纳米二氧化硅与辐射硫化三元乙丙橡胶相互作用的研究

用Kraus方程、IR光谱和交联密度等手段研究了纳米二氧化硅与辐射硫化三元乙丙橡胶间的相互作用。Kraus曲线显示纳米二氧化硅与辐射硫化三元乙丙橡胶之间存在着相互作用；红外光谱的结果表明纳米二氧化硅与橡胶分子发生了化学反应，生成了化学键。用平衡溶胀法测定了纳米二氧化硅填充辐射硫化三元乙丙橡胶的交联密度，发现当填料含量低于40phr时，填充辐射胶的总交联密度随填料用量增加而提高；继续增加填料含量，总交联密度不再继续提高；物理交联密度也呈现出相同的变化趋势。同时，纳米二氧化硅与辐射硫化三元乙丙橡胶的相互作用增强，使得硫化胶的力学性能随着相互作用的加强而得到改善。     

三元乙丙橡胶/蒙脱土纳米复合材料制备中硫化体系的比较

采用了熔融插层和两种硫化体系硫磺 促进剂和过氧化物体系制备了三元乙丙橡胶 蒙脱土纳米复合材料 ,并将这两种体系形成的纳米复合材料进行了形态、力学性能和光学性能的比较 ,同时采用Flory Rehner方程对它们的硫化行为进行了评价 .X射线衍射 (XRD)、透射电镜 (TEM)、力学性能和光学性能的测试结果表明 ,由硫磺硫化体系制备的纳米复合材料为不透明和剥离型 .其原有的d0 0 1 衍射峰消失 ,有序层被剥离成 10 0～ 2 0 0nm的片层均匀分散在EPDM基体中 ,其力学性能有了极大的提高 ;而过氧化物体系制备的纳米复合材料为半透明和插层型 .对两种体系的硫化行为的评价结果表明 ,随着有机蒙脱土加入量的增加 ,硫磺 促进剂硫化体系的t90 延长 ,交联密度减小 ,最大 最小转矩也变小 ;而过氧化物硫化体系的相应值却变化不大     

三元乙丙橡胶/聚丙烯热塑性弹性体

综述了三元乙丙橡胶/聚丙烯(EPDM/PP)热塑性弹性体的发展历程、市场情况以及EPDM/PP热塑性弹性体的结构、性能及其影响因素。EPDM/PP热塑性弹性体由EPDM和PP通过动态硫化技术制备而成,在室温下具有橡胶的高弹性,在加工温度下具有塑料的流动性。在性能上,EPDM/PP热塑性弹性体受加工设备、共混工艺、配合体系的综合影响。     

动态硫化EPDM／PP共混体系中PP相的结晶度及晶体结构的研究

研究了动态硫化ＥＰＤＭ／ＰＰ共混物中ＰＰ相的结晶度及晶体结构,同时讨论了制备工艺条件以共混物中ＰＰ相的结晶度和晶体结构的影响。结果表明：在动态硫化ＥＰＤＭ／ＰＰ共混物中,硫化的ＥＰＤＭ的分子键没有穿入ＰＰ的晶区,ＰＰ的结晶度随ＥＰＤＭ含量的增加而下降。提高共混温度,加入软化剂或碳黑均使共混物中ＰＰ的结晶度降低,共混时间１５ｍｉｎ时,共混物中ＰＰ相的结晶度最低,但ＰＰ的晶格不受制备工艺条件的影响。     

表面接枝改性纳米二氧化硅填充聚丙烯的结晶行为

应用差示扫描量热方法研究了纳米二氧化硅 (SiO2 )及其表面接枝改性对聚丙烯 (PP)结晶过程、等温与非等温结晶动力学的影响 ,并研究了上述等温结晶的熔融行为和平衡熔点 .研究发现纳米SiO2 具有明显的异相成核效应 ,能够提高PP的结晶温度、熔融温度、结晶度和结晶速率 ,但降低聚丙烯结晶的完善程度 .粒子的表面接枝处理 ,因改善了粒子与基体的亲和性而有利于粒子成核效应的提高 ,而且此效应尚与粒子的分散相关     

电感耦合等离子发射光谱法测定三元乙丙橡胶中钒

建立电感耦合等离子发射光谱法测定三元乙丙橡胶中金属钒含量的方法.样品经高温灰化、溶解后,以1.0％的硝酸溶液进行稀释,射频功率为1200 W,分析谱线为292.401 nm,等离子体气为氩气,流量为15.0 L/min,辅助气流量为1.50 L/min,雾化气为氩气,压力为200 kPa,观测高度为10 mm,采用等离...     

二氧化硅@聚合物同轴纳米纤维

The preparation and formation mechamsm ot silica/polyvinylpyrrolidone(PAN) coaxial nanofibers were presented in this paper. The PVP-PAN composite nanofibers were obtained via an electrospinning technique, while SiO2 nanoparticles were prepared according to a Stoeher method. The measurements of water contact angle(WCA), the compared results of silica coating PVPPAN composite nanofibers with PAN nanofibers indicate that much PVP resided on the composite nanofiber surface, which resuks in the occurrence of SiO2@polymer coaxial nanofibers due to the formation of hydrogen bonding between silica and composite nanofibers and subsequent adsorption of silica on the fiber surface.     

纳米级SiO2填充PVC/CPE复合材料研究

80年代以后发展起来的纳米材料被称为"21世纪最有前途的材料",已成为材料学中跨世纪的研究热点[1].纳米级无机粒子/聚合物复合材料是纳米材料中的一种具有重要价值的新型材料,可广泛应用于橡胶、塑料、纤维三大合成材料之中[2].其中,纳米级SiO2是纳米材料中的重要一员,它被称作跨世纪的高科技材料[3].因此, 本文就纳米级SiO2填充PVC/CPE复合材料进行探讨.     

纳米二氧化硅改性CPE的研究

采用纳米级SiO2改性氯化聚乙烯（CPE），探讨了SiO2用量、表面处理方法、加工工艺等因素对改性CPE力学性能的影响。通过机械共混制备了CPE／SiO2共混材料，性能测试表明：改性后CPE的硬度、300％定伸应力、断裂伸长率、拉伸强度等力学性能均有较大的提高。     

微波辐射下纳米二氧化硅接枝正辛醇的表面改性

在微波辐射下用正辛醇对SiO2纳米粒子进行表面接枝改性。改性SiO2纳米粒子的表征结果显示其亲油疏水性得到了很大提高。     

Radiation effects on SBR–EPDM blends: A correlation with blend morphology

The effect of γ radiation on the morphological and physical properties of Styrene–butadiene rubber (SBR) and Ethylene–propylene–diene monomer (EPDM) blends has been investigated. An attempt has been made to establish a correlation between various parameters like Gordon–Taylor parameter (k), hydrodynamic interaction parameter (Δ[η]_mix), chemical shift factor (b), Charlesby–Pinner parameter (p₀/q₀) and polymer–polymer interaction parameter (χ). The results showed a close dependence of mechanical and physical properties of irradiated blends on these parameters. The probability of spur overlap has been found to increase with the increase in EPDM content in the blends, which in turn results in significant improvement in the mechanical properties of the irradiated SBR–EPDM blends with higher EPDM fraction. The efficiency of four multifunctional acrylates as crosslinking aid for the radiation‐induced vulcanization of SBR–EPDM blend was also studied. The results established lower efficiency of methacrylates over acrylates in the process and indicated that among the crosslinking agents studied trimethylolpropane triacrylate is the most efficient one. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1676–1689, 2006     

Radiation effect on properties of carbon black filled NBR/EPDM rubber blends

Rubber blend of acrylonitrile butadiene rubber (NBR) and ethylene-propylene diene monomer (EPDM) rubber (50/50) has been loaded with increasing contents, up to 100 phr, of reinforcing filler, namely, high abrasion furnace (HAF) carbon black. Prepared composites have been subjected to gamma radiation doses up to 250 kGy to induce radiation vulcanization under atmospheric conditions. Mechanical properties, namely, tensile strength (TS), tensile modulus at 100% elongation (M₁₀₀), and hardness have been followed up as a function of irradiation dose and degree of loading with filler. On the other hand, variation of the swelling number as a physical property, as a function of same parameters, however, in car oil as well as brake oil has been undertaken. In addition, the electrical properties of prepared composites, namely, their electrical conductivity, were also evaluated. The thermal behavior of the prepared composites was also investigated. The results obtained indicate that improvement has been attained in different properties of loaded NBR/EPDM composites with respect to unloaded ones.     

Heat source and voiding signatures of Mullins damage in filled EPDM

The thermomechanical coupling of Mullins damage in filled EPDM has been investigated by analysing the self-heating via Infrared thermography (IR) and the voiding fraction by Digital Image Correlation (DIC). The volumetric strain measured during the rubber deformation is found to be predominantly associated with damage, while thermal dilatation caused by self-heating has a negligible contribution. On this basis, the thermomechanical coupling of Mullins phenomena has been identified by evaluating the strain and time dependence of the following criteria: the tangent modulus, the voiding rate and the heat sources. The tangent modulus that reaches a maximum at the strain transition from a series of cycle to another is found to be an appropriate mechanical signature of Mullin softening. At the same strain transition, both voiding rate upturn and heat source upturn are observed. These signatures suggest the Mullins damage to be mainly associated at high strain rate with the (re)-activation of dissipative cavitation mechanisms, by nucleation of new cavities and/or acceleration of cavities growth.     

STUDY ON THE MISCIBILITY OF DYNAMICALLY VULCANIZED EPDM/PP BLEND BY POSITRON ANNIHILATION SPECTROSCOPY*

Positron annihilation spectroscopy (PAS) was utilized to investigate the relationship between the free-volume holeproperties and miscibility of dynamically vulcanized EPDM/PP blend. The results showed that the noncrystalline region ofPP and EPDM in the blend was partially miscible and the miscibility of the blend became worse when the weight percent ofEPDM was <50%. This was also demonstrated by DMTA and mechanical properties of the blends with variouscompositions.     

EPDM/PP热塑性弹性体在循环应力下的老化行为研究

本文研究了动态硫化EPDM/PP热塑性弹性体的动态疲劳老化行为,考察了其力学性能的变化,并分析了产生力学性能下降的原因。实验结果表明,随着疲劳时间的延长、疲劳振幅的增大,材料的断裂强度降低,并认为疲劳过程中完全硫化的EPDM橡胶粒子和热塑性塑料PP界面处的分子链断裂、滑移导致了断裂强度的降低;紫外光的加入,加速了材料在疲劳过程的分子链断裂、滑移速率,使材料的断裂强度有更大程度的降低;在机械疲劳老化单独作用下,材料体系几乎没有发生氧化反应,而紫外光的加入,促使了机械疲劳老化过程中氧化反应的发生。     

The distribution coefficient of oil and curing agent in PP/EPDM TPV

The distribution coefficients of oil and curing agent in PP/EPDM TPV were calculated by measuring the melting point of the PP phase using differential scanning calorimetry (DSC). The PP/EPDM TPV was prepared by using a twin screw extruder and a peroxide curing agent was used. The peroxide induces the degradation of PP, resulting in the decrease of T_m. The oil in PP phase also decreases the Tm. Based on the T_m difference among pure PP and PP/EPDM TPV before and after extraction by cylcohexane, the calculated oil distribution coefficient is 0.537. The addition sequence of PP, oil, and curing agent has a significant effect on the T_m and the calculated curing agent distribution coefficient is 0.52. Both of the coefficients are less than 1. Based on the calculation of the two coefficients, a rationale design of thermoplastic vulcanizate (TPV) can be made by proper control of raw materials, addition sequence, and processing parameters. Copyright © 2007 John Wiley & Sons, Ltd.     

Physico-Mechanical Characteristics of Some EPDM/Plasticized PVC Blends

Summary: In this study were prepared blends based on ethylene propylene terpolymer rubber (EPDM) and plasticized poly (vinyl chloride) (PVC). These blends are immiscible and need to be compatibilized. The following compatibilization methods were used: (1) addition of a compatibilization agent; there were used: maleinized EPDM, maleinized polyethylene (PE), chlorinated polyethylene (CPE) and maleinized polypropylene (PP); chlorinated polyethylene has proved to be the most efficient; the amount of the added CPE giving the best physico-mechanical characteristics was of 7,5 parts to 100 polymer parts; (2) reactive compatibilization, using crosslinked copolymer formation strategy; three different crosslinking systems were used: (a) common method with sulphur and accelerators, (b) crosslinking with benzoyl peroxide and trimethylpropane trimethacrylate (TMPT DL 75), (c) vulcanization with phenol resin and tin chloride. The best physico-mechanical characteristics were obtained with the EPDM/plasticized PVC blends crosslinked with 8 phr phenol resin. Such types of polymer blends can be processed by methods specific for plastics, removing thus vulcanization operation required in case of elastomers. These blends can be used in the manufacture of hoses, gaskets, footwear constituents etc.     

Morphology and non-isothermal crystallization of dynamically vulcanized PP/EPDM blends in situ compatibilized via magnesium dimethacrylate

Polypropylene/ethylene-propylene-diene rubber (PP/EPDM) blends in situ compatibilized by magnesium dimethacrylate (MDMA) were fabricated via peroxide-induced dynamic vulcanization. Scanning electron microscope observation indicated that the size of cross-linked EPDM particles decreased with incorporation of MDMA. Polarizing Optical Microscope (POM) analysis suggested that the spherulite size of PP phase decreased sharply with incorporation of MDMA during dynamic vulcanization. The Pseudo-Avrami, Ozawa and Mo's models were applied to analyze the non-isothermal crystallization kinetics of the composites. The analyzed data indicated that the crosslinked EPDM particles and homopolymerized MDMA acted as heterogeneous nucleating agents, which enhanced the crystallizability and decreased the spherulite size of the PP phase. In addition, the non-isothermal crystallization activation energy (ΔE) was calculated through the Kissinger and Friedman methods, and the ΔE value was found increase with incorporation of MDMA.