CaSO4晶须与EPDM／PP共混型热塑性弹性体复合材料的研究

研究了ＣａＳＯ４晶须与三元乙丙橡胶／聚丙烯共混型热塑性弹性体复合材料的物理机械性能、耐热性能、热老化性能、材料的和各向异性、流变性能,考察了复合材料物理机械性能与晶须用量、界面特性、弹性模量等之间的依赖关系。应用ＳＥＭ观察和ＤＳＣ热分析以及ＴＧ热重分析研究复合材料结构－性能间关系中存在的一些制约机理。     

PP及PP/EPDM共混物室内外老化行为的研究

通过中国西部3个地区（新疆尉犁、西藏拉萨和四川成都）室外自然老化和室内加速老化（热氧、紫外老化）的对比,研究了聚丙烯及聚丙烯/三元乙丙橡胶（PP/EPDM）共混物室内外老化前后力学性能的变化和表面微观形态的变化,以及其室内外老化的对应关系。结果表明,室外老化初期PP的拉伸强度提高,老化中后期随着降解程度加剧拉伸强度下降;EPDM的加入提高了PP的耐老化性能,其中成都地区老化试样最为明显,24个月后拉伸强度保持率高达115 %;PP和PP/EPDM共混物室内热氧老化后拉伸强度变化不大,紫外老化后拉伸强度则呈现下降趋势;综合考虑热氧和紫外老化,通过时间等效关系可以更好地联系室内外老化,为预测材料在自然状态下的服役寿命奠定了基础。     

EPDM与PP相容性研究的新发展

阐述了EPDM／PP共混型热塑性弹性体的发展历史，物料特性对相容性的影响、制备工艺对相容性的影响、增容研究、及研究展望。     

具有“沙袋”结构的PP/EPDM/CB导电复合材料的形态构建及性能研究

提出通过构建类似拳击训练沙袋的硬核-软壳分散相结构来同时实现导电高分子复合材料的高电导率和高韧性这一设想,并通过两步熔融共混法构建了这种具有“沙袋”分散相结构的聚丙烯（PP）/三元乙丙橡胶（EPDM）/炭黑（CB）导电复合材料,其中,CB粒子选择性分布于EPDM分散相中。通过定量计算发现,无论从热力学角度还是动力学角度,CB粒子均倾向于选择性分布在EPDM中,这也阐明了“沙袋”分散相结构的形成机理。此外,性能测试表明,这种具有“沙袋”分散相结构的导电复合材料的体积电导率和缺口冲击强度随炭黑含量的增加呈现反常的同步增长。     

动态硫化PP／EPDM性能对共混工艺的依赖及其机理研究

本文通过对一步法和母料法两种共混工艺制备的动态硫化ＰＰ／ＥＰＤＭ力学性能、拉伸形变特性,熔体流动行为,交联程度和微观结构等的表征和分析,研究了动态硫化ＰＰ／ＥＰＤＭ性能对共混工艺的依赖及其作用机理。结果显示,在保证有效地提高材料加工流动性的前提下,母料法能有效地抑制动态硫化中ＰＰ的降解,提高ＥＰＤＭ的交联程度,粒度均匀性和分散均匀性,从而强化材料的增韧效果以及其它力学性能,并提高材料性能的均匀性。     

交联硫化体系对PP／POE／EPDM热塑性弹性体性能的影响

采用动态硫化法制备聚丙烯／聚烯烃弹性体／三元乙丙橡胶（PP/POE／EPDM）共混型热塑性弹性体,研究了交联前后不同POE／EPDM并用对比体系力学性能的影响。采用交联剂过氧化二异丙苯（DCP）及DCP／S硫化体系对PP／POE／EPDM体系进行硫化,研究了力学性能的变化。结果表明,EPDM可有效降低材料的硬度和断裂永久变形。助交联剂硫黄（S）对PP／POE／EPDM体系有较好的硫化作用,固定DCP用量为3份,S用量为0．4份时,体系力学性能最佳,交联对体系硬度影响很小。     

EPDM-g-MAH对PP膨胀阻燃材料性能的影响

采用氮磷膨胀型阻燃剂制备了无卤阻燃聚丙烯(PP)材料,研究了马来酸酐(MAH)接枝三元乙丙橡胶(EPDM)(EPDM-g-MAH)对PP无卤阻燃材料性能的影响.结果表明:加入EPDM-g-MAH可提高阻燃剂和PP基体间的界面作用,降低试样在燃烧过程中的熔融滴落现象,且加入EPDM-g-MAH提高了阻燃PP的力学性能.此外,加入EPDM-g-MAH可提高PP无卤阻燃材料在高温(600～800℃)下的炭层热稳定性以及材料的最大热分解速率,但会降低材料的最大热分解温度.因此,少量的EPDM-g-MAH可以提高PP无卤阻燃材料的极限氧指数(LOI),但当w(EPDM-g-MAH)超过10％时,PP无卤阻燃材料的LOI下降,阻燃性能降低.     

Dynamic mechanical and impact properties of polypropylene/EPDM blends

It was established by instrumented impact testing on notched Charpy specimens (DIN 53453 standard, No. 2 bar) that PP homopolymers impact modified by EPDM sorts of different melt viscosities at a rate lower than 10% were subject to brittle fracture in a wide temperature range. The most efficient of the EPDM impact modifiers had melt viscosities similar to that of the starting PP under the conditions of mixing. The course of maximum load at rupture (F_max) and notched impact strength as functions of temperature showed some analogies with one another as well as with the dynamic mechanical storage (E′) and with the mechanical loss factor (tan δ). Thus, linear regression analysis was applied to the following relations: F_max vs. (E′; tan δ; impact strength), F²_max vs. (tan δ, impact strength) and impact strength vs. tan δ. The optimum correlation coefficients were obtained for F_max vs. E′ and impact strength vs. tan δ. The supposed linearity of the former relation suggested that notched small Charpy specimens behaved as linear elastic bodies at high-rate three-point bending while the latter function referred to the significant role of relaxation of the EPDM impact modifier in the dissipation of impact energy during brittle or semi-brittle fracture of the two-phase PP/EPDM blends. The above relations are rendered probable by the fact that frequency of impact load is 10² to 10³ Hz while that of the dynamic mechanical measurements is about 10¹ Hz.     

Effects of blend composition and dynamic vulcanization on the morphology and dynamic viscoelastic properties of PP/EPDM blends

The morphology and dynamic viscoelastic properties of isotactic polypropylene (PP) blended with oil-free/oil-extended ethylene–propylene–diene (EPDM) rubbers were studied. Unvulcanized and dynamically vulcanized blends with the compositions PP/EPDM = 50/50 and = 30/70 were investigated. The morphology was observed by phase contrasted atomic force microscopy. The dynamic viscoelastic properties were determined with a rheometer of plate–plate configuration. It was shown that the rheological behavior was strongly affected by both the composition and the morphology of the blends. Significant improvement in the flowability of the dynamically vulcanized blends was observed when oil-extended EPDM was used instead of the oil-free version. It was demonstrated that the rheological properties are mostly controlled by the elastomer phase at low frequencies, while in the high-frequency range the influence of PP becomes dominant. The peculiarities in the rheological behavior of the thermoplastic elastomers (uncured blends, TPE) and thermoplastic dynamic vulcanizates (TPV, dynamically cured blends) containing oil-extended EPDMs were traced to a limited compatibility between the PP and EPDM components in the melt. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

An investigation of silver electrodeposition from ionic liquids: Influence of atmospheric water uptake on the silver electrodeposition mechanism and film morphology

The electrodeposition of silver from two ionic liquids, 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF₄]) and N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide ([C₄mPyr][TFSI]), and an aqueous KNO₃ solution on a glassy carbon electrode was undertaken. It was found by cyclic voltammetry that the electrodeposition of silver proceeds through nucleation–growth kinetics. Analysis of chronoamperometric data indicated that the nucleation–growth mechanism is instantaneous at all potentials in the case of [BMIm][BF₄] and [C₄mPyr][TFSI], and instantaneous at low overpotentials tending to progressive at high overpotentials for KNO₃. Significantly, under ambient conditions, the silver electrodeposition mechanism changes to progressive nucleation and growth in [C₄mPyr][TFSI], which is attributed to the uptake of atmospheric water in the IL. It was found that these differences in the growth mechanism impact significantly on the morphology of the resultant electrodeposit which is characterised ex situ by scanning electron microscopy and X-ray diffraction.     

聚苯胺/磺化EPDM锌离聚体导电复合物的制备与性能

在十二烷基苯磺酸存在下，用原位乳液聚合技术聚合苯胺，制得了聚苯胺和磺化乙丙橡胶（EPDM）锌离聚体复合物，EPDM锌离聚体由EPDM磺化及中和制得。用磺化度分别为0.10,0.24,0.40mmol/g的EPDM锌离聚体作为基质制备出各自的复合物，复合物可以熔融热塑加工，其导电率呈现的渗滤阈值为13%，在聚苯胺质量分数相同的情况下，磺化度小的复合物的电导率高于磺化度大的复合物。当磺化度为0.10mmol/g、聚苯胺质量分数为6%～11%和磺化度为0.24mmol/g、聚苯胺质量分数为2%～11%时，复合物表现出热塑性弹性体的行为，扯断伸长率达200%～500%，永久变形小于40%，用间甲酚进行二次掺杂后复合物的电导率有所提高，加入硬脂酸锌会降低复合物的电导率及力学性能。     

PP/EPDM热塑性弹性体结晶与熔融行为研究

采用动态光交联法制备了PP／EPDM[聚丙烯／（乙烯／丙烯／二烯）共聚物]热塑性弹性体。运用广角X射线衍射（WAXD），偏光显微镜（POM）与差示扫描量热仪（DSC）对PP的结晶形态及结晶与熔融行为进行表征。结果表明，EPDM的加入妨碍PP形成完善的球晶，而动态光交联体系中PP的球晶更不完善；动态光交联对PP的结晶温度及熔点影响不大，结晶度低于未交联体系的。     

丙烯酸接枝聚丙烯对聚丙烯／环氧化三元乙丙橡胶共混体系形态和性能的影响

研究了丙烯酸接枝聚丙烯（PP—g-AA）作为增容剂对聚丙烯（PP）／环氧化三元乙丙橡胶（eEPDM）共混体系形态和性能的影响。结果表明，在以PP为连续相而eEPDM为分散相时，PP—g-AA的加入大大提高了两相间的相容性，导致eEPDM分散相的细化；PP—g-AA中的羧基与eEPDM中的环氧基团发生了化学反应，形成了接枝共聚物，降低了PP／eEPDM之间的界面张力，起到了很好的界面增容剂的作用，对共混体系韧性的提高非常有利。     

The microwave-assisted ionic liquid nanocomposite synthesis: platinum nanoparticles on graphene and the application on hydrogenation of styrene

The microwave-assisted nanocomposite synthesis of metal nanoparticles on graphene or graphite oxide was introduced in this research. With microwave assistance, the Pt nanoparticles on graphene/graphite oxide were successfully produced in the ionic liquid of 2-hydroxyethanaminium formate [HOCH₂CH₂NH₃][HCO₂]. On graphene/graphite oxide, the sizes of Pt nanoparticles were about 5 to 30 nm from transmitted electron microscopy (TEM) results. The crystalline Pt structures were examined by X-ray diffraction (XRD). Since hydrogenation of styrene is one of the important well-known chemical reactions, herein, we demonstrated then the catalytic hydrogenation capability of the Pt nanoparticles on graphene/graphite oxide for the nanocomposite to compare with that of the commercial catalysts (Pt/C and Pd/C, 10 wt.% metal catalysts on activated carbon from Strem chemicals, Inc.). The conversions with the Pt nanoparticles on graphene are >99% from styrene to ethyl benzene at 100°C and under 140 psi H₂ atmosphere. However, ethyl cyclohexane could be found as a side product at 100°C and under 1,520 psi H₂ atmosphere utilizing the same nanocomposite catalyst.     

POE/EPDM TPV的结构与性能研究

采用动态硫化法制备了聚烯烃弹性体（POE）三/元乙丙橡胶（EPDM）热塑性硫化胶（TPV）,并对其力学性能、微相结构和应力松弛进行了研究。结果表明,POE/EPDM TPV的应力-应变曲线具有典型的弹性体特征;较POE而言,POE/EPDM TPV具有较低硬度和永久形变;EPDM橡胶相的粒径在几微米到几十微米之间,较均匀地分散在POE连续相中;TPV的应力松弛速率随EPDM用量的增加而降低,随应变的增大而加快。     

EPDM/POE/PP热塑性硫化橡胶材料的制备及性能研究

以三元乙丙橡胶(EPDM)/乙烯-辛烯共聚物(POE)/聚丙烯(PP)为原料,在PP含量固定的情况下,将POE部分取代EPDM,采用动态硫化技术制备出EPDM/POE/PP三元热塑性橡胶材料(TPV),研究不同含量的POE对材料力学性能、流变性能和微观形貌的影响。结果显示,随着POE含量的增加,三元TPV材料的硬度和熔体质量流动速率不断增大;拉伸强度和断裂伸长率呈线性增大,当EPDM/POE/PP比例为45/40/15时,材料力学性能达到最大值。流变性能和微观形貌分析结果表明,EPDM/POE/PP三元TPV材料具有良好的综合性能。     

Influence of Process Parameters on the Mechanical and Foaming Properties of PP Polymer and PP/TALC/EPDM Composites

In this study, PP and Talc/EPDM/PP composite materials are used. Foaming process is achieved by a conventional injection molding method. The influence of injection pressure and melting temperature on the average cell dimension, cell number, skin layer thickness, foam density and mechanical properties of investegated foam materials were evaluated. It is observed that cell density is increased by the increment of injection pressure. However, the values of skin layer thickness, density, cell diameter and charpy impact strength are decreased. In addition, the values of skin layer thickness, cell density, density and impact strength are increased with the increment of melting temperature.     

基于HDPE/EPDM TPV的超疏水表面的构建及性能

以高密度聚乙烯(HDPE)/三元乙丙橡胶(EPDM)热塑性硫化胶(TPV)为原材料,采用金相砂纸为模板,通过模压法在TPV表面构建出超疏水表面。FE-SEM的观察表明,以金相砂纸为模板可在TPV表面获得具有较高保真度的微米级粗糙结构,模压过程中TPV表面发生的塑性变形,使得TPV表面具有比砂纸表面更为复杂的粗糙结构;润湿性测试结果表明,基于TPV的粗糙表面具有良好的疏水性,当磨料目数高于W14号砂纸时,模压后TPV表面与水的接触角可超过150°,且滚动角在10°以内,符合Cassie模型;采用W10号砂纸为模板制备的TPV表面具有最佳的超疏水性能。     

十溴二苯醚与Sb2O3对EPDM/PP的阻燃化研究

用氧指数、力学性能、热失重分析方法研究了十溴二苯醚(FR-10)以及与Sb2O3配合使用对三元乙丙橡胶／聚丙烯(EPDM／PP)阻燃耐热性和力学性能的影响。结果表明。单独使用FR-10或Sb2O3对EPDM／PP有一定的阻燃作用,但效果不明显;FR-10与Sb2O3配合使用具有明显的协同阻燃作用,阻燃效果较好。阻燃剂的加人会使共混体系的力学性能下降。加人FR-10及其与Sb2O3的配合物虽然降低了EPDM／PP的起始失重温度。但不影响其正常使用。     

Preparation and electrochemical properties of functionalized ionic liquid self-assembled modified graphite electrode

A modified graphite electrode with functionalized ionic liquid (IL) pyridinium derivative of β-cyclodextrin ([CDbPy]BF₄) was prepared by layer-by-layer self-assembly technique. With ferrocene as probe, the characterization of the (CDIL/PDDA)_n/GE SAMs in the solution of phosphate (PBS, pH 7.0) was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronocoulometry. The electrochemical behavior of p-chloronitrobenzene (p-CNB) at the modified electrode was studied. It was found that the modified electrode could catalyze the reduction of p-CNB and made the cathode peak move about 100 mV in positive direction in the solution of 0.1 mol/L PBS (pH 7.0). Differential pulse voltammetry (DPV) was applied to the determination of p-CNB in waste water with satisfactory results. The detection limit and the linear range of the concentration of p-CNB to the reduction peak current were 8.0 × 10⁻⁸ mol/L and 3.0 × 10⁻⁷–1.0 × 10⁻⁵ mol/L, respectively.