Comparative analysis of ultrasonically devulcanized unfilled SBR,NR, and EPDM rubbers

The comparative study of the continuous ultrasonic devulcanization of various unfilled rubbers [natural rubber, styrene–butadiene rubber (SBR), ethylene–propylene–diene rubber (EPDM)] is carried out by means of a ultrasonic reactor. The power consumption, gel fraction, crosslink density, cure behavior, and physical properties of devulcanized rubbers were measured. The glass transition temperatures of virgin, vulcanized, and devulcanized rubbers were determined in order to characterize the difference in the mobility of rubber molecules for each rubber before and after devulcanization. Thermogravimetric analysis was also used to determine thermal stability of the various rubbers. A unique correlation between gel fraction and crosslink density indicated significant differences in the efficiency of devulcanization of various rubbers. Under certain devulcanization conditions, the mechanical properties of revulcanized SBR and EPDM rubbers were found to improve compared to those of the original rubbers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 434–441, 2003     

Continuous ultrasonic devulcanization of NR/SBR blends

The ultrasonic devulcanization of sulfur‐cured natural rubber (NR)/styrene–butadiene rubber (SBR) blends was studied with the goal of understanding the devulcanization of rubber vulcanizates in which two networks of different natures were present. Also, similarities and differences in the devulcanization behaviors of NR, SBR, and their blends were found. During the devulcanization of cured NR/SBR blends, we observed that, as for NR, the ultrasonic power consumption for 75/25 and 50/50 (w/w) NR/SBR blends passed through a maximum at 7.5 μm. For SBR and 25/75 (w/w) NR/SBR blends, the power consumption increased with increasing ultrasonic amplitude. The higher power consumption led to a higher degree of devulcanization. The crosslink densities of the devulcanized 25/75, 50/50, and 75/25 (w/w) NR/SBR blends were lower than those of the devulcanized NR and SBR, possibly because of the reduced degree of unsaturation. The tensile properties of the revulcanized blends were lower than those of the virgin vulcanized blends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 160–168, 2002     

影响废旧轮胎胶粉热-机械剪切脱硫再生效果的因素

利用自行研制的长径比为60/1的强剪切型双螺杆挤出机对废旧轮胎胶粉进行热-机械剪切脱硫,用傅里叶变换红外光谱对脱硫胶粉进行了表征,考察了胶粉粒径和喂料螺杆转速与主机转速之比对脱硫胶粉凝胶含量、交联密度及再生胶力学性能的影响,以及脱硫过程中胶粉相对分子质量及其分布的变化。结果表明,随着胶粉粒径的增大,胶粉所受到的剪切力增强,脱硫效果也越好。随着转速比的增加,胶粉的脱硫程度提高;脱硫过程的第1个阶段是交联网络的破坏,第2个阶段除交联网络的破坏外分子主链也发生降解,再生胶的力学性能先增大后减小;当转速比为1.4时再生胶的扯断伸长率和弹性最好,拉伸强度也相对较高。     

轮胎胶高剪切应力诱导脱硫反应的影响因素

采用在轮胎胶粉与三元乙丙橡胶(EPDM)混合物的熔融挤出过程中提高双螺杆挤出机螺杆转速的高剪切应力诱导方法,研究了轮胎胶粉品种和烷基酚多硫化物促进剂对轮胎胶脱硫共混物的凝胶含量、溶胶分子链结构及脱硫共混物共混丁苯橡胶再硫化材料力学性能的影响。试验结果表明,胶粉品种对所得脱硫共混物溶胶中的双键含量及再硫化材料的拉伸强度具有重要影响;烷基酚多硫化物促进剂420和450具有明显促进脱硫反应和抑制交联副反应的作用,有效减小再硫化材料凝胶粒子尺寸,聚合型促进剂450兼具有抗氧化降解和抑制加成副反应的功能。     

非极性硫化橡胶微波脱硫的研究＊

从微波能在非极性硫化橡胶中的转换规律着手,考察了不同的胶种、补强剂和废硫化胶粒径与脱硫时间以及温度的相关性,探讨了这些因素对脱硫胶物理性能和溶胀特性的影响。结果表明,粒径大的硫化胶物料温升速度快;ＮＲ硫化胶的温升速度比ＳＢＲ硫化胶快;炭黑补强硫化胶的温升速度比白炭黑补强硫化胶快。溶胀特性数据表明,ＮＲ的脱硫效果优于ＳＢＲ,硫化胶粒（粒径１～３ｍｍ）的脱硫效果优于硫化胶粉（４０目和６０目）;白炭黑补强硫化胶的脱硫效果优于炭黑补强硫化胶     

废旧橡胶再生新技术研究进展

从机理、工艺、优缺点等方面介绍了国内外废旧橡胶再生新技术的研究进展,并对几种典型的再生技术作了比较。     

Properties of natural rubber vulcanizates containing mechanochemically devulcanized ground tire rubber

The devulcanization of ground tire rubber (GTR) was carried out with a self-designed pan-mill type mechanochemical reactor. Gel fraction and crosslink density measurements confirmed the occurrence of stress induced mechanochemical devulcanization of GTR. The partially devulcanized GTR (dGTR) was blended with virgin natural rubber (NR) at different ratios. The curing characteristics and mechanical properties of these composites were investigated and compared with those composites of raw ground tire rubber (rGTR) and NR. The results showed that the tensile properties of the dGTR/NR vulcanizates were much better than those of the rGTR/NR vulcanizates, which are comparable to or even better than the virgin vulcanizate, indicating the significant benefit of mechanochemical devulcanization. At the GTR content of 10%, the tensile strength of the dGTR/NR blends increased to 23.2 MPa from 13.7 MPa of the rGTR/NR blends, enhanced by 69% through partial devulcanization of GTR, and the elongation at break increased by 47%.     

硫化胶微波脱硫过程中的非热效应

以NR胎面胶探讨硫化胶微波脱硫过程中微波的非热效应。结果表明，经过微波短时间处理的硫化胶达到溶胀平衡时的溶胀指数明显大于未经过微波处理的硫化胶；硫化胶温度较低时，交联网络遭到的破坏主要来自微波的非热效应作用；微波对硫化胶的断键作用较常规加热更为剧烈；经过微波处理的硫化胶小分子抽取物质量分数比没有经过微波处理的硫化胶小且不随微波处理时间变化；硫化胶微波脱硫制备再生胶效率较高，脱硫温度较低，对环境污染程度较小，再生胶物理性能较好。     

影响Co-Mo系耐硫变换催化剂活性的因素

分别从预硫化效果、反硫化、工艺条件、床层偏流、开停车等方面分析了导致Co—Mo系耐硫变换催化剂活性降低的原因,结合生产操作运行的实践,指出通过采用较低的入口温度、保持工艺操作参数平稳、避免反硫化的产生等方法来减少该类型催化剂活性降低。     

老化对NR硫化胶的影响

研究了热空气老化和真空老化对ＮＲ硫化胶结构和性能的影响,采用化学探测剂脱硫的方法测定了老化过程中ＮＲ硫化胶交联密度及交联键分布变化的情况,同时测定了硫化胶的力学性能和动态性能随时间变化的情况。结果显示,热空气老化使硫化胶的交联密度增加,但力学性能损失严重,原因是主链氧化断裂。真空老化使ＮＲ硫化胶交联密度略微降低,但力学性能保持良好,类似于硫化返原。热空气老化使ＮＲ硫化胶的动态性能改善,而真空老化后