甲基丙烯酸丁酯接枝天然橡胶核壳结构的制备与表征

Preparation and Characterization of a Natural Rubber Core/PBMA Shell by Grafting Polymerization

以过硫酸钾(KPS)为引发剂,采用种子乳液聚合的方法合成了天然橡胶(NR)-g-甲基丙烯酸丁酯(BMA)共聚物。采用正交实验的方法研究了引发剂用量、反应温度、NR/BMA质量比对接枝率和接枝效率的影响,并采用红外(IR)、差示扫描量热法(DSC)以及透射电镜对NR-g-BMA进行了表征。结果显示:当NR/BMA质量比为100/80、KPS用量为0.25 phr(每100 g干基质量)、反应温度为60℃时接枝率和接枝效率最高;红外谱图表明BMA成功接枝到NR分子链上;DSC分析表明NR和PBMA为部分相容体系;TEM观察发现NR-g-BMA胶乳粒子是NR为核,PBMA为壳的核壳结构。按照不同配比制备了甲基丙烯酸丁酯接枝天然橡胶(GNR)与天然橡胶(NR)共混硫化胶膜,并测定了共混硫化胶膜老化前后的力学性能、邵氏硬度A、交联密度。结果表明,GNR/NR硫化胶膜相较于单纯天然橡胶的老化前后的抗拉伸强度及撕裂强度有明显的提高。

The grafting of the butyl methacrylate（BMA） monomer onto natural rubber using potassium persulfate（KPS）as an initiator was carried out by seeded emulsion polymerization. The effects of NR/BMA mass ratio, initiator amount and reaction temperature on grafting degree and grafting efficiency were investigated using orthogonal experimental design. The NR-g-BMA was characterized by Fourier transform infrared（FT-IR） spectroscopy, differential scanning calorimetry（ DSC）, and transmission electron microscope（ TEM）. The results showed that the grafting degree and grafting efficiency were the highest when NR/BMA was 100/80, the initiator amount was 0.25 phr and reaction temperature wais 60 ℃. IR spectra indicated that BMA was successfully grafted onto NR, DSC curves revealed NR/PBMA was a partially compatible system and TEM studies demonstrated NR-g-BMA latex particles had a clear NR core/PBMA shell structure.The blended vulcanized films were prepared according to different mass ratio of NR-g-BMA（ GNR） and natural rubber（ NR）. Furthermore, the mechanical properties such as tensile strength and tear strength when before and after aging, hardness, crosslink density were investigated.The results showed that compared to natural rubber, the tensile strength and tear strength before and after aging of GNR/NR blended vulcanized films significantly increased.