EVM基共混物的阻尼性能

选用双叔基过氧化异丙基苯(BIPB)作为硫化剂,采用动态粘弹谱仪(DMA)对乙烯-醋酸乙烯酯橡胶(EVM)/乙丙胶(EPDM)和EVM/丁腈胶(NBR)两种共混体系的阻尼性能进行了研究.考察了聚氯乙烯(PVC)、N-环己基-2-苯井噻唑次磺(CZ)以及过氧化二异丙苯(DCP)对EVM基共混物阻尼性能的影响.实验结果表明...     

EPDM/ENR宽温域阻尼材料的制备及阻尼机理

采用饱和非极性三元乙丙橡胶(EPDM)和不饱和强极性环氧化天然橡胶ENR-50制备出EPDM/ENR-50二元共混阻尼材料。利用扫描电镜/X射线能谱分析、原子力显微镜分析表明,该共混体系拓宽阻尼温域的机理在于两相中硫化剂的迁移,即共混硫化交联过程中,饱和非极性的EPDM相中的硫化剂向极性不饱和的ENR-50相迁移,导致二元共混物中ENR-50交联密度比其单独硫化时高,阻尼内耗峰向高温方向外扩,而EPDM相的交联密度比单独硫化时低,阻尼内耗峰向低温方向外扩,最终得到了温度范围从-72.3℃到52.9℃(tanδ0.13)的宽温域阻尼材料。为了改进二元共混橡胶的阻尼性能和力学性能,进一步制备了EPDM/ENR-50/氯丁橡胶(CR)三元共混阻尼材料,所得三元共混胶的有效阻尼(tanδ0.3)温域范围超过120℃,同时材料具有良好的力学性能。     

PP／EPDM共混物的X射线衍射研究

用WAXD研究PP/EPDM共混物的结果表明,PP晶相中除了主要含有α-单斜晶型PP之外,还存在β-六方晶型PP结构特征,这归结于试样的冷却速度以及EPDM充当了β-晶型PP的非均相成核剂。β-晶型含量(K)取决于共混物组成,在10％EPDM时,K有极大值(19.53％)。本文还研究了β-晶型的形成对α-晶型结构的影响,共混物中EPDM含量为10％时,α-晶型的表观晶体尺寸、峰强度以及共混物的总结晶度均有极小值。     

二苯甲烷双马来酰亚胺对硅橡胶/三元乙丙橡胶共混物硫化特性和力学性能的影响

在硅橡胶(MVQ)和三元乙丙橡胶(EPDM)及其共混物中加入交联剂二苯甲烷双马来酰亚胺(BMI),研究了BMI对MVQ、EPDM及其共混物的硫化特性和力学性能的影响。EPDM的硫化活性低,正硫化时间是MVQ的3倍,共混物的共硫化性和相容性不佳。BMI能降低EPDM的活化温度,提高EPDM的硫化速度,同时减慢MVQ的硫化速度,从而使二者的硫化速度趋于接近。在MVQ/EPDM共混物中,BMI能使MVQ和EPDM在较低温度下同步反应,实现两组分的共硫化,改善MVQ与EPDM的相容性,提高了MVQ/EPDM共混物的力学性能。     

动态硫化EPDM／PP热塑性弹性体动态力学性能的研究

应用动态热力学分析仪测定了动态硫化EPDM／PP共混物的动态力不宪为,Tg峰的变化,表明P的非晶部分与EPDM具有部分互溶性,同时讨论了共混物动态模量的特点,研究了不同橡塑比,硫化剂和软化剂用量对动态硫化EPDM／PP共混物动态力学性能的影响。     

受阻酚封端聚氨酯/环氧树脂共混物阻尼材料的结构与性能EI北大核心CSCD

制备了系列受阻酚封端聚氨酯/环氧树脂(EP)共混物阻尼材料,研究了组成比和云母对共混物动态力学性能和拉伸性能的影响。结果表明,EP的加入显著拓宽了阻尼温域和改善了阻尼性能,随着EP用量的增加,共混物的拉伸强度显著增加,但断裂伸长率降低。加入填料云母后,材料的阻尼性能和拉伸性能均有所提升。     

利用超临界CO2调控聚合物二元共混物的相形貌及力学性能

共混物的相态结构在很大程度上决定了共混物的物理性质。本工作以超临界CO_2为溶剂,通过改变工艺来调控聚丙烯(PP)/三元乙丙橡胶(EPDM)共混物的相形貌,进而利用动态力学分析(DMA)仪研究其力学行为。结果表明,利用CO_2在PP和EPDM基体中较大的溶解度和溶胀度差异,在CO_2环境下退火处理PP/EPDM,可以显著增加EPDM相体积分数,进而促使EPDM相形貌从海-岛状结构向双连续结构转变。力学性能测试结果表明,在相同EPDM含量下,真空热退火后材料性能并没有发生显著变化,而经过CO_2退火后材料的储能模量和损耗模量均有提高,这意味着材料的刚性和韧性都得到提升。     

受阻酚封端聚氨酯/环氧树脂共混物阻尼材料的结构与性能

制备了系列受阻酚封端聚氨酯/环氧树脂(EP)共混物阻尼材料,研究了组成比和云母对共混物动态力学性能和拉伸性能的影响。结果表明,EP的加入显著拓宽了阻尼温域和改善了阻尼性能,随着EP用量的增加,共混物的拉伸强度显著增加,但断裂伸长率降低。加入填料云母后,材料的阻尼性能和拉伸性能均有所提升。     

乙烯-醋酸乙烯酯橡胶的共混改性

乙烯-醋酸乙烯酯橡胶(EVM)是一种重要的合成橡胶。文中介绍了不饱和羧酸盐增强EVM、EVM增韧改性尼龙1010和EVM/三元共聚尼龙共混物的研究工作。原位合成的不饱和羧酸盐能够显著改善EVM硫化胶的力学性能,是制备高性能和功能化EVM硫化胶的有效方法。EVM能够有效地增韧尼龙1010,EVM中醋酸乙烯酯的含量和EVM的门尼黏度是影响增韧效果的关键因素。采用三元共聚尼龙与EVM动态硫化,可以制备具有良好力学性能的热塑性弹性体。将EVM与塑料共混可以制备一系列具有良好力学性能和不同硬度的EVM共混物,这对于EVM材料的开发和应用具有重要的意义。     

硅橡胶/EPDM共混物在日本上市

日本合成橡胶公司和东芝有机硅公司开始销售他们共同开发的一种新材料——硅橡胶/三元乙丙橡胶(EPDM)共混物。在硅橡胶和EPDM的共混过程中,使用了一种特殊的添加剂,通过缓慢的化学结合,克服了硅橡胶和EPDM各自的缺点,终于开发出了耐热性能好、机械强度高的共混物。这种硅橡胶/EPDM共混物同单纯的硅橡胶比较,机械强度高、耐热水性优良;同单纯的EPDM比较,耐热性提高了约20℃。     

动态硫化对共混物TPU/EVM动态力学性能的影响

橡胶加工分析仪RPA2000测试发现,动态硫化后共混物的储能模量G′升高,应变和温度依赖性减弱,Payne效应减弱,损耗因子tanδ降低,但频率依赖性与动态硫化前相似;RPA2000温度扫描中发现,在温度低于80℃时,动态硫化后G′反而降低,动态粘弹谱仪(DMA)测试也显示,动态硫化后共混物在高弹态时储能模量比硫化前低,原因可能是交联网络破坏了在高弹态时对模量贡献很大的热塑性聚氨酯(TPU)与白炭黑之间形成的键合橡胶。     

TPU/EVM共混体系的动态硫化工艺

比较了通过HAAKE Rheocord90转矩流变仪用两种不同的动态硫化混炼方法对热塑性聚氨酯弹性体/乙烯-醋酸乙烯酯共聚物(TPU/EVM)共混体系性能的影响,硫化剂选用过氧化二异丙苯(DCP);探讨了密炼室转子转速和混炼温度对动态硫化共混物性能的影响。通过相差显微镜和傅立叶变换红外光谱仪(FT-IR)对硫化后共混物的微观结构进一步分析表明:动态硫化后的共混体系力学性能优于未硫化体系;两种不同动态硫化法制备的共混物性能相比,B法优于A法,且B法中两相呈明显互锁结构,相畴较小且均匀;FT-IR表明EVM主链的亚甲基和侧链的甲基参与了交联反应,且主要在亚甲基上;转速为30 r/min和混炼温度为150℃时共混物的综合力学性能最优。     

新型高阻尼宽温域氯化丁基橡胶复合材料制备及性能研究

以氯化丁基橡胶为基体材料,通过反增塑作用技术,成功制备出高阻尼宽温域氯化丁基橡胶复合材料,并研究其阻尼性能、力学性能及微观结构。结果表明：复合材料CIIR/CP-70/PF体系的损耗因子-温度（tanδ-T）曲线仅一个单峰,属热力学相容体系,与纯CIIR基体橡胶相比,复合材料的tanδ峰明显向高温移动,且最大损耗因子值及对应温度均大幅度提高,且峰值增加到1.38左右,有效阻尼温域范围90℃以上。同时,CP-70与PF的加入可兼具提高CIIR基体材料力学性能,具有很好的实用价值。SEM及DSC分析结果证明,CP-70以无定形状态分散在CIIR基体中,且CP-70与基体CIIR间存在反增塑作用。     

超支化聚氨酯/聚丙烯酸酯乳液的制备与阻尼性能的研究

以异佛尔酮二异氰酸酯(IPDI)、聚醚二元醇(PTMEG)和丙烯酸酯类单体为主要原料,三羟甲基丙烷(TMP)和自制的超支化聚氨酯(HBPU)为交联剂,合成了聚氨酯(PU)/聚丙烯酸酯(PA)水性乳液。热重分析(TGA)及动态力学分析(DMA)研究表明,采用两种交联剂合成的聚合物耐热性能相差不大,均具有良好的阻尼性能(阻尼因子tanδ约为0.75,tanδ>0.3的温度范围约为60℃);随着PA组份含量的增加,阻尼性能越好。     

Quantitative mapping of surface elastic moduli in silica-reinforced rubbers and rubber blends across the length scales by AFM

The surface elastic moduli of silica-reinforced rubbers and rubber blends were investigated by atomic force microscopy (AFM)-based HarmoniX material mapping. Styrene–butadiene rubbers (SBR) and ethylene–propylene–diene rubbers (EPDM) and SBR/EPDM rubber blends with varying concentrations of silica nanoparticles (0, 5, 10, 20, 50 parts per hundred rubber, phr) were prepared to investigate the effect of different composition on the resulting morphology, filler distribution and elastic moduli of a specific rubber or rubber blend sample. For SBR, the elastic modulus values varied from 0.5 MPa for unfilled SBR to 5 MPa for 50 phr reinforced SBR with the increase in the concentration of filler. For EPDM, the corresponding values increased from 1.4 MPa for unfilled EPDM to 4.5 MPa for 50 phr reinforced EPDM. Local stiff and soft domains in silica-reinforced SBR and EPDM rubbers and rubber blends were identified by HarmoniX AFM imaging. While the stiff silica particles show modulus values as high as 2 GPa, the rubber matrix reveals modulus values in the range of ca. 30 MPa for the rubber blends to ca. 300 MPa for the unfilled rubbers. The lower value of elastic modulus of the EPDM phase in the blend, compared to the blank EPDM compound can be attributed to the presence of Sunpar oil in the compound which has a very good affinity with EPDM and decreases the rubber modulus. The elastic moduli maps revealed an increase of the areal fraction of silica particles showing an intrinsic surface modulus value with rising silica content in the compound preparation mixture. HarmoniX AFM measurements revealed the formation of larger silica aggregates in EPDM in contrast to SBR where isolated silica particles were observed. For silica-reinforced rubber blends a phase separation into a soft (ca. 40 MPa) and a significantly harder phase could be observed (ca. 500 MPa–1.5 GPa) indicating the incorporation of silica particles in the SBR phase. Using HarmoniX AFM imaging significantly higher surface elastic moduli were observed compared to those obtained by bulk tensile testing. Possible reasons for the observed differences between bulk modulus values and those measured by AFM are discussed in detail, including the aspect of different averaging procedures like inherent to surface probing by AFM versus bulk tensile testing, different filler distributions in SBR and EPDM and the AFM modulus calibration procedures.     

Morphology, mechanical and thermal behavior of acrylate rubber/fluorocarbon elastomer/polyacrylate blends

Novel thermoplastic elastomers derived from binary and ternary blends of polyfunctional acrylates, acrylic rubber (ACM) and fluorocarbon rubber (FKM) were analyzed by using Transmission Electron Microscopy (TEM), Differential Scanning Calorimetry (DSC), Dynamic Mechanical Thermal Analysis (DMTA) and mechanical tests. TEM revealed the presence of a single-phase structure for both acrylate rubber/fluorocarbon elastomer (ACM/FKM) and ACM/polyacrylate binary blends. Increase of FKM concentration in the ACM/FKM/polyacrylate ternary blend resulted in phase separation of FKM from the ternary blend. The FKM formed a dispersed phase with polynodal particle distribution and irregular shape ranging from ellipsoidal to highly elongated form with inclusion of ACM. The FKM/polyacrylate binary blend showed complete phase separation. Ageing of the blend increased the domain size of the dispersed phase. Differential scanning calorimetric (DSC) and DMTA studies showed no major changes in the T _gs of individual polymers in the blend, although the peak tan values were affected on changing the composition of the blends. Vulcanization of the thermoplastic elastomer (TPE) changed the phase morphology with increase in particle size. There is a distinct difference in morphology of statically and dynamically vulcanized blends.     

Cut-growth behaviour of EPDM-bromobutyl rubber blends under repeated stressing

Cut-growth behaviour of ethylene-propylene -diene rubber (EPDM), bromobutyl rubber (BIIR) and their blends under dynamic loading has been studied over a range of temperatures. The crack-growth resistance increases with the increase of BIIR content in the gum and filled blends. The 30: 70 EPDM : BIIR blend, however, gives the best fatigue resistance because of morphology and strain energy density factors. Failure surfaces have been examined both by photography and electron microscopic techniques. The crack always propagates from the precut. The rate of crack propagation is faster for EPDM gum samples. The blends show fracture features intermediate between those of fractured BIIR and EPDM rubbers. Straight flow lines, cracks and fatigue striations (10 to 15m distance between two consecutive striations) are observed for gum samples. The flow lines are increased and the cracks are reduced for filled samples. The fractography of the crack front at the precut and that away from it are similar. At a higher temperature (100° C), there is a reduction of fatigue life for the blends and pure rubbers. Many cracks are observed on the fracture surface of gum and filled samples.     

氧化石墨烯对阻尼丁腈橡胶抗老化性能的影响

以丁腈橡胶(NBR)为基体,添加由改进Hammer法制备的氧化石墨烯(GO)和经过表面改性过的氧化石墨烯(MGO),制备出有着较高阻尼性能的阻尼材料,借助DMA,AFM,SEM等手段,研究NBR/GO与NBR/MGO共混物的阻尼与抗老化性能,研究结果表明,加入GO与MGO于NBR中后,损耗角正切值(tanδ)增大,且其抗老化性能也有所改善,添加较少量GO于基体中时,其抗老化性能较好,添加MGO于基体中时,添加量与共混物的抗老化性能关系不明显,说明GO和MGO的分散性对其抗老化性能有正相关性。通过微观分析发现,团聚是共混物抗老化性能下降的主要原因,而添加GO和MGO后所形成的界面效应则是其阻尼性能和抗老化性能优良的主要原因。