短支链PP对长支链PP加工流变行为的影响及机理

研究了线型等规聚丙烯(iPP)和短支链聚丙烯(SCBPP)的引入对长支链聚丙烯(LCBPP)加工流变行为的影响。结果表明:将线型iPP引入LCBPP相当于降低了长支链分子在共混体系中的含量;而当SCBPP引入LCBPP时,由于短支链的隔离作用会使LCBPP分子链间距增大,并且阻碍了LCBPP长支链分子间的缠结,而未缠结的长支链则起到类似增塑剂的作用。因此,线型iPP和SCBPP的引入均会使LCBPP的剪切黏度降低,其中在用量相同的条件下,SCBPP对LCBPP剪切黏度的降低效果明显优于线型iPP。     

挤出工艺对POE/PP热塑性硫化胶性能的影响

采用双螺杆挤出机制备茂金属聚烯烃弹性体(POE)/聚丙烯(PP)热塑性硫化胶(TPV),研究螺杆转速和硫化温度对TPV微观结构和物理性能的影响。结果表明,POE/PPTPV中POE为分散相,PP为连续相;当挤出机螺杆转速为400r.min-1、硫化温度为190～200℃时,TPV的综合物理性能良好。     

热处理对MMT填充PP的结晶性能影响

研究了热处理对聚丙烯(PP)/MMT复合材料结晶性能的影响.结果表明:适当地对共混体系进行热处理,分子链段加速重排以提高结晶度和使晶体结构趋于完善.聚合物的一部分结晶形态逐渐由β晶型向α晶型转变.PP/MMT复合材料的结晶度提高.     

Influence of various crosslinking systems on the mechanical properties of gas phase EPDM/PP thermoplastic vulcanizates

Dynamically cured thermoplastic elastomers or thermoplastic vulcanizates (TPVs) are widely used nowadays for their unique characteristics. In this paper, gas phase ethylene–propylene–diene terpolymer (GEPDM)/Polypropylene (PP) TPVs with various crosslinking systems have been extensively studied to optimize the curative level in each crosslinking system with special reference to their mechanical properties. Optimized systems were compared for heat aging, recyclability, crosslink density, morphology studies, and dynamic mechanical analysis. Crosslinking by peroxide in the presence of triallyl cyanurate as a coagent gives best overall performance with reference to excellent heat aging behavior, tension set, and compatibility between GEPDM and PP. Conventional EPDM/PP system was also compared with GEPDM/PP system. GEPDM/PP system was found to exhibit better behavior in all respects. Significant correlations were obtained between delta torque values obtained from Moving Die Rheometer and modulus or cross link density of TPVs irrespective of the nature of crosslinking agent. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5463–5471, 2006     

Crystallization behavior and foaming properties of polypropylene containing ultra‐high molecular weight polyethylene under supercritical carbondioxide

In this study, a systematic investigation on the nonisothermal crystallization kinetics of conversional polypropylene (PP) containing various amounts of ultra‐high molecular weight polyethylene (UHMWPE) was reported, and the effects of UHMWPE on crystallization behavior of these PP materials and their foaming properties were also presented. The kinetic studies revealed that the incorporation of UHMWPE into PP led to an increase in the crystallization temperature and temperature range during the crystallization process as well as the relative crystallinity. This behavior was attributed to a comprehensive effect of the nucleation and entanglement of the UHMWPE chains. The kinetic models based on Ozawa's and Mo's methods were used to analyze the nonisothermal crystallization behaviors. It was found that the latter succeeded in describing the nonisothermal crystallization behavior of the PP containing UHMWPE, while the former was not appropriate. The activation energy for the nonisothermal crystallization determined by Kissinger's method also indicated that the crystallization ability of PP was improved with the addition of UHMWPE. Owing to the modification of the crystallization kinetics of the PP materials by introduction of UHMWPE, the foaming properties (i.e., cell uniformity and expandability etc.) were improved significantly. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

低碳醇对氟碳与碳氢表面活性剂复配体系泡沫性能的影响

普通碳氢表面活性剂与磺基甜菜碱氟碳表面活性剂(FS)相比,泡沫性能和耐油性不好。醇通常强烈地影响表面活性剂的自组织行为,醇的加入能提高表面活性剂的泡沫性能。本文采用Ross-Miles法探讨了低碳醇对FS与阴离子碳氢表面活性剂(AOS)复配体系FS/AOS泡沫性能的影响。结果表明,当甲醇、无水乙醇、异丙醇浓度分别为5%、3%、3%,复配体系FS/AOS的起泡性能和泡沫稳定性仍较好,在加入醇之后,煤油含量60%～80%时起泡性能和泡沫稳定性仍较好。不同碳数的低碳醇对复配体系泡沫性能的影响规律为:发泡性能甲醇最好、异丙醇次之、无水乙醇最差,异丙醇的稳泡性能较甲醇和无水乙醇差。     

Preparation and properties of branched polybutylenesuccinate

To obtain long branched polybutylene succinate (PBS), modified PBSs were prepared by introducing a branching agent, trimethylol propane (TMP), to the polycondensation system of succinic acid and 1,4‐butanediol. Molecular parameters such as absolute molecular weight and root‐mean‐square (RMS) radius of the modified PBSs were measured by gel permeation chromatography (GPC) with a multiangle laser light‐scattering (MALLS) detector. The RMS radius of TMP05, PBS prepared by incorporating 0.5 wt % TMP during polycondensation, was the smallest of all PBSs tested at the same molecular weight. The notable shear thinning and much reduced loss tangent for TMP05 qualitatively supported the difference in their molecular structures predicted by GPC. The analytical results indicated that introducing 0.5 wt % TMP produced PBS with chain branches long enough to produce molecular entanglements. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1388–1394, 2001     

纳米SiO2对动态硫化EPDM/PP热塑性硫化胶性能的影响

采用不同硫化体系动态硫化制备三元乙丙橡胶/聚丙烯热塑性硫化胶(EPDM/PP TPVs),并在制备的过程添加不同量的纳米SiO2。结果表明酚醛树脂2402动态硫化得到的EPDM/PP TPVs性能最佳。随着纳米SiO2添加量的增加,EPDM橡胶粒子的粒径先减小后增大,当纳米SiO2的添加量为10份时,EPDM橡胶粒子的粒径达到最小。流变性能研究表明添加纳米SiO2使EPDM/PP TPVs的加工性能变差。动态机械分析仪(DMA)研究表明纳米SiO2提高了TPVs中PP相的玻璃化转变温度。当纳米SiO2的添加量为10份,TPVs的拉伸强度达到最高为23.7MPa,提高了19.1%,断裂伸长率达到最大为431%,提高了11.1%。纳米SiO2使EPDM/PP TPVs的热稳定性和耐热老化性能变好。     

Nanodiamond-based PP/EPDM thermoplastic elastomer composites: Microstructure,tribo-dynamic,and thermal properties

Attempts have been made for the first time to employ graphitized nanodiamond with the cage-like structure to prepare thermoplastic elastomer (TPE) nanocomposites based on polypropylene (PP) and ethylene-propylene-diene rubber (EPDM), with improved tribo-dynamic properties. Samples were prepared via melt mixing process, and maleated polypropylene (PP-g-MAH) was used to promote the interfacial interactions between the components and partitioning of nanodiamond particles in polymer phases. Microstructure characterization revealed significant reduction in the size of EPDM droplets if nanodiamond particles are preferentially wetted by the polypropylene phase. Nanoindentation and scratch tests performed on the surface of prepared nanocomposites exhibited enhanced surface stiffness and scratch resistance. Rheomechanical spectroscopy (RMS) and dynamic mechanical analysis (DMTA) showed enhanced melt elasticity for the interfacially compatibilized nanocomposites, which is attributed to the antiplasticizing characteristics of the caged shape nanodiamond particles. More interestingly, nanodiamond particles exhibited plasticizing behavior for the nanocomposite in molten state. All interfacially compatibilized nanodiamond composites showed enhanced thermal resistivity. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

动态硫化EPDM/PP共混物力学性能的研究

考察了硫黄用量和聚合物共混比对动态硫化ＥＰＤＭ／ＰＰ热塑性弹性体性能的影响。结果表明,随着硫黄用量增大,ＥＰＤＭ／Ｐ共混物的拉伸强度、１００％定伸应力和扯断伸长率先增大后减小、硬度有所增大,随着ＰＰ用量的增大,ＥＰＤＭ／ＰＰ共混物的拉伸强度、１００％定伸应力和硬度均有所增大,扯断伸长率也先大后减小。ＰＰ用量的变化对这些性能的影响更显。     

SBR/PP动态硫化热塑性弹性体的制备及其力学性能的研究

研究了聚丙烯（PP）牌号、橡塑比、硫化体系和不同填料对丁苯橡胶／聚丙烯（SBR／PP）动态硫化热塑性弹性体力学性能的影响。研究结果表明：选用牌号为EPC-30R—H的PP与SBR共混，橡塑比为70／30（质量比），硫磺的用量为1．25份左右（或DCP的用量为1．5份左右），沉淀白炭黑用量为30份，而滑石粉用量为30份时，共混物的综合力学性能较好。     

基于废旧轮胎胶粉的热塑性弹性体的制备及发泡性能研究

通过沥青改性胶粉及采用相容剂与聚丙烯共混制备了性能优良的热塑性弹性体(TPE)材料,并以超临界流体为发泡剂对其发泡性能进行了研究。实验结果表明,胶粉通过沥青改性后,可以明显地提高TPE的拉断伸长率,并且发泡TPE的泡孔平均直径增大,泡孔密度减少,相对密度减小,但是随着沥青用量的增加,材料的粘度降低,从而出现泡孔破裂和塌陷现象,最后导致泡孔平均直径和泡孔密度减小,相对密度增加。相容剂苯乙烯嵌段共聚物接枝马来酸酐(SEBS-g-MA)可以提TPE的拉断伸长率并改善泡孔结构。温度的升高和饱和压力的增大,都导致了发泡弹性体的泡孔增大,泡孔密度和相对密度减小。     

CaCO_3对EPDM/PP热塑性弹性体性能的影响

在双螺杆挤出机上采用动态硫化的方法制备CaCO3改性三元乙丙橡胶/聚丙烯(EPDM/PP)共混型热塑性弹性体(TPV),研究了CaCO3添加量对热塑性弹性体拉伸性能、流动性能和邵氏A硬度的影响,并对材料进行热失重分析、差示扫描量热分析以及X射线衍射分析。结果表明:CaCO3对TPV有增强的作用,随着CaCO3含量的增加,热塑性弹性体的拉伸强度和断裂伸长率有很大提高,当CaCO3质量分数为9%时,拉伸强度、断裂伸长率、100%定伸应力与邵氏A硬度达到最大值,随后逐渐降低;CaCO3的加入增加了TPV的流动性,使其热稳定性提高,结晶温度降低,使PP的β(300)晶面消失。     

配方和共混方法对EPDM／PP性能的影响

研究了不同硫化体系,混炼方式,软化剂和补强剂的用量对动态硫化ＥＰＤＭ／ＰＰ共混物性能的影响。实验得出,树脂硫化体系综合性能最好;加工方式以二步混炼效果较好。采用树脂硫化体系,环烷油和白炭黑用量分别为４０份和１０份时,经一步混炼制出的共混物的拉伸强度为７．６９ＭＰａ,扯断伸长率为２６０％,撕裂强度为４１．６９ｋＮ／ｍ,屈挠大于１０万次,硬度为（邵尔Ａ）８５度,加工流动性好。     

低硬度EPDM/PP热塑性弹性体力学性能的研究

就不同参数的三元乙丙橡胶(EPDM)、酚醛树脂硫化剂用量和催化剂与活化剂质量比对三元乙丙橡胶／聚丙烯(EPDM／PP)热塑性弹性体的力学性能和交联密度的影响进行了研究，结果表明：选择END型高不饱和度、适中乙烯含量、高充油型EPDM是制备低硬度热塑性弹性体的较佳选择；当酚醛树脂用量5-7份，催化剂／活化剂质量比为0．12—0．2时，获得的弹性体综合力学性能最好；比较发现，自制的低硬度热塑性弹性体力学性能已接近或达到国外同类产品水平。     

PP/微球复合材料的发泡行为及力学性能

选用PP(EPS30R)、PP(K9928)为基体材料,分别加入EK405、EK406微球母粒,在二次开模条件下制备微发泡PP/微球复合材料,研究不同特性树脂和微球母粒对PP/微球复合材料发泡行为及力学性能的影响规律。结果表明:微球母粒EK406适合于PP/膨胀微球复合材料的发泡,发泡倍率达12%,泡孔平均直径和泡孔密度分别为29.94μm、7.93×106个/cm3,能够获得泡孔细小、均匀而致密的微发泡聚丙烯材料。熔体指数低的PP材料适合于微球发泡,发泡质量较好,综合性能理想,拉伸和冲击强度分别为18.52 MPa、13.18 kJ/m2,比强度达到23.03。     

改性剂对聚丙烯流变性能和发泡行为的影响

在改性聚丙烯PPFP1920中加入丙烯酸类树脂改性剂(记作G200)进行共混改性,制备了PPFP1920/G200复合材料,研究了G200含量对聚丙烯流变性能、发泡行为的影响.结果表明:随着G200含量的增加,复合材料的熔体流动速率大幅降低,复数黏度和低频储能模量提高,低频损耗因子降低,熔体弹性变好,复合材料可发泡性提...     

Effect of die geometry on foaming behaviors of high‐melt‐strength polypropylene with CO2

This article reports on a systematic study that was conducted to investigate the effects of die geometry (i.e., pressure and pressure drop rate) on the cell nucleation and growth behaviors of noncrosslinked high‐melt‐strength (HMS) polypropylene (PP) foams blown with supercritical CO₂. The experimental results showed that the cellular morphologies of PP foams were sensitive to the die geometry. Furthermore, the initial expansion behavior of the foam extrudate at the die exit was recorded using a high‐speed CCD camera. This enabled us to achieve a more thorough understanding of the effect of die geometry on both the initial expansion behavior and the final cellular morphology of HMS PP foams. The effect of die temperature on cell morphology was also studied. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

EPDM/POE/PP共混制备热塑性弹性体的性能研究

采用动态硫化的方法制备三元乙丙橡胶（EPDM）/聚烯烃弹性体（POE）/聚丙烯（PP）热塑性弹性体,讨论了EPDM、硫化剂、炭黑的用量和填料种类对热塑性弹性体性能的影响。结果表明：随着EPDM用量的增加,EPDM/POE/PP热塑性弹性体的拉伸强度、定伸应力和硬度都呈减小趋势,而拉断永久变形呈上升趋势;随着SP-1055用量的增加,其压缩永久变形显著降低;随着炭黑用量的增加,弹性体的拉伸强度、定伸应力和硬度先下降后增加,而拉断伸长率、拉断永久变形和压缩永久变形先增大后降低;在不同填料种类中用N85作为填料时,弹性体的综合性能最好,压缩永久变形最小。     

Investigation on the cell nucleation and cell growth in microcellular foaming by means of temperature quenching

The cell nucleation and real‐time cell growth with increasing cell growth time in microcellular foaming were investigated by means of temperature quenching in a supercritical CO₂ pressure‐quench process. Samples of uniform size and shape were saturated in a vessel under conditions of 100–180°C and 30 MPa, and then depressurized to the atmosphere in 10 s. After depressurization, these samples were removed from the vessel at prescribed intervals, and immediately immersed in an ice‐water slurry to obtain foamed samples with various cell growth times. It was found that the nucleation density is closely correlated to the gas absorption capacity of the polymer matrix, so that the final cell density should not be adopted as the nucleation density, as done commonly. The change of cell structure and mass density with increasing cell growth time was dominated by gas diffusion behavior, which was strongly influenced by the temperature. The final cell structure was mainly determined by the cell growth step, where gas diffusion played a key role. The final cell density was in direct proportion to the gas remaining in the substrate, which ranged from 6.0 × 10⁹ to 4.7 × 10⁶ cells/cm³. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 163–171, 2004