和结晶速度减小,HE2/E-TMB的成核速率随M/N比值的减小而减小。     

增韧母料ETMB对PE-HD/ETMB力学性能的影响

以2200J高密度聚乙烯(PE-HD)为基体树脂,乙丙弹性体和丁苯弹性体为增韧剂,加入适量引发剂、阻交联剂等,通过特殊的技术和化学反应研制出不同系列聚乙烯增韧母料(ETMB),将ETMB与2200J PE-HD热机械共混制得PE-HD/ETMB共混物.研究了ETMB中弹性体不同配比、基体树脂和弹性体不同配比、不同阻交联...     

刚性增韧高密度聚乙烯母料的形态结构和熔体流动速率

用透射电镜和熔体流动速率(MFR)仪研究了刚性增韧高密度聚乙烯(HDPE)母料(E-TMB)的形态结构和MFR.结果表明,E-TMB的形态结构为:HDPE为连续相,弹性体为分散相,分散相呈包容相当数量HDPE的胞状(香肠状)结构;其熔体具有一定的流动性,MFR随乙丙弹性体与丁苯弹性体配比、基体树脂与弹性体配比的逐渐减小而减小;阻交联剂的加入使MFR增大,MFR在阻交联剂二甲基亚砜用量为0.024 mol时最小.     

PP/HDPE/弹性体三元共混改性的研究

用双螺杆挤出机制备了聚丙烯(PP)/高密度聚乙烯(HDPE)/弹性体三元共混物,分别探讨了3种弹性体乙烯-辛烯嵌段共聚物(OBC)、苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)、苯乙烯-乙烯/丁烯-苯乙烯嵌段共聚物(SEBS)的含量对PP三元共混物力学性能的影响,并通过扫描电子显微镜观察其脆断表面形态。结果表明,OBC、SBS、SEBS和HDPE都对PP起到了一定的协同增韧作用,SEBS对PP的增韧效果最佳;SEM表明三元共混力学性能与相形态密切相关;所制备的PP/HDPE/OBC三元共混物的加工性能较好。     

塑料基体中MAPE/HDPE比例对木塑复合材料力学性能的影响

以高密度聚乙烯(HDPE)和马来酸酐接枝聚乙烯(MAPE)共混物为塑料基体,以木粉为填料,用注塑成型法制备木塑复合材料,研究MAPE/HDPE质量比变化对塑料基体和木塑复合材料力学性能的影响.结果表明:MAPE/HDPE比变化对MAPE/HDPE共混形成的塑料基体强度基本没有影响,但对由该共混物所制得的木塑复合材料的强度影响显著;在相同的木粉含量下,保持配方中MAPE和HDPE的总含量不变,木塑复合材料的拉伸强度随MAPE/HDPE比率增大先迅速增加,然后趋于平缓.冲击强度随MAPE/HDPE比增大逐渐减小.     

PP/EPDM-g-MAH/TPU共混物流变行为的研究

以EPDM g MAH为增容剂 ,采用熔融共混技术制备了热塑性聚氨酯弹性体 (TPU)增韧聚丙烯 (PP)材料 ,研究了PP/EPDM g MAH/TPU共混物的流变行为 ,重点讨论了增容剂EPDM g MAH对共混物流变行为的影响。结果表明 :共混物熔体的非牛顿指数n <1,且随EPDM g MAH用量的增加而减小 ,表观粘度随剪切速率和剪切应力的增大而降低 ,熔体符合假塑性流体的流动规律 ;温度升高 ,表观粘度降低 ;随着EPDM g MAH用量的增加 ,共混物的表观粘度升高 ,粘流活化能有所减小     

高刚性高韧性PE-HD/E-TMB共混物的性能

用自制增韧母料(E-TMB)与高密度聚乙烯(PE-HD)热机械共混制得PE-HD/E-TMB共混物,研究了E-TMB中基体树脂和丁苯弹性体质量比(H/E)对共混物力学性能、熔体流动速率(MFR)和热稳定性能的影响.结果表明,当PE-HD/E-TMB共混物中丁苯弹性体的质量分数为6.3%时,E-TMB使PE-HD在保持优...     

两类增韧HDPE的力学性能及熔体流动性

以高密度聚乙烯(HDPE)为基体树脂、(乙烯／丙烯)共聚物和丁苯橡胶为增韧剂制得增韧母料(E-TMB)。分别采用将E-TMB与HDPE热机械共混和将(乙烯／丙烯)共聚物、丁苯橡胶与HDPE简单共混的方法制备了HDPE／E-TMB及HDPE／弹性体两类增韧HDPE。结果表明,HDPE／E-TMB的悬臂梁缺口冲击强度的提高幅度、拉伸屈服应力保持率均显著优于HDPE／弹性体,二者的弯曲弹性模量保持率基本相同;HDPE／E-TMB的熔体流动速率比HDPE／弹性体的小,但仍适宜于注射成型和挤出成型。     

Coupled mass diffusion and structural deformation of elastomer seals exposed to rapid gas decompression

A sequentially coupled structural–mass diffusion model has been proposed to evaluate the behaviour of elastomer O-rings exposed to rapid gas decompression in the presence of CO₂. The coupling between mass diffusion and the structural deformation of the O-ring was achieved by employing the Peng–Robinson equation of state and two user-subroutines to evaluate the pressure exerted by the rapidly expanding gas. The finite element analysis (FEA) model has been used to evaluate stress and strain distribution inside the O-ring during rapid gas decompression. It was shown that the nominal stresses go through a stress–state change from compression to tension during the decompression cycle, and the strain rate during the stress–state change is dependent upon the decompression rate. The FEA model revealed that the elements in the centre region of the O-ring's cross-section experience high tensile strains and stresses during each decompression cycle.     

聚氨酯弹性体的降解及其稳定剂

评述了聚氨酯弹性体所经历的热氧降解、水解,光降解和微生物降解等降解过程。介绍了用于抑制这些降解的多种稳定剂以及它们的稳定机理。     

喷涂聚脲弹性体技术的应用

介绍了喷涂聚脲弹性体系列材料的生产工艺、施工参数及性能。在贮水池、船舶舱室地板、建筑物屋面及地面的应用表明：该材料性能优良,前景十分广阔。     

Electrically and thermally conductive elastomer/graphene nanocomposites by solution mixing

The greatest challenge in developing polymer/graphene nanocomposites is to prevent graphene layers stacking; in this respect, we found effective solution-mixing polymers with cost-effective graphene of hydrophobic surface. Since graphene oxide is hydrophilic and in need of reduction, highly conducing graphene platelets (GnPs) of ∼3 nm in thickness were selected to solution-mix with a commonly used elastomer – styrene–butadiene rubber (SBR). A percolation threshold of electrical conductivity was observed at 5.3 vol% of GnPs, and the SBR thermal conductivity enhanced three times at 24 vol%. Tensile strength, Young's modulus and tear strength were improved by 413%, 782% and 709%, respectively, at 16.7 vol%. Payne effect, an important design criteria for elastomers used in dynamic loading environment, was also investigated. The comparison of solution mixing with melt compounding, where the same starting materials were used, demonstrated that solution mixing is more effective in promoting the reinforcing effect of GnPs, since it provides more interlayer spacing for elastomer molecules intercalating and retains the high aspect ratio of GnPs leading to filler–filler network at a low volume fraction. We also compared the reinforcing effect of GnPs with those of carbon black and carbon nanotubes.     

Influence of soft segment molecular weight on the mechanical hysteresis and set behavior of silicone-urea copolymers with low hard segment contents

Effect of polydimethylsiloxane (PDMS) soft segment molecular weight (M_n = 3200, 10,800 and 31,500 g/mol) and urea hard segment content (2.0-11.4% by weight) on the hysteresis and permanent set behavior of segmented silicone-urea (TPSU) copolymers were investigated. In spite of very low hard segment contents, all copolymers formed self-supporting films and displayed good mechanical properties. When the mechanical hysteresis and set behavior of the silicone-urea copolymers with similar hard segment contents (around 7.5% by weight) but based on PDMS-3K, PDMS-11K and PDMS-32K were compared, it was very clear that as the PDMS molecular weight increased, hysteresis and instantaneous set values decreased significantly. Copolymers based on the same silicone soft segment (PDMS-11K or PDMS-32K) but with different hard segment contents showed a linear increase in hysteresis and a slight decrease in the instantaneous set as a function of hard segment content. Constant initial stress creep experiments also showed lower creep as the PDMS segment molecular weight increased for copolymers with similar urea contents. Since the critical entanglement molecular weight (M_e) of PDMS is stated to be 24,500 g/mol, our results tend to suggest important contribution of chain entanglements on the hysteresis and instantaneous set of these silicone-urea copolymers.     

聚丙烯基热塑性弹性体的发展概述

聚丙烯基热塑性弹性体是目前发展较快、应用较广的一类新型高分子材料,已在许多方面取代了传统热固性橡胶。本文综述了各种类型聚丙烯热塑性弹性体的生产研制单位、性能及用途等     

Dewetting of polymethyl methacrylate on the patterned elastomer substrate by solvent vapor treatment

The dewetting evolution process of polymethyl methacrylate (PMMA) film on the flat and prepatterned polydimethylsiloxane (PDMS) substrates (with square microwells) by the saturated solvent of methyl ethyl ketone (MEK) treatment has been investigated at room temperature by the optical microscope (OM) and atomic force microscope (AFM). The final dewetting on the flat PDMS substrate led to polygonal liquid droplets, similar to that by temperature annealing. However, on the patterned PDMS substrate, depending on the microwells' structure of PDMS substrate and defect positions that initiated the rupture and dewetting of PMMA, two different kinds of dewetting phenomena, one initiated around the edge of the microwells and another initiated outside the microwells, were observed. The forming mechanism of these two different dewetting phenomena has been discussed. The microwells were filled with liquid droplets of PMMA after dewetting due to the formation of fingers caused by the pinning of the three-phase-line at the edge of the microwells and their rupture.     

聚氨酯弹性体的发展概况与应用前景

概述了聚氨酯弹性体的发展历史和技术进步情况。介绍了聚氨酯弹性体制品的主要应用领域及其广阔的应用前景。     

Effect of mesophase separation and crystallization on the elastomeric behavior of olefin multi-block copolymers

The mesophase separation and crystallization as well as the elastomeric properties of olefin multi-block copolymers (OBCs) are studied. The solid state morphologies of the OBCs are determined by the competition between mesophase separation and crystallization of hard blocks. The OBC with lower Δ_C8 (octene content difference between soft and hard blocks) displays a spherulitic superstructure, while the OBC with higher Δ_C8 exhibits mesophase separation. The two OBCs show very different elastomeric properties. Wide-angle X-ray scattering shows that the two OBCs have different deformation mechanisms. It is proposed that the cooperative deformation of crystalline phase makes an important contribution to the elastomeric properties.     

Enhancing polyurethane properties via soft segment crystallization

Semi-crystalline polyester diols with relatively high melting points and enthalpies of crystallization are shown to form nearly co-continuous lamellar structures in thermoplastic polyurethanes using polyether soft segments. This high aspect ratio crystalline structure results in materials with exceptional tensile and elastic properties compared to materials made with conventional semi-crystalline soft segments such as polycaprolactone or polybutylene adipate. Additions of semi-crystalline soft segment to foam formulations also result in increased hardness measured by standard foam hardness tests. Halpin-Tsai and percolation model analyses of the results suggest that the crystalline regions exert a global influence on the elastomer structure.