氧化海藻酸钠/天然乳胶复合材料的制备与性能

Preparation and Properties of Dialdehyde Sodium Alginate/Natural Rubber Composite

采用高碘酸钠对海藻酸钠进行氧化处理,制备了具有二醛结构的氧化海藻酸钠(DASA),并通过物理共混法加入到天然乳胶(NR)中,制备了NR/DASA复合膜。DASA中的醛基与NR中的蛋白质发生共价交联反应,大幅降低了NR/DASA复合膜蛋白质溢出量。当DASA氧化度为0.17 mmol/g,添加量(质量分数,下同)为10%时,NR/DASA复合膜蛋白质溢出量由1 420μg/g降至42μg/g,说明DASA可将蛋白质有效固定在NR膜内部,从而充分发挥蛋白质对NR的促硫化和防老化等作用。力学性能测试表明,NR/DASA复合膜经硫化处理后拉伸强度提升了28.9%,加速老化后,拉伸强度降低量仅有2.7 MPa。此外,改性后NR膜的表面平整度、耐溶剂性能和耐热降解性能也得到了明显提高。

Protein is an important component of natural latex(NR).However,it is easy to migrate onto the surface during the process of film formation,resulting in high protein spillover,which leads to allergies and mildew easily.Traditional solutions such as chlorination and radiation are very complex and tend to cause serious environmental pollution issues.Dialdehyde sodium alginate(DASA)has a strong covalent cross-linking effect on proteins and there are few reports on the reduction of NR protein spillover.In this paper,DASA was prepared by oxidation of sodium alginate with sodium periodate.The results showed that the oxidation degree of DASA increased with the concentration of sodium periodate,but the molecular weight decreased.The protein spillage of NR/DASA composite film prepared by physical blending decreased from 1 420μg/g to 42μg/g,indicating that the covalent cross-linking reaction between the aldehyde group in DASA and the protein decreased the mobility of proteins,hence greatly reduced the protein spillover of NR/DASA film.Meanwhile mildew and contact allergy effect can be alleviated.The uniform distribution of the protein in NR film can also increase the solubility of the vulcanization accelerator,which makes the vulcanization reaction easier.Furthermore,the protein can also consume the peroxide radicals generated in the NR film during storage,thus lowering its aging rate.The tests of mechanical properties show that the tensile strength of NR/DASA composite film increases by 28.9%after vulcanization,and only decreases by 2.7 MPa after accelerating the aging treatment.Atomic force microscopy(AFM)and thermogravimetric(TG)analysis show that the surface smoothness and thermal degradation resistance of the NR/DASA films are also significantly improved.In addition,the solvent resistance of NR/DASA films in cyclohexane and petroleum ether is also greatly improved.