5种典型加工工艺天然橡胶的结构与性能

天然橡胶（NR）作为一种植物性高分子,其分子结构和性能既受橡胶树生物合成的影响,也与加工工艺有很大关系。为了科学对比加工工艺对NR结构和性能的影响,本文采用相同橡胶树品种所产胶乳,参照现行工厂生产条件,制备了5种典型加工工艺的NR,即全乳胶（WF）、烟片胶（RSS）、风干片（ADS）、恒粘胶（CV）和20号胶（TSR）。生胶结构分析表明,NR加工过程中会发生由熟化导致的非胶组分分解和橡胶烃的结构化,具体表现为氮含量降低、数均分子量增大、分子量分布变窄、凝胶含量上升、塑性初值和门尼黏度增加,其中以TSR的熟化程度最高,而CV能够保留其固有分子结构,熟化程度最低。硫化胶性能分析表明,非胶组分的分解有利于提高NR的硫化速度和交联密度,从而提高硫化胶的力学性能;橡胶烃的结构化能够增加硫化胶中的物理缠结网络,使其更容易发生应变诱导结晶,并通过增加能量耗散,提高硫化胶的疲劳性能。综合来看,硫化胶力学性能的优劣顺序为：TSR>ADS>RSS>WF>CV。

Structure and Mechanical Properties of Natural Rubber from Five Typical Processing Technologies

The structure of natural rubber (NR) is not only affected by the biosynthesis of rubber trees, but also has a lot to do with the processing technology. In order to scientifically compare the effects of the processing technology, in this paper, the latex produced by the same rubber tree was collected to prepare NR using five typical processing technologies according to the current factory production conditions, namely WF, RSS, ADS, CV, TSR. The analysis of the raw rubber structure showed that the decomposition of non-rubber components and the structuring of rubber hydrocarbons caused by maturation would occur during the processing. The specific manifestations were reduced nitrogen content, increased number average molecular weight, narrowed molecular weight distribution, and higher gel content, which caused the increase of initial value of plasticity and Mooney viscosity. Among them, TSR had the highest degree of structure, while CV could retain its inherent molecular structure and had the lowest degree of structure. The performance analysis of the vulcanizates showed that the decomposition of non-rubber components was beneficial to increasing the curing rate and crosslinking density of natural rubber, thereby improving the static mechanical properties of the vulcanizates. The structuring of the rubber hydrocarbon could increase the physical entanglement in the vulcanizates. The network made it more prone to strain-induced crystallization and improve dynamic fatigue performance by increasing energy dissipation. Taken together, the order of the static and dynamic mechanical properties of vulcanizates is: TSR > ADS > RSS > WF > CV.