Gel formation in diimide‐hydrogenated polymers

The hydrogenation of diene‐based polymers via diimide is a very attractive alternative to the conventional catalytic hydrogenation route based on gaseous molecular hydrogen. However, serious crosslinking always accompanies it and limits the end‐use properties of the polymers. Gel formation in polymers that are hydrogenated via diimide has been investigated in detail through an inspection of all the chemical reactions involved in the process. The results indicate that hydrogen peroxide decomposition, some reactions related to oxygen, and the redox reaction between hydrogen peroxide and hydrazine are capable of generating radicals. However, radicals generated in the aqueous phase do not appear to initiate the crosslinking of diene‐based polymers in the latex form. It is proposed that the primary radicals giving rise to crosslinking are generated in the polymer phase in situ, and the step responsible for generating these organic radicals is possibly the diimide disproportionation reaction. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1122–1125, 2005     

恒粘天然橡胶理化性能的研究

用粘度稳定剂处理天然橡胶鲜胶乳和湿杂胶，研究了粘度稳定剂种类及处理方法对橡胶的P0、PRI、MV、氮含量和加速贮存硬化值（△P）等的影响。结果表明，鲜胶乳所制得的恒粘胶经加速贮存后的△P≤1个塑性值，门尼粘度值变化量（△MV）≤3个门尼值。其它性能虽有变化，但均能达到天然生胶标准的要求。自然凝固制得的恒粘胶的P0、PRI和MV相对较高，氮含量相对较低。粘度稳定剂延长了鲜胶乳的凝固时间。粘度稳定剂处理后的杂胶，△P和△MV减少，但恒粘效果不及鲜胶乳制得的恒粘胶。     

汽车用橡胶制品的发展

介绍了橡胶制品应用于汽车中的现状，统计了各种汽车中的橡胶用量、汽车橡胶制品使用的胶种及比例、世界汽车年产量，橡胶消耗量，轮胎生产量及世界前30名橡胶制品企业销售额。对汽车用橡胶制品的特点及发展趋势作了较系统的介绍。     

坦克装甲车辆用橡胶履带板的研究开发

探讨了坦克装甲车辆用橡胶履带板（ＴＴＲＰ）的损坏摸式及其机理，从胶料配合，性能测试等方面评 ＴＴＲＰ的研究开发进展，并对我国ＴＴＲＰ的研究提出了建议。     

炭黑对轮胎胎面胶热物性的影响

研究了炭黑品种和用量对轮胎胎面胶热扩散系数(α)、导热系数(λ)及比热容(C)3种热物性参数的影响规律。结果表明,随着炭黑填充量的增加,胎面胶的α及λ均逐渐增大,C逐渐减小。炭黑的结构性对胎面胶α的影响程度大于炭黑的粒径;温度相同时,炭黑的结构性越高,其填充胎面胶的α越大;随着炭黑填充量的增加,3种炭黑填充胎面胶α之间的差距呈现先增大后减小的变化趋势。炭黑的结构性及粒径对胎面胶C的影响没有固定的规律,但在低温区,炭黑的粒径越大,其填充胎面胶的C越大,且炭黑填充量对此差距无影响。炭黑的结构性对胎面胶λ的影响程度大于炭黑的粒径;温度相同时,炭黑的结构性越高,其填充胎面胶的λ越大;当炭黑用量较低时,其对胎面胶λ的影响程度相对较小,随着炭黑填充量的增加,3种炭黑填充胎面胶λ之间的差距呈现先增大后减小的变化趋势。     

稀土丁异戊橡胶改性天然橡胶的应用研究

采用稀土丁异戊橡胶代替顺丁橡胶，测试并分析了改性天然橡胶的低温性能及相关性能。结果表明，稀土丁异戊橡胶改性的天然橡胶室强力学性能和粘接性能与顺丁橡胶改性的天然橡胶相近，但低温性能有较大的改善。在-40℃下贮存2h后，顶丁橡胶改性天然橡胶硫化胶有明显的结晶现象，其剪切模量较室温下的相应值增加了6倍，而稀土丁异戊橡胶改性的天然橡胶硫化胶保持了良好的弹性，其剪切模量值与室温下的相当。     

Effect of Ammonia on Silicone Rubber-Glass Adhesion

The adhesion energy between silicone rubber and glass has been obtained from the Johnson, Kendall and Roberts' test. The specific effect of ammonia on the quasi-equilibrium value has been studied as a function of the degree of crosslinking of the elastomer. For PDMS networks with lower molecular weight between crosslinks, the effect is more pronounced but completely reversible. This has been related to the increase in the non-dispersive part of the surface energy of the silicone due to the imbibed ammonia. In incompletely crosslinked hydroxyl-terminated PDMS, ammonia has a catalytic effect and is responsible for chemical bonding between the unreacted hydroxyl groups of the PDMS and the hydroxyl groups on glass.     

CaCO3/natural rubber latex nanometer composite and its properties

Calcium carbonate/natural rubber (NR) latex nanometer composites were prepared by adding nanometer CaCO₃ whose surface had been treated to natural rubber latex (NRL) before sulfuration. The physical, thermooxidative aging, and thermal degradation properties and the ultra‐microstructure were analyzed with a multipurpose material testing meter, a thermal analysis meter and a Philips XL‐30 SEM, respectively. The results showed that the structures and properties of nanometer composites could be clearly improved by NRL mixed with surface‐treated nanometer CaCO₃. The physical properties of the nanometer composites were best when the content of surface treatment agent was 2.5% (to nanometer CaCO₃), the nanometer CaCO₃/NRL content was 3:100, and the stirring time for treating the surface of the nanometer CaCO₃ was 20 min. Simultaneously, the thermooxidative aging resistance of the nanometer composites also was significantly improved. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3442–3447, 2006     

Natural rubber–ethylene‐propylene‐diene rubber covulcanization: Effect of reinforcing fillers

Filled covulcanizates of elastomer blend comprising natural rubber (NR) and ethylene‐propylene‐diene rubber (EPDM) of commercial importance were successfully prepared by using a multifunctional rubber additive; namely, bis(diisopropyl)thiophosphoryl disulfide (DIPDIS). A Two‐stage vulcanization technique further improved the physicochemical properties of the blend vulcanizates by restricting, through the formation of polar rubber bound intermediates, the migration of curative and filler from lower to highly unsaturated rubber. Scanning electron microscopy studies indicate homogeneity and coherency in the morphology of the two‐stage vulcanizates. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1001–1010, 2002; DOI 10.1002/app.10361