PPC／NBR弹性体的结构与性能

本文研究了聚丙撑碳酸酯(PPC)/丁腈橡胶(NBR)弹性体结构形态、动态力学性能、力学性能、耐油、耐热氧老化及耐化学介质稳定性。发现PPC/NBR弹性体呈现IPN结构特征,加入PPC使NBR拉伸强度、扯断伸长率大幅度提高。PPC/NBR弹陸体具有优良的耐油及耐热氧老化稳定性。     

弹性体偶联剂结构对PVC/PPC性能的影响

NBR－PPC弹性体偶联剂能促进PPC（聚丙撑碳酸酯）与PVC（聚氯乙烯）之间的相容性，改善共混物的力学性能，并在共混体系中产生轻度交联。偶联剂组成在NBR／PPC比例为70／30，NBR（丁腈橡胶）含腈量为34％，BPO过氧化苯甲酸用量为2．5份时，共混物的综合力学性能最佳，但偶联剂预先硫化时间不宜过长．     

共混方法对聚氯乙烯/聚丙撑碳酸酯相容性影响

本文分别用溶液法和熔融法制得聚氯乙烯（PVC）与聚丙撑碳酸酯（PPC）共混试样，用DSC证明PVC／PPC共混物不相容，但它们不相容的程度受分子量、共混比例等因素的影响，并根据玻璃化转变温度（Tg）计算出溶液共混试样PPC富相中PVC的重量百分含量。NBR／PPC弹性体作偶联剂对PVC／PPC共混体系具有较好的增容作用，共混物中PPC的用量及分子量对共混体系性能有一定的影响。     

插层型NBR/膨润土混杂材料及其对PVC增韧作用的研究

研究了胶乳插层法制备的丁腈橡胶 /有机改性膨润土 (NBR/OMB)混杂材料的力学性能和微观结构及其对聚氯乙烯 (PVC)的增韧作用。结果表明 :胶乳插层法制备的NBR/OMB混杂材料具有优异的力学性能 ;TEM和XRD结果表明 ,有部分NBR大分子嵌入到膨润土层间 ,形成较均匀、细致的分散。NBR/OMB混杂材料增韧PVC的效果明显优于NBR ,增韧后拉伸强度和弯曲强度的保持率明显提高     

高耐磨低生热NBR/TBIR复合材料的结构与性能

采用高反式-1,4-丁二烯-异戊二烯共聚橡胶(TBIR)对丁腈橡胶(NBR)进行改性, 制备了高耐磨、 低生热输送轮用白炭黑填充的NBR/TBIR橡胶纳米复合材料. 研究了NBR/TBIR橡胶纳米复合材料的交联密度、 物理力学性能及填料分散性, 探讨了材料的结构对性能的影响. 研究结果表明, 与纯NBR相比, NBR/TBIR橡胶纳米复合材料的硫化速率和交联密度随TBIR用量的增加而增大; 在保持NBR硫化胶基本力学性能、 耐老化性能和耐溶剂性能基本不变的前提下, TBIR的加入使NBR/TBIR硫化胶的耐磨性提高15%, 动态压缩生热降低5%, 动态压缩永久变形降低22%, 白炭黑分散水平提高; 与丁腈橡胶/顺丁橡胶[NBR/BR(80/20), 质量份数比]硫化胶相比, NBR/TBIR(80/20, 质量份数比)硫化胶具有更低的动态压缩生热和动态压缩永久变形及更好的填料分散性.     

共混硫化丁腈橡胶-氯丁橡胶的物理性能

将丁腈橡胶(NBR)和氯丁橡胶(CR)按不同质量分数共混并硫化,研究了硫化橡胶在自然环境、热空气老化、热油老化等条件下的物理性能,并测定了硫化橡胶与镀铜钢丝的粘合性能.结果表明,随着CR质量分数的增大,混炼胶的焦烧时间逐渐缩短.经热空气老化后,NBR的硬度增加幅度比CR的硬度增加幅度大,拉断强度降低幅度则比CR的小得多.此外,NBR的耐油性能优于CR.就物理性能以及与镀铜钢丝的粘合性能而言,单一NBR和单一CR优于共混NBR/CR.     

氯化聚丙撑碳酸酯增容聚丙撑碳酸酯/秸秆粉复合材料的制备及性能

聚丙撑碳酸酯(PPC)是一种新型热塑性生物降解材料,但其热性能及力学性能较差,应用受到限制。以秸秆粉这种农作物副产品作为增强体改性PPC,既可以提高PPC的力学性能同时又可开发利用秸秆资源。氯化聚丙撑碳酸酯(CPPC)是聚丙撑碳酸酯(PPC)经过氯化得到的,对天然纤维表面具有良好的浸润性和粘结性。本文以CPPC为增容剂,通过熔融共混法制备了PPC/秸秆粉复合材料。采用扫描电子显微镜(SEM)、拉伸实验、动态力学性能测试(DMA)及转矩流变仪对复合材料的结构及性能进行了表征,重点考察了CPPC的添加量对复合材料力学和流变性能的影响。结果表明,当CPPC质量分数为1.8%时,可使添加质量分数为30%秸秆粉的PPC复合材料拉伸强度提高38%,模量提高30%。同时,CPPC的引入使复合材料的粘度下降,改善了PPC/秸秆粉复合材料的加工性能。因此,作为增容剂的CPPC为制备高性能PPC/天然纤维复合材料提供了新的解决办法。     

取代基对PPC/聚苯醚羧酸酯共混体系相容性的影响

由二氧化碳活化并与环氧丙烷共聚而成的脂肪族聚碳酸酯(PPC)是一类有发展前途的新型高分子弹性体。研究它与其它高聚物的混容性及混容机制对于开拓这一新材料的应用领域具有十分重要的意义。本文合成了一系列不同取代度和不同链长酯基的聚苯醚羧酸酯[E(x)-C^yPPO]^[3],探索了PPC与各聚苯醚狡酸醋的混容性,讨论了聚苯醚梭酸酷的取代度及侧基链长对PPC/E(x)-C^yPPO共混体系混容性的影响。     

接枝和交联对纳米SiO_2改性NR/PP共混型热塑弹性体的影响

动态硫化制备纳米二氧化硅(SiO2)改性天然橡胶/聚丙烯共混型热塑性弹性体(NR/PP TPE).研究了马来酸酐/苯乙烯/过氧化二异丙苯(MAH/St/DCP)多单体“就地”熔融接枝、交联对TPE力学性能、耐溶剂性能和耐热变形性能的影响,并用SEM分析了TPE的断面形貌.结果表明:纳米SiO2和MAH/St/DCP的最佳质量分数分别为0.03和0.0375/0.0188/0.00375时,MAH/St/DCP接枝、交联改性NR/PP/纳米SiO2TPE的力学性能、耐溶剂性能和耐热变形性能最佳.MAH/St/DCP“就地”接枝、交联通过细化交联NR分散相、改善交联NR分散的均匀性和增加两相之间的共交联,使NR与PP两相界面结合强度明显提高,NR/PP TPE的综合性能得到明显的改善.     

微相分离结合氢键复合构筑弹性体

通过嵌段聚合物的微相分离和高分子氢键复合,使用聚苯乙烯-b-聚丙烯酸-b-聚苯乙烯(SAS)三嵌段聚合物和聚氧化乙烯(PEO)均聚物构筑了具有多层次结构的弹性体(SA/E).聚丙烯酸(PAA)与PEO形成柔性的氢键复合物(PAA/PEO),刚性的聚苯乙烯(PS)与PAA和PEO不相容而发生微相分离,PS作为交联点连接着柔性的PAA/PEO.与PAA/PEO氢键复合物相比,SA/E弹性体力学性能明显提升,通过控制PS质量分数可调节弹性体的模量和强度等力学性能. SA/E弹性体表现出湿度敏感性.并且弹性体经拉伸训练后可获得一定的取向性,弹性回复率保持在98%以上.本弹性体在湿度传感、柔性器件、医用材料等领域具有潜在应用,为构筑新型弹性体提供思路.     

交联助剂对PPC／NBR弹性体结构和性能的影响

研究了马来酸酐（ＭＡ）及异氰脲酸三烯丙酯（ＴＡＩＣ）对聚丙撑碳酸酯／丁腈橡胶共混弹性体结构和性能的影响，发出加入ＭＡ或ＴＡＩＣ能有效地改善交联网络；加入适量ＭＡ能显著改善共混弹性体热氧老化稳定性；加入ＴＡＩＣ使共混弹性体具有优良的高弹特性和力学性能。     

偶联剂对聚氯乙烯－聚丙撑碳酸酯共混体系力学性能的影响

偶联剂对聚氯乙烯－聚丙撑碳酸酯共混体系力学性能的影响王胜杰，黄玉惠，丛广民（中国科学院广州化学研究所广州５１０６５０）关键词聚氯乙烯，聚丙撑碳酸酯，偶联剂，丁腈胶，过氧化苯甲酰，共混聚氯乙烯（ＰＶＣ）是用量巨大的通用塑料，其软性制品需用大量的增塑剂，...     

High actuation performance offered by simple diene rubbers

Dielectric elastomers are materials well known for their superior actuation behavior under applied electric field. The simplicity of material fabrication and clear working principle of dielectric elastomer actuators (DEAs) can offer various applications of dielectric elastomers. In this work, we have compared a number of different types of commercially available elastomers in terms of actuation performance. It was found that well‐known commercial rubbers like acrylonitrile‐butadiene rubbers (NBR) can offer higher actuation performance in DEAs than the frequently used dielectric elastomers, such as acrylic rubber and silicone. The acrylonitrile content of the NBR was found to play an important role in the dielectric and consequently actuation properties. More interestingly, we observed that addition of organic oil, such as dioctyl adipate, can greatly enhance the actuation performance. Copyright © 2016 John Wiley & Sons, Ltd.     

Direct visualization of the nanoscopic three‐phase structure and stiffness of NBR/PVC blends by AFM nanomechanical mapping

The PeakForce Quantitative Nanomechanical Mapping based on atomic force microscope (AFM) is employed to first visualize and then quantify the elastic properties of a model nitrile rubber/poly(vinyl chloride) (NBR/PVC) blend at the nanoscale. This method allows us to consistently observe the changes in mechanical properties of each phase in polymer blends. Beyond measuring and discriminating elastic modulus and adhesion forces of each phase, we tune the AFM tips and the peak force parameters in order to reliably image samples. In view of viscoelastic difference in each phase, a three‐phase coexistence of an unmixed NBR phase, the mixed phase, and PVC microcrystallites is directly visualized in NBR/PVC blends. The nanomechanical investigation is also capable of recognizing the crosslinked rubber phase in cured rubber. The contribution of the mixed phase was quantified and it was found that the mechanical properties of blends are mainly determined by the homogeneity and stiffness of the mixed phase. This study furthers our understanding the structure–mechanical property relationship of thermoplastic elastomers, which is important for their potential design and applications. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 662–669     

Thermal stability of acrylonitrile/chlorosulphonated polyethylene rubber blend

The properties of chlorosulphonated polyethylene (CSM) rubber, acrylonitrile rubber (NBR) and their blend (50/50 w/w) were studied. Fourier transform infrared (FTIR) studies supported that CSM/NBR rubber blend is self curable, when cross-linking takes place between acrylonitrile groups of NBR and –SO₂Cl groups or in situ generated allyl chloride moieties of CSM. The thermal stability of vulcanizates was analyzed in nitrogen by thermogravimetry. It was found that the initial degradation temperature of elastomer based on CSM rubber is lower than of pure NBR rubber. By adding NBR to CSM rubbers, the degradation temperature of crosslinked material increased, indicating higher thermal stability. The activation energy for the degradation are determined using the Arrhenius equation The activation energies for the rubber blends are higher than for elastomers based on pure rubbers. It was found that the mass loss of the blends at any temperature was between those of the pure rubbers. The differential scanning calorimetry (DSC) was used for the glass transition temperature determination. It is estimated thermodynamic immiscibility of NBR/CSM blend based on noticed two different glass transition temperatures, corresponding to CSM and NBR rubbers.     

Thermal properties and flammability of nanocomposites based on diene rubbers and naturally occurring and activated halloysite nanotubes

This article presents a procedure of the activation of halloysite and a method of the synthesis of nucleus-sheath type filler. The effects of the nanoadditives obtained on the thermal properties, flammabilities and fire hazards of peroxide and sulfur vulcanizates of NBR and SBR rubbers, are discussed. Based on the test results obtained by derivatography, oxygen index, FAA micro-calorimeter and cone calorimeter, the thermal stability, flammability, and fire hazard of the nanocomposites investigated were determined. The results obtained were interpreted from the point of view of the chemical structure of the diene elastomers investigated, their spatial network structure, and the method of halloysite modification.     

Thermal properties of diene elastomers

The paper presents the results of investigating the effect of the macromolecule chemical structure and the spatial network structure of butadiene (BR), butadiene-styrene (SBR) and butadiene-acrylonitrile (NBR) rubbers on their thermal properties. The rubbers were cross-linked by the conventional method by means of dicumyl peroxide or sulfur as well as by the non-conventional way using iodoform (CH₃I). The rubber and their vulcanizates were assessed by the derivatographic method (under air) and by means of differential scanning calorimetry (DSC) under inert gas. The thermal cross-linking degree of the polydienes and the efficiency of the cross-linking processes, dependent on both the chemical structure of elastomer macromolecules and their spatial network structure were determined. The cross-linking of elastomers with iodoform changes the thermal properties of polymers, significantly increasing their glass transition temperature during both sample heating and cooling, which results from the increase in mutual interaction of macromolecules connected with their modification with iodine compounds.     

Dielectrical and electro-mechanical behavior of NBR at high electric field strength

The aim of this work is to present a new approach to characterize the dielectric properties of elastomers especially at low frequencies and high electric field strength, close to the operating conditions of dielectric elastomer actuators (DEA). By means of an electro-rheological measuring cell, static (DC) and alternating (AC) high electric field strength were applied to different types of acrylonitrile-butadiene rubbers (NBR), with varying content of polar acrylonitrile groups. Based on fundamental theory of electricity complex permittivity and polarization were calculated from Coulomb stress measurements at varying frequencies. During high voltage measurements it was observed, that dielectric loss current increases, if a certain critical field strength is exceeded. It is shown, that polar NBR rubbers exhibit a critical field strength far below of the non-polar polybutadiene rubber (BR), acting as a reference sample. NBR exhibits extraordinary high permittivity at low frequency, which makes this material as a favorite candidate for DEA. Furthermore, mechanical properties of NBR can be easily altered by application of an alternating electric field. This phenomenon opens new opportunities in a great variety of applications.