动态硫化BR/EVA/SBS/HIPS热塑性弹性体的增强研究

采用动态硫化法制备了顺丁橡胶(BR)/乙烯-醋酸乙烯共聚物(EVA)/苯乙烯-丁二烯-苯乙烯共聚物(SBS)/高抗冲聚苯乙烯(HIPS)热塑性弹性体(TPE),通过在BR中充填炭黑的方式对复合体系进行增强,对其力学性能及断面微观结构进行了研究。结果表明,对于动态硫化BR/EVA/SBS/HIPS共混型TPE,当BR相中炭黑填充量在0~80phr的范围内,其动态硫化产物均表现出TPE的特征;随着炭黑用量的提高,复合体系的拉伸强度、撕裂强度、邵氏硬度趋于显著提高,断裂伸长率趋于下降,而扯断永久形变则趋于不变;未填充炭黑TPE的拉伸断面上两相界面结合良好;炭黑填充后的TPE的断面起伏较大但平滑,表明弹性较强。     

动态硫化EPDM/EVA热塑性弹性体的制备与性能

采用动态硫化法制备了三元乙丙橡胶(EPDM)/乙烯-醋酸乙烯共聚物(EVA)共混型热塑性弹性体(TPE),并对其力学性能和微观相结构进行了研究。结果表明,动态硫化EPDM/EVA型TPE的拉伸强度及撕裂强度均随EVA含量的增加而提高,当EVA含量低于50wt.%时,其应力-应变曲线呈现出典型的弹性体特征;EPDM/EVA的共混比为60/40时,所制备的TPE表现出了良好的综合性能;EPDM分散相粒径在20μm以下且较均匀地分散EVA基体中。     

充油BR/EVA/SBS/HIPS TPV的结构与性能

采用动态硫化法制备了充油顺丁橡胶(BR)/乙烯-醋酸乙烯共聚物(EVA)/苯乙烯-丁二烯-苯乙烯共聚物(SBS)/高抗冲聚苯乙烯(HIPS)共混型热塑性硫化胶(TPV),研究了在树脂相中填充芳烃油对TPV性能和亚微观结构的影响.结果表明,随着芳烃油用量的提高,TPV的硬度、拉伸永久变形、强度均呈显著下降趋势,而拉断伸长...     

BR／HDPE动态硫化共混体系橡塑并用材料的研究

以硫黄和DCP为交联剂,用动态硫化方法制备了BR/HDPE共混改性材料。当橡塑比为60/40～70/30时获得的热塑性弹性体,其伸但强度为10～20MPa,扯断伸长率350～520％,永久变形20～103％,硬度(邵氏A)76～90,炭黑对TPE有明显的补强效应,硫黄体系的TPE具有较大的扯断伸长率,而DCP体系的TPE的拉伸强度高,永久形变小,DCP可交联共混物中的BR和PE,使PE的结晶度降低。S和DCP交联体系共混物中PE的结晶度、结晶温度、非等温结晶的结晶能力、n值基本上不随BR量的多寡而变化,BR不影响PE的结晶机制。     

交联剂用量对BR/EVA热塑性硫化胶性能的影响

采用动态硫化法制备了BR/EVA热塑性硫化胶(TPV),考查了硫化体系中硫黄用量对混炼胶的硫化行为、静态硫化胶的溶出物含量及性能的影响,并对BR/EVA型TPV的力学性能及微观结构进行了研究。结果表明,随着硫黄用量的提高,混炼胶硫化历程中的平坦期较长,但t90趋于明显降低,静态硫化胶溶出物含量及力学性能均呈下降趋势;当硫黄用量为0.5份时,静态硫化胶及BR/EVA TPV表现出良好的综合性能。显微镜照片表明,BR硫化胶的粒状物平均尺寸为5～10μm左右,较均匀地分散在EVA树脂基体中;FE-SEM的测试表明,TPV的断面平滑,TPV具有良好的形变回复性。     

多元共混动态硫化SBR热塑性弹性体的研究

本文采用动态硫化技术,借助Brabender流变仪,研究了SBR/HDPE/EVA和SBR/HDPE/EVA/EPDM多元共混热塑性弹性体。结果表明,添加EVA可使共混物永久变形降低;添加EPDM可使共混物拉伸强度增高;适量的增塑剂可改善加工性能;动态硫化多元共混SBR热塑性弹性体具有返炼再生性能。     

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.     

BR/EVA/HIPS TPV的制备和性能研究

采用苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)改善BR/乙烯-乙酸乙烯酯共聚物(EVA)/高抗冲聚苯乙烯(HIPS)共混物的界面相容性,通过动态硫化法制备BR/EVA/HIPS TPV,并对其性能进行研究.结果表明:未加入SBS的BR/EVA/HIPS共混物未表现出橡胶类弹性体特征,而加入适量SBS的共混物表现出典型橡胶类弹性体特征;当SBS用量为8～12份时,BR/EVA/HIPS TPV的综合物理性能较好,拉伸断面平滑,界面相容性良好.     

PP/SBS/WGRT热塑性弹性体的制备及性能

用熔融法制备了聚丙烯(PP)/废旧轮胎胶粉(WGRT)共混体系,通过苯乙烯-丁二烯-苯乙烯热塑性弹性体(SBS)界面增容,获得了热塑性弹性体(TPE),对其力学性能和微观形貌进行了研究。结果表明:对于PP/WGRT共混体系,随着PP含量的增加,拉伸强度和模量趋于急剧增加,断裂伸长率均低于100%;采用SBS增容后,复合体系拉伸强度和撕裂强度获得显著提高,断裂伸长率最高可达120%,共混体系符合弹性体特征。拉伸断面的形貌研究表明,增容后体系的界面的结合获得极大的改善。     

HDPE/TPE消光膜结构与性能的研究

高密度聚乙烯(HDPE)薄膜具有较好的拉伸强度、硬度、阻隔性和消光性等,但是其结晶度较高导致薄膜柔软度不够,而且单一组分树脂薄膜的消光特性不如共混体系的好。采用热塑性弹性体丙烯-乙烯共聚物(TPE)对HDPE薄膜进行改性,通过调节热塑性弹性体(TPE)的含量,制备出组分比例不同的共混物薄膜,测试了各薄膜的光学性能和力学性能,并对其进行DSC、光学显微镜PLOM和原子力显微镜AFM观察,研究TPE对HDPE薄膜光学性能和力学性能的影响。结果表明,添加TPE后,HDPE共混物薄膜的结晶度比纯的HDPE薄膜的低,薄膜柔软度增加;当TPE含量为50%时,HDPE/TPE薄膜的柔软度、弹性模量和拉伸强度都与对比消光膜的比较接近。AFM和PLOM观察结果表明,随着TPE含量的增加,薄膜的表面粗糙度增加、微观晶体结构分布更加均匀,是使其消光性能变优的原因。     

Effects of dynamic vulcanization on the physical,mechanical, and morphological properties of high‐density polyethylene/(natural rubber)/(thermoplastic tapioca starch) blends

Blending of high density polyethylene (HDPE), natural rubber (NR), and thermoplastic tapioca starch (TPS) have been studied. Two series of samples having 5–30 wt% of TPS were prepared: (a) unvulcanized blends (control) and (b) dynamically vulcanized HDPE/NR/TPS blends. The composition of the HDPE/NR was constant and fixed at a blend ratio of 70/30. Morphology studies by SEM showed that the TPS particles were homogeneously dispersed and well‐embedded in vulcanized HDPE/NR matrix. The SEM micrographs showed agreement with the tensile strength and elongation at break values. Tensile strength improved significanly when the HDPE/NR/TPS blends were vulcanized by using sulfur curative system. The enhancement in tensile properties is attributed to the crosslinking reaction within the NR phase. J. VINYL ADDIT. TECHNOL., 18:192–197, 2012. © 2012 Society of Plastics Engineers     

Use of crosslinking agent to produce high-performance PLA/EVA blends via reactive processing

Poly (lactic acid) (PLA) is one of the most currently investigated polymers due to its production from renewable sources and biodegradability. Being a brittle polymer, PLA has low toughness, limiting its use for commercial applications. Therefore, the present work aims to produce PLA blends, using the ethylene-vinyl acetate copolymer (EVA), dynamically vulcanized with dicumyl peroxide (DCP) as a crosslinking agent. A 70/30 mixture of PLA/EVA was produced with 0.2, 0.4, 0.6, 0.8, and 1.0 phr DCP. The produced blends were characterized by torque rheometry, melt flow index (MFI), gel content, thermogravimetry (TG), and differential scanning calorimetry (DSC). Tensile properties, impact strength, heat deflection temperature (HDT), and blends morphologies (SEM) were also studied. The presence of increased dynamically vulcanized systems with added DCP was verified through torque rheometry, MFI, and gel content. Substantial increases in the impact strength and elongation at break were observed in PLA/EVA/DCP, providing super-tough materials at 0.6, 0.8, and 1.0 phr of DCP, with impact strengths of 829.5, 860.3, and 890.2 J/m and elongation at break of 138.5, 146.8, and 120.4%, respectively. These results are promising when compared with engineering polymers and blends. This is probably due to in situ compatibilizer PLA-g-EVA, which resulted in a homogeneous morphology as evidenced by SEM images.     

PP/EVA共混物的动态硫化研究

研究了动态硫化对聚丙烯/乙烯-醋酸乙烯酯共聚物(PP/EVA)共混物的性能和结构的影响。结果表明:动态硫化使PP/EVA共混物的力学性能(尤其是韧性)获得显著提高;通过对交联剂BIPB用量和助硫化剂S用量的合理控制可制得综合性能优异的PP/EVA动态硫化共混物;动态硫化可细化分散于PP基体中的EVA颗粒粒径,改善EVA的分散效果。最终制得的抗冲PP料主要性能均达到或超过国外同类产品水平。     

辐射交联LDPE/EVA混合体系泡沫片材性能的研究

辐射交联LDPE/EVA混合体系泡沫片材表观光滑、柔软,手感好,表观密度较小,材料具有优异的力学性能,较高的拉伸强度、断裂伸长率和撕裂强度。进一步研究了产生宏观性能差异的原因是辐射交联LDPE/EVA混合体系泡沫片材制备成型工艺的特殊性,体系的交联度对制品性能影响很大。通过凝胶分析知道交联度与辐照剂量、LDPE树脂的物理性能和EVA树脂在混合体系的含量有关。此外,LDPE树脂的物理性能和EVA在混合体系的含量对材料宏观性能也有影响。     

Orientation effects on the deformation and fracture properties of high‐density polyethylene/ethylene vinyl acetate (HDPE/EVA) blends

In this paper, the tensile deformation and fracture toughness of high‐density polyethylene (HDPE)/ethylene vinyl acetate (EVA) blends, obtained by dynamic packing injection moulding, have been comprehensively investigated in different directions of rectangle samples, including longitudinal, latitudinal and oblique directions relative to the flow direction. Two kinds of EVA were used with VA content 16 wt% (16EVA) and 33 wt% (33EVA) to control the interfacial interactions. The results indicate that molecular orientation and interfacial interaction play very important roles to determine the tensile behaviour and fracture toughness. Biaxial‐reinforcement of tensile strength was seen for HDPE/16EVA blends but only uniaxial‐reinforcement was observed for HDPE/33EVA blends. The difference is caused by the different interfacial interactions as highlighted by the peel test, scanning electron microscopy (SEM) observation as well as theoretical evaluation. Very high impact strength, decreasing with increasing EVA content, was observed when the fracture propagation is perpendicular to the shear flow direction, while a low impact strength, increasing slightly increasing with EVA content, was seen when the fracture propagation is parallel to the shear flow. The fracture of oblique samples is always along the flow direction instead of along the impact direction or tensile direction. The tensile behaviour and fracture toughness are discussed on the basis of the formation of transcrystalline zones, orientation of EVA particles and matrix toughness of HDPE in different directions. Copyright © 2004 Society of Chemical Industry     

Influences of blend proportions and curing systems on dynamic,mechanical, and morphological properties of dynamically cured epoxidized natural rubber/high‐density polyethylene blends

Thermoplastic elastomers (TPEs) based on dynamically cured epoxidized natural rubber/high‐density polyethylene (ENR/HDPE) blends were prepared. Influence of the process oil, blend proportion, and curing systems were investigated. It was found that the oil‐extended thermoplastic vulcanizates (TPVs) exhibited better elastomeric properties and improved ease of the injection process. Increasing the proportion of ENR caused increasing elastic response of elongation at break, tension set properties, and tan δ. It was also found that the TPV treated with phenolic resin exhibited superior mechanical properties and the smallest vulcanized rubber domains. The TPV treated with the conventional peroxide co‐agent curing system showed superior strength properties but had poor elastomeric properties. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers     

HDPE/EVA/LDPE共混物拉伸性能和流变性能研究

用ＥＶＡ、ＬＤＰＥ、ＣａＣＯ３改性,填充ＨＤＰＥ,研究了它们的用量,品种对共混珠拉伸性能和流变性能的影响。结果表明,共混物熔体为假塑性流体。ＥＶＡ、ＬＤＰＥ用量增加,共混物拉伸强度下降,但断裂伸长率和熔体流动性提高。     

Structure and properties of PP/POE/HDPE blends

This work was aimed to counteract the effect of ethylene‐α‐olefin copolymers (POE) by reinforcing the polypropylene (PP)/POE blends with high density polyethylene (HDPE) particles and, thus, achieved a balance between toughness and strength for the PP/POE/HDPE blends. The results showed that addition of HDPE resulted in an increasing wide stress plateau and more ductile fracture behavior. With the increase of HDPE content, the elongation at break of the blends increased rapidly without obvious decrease of yield strength and Young's modulus, and the notched izod impact strength of the blends can reach as high as 63 kJ/m² at 20 wt % HDPE loading. The storage modulus of PP blends increased and the glass transition temperature of each component of the blends shifted close to each other when HDPE was added. The crystallization of HDPE phase led to an increase of the total crystallinity of the blend. With increasing HDPE content, the dispersed POE particle size was obviously decreased, and the interparticle distance was effectively reduced and the blend rearranged into much more and obvious core‐shell structure. The fracture surface also changed from irregular striation to the regularly distant striations, displaying much obvious character of tough fracture. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011