Natural rubber (NR) contains cis-1,4-polyisoprene and many kinds of non-rubber components, e.g., proteins, lipids and phospholipids, which are believed to affect the properties of NR. Oxidative degradation is one of the problems for rubber performance, which shorten the service life of the product. To overcome this problem, the influence of fatty acids and proteins on the cure properties, heat-ageing behaviours, and ozone resistance of NR vulcanizates were investigated. The peroxide vulcanization was chosen to avoid the effect of essential fatty acid and proteins. The purified NR, deproteinized NR (DPNR) and lipids-removed NR (LRNR) were mixed with model fatty acid (stearic acid) and amino acid (alanine). It was found that the cure behaviour of these mixed samples showed almost the same trend. After removing proteins, the rate of oxidative degradation was faster than that of the lipid-removal samples. Lower lipid content would result in less oxidative degradation of the rubber. These findings can infer that the endogenous proteins in NR act as natural antioxidants, while the endogenous lipids are pro-oxidants.

天然橡胶（NR）含有顺式-1,4-聚异戊二烯和许多非橡胶成分，例如蛋白质，脂质和磷脂，据信会影响NR的性能。氧化降解是橡胶性能的问题之一，这会缩短产品的使用寿命。为了克服这个问题，研究了脂肪酸和蛋白质对NR硫化橡胶的固化性能，热老化性能和耐臭氧性的影响。选择过氧化物硫化以避免必需脂肪酸和蛋白质的影响。将纯化的NR，​​去蛋白的NR（DPNR）和去除脂质的NR（LRNR）与模型脂肪酸（硬脂酸）和氨基酸（丙氨酸）混合。发现这些混合样品的固化行为显示出几乎相同的趋势。去除蛋白质后，氧化降解速率比脂质去除样品快。较低的脂质含量将导致橡胶的氧化降解较少。这些发现可以推断NR中的内源性蛋白质起天然抗氧化剂的作用，而内源性脂质是促氧化剂。