不同品系天然橡胶硫化胶耐老化性能的研究

采用热空气老化箱常规法结合热重分析(TG)法、差示扫描量热(DSC)法及橡胶加工分析(RPA)法研究了2种不同品系NR硫化胶的耐老化性能.实验结果表明:品系PB68硫化胶的耐老化性能比品系RRIM600硫化胶的好.     

Single point incremental forming of bilayer sheets made of two different thermoplastics

A novel configuration of bilayer composite sheets containing different polymers is described and used for the first time in the single point incremental forming (SPIF) process. These bilayer sheets made of polypropylene (PP) and Santoprene are fabricated by hot welding, and shaped with cone-like geometry by SPIF. The bilayer configuration is such that only one of the containing polymers is in contact with the forming tool. During the SPIF processing, the bilayer sheets show a noticeable difference in the mechanical response, depending mainly on the polymer that is not in contact with the forming tool, which is related to a lower polymer softening. The performance of the bilayer sheets is compared against the neat polymers and a blend of these with a mass ratio of 1:1. The observed effect is introduced as a dual effect of properties that brings together in a single composite sheet, properties for a better performance in SPIF and wider functionality of the fabricated parts, evidenced by a lower material softening and higher mechanical strength, in comparison with the two individual polymers, and even better than the blend of both. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47093.     

Design of heat-triggered shape memory polymers based on ethylene-acrylic acid copolymer/nitrile-butadiene rubber thermoplastic vulcanizates

Heat-triggered shape memory polymers (HSMPs) consisting of ethylene-acrylic acid copolymer (EAA) and nitrile-butadiene rubber (NBR) were fabricated by peroxide-induced dynamic vulcanization; meanwhile, in order to realize rapid and reconfigurable shape fixity and shape recovery, a facile and effective strategy was designed. Morphological structure and interface interaction are decisive factors for HSMPs, the FE-SEM images showed the average diameter of NBR particles in EAA/NBR TPVs was 5 to 8 μm and the strong interface interaction between EAA matrix and NBR particles provided critical assistance in keeping the temporary shape of deformed rubber particles and storing stronger elastic driving force. The shape memory behavior of EAA/NBR TPVs was characterized and the result demonstrated that excellent shape-fixity (>91%), shape-recovery (>93%), and fast recovery speed (<30 s) could be obtained at suitable deformation temperature of 95°C. The results of dynamic mechanical analysis and shape memory research showed that the high modulus value supported the improvement of shape-fixity ratio and the appropriate ratios of EAA/NBR TPVs were the key factors for excellent shape memory performance. The novel HSMPs expected to open up potential applications in the field of sensors and self-assembling smart devices.     

气相色谱-质谱联用法鉴定硫化胶中促进剂

采用气相色谱-质谱联用法鉴定分析硫化胶中促进剂种类。结果表明,部分促进剂在橡胶硫化过程中发生了分解及重组反应,但通过其单体及反应产物的特征离子基本可以定性硫化胶所使用的促进剂种类,其中噻唑类和次磺酰胺类促进剂由于含有苯并噻唑碎片,当有次磺酰胺类促进剂存在时,不能确定该配方中是否含有促进剂M。     

基于PP-B/EPDM热塑性硫化胶超疏水表面的构建与性能研究

用金相砂纸为模板,嵌段共聚聚丙烯/三元乙丙橡胶(并用比为50/50)热塑性硫化胶(TPV)为基体,构建模压TPV超疏水表面,并对其超疏水性进行研究。结果表明:模压TPV具有良好的超疏水性,疏水层厚度约为60μm;W5,W7和W10砂纸模压TPV表面与水的接触角大于150°且滚动角小于10°,符合超疏水表面要求;W10砂纸模压TPV表面的超疏水性最佳;Cassie空气垫模型表明,模压TPV表面的气-液界面的面积分数大于0.8,具有良好的超疏水性。     

过氧化物动态硫化EPDM/PP热塑性弹性体的等温结晶行为

通过差示扫描量热分析法详细表征了PP、PP/过氧化物、EPDM/PP及过氧化物动态硫化EPDM/PP(TPV)的等温结晶行为。结果表明,与EPDM的简单共混既降低了PP的结晶速率也降低了PP的结晶度,过氧化物动态硫化后交联的EPDM颗粒作为异相成核剂,能大大提高PP的结晶速率但也严重地降低了PP的结晶度,TPV的Avrami指数为3.5,符合异相成核的三维球型生长方式。X射线衍射结果表明,4组样品的晶体结构完全相同,仍为α型单斜晶体。熔融曲线显示过氧化物/PP及TPV相比PP,在153℃出现额外熔融峰,PP原有的160℃熔融峰逐渐消失而153℃熔融峰强度逐渐增强且体系的结晶度逐渐降低。采用移动窗口二位相关红外对TPV熔融行为进行研究,发现153℃处的熔融峰对应于10个和5个单体单元螺旋序列结构,160℃时对应12个单体单元螺旋序列结构。较低的结晶温度有助于长螺旋序列结构的形成及PP结晶度的提高。     

通用氯丁硫化胶干热老化与湿热老化

研究了通用氯丁硫化胶在６０℃干热和６０℃、相对湿度９５％的湿热条件下老化时，拉伸强度、扯断伸长率，１００％定伸应力、邵氏硬度、压缩永久变形、压缩应力松弛等性能变化，表明湿热条件明显加速了氯丁硫化胶的老化。     

硫化橡胶微波脱硫机理的再讨论

从微观结构的角度讨论了天然硫化橡胶微波脱硫的反应过程。微波脱硫的实质是交联网络中的极性基团吸收微波的能量转化成分子热运动的动能，或者是由于取向极化发生极性基团与周围网络的内摩擦，生成足够的热量促使化学键发生断裂。通过对文献数据的处理，计算出不同交联点的断裂时间，认为微波脱硫可以实现炭黑聚集体、炭黑一橡胶、碳氢键、多硫交联键、低硫交联键、碳碳键的依次断裂，从而控制最佳脱硫效果。在脱硫过程中可能伴随着热氧老化、环化以及再交联等副反应。     

乳液法氢化丁苯橡胶的表征及其性能

用傅里叶变换红外光谱表征了由丁苯胶乳加氢制备的氢化丁苯橡胶(HSBR),测定了其生胶力学性能。以过氧化二异丙苯为硫化剂,研究了氢化度98%的HSBR的静态、动态力学性能及耐老化和耐化学品性能。结果表明,氢化度98%的HSBR的各种碳碳双键基本饱和,是一种典型的热塑性弹性体,具有较好的力学性能和优异的耐老化性能。硫化胶的拉伸强度可达27.6 MPa,扯断伸长率为300%,撕裂强度44 kN/m;阿克隆磨耗量0.03 cm3,动态压缩永久变形3.75%,动态生热33℃。经过150℃×72 h老化后,其拉伸强度和撕裂强度不变;硫化胶对酸、碱、醇及丙酮有很好的抗耐性,但在甲苯中溶胀严重。     

NR—BR／EPDM并用胶硫化的研究

研究了天然橡胶（ＮＲ）、顺丁橡胶（ＢＲ）与三元乙丙橡胶（ＥＰＤＭ）并用胶的硫化条件和经活性剂ＤＳ处理的ＥＰＤＭ用量对并用胶性能的影响。试验结果表明，采用ＮＲ－ＢＲ／ＥＰＤＭ（７０／３０，质量比）并用胶１００份，碳黑６０份、氧化锌４份、活性剂ＤＳ２．５份、促进剂２．５份、硫化剂２．５份、其他助剂１０份的加工配方，可以制得综合性能好的单用胶，它具有强度高、弹性高、拉伸疲劳性及粘接性好、耐老化和耐臭氧性