天然橡胶胶乳/丙烯酸异辛酯体系的辐射交联研究

Radiation vulcanization of natural rubber latex using i-octyl acrylate

为开发天然橡胶在塑料增韧中的应用,通过天然橡胶乳液辐射硫化,可以将其制成粉末橡胶。而天然橡胶的交联程度直接影响其性能,因此有必要研究其辐射交联行为。研究了天然橡胶胶乳(NRL)在丙烯酸异辛酯(OA)存在下的γ射线辐照交联行为,探讨了吸收剂量、剂量率、交联敏化剂浓度对交联行为的影响。结果表明,凝胶含量随吸收剂量增加而增大,在10kGy以后变化不大。吸收剂量率增大,凝胶含量略有下降。加入少量OA(1%)辐照后,橡胶的凝胶含量明显提高。在吸收剂量25kGy和含5%OA的情况下,凝胶分数可达90%。辐射交联的动力学研究表明在OA为交联敏化剂的条件下,NRL的辐射交联行为符合Charlesby?Pinner关系式,为无规交联,并且交联G值约为3.8。

Powdered natural rubber can be prepared by using gamma-rays vulcanization and special drying method from natural rubber latex (NRL). This kind of powdered natural rubber would be expected to toughen plastics as an impact modifier and the property of natural rubber depends on its crosslinking degree. Therefore, it is necessary to study the crosslinking behavior of NRL under gamma irradiation. In the paper, the NRL was vulcanized with i-octyl acrylate (OA) as a crosslinking sensitizer under gamma irradiation. The influences of absorbed dose, dose rate and crosslinking concentration were discussed. The radiation vulcanization of NRL depends significantly on absorbed dose and crosslinking sensitizer content. The gel fraction of NR increased with absorbed dose and OA content, and it increased slightly above 10kGy. With increasing dose rate, the gel fraction decreased slightly. The highest gel fraction (about 90%) reached at dose of 25kGy with 5% OA. In the system, the radiation crosslinking behavior of NRL with OA as a crosslinking sensitizer could be described well with Charlesby-Pinner equation and G(x) was calculated to be about 3.8.