动态硫化法PP/EPDM/纳米SiO_2双重粒子协同增韧改性研究

以三元乙丙橡胶 (EPDM)作弹性粒子 ,以纳米SiO2 作刚性粒子 ,通过动态硫化方法制备了PP/EPDM/纳米SiO2 三元改性材料 ,并采用力学性能测试、动态力学试验、DSC分析和偏光显微镜观察等方法 ,研究了该材料的结构与性能。结果表明 ,纳米SiO2 与EPDM对PP具有协同增韧和增强效应 ,这种效应与 2种粒子的浓度比相关 ,当纳米SiO2 质量分数为 3 %、EPDM质量分数为 1 0 %时 ,协同作用最明显。 2种粒子使PP出现较大的低温损耗模量峰 (E″)和内耗峰 (tanδ) ,并具有成核作用 ,使PP结晶温度提高 ,结晶速率加快 ,形成的球晶细小而均匀 ,并同时提高结晶度和熔点。     

三元乙丙橡胶/聚丙烯动态硫化热塑性弹性体的相态结构

用扫描电镜研究了三元乙丙橡胶(EPDM)聚/丙烯(PP)动态硫化热塑性弹性体(TPV)相态结构的形成过程,探讨了交联密度、制备工艺、螺杆转速对EPDM/PP TPV相态结构的影响。结果表明,采用以酚醛树脂为硫化剂的动态硫化工艺制备的EPDM/PP TPV,其相态结构实现了由EPDM和PP组成的双连续相到以EPDM为分散相、PP为连续相的转变;当硫化剂用量为7份时,橡胶相硫化速率和交联密度最大;当螺杆转速为180 r/m in时,反应性挤出工艺较之密炼机工艺制备的EPDM/PP TPV的橡胶粒子更细小、分散更均匀。     

动态硫化法PP／EPDM／纳米SiO2双重粒子协同增韧改性研究

以三元乙丙橡胶（EPDM）作弹性粒子,以纳米SiO2作刚性粒子,通过动态硫化方法制备了PP／EPDM／纳米SiO2三元改性材料,并采用力学性能测试,动态力学试验,DSC分析和偏光显微镜观察等方法,研究了该材料的结构与性能。结果表明,纳米SiO2与EPDM对PP具有协同增韧和增强效应,这种效应与2种粒子的浓度比相关,当纳米SiO2质量分数为3％,EPDM质量分数为10％时,协同作用最明显,2种粒子使PP出现较大的低温损耗模量峰（E″）和内耗峰（tanδ),并具有成核作用,使PP结晶温度提高,结晶速率加快,形成的球晶细小而均匀,并同时提高结晶度和熔点。     

动态硫化法制备三元乙丙橡胶/聚酰胺热塑性弹性体

采用动态硫化技术制备了三元乙丙橡胶(EPDM)／聚酰胺(PA)热塑性弹性体,研究了增容剂种类及用量、硫化体系及其用量、加料顺序、PA用量对其性能的影响,用扫描电镜分析了其相态结构。结果表明,用13份(质量份,下同)的氯化聚乙烯作为增容剂时,对该共混体系的增容效果最好;硫黄硫化体系是EPDM／PA热塑性弹性体的最佳硫化剂,当硫黄用量为2份时,既保证了该热塑性弹性体中的橡胶相能充分交联,又可避免过硫化对产品性能造成的负面影响;PA用量为35份的EPDM／PA热塑性弹性体具有良好的力学性能、耐溶剂性能和耐热老化性能;EPDM以平均粒径为2～5μm的粒子形态均匀分布于PA连续相中。     

石蜡油对动态硫化EPDM/PP热塑性弹性体力学性能的影响

通过双螺杆挤出机制备了动态硫化三元乙丙橡胶(EPDM)/聚丙烯(PP)热塑性弹性体。运用抽提法测试了该EPDM/PP弹性体的凝胶含量,并采用万能试验机等对其力学性能进行测试,研究了软化剂石蜡油的添加量对动态硫化EPDM/PP热塑性弹性体力学性能的影响。结果表明:当石蜡油添加量为20%时,EPDM/PP共混物的凝胶含量最大;当石蜡油添加量为25%时,EPDM/PP共混物的拉伸强度和断裂伸长率均达到最大值。此外,石蜡油的引入不仅能降低EPDM/PP热塑性弹性体的硬度和压缩永久变形,还能提高材料的耐热氧老化性能,其适宜添加量为20%~25%。     

DCP对动态硫化EPDM/PP性能的影响

以过氧化二异丙苯(DCP)为硫化剂,通过双螺杆挤出机进行三元乙丙橡胶/聚丙烯(EPDM/PP)的共混挤出制备动态硫化EPDM/PP热塑性弹性体,采用转矩流变仪对EPDM/PP热塑性弹性体进行硫化特性测试,运用抽提法测试EPDM/PP热塑性弹性体的凝胶含量,研究了不同DCP含量下EPDM/PP热塑性弹性体的硫化特性及凝胶含量的变化情况,并对EPDM/PP热塑性弹性体材料性能进行分析研究。结果表明:当DCP含量为0.6%时,EPDM能完全交联,共混体系黏度最大,扭矩最高;当DCP含量为0.9%时,EPDM/PP热塑性弹性体综合性能最佳;当DCP含量为1.2%时,EPDM/PP热塑性弹性体的凝胶含量最大,但PP的降解程度逐渐增加,拉伸性能开始降低;当DCP含量为1.5%至1.8%时,PP的降解程度剧烈,EPDM/PP热塑性弹性体性能较差。     

三元乙丙橡胶/聚丙烯体系动态硫化速率及热塑性弹性体定伸应力的影响因素

采用转矩流变仪制备了动态硫化三元乙丙橡胶（EPDM）/聚丙烯（PP）热塑性弹性体（TPV）,考察了EPDM/PP共混物的硫化速率及TPV定伸应力的影响因素。结果表明,提高混炼温度、转速及减少EPDM充油量可以提高硫化速率,当混炼温度为195℃、转速为50 r/min、充油质量分数为30%时,TPV的定伸应力达到最大值;随着低双键含量的EPDM（LEPDM）含量的增加,EPDM/PP共混物的硫化速率和TPV的定伸应力逐渐减小,当LEPDM质量分数达到60%时,硫化速率和定伸应力趋于稳定。     

纳米SiO2对动态硫化EPDM／PP热塑性弹性体性能的影响

在开炼机上采用动态硫化的方法制备纳米SiO2改性三元乙丙橡胶（EPDM）／聚丙烯（PP）共混型热塑性弹性体（TPV）,研究了纳米SiO2的加料顺序和用量对热塑性弹性体的力学性能、维卡软化温度的影响．并对改性后的TPV进行返炼．研究其热塑性能。结果表明：将纳米SiO2先与EPDM混炼均匀．然后加入其它助剂．制得EPDM母炼胶,再与PP共混制备得到的TPV力学性能较好,且纳米SiO2用量为4份时TPV的综合性能最佳;随着纳米SiO2用量的增加,TPV的维卡软化温度升高;返炼后的改性TPV力学性能稍有下降,但具有良好的热塑性。     

相容剂及硫化体系对EPDM/LDPE热塑性弹性体性能的影响

采用两种不同硫化体系通过动态硫化工艺制备EPDM/LDPE热塑性弹性体(TPE),并采用EVA对体系进行相容.结果表明:随着EVA用量的增大,EPDM/LDPE共混物的剪切粘度逐渐减小,加工流动性提高;与硫黄硫化EPDM/LDPE TPE相比,过氧化物硫化EPDM/LDPE TPE的物理性能较差,耐热性能较好;当EVA用量为18份时,EPDM/LDPE TPE的综合性能较好.     

低硬度动态硫化EPDM/PP TPV的开发

研究了橡胶/塑料/填充油比例（R/P/O）、树脂硫化体系对低硬度动态硫化三元乙丙橡胶（EPDM）/聚丙烯（PP）热塑性硫化橡胶（TPV）的硬度和力学性能的影响.获得配方（质量份,橡胶为100份）为：PP为30份;油为80份;酚醛树脂用量为6份;SnCl2为1份.其力学性能为邵尔硬度55 A;拉伸强度6.12 MPa、断裂伸长率553%;达到国外同类产品水平.     

Effects of crosslinked elastomer particles on heterogeneous nucleation of isotactic PP in dynamically vulcanized EPDM/PP and EOC/PP blends

The isothermal and non-isothermal crystallizations of PP in neat form and in the TPVs EPDM/PP and EOC/PP were investigated using differential scanning calorimetry (DSC). The crystallization of PP was systematically studied by fitting mathematical models, and was later confirmed by X-ray diffraction (XRD) and by scanning electron microscopy (SEM). The experiments revealed that crosslinked elastomer particles first accelerated the primary nucleation of the PP matrix, acting effectively as a nucleating agent that reduces the induction time while increasing the nucleation efficiency. In the secondary nucleation regime (growth of spherulites), the crosslinked elastomer particles enhanced crystal growth rate, reducing the nucleation energy contribution from PP chain folding. Moreover, the crosslinked elastomer particles increased the final thickness of PP lamellae from that of neat PP, and this was corroborated by the XRD results. On comparing the two types of elastomer, it was found that the EOC particles were more effective in heterogeneous cell nucleation than the EPDM particles. The morphological study by SEM revealed completely altered PP spherulite size and shape, as well as their altered distribution, affected by heterogeneous nucleation effects of the crosslinked elastomer particles.     

纳米SiO2粒子对PP结晶行为的影响

通过X-射线光电子能谱（XPS）对经偶联剂处理的纳米SiO2粒子（简称烷基化SiO2纳米粒子）和聚甲基丙烯酸甲酯（PMMA）接枝包覆SiO2纳米粒子（简称SiO2-g-PMMA复合纳米粒子）的表面组成进行分析。将纳米SiO2粒子，烷基化SiO2纳米粒子，复合纳米粒子分别与基体PP复合制备复合材料，通过DSC，WAXD和TEM等测试方法详细研究了PP/SiO2复合材料的结晶行为与力学性能，结果发现：纳米SiO2粒子与烷基化SiO2纳米粒子并不改变基体PP的结晶形态，而复合纳米粒子诱发了基体PP的β晶型结晶，复合纳米粒子比较均匀地分散于PP基体中，对复合材料的力学性能有较大的改善。     

Phase morphology and melt rheological behavior of uncrosslinked and dynamically crosslinked polyolefin blends: role of macromolecular structure

Thermoplastic vulcanizates (TPVs) based on polypropylene (PP) with ethylene–octene copolymer (EOC) and ethylene propylene diene rubber (EPDM) have been prepared by co-agent-assisted peroxide crosslinking system. The study was pursued to explore the influence of two dissimilar polyolefin polymers having different molecular architecture on the state and mode of dispersion of the blend components and their influence on melt rheological properties. The effects of dynamic crosslinking of the PP/EOC and PP/EPDM have been compared with special reference to the concentration of crosslinking agent and ratio of blend components. Morphological analyses show that, irrespective of blend ratio, dynamic vulcanization exhibits a dispersed phase morphology with crosslinked EOC or EPDM particles in the continuous PP matrix. It was found that viscosity ratio plays a crucial role in determining the state and mode of dispersion of blend components in the uncrosslinked system. The lower viscosity and torque values of uncrosslinked and dynamically crosslinked blends of PP/EOC in the melt state indicates that they exhibit better processing characteristics when compared to corresponding PP/EPDM blends.     

Investigation of surface properties and elastomeric behaviors of EPDM/EOC/PP thermoplastic vulcanizates with different octene contents

Phase morphology, phase compatibility, and elastomeric properties of the ternary EPDM/EOC/PP TPVs were investigated, to determine the influence of octene comonomer content in the EOC molecules on these properties. Such effects are expected as the comonomer impacts the chemical interactions and the chain flexibility of EOC. Viscosity ratio and interfacial properties of the phases were determined, and later related to the morphological structure and the phase compatibility in the ternary TPVs. Increasing octene comonomer content in the EOC reduced surface and interfacial tensions in the TPVs, thereby improving the work of adhesion and the phase compatibility. The study also confirmed that the morphological structure of the TPVs had core–shell elastomer particles dispersed in a continuous PP matrix. Furthermore, elastomeric behavior of the TPVs with various octene contents in the EOC was also assessed. The results revealed improved stress relaxation with low molecular damping and with low permanent set when EOC with higher octene comonomer content was included. Therefore, in the present study the EOC as third component improved phase compatibility and strengthened elastomeric properties of the TPVs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44857.     

纳米SiO2改性EPDM/PP热塑性弹性体(TPE)性能研究

试验研究了纳米SiO2改性三元乙丙橡胶／聚丙烯(EPDM／PP)热塑性弹性体(TPE)的性能。结果显示：纳米SiO2对EPDM／PP热塑性弹性体的拉仲强度、扯断伸长率、耐磨性、抗老化性能以及热变形温度等性能指标均有不同程序的影响。所得结论可为有关工程应用提供理论指导。     

动态填充注塑成型PP/nano-SiO2复合材料的力学性能与形貌分析

采用动态填充注塑成型(DFIM)制备了聚丙烯/二氧化硅(PP/nano-SiO2)复合材料。结果表明:与传统的注塑成型技术相比,采用DFIM法制备的PP/nano-SiO2复合材料的拉伸强度和冲击强度比纯PP材料和常规注射制备的复合材料有了较大提高;nano-SiO2通过DPIM技术可以更好地分散在PP基质中,形成的团聚较少。DFIM法制备的PP/nano-SiO2复合材料力学性能的提高,主要归因于nano-SiO2颗粒的均匀分布,使球晶的数量急剧增加,球晶的尺寸明显减小,小晶体有助于形成材料裂纹,从而进一步提高材料的力学性能。     

High‐performance styrenic thermoplastic vulcanizates for long‐term application

Styrenic thermoplastic vulcanizates (STPVs) were developed for long‐term high‐temperature applications. These STPVs consist of polypropylene as the continuous phase and a crosslinked modified hydrogenated styrenic block copolymer (mHSBC) as the dispersed phase. The present study compared STPVs with conventional TPVs (CTPVs) containing EPDM/PP. The STPVs showed a 20% improvement in solvent resistance after 500 h of immersion in IRM 903 oil at 125°C, and the swelling of oil did not increase with time. The elastic recovery was 50% better than with CTPVs. Tensile property retention was approximately 10% higher after aging for 1440 h at 125°C when compared to CTPVs. These observed property improvements for STPVs relative to conventional TPVs can possibly be explained by the unique morphology of the resulting STPV compounds. These performance characteristics make STPVs more suitable for high‐temperature air and chemical environmental applications. This new TPV technology is expected to bridge the gap between polypropylene/EPDM TPVs and more costly engineering TPVs. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effects of compounding procedure on morphology development,melt rheology,and mechanical properties of nanoclay reinforced dynamically vulcanized EPDM/polypropylene thermoplastic vulcanizates

New nanocomposite thermoplastic vulcanizates (TPVs) comprising dynamically cross‐linked nanoscale EPDM rubber particles dispersed throughout the polypropylene (PP) matrix have been prepared by both batch and continuous melt blending of PP with EPDM in the presence of vulcanizing ingredients, nanoclay and maleated EPDM (EPDM‐g‐MA) as compatibilizer. X‐ray diffraction, linear melt viscoelastic measurement, and tensile mechanical behavior results revealed that the developed microstructure is strongly affected by the type of the melt compounding process as well as the route of material feeding. When EPDM phase was precompounded with a vulcanizing agent, nanoclay, and EPDM‐g‐MA prior to the melt blending with PP, not only nanosize cross‐linked rubber particles appeared uniformly throughout the PP continuous phase, but also the melt blending leads to the significant enhancement of the mechanical properties compared with counterpart samples prepared by one‐step melt mixing process. Also better dispersion of nano layers in the rubber compound before melt blending with PP results in higher mechanical properties of the resulted TPV. POLYM. ENG. SCI., 56:914–921, 2016. © 2016 Society of Plastics Engineers     

Dramatic influence of compatibility on crystallization behavior and morphology of polypropylene in NBR/PP thermoplastic vulcanizates

In this study, the isothermal/nonisothermal crystallization behavior of polypropylene (PP) in acrylonitrile butadiene rubber (NBR)/PP thermoplastic vulcanizates (TPVs) prepared with three different processing methods, the compatibility effect therein, and the mechanism involved were studied. We concluded that the vulcanized NBR particles in TPVs act as heterogeneous nucleation centers and increase the number of nuclei. The crystallization rate of PP thereby increases and the growth of PP spherulites is restrained because of the isolation of vulcanized NBR particles. Since the addition of compatibilizer improves the compatibility of NBR and PP, the smaller and uniformly dispersed NBR particles are obtained, resulting in more and smaller PP crystals as well as higher crystallization rate, compared with Ultra-fine fully vulcanized NBR particles (UFNBR)/PP TPV and NBR/PP TPV without compatibilization. The isothermal crystallization kinetics of PP in TPVs obeys the Avrami equation, whereas the nonisothermal crystallization kinetics is well described by the equation of Mo et al.     

Crosslink densities and phase morphologies in thermoplastic vulcanizates

The degree of EPDM crosslinking during dynamic vulcanization of a PP/ EPDM thermoplastic vulcanizate (TPV) was modified by varying its phenolic curative content. The rise in TPV viscosity, the drop in its swelling, the change in its NMR MAS lineshape, and the increase in its EPDM domain AFM force modulation hardness verified the increase in EPDM crosslink density with increasing curative content. Further, the EPDM crosslink extent in TPV was measured by either the bound phenolic or the residual diene content both determined by solid state NMR. SEM morphologies of cryo-faced and ruthenium-stained TPVs with varying curative contents were analyzed to determine the effects of cure on EPDM domain sizes and PP ligament thickness. A narrowing of the EPDM domain size distribution, with a decrease in the third moment of the distribution, was observed with increasing EPDM crosslink density. Correspondingly, the PP ligament number-average thickness was raised slightly.