New ways to improve the damping properties in high‐performance thermoplastic vulcanizates

The incorporation of viscoelastic materials represents an effective strategy to reduce the vibratory level of structural components. Thermoplastic vulcanizates (TPVs) are a special type of viscoelastic material that combines the elastomeric properties of rubbers with the easy processing of thermoplastics. In the present work, we propose innovative ways to improve the damping properties of high‐performance TPVs by using rubbers with carboxylic functionalities. For that, TPVs from physical blends of carboxylated hydrogenated acrylonitrile butadiene rubber (XHNBR) and polyamide 6 (PA6) were prepared. The chain dynamics of different mixed crosslink systems containing peroxide, metal oxides and hindered phenolic antioxidants were investigated in order to find the most suitable strategy to design a high‐performance TPV system with upgraded damping properties. The results indicate that the damping performance of the TPV system can be tailored by controlling the type and magnitude of the bonding interactions between the mixed crosslink system and the XHNBR rubber phase. Therefore, this study demonstrates the potential of TPV systems containing carboxylic rubbers as high‐performance damping materials. © 2020 Society of Chemical Industry     

三元乙丙橡胶/聚丙烯热塑性硫化胶细观力学数值模拟分析Ⅱ.三元乙丙橡胶结构对细观力学性能的影响

通过建立三元乙丙橡胶(EPDM)/聚丙烯(PP)热塑性硫化胶(TPV)的细观尺寸多颗粒随机分布的RVE模型,研究了分散相EPDM粒子形状及大小、间距对TPV应力和弹性模量的影响。结果表明,在分散相EPDM体积分数不变的条件下,EPDM粒子形状越接近圆形,TPV的应力值越低,EPDM粒径的减小可提高TPV的弹性模量;EPDM粒子间距增大,TPV的应力值下降,TPV中EPDM体积分数越高,其应力值受EPDM粒子间距的影响越显著。     

增容高抗冲聚苯乙烯/高乙烯基聚丁二烯橡胶热塑性硫化胶的Mullins效应及其可逆性

采用动态硫化法制备了苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)增容高抗冲聚苯乙烯(HIPS)/高乙烯基聚丁二烯橡胶(HVPBR)热塑性硫化胶(TPV),考察了SBS用量对TPV物理机械性能的影响,表征了TPV的微观形貌,并研究了TPV的Mullins效应及其可逆性。结果表明,SBS可显著改善HIPS/HVPBR体系的相容性,其用量为12份时,TPV的物理机械性能较好;SBS增容TPV的断面平整、结构致密,界面相互作用明显增强;SBS增容TPV在循环单轴拉伸过程中出现明显的Mullins效应,提高应变速率时,TPV的最大应力和内耗呈增大趋势,瞬时残余形变则减小;当拉伸比相同时,TPV经第1次拉伸热处理后,第2次单轴拉伸中TPV的最大应力和内耗均增大,瞬时残余形变则减小。     

混炼型聚氨酯橡胶/聚十二内酰胺热塑性硫化胶动态硫化历程与性能

采用动态硫化方法制备了混炼型聚氨酯橡胶（MPU）/聚十二内酰胺（PA 12）热塑性硫化胶（TPV）,通过控制动态硫化时间探究了该TPV的动态硫化历程,同时研究了不同动态硫化阶段共混物的物理机械性能和动态力学性能。结果表明,随着动态硫化时间的延长,MPU/PA 12 TPV逐步完成相转变,在温度和剪切作用下,MPU相由连续相转变为分散相,而PA 12则由分散相转变为连续相;随着动态硫化时间的延长,MPU/PA 12共混物的储能模量升高,损耗模量降低,损耗因子减小。此外,随着动态硫化时间的延长,MPU/PA 12共混物的综合力学性能提高。     

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.     

硫黄在NR硫化胶中的溶解及扩散

根据分配定律，测定了４０℃时硫黄在ＮＲ硫化胶中的溶解度为１０４，硫黄在胶料与硫化胶之间的分配因子Ｋ为０８４，由此计算出４０℃时硫黄在胶料中的溶解度为１２４。根据硫黄实验扩散曲线计算硫黄在硫化胶中的平均扩散系数Ｄ为３２×１０－５ｍｍ２·ｓ－１，由此推算出４０℃下任意贮存时间内硫黄从胶料向硫化胶迁移的理论扩散曲线。     

Swelling behaviour of rubber vulcanizates: 2. Effects of tensile strain on swelling

The effects of tensile strain on the swelling behaviour of acrylonitrile-butadiene copolymer rubber vulcanizates were studied by real-time pulsed nuclear magnetic resonance (n.m.r.) measurements and volume swelling measurements at equilibrium. It was shown that tensile strain causes an increase of the initial swelling rate evaluated by n.m.r. measurements and of the swelling ratio of the rubber matrix at equilibrium. This behaviour was discussed qualitatively in terms of the molecular mobility of the network chains on the basis of Treloar's theory for swelling under deformation. It was suggested that the presence of reinforcing fillers in the rubber matrix exerts two noticeable effects on swelling under deformation: (1) a transient effect through some oriented structure induced by stretching, which restricts the increase of the swelling rate; (2) a strain amplification effect, which causes the increase of the average local strain in the rubber matrix and enhances the swelling ratio more remarkably proportional to the filler concentration as compared with that of the unfilled system.     

热分析在橡胶工业中的应用

评述了热分析在测定硫化胶的基本组成，配方设计中增塑剂和防老剂的选择，监控股料老化和硫化等方面的应用。热分析具有灵敏度高、快速、可靠和使用方便等特点。     

Pressure Response through Valve for Continuous Oil-Water Separation Based on a Flexible Superhydrophobic/Superoleophilic Thermoplastic Vulcanizate Film

Highly efficient oil-water separation shows urgent demand in industrial applications, especially in oil-spill accidents and organic solvent separation. Herein, a novel method is proposed for continuous oil-water separation by a pressure response through valve, which is loaded in a flexible convolute superhydrophobic/superoleophilic film based on low-density polyethylene (LDPE)/ethylene-propylene-diene terpolymer (EPDM) thermoplastic vulcanizate (TPV). The superhydrophobic/superoleophilic LDPE/EPDM TPV film (with contact angles of oil and water are 0° and 161.9°± 2.2°) is prepared only via a molding process where sandpaper is used as the template. The superhydrophobic/superoleophilic property of the TPV film shows robust performance in the activity endurance test. More importantly, the flexible LDPE/EPDM TPV film can be easily rolled up and loaded in through valve, which is the pressure response channel in oil-water separation. The typical separation pressure of oil and water is 3.01 and 6.17 kPa, which means the oil can be completely separated from the oil-water mixture under proper pressure in the pressure response through valve.