Effect of rubber confined in nano-space of nanomatrix structure on the mechanical properties

为了阐明纳米结构橡胶优异力学性能的原因，研究了缠结等物理相互作用对其力学性能的影响。在胶乳阶段，苯乙烯与天然橡胶接枝共聚，形成纳米基体结构；因此，平均直径约为1 μ m的天然橡胶分散体在厚度为10 ~ 60 μ m的聚苯乙烯纳米基体中分散良好。聚苯乙烯纳米颗粒平均直径约为5 nm，分散在纳米基质中，聚苯乙烯纳米颗粒之间存在天然橡胶。采用安东帕MCR 302流变仪测定了聚苯乙烯纳米颗粒和天然橡胶在纳米基质中的作用。用尿素和十二烷基硫酸钠对HANR胶乳进行脱蛋白处理，制备脱蛋白天然橡胶（DPNR）。以过氧化氢叔丁基和四乙烯五胺为原料，在乳胶阶段进行了苯乙烯与天然橡胶的接枝共聚反应。接枝乳胶凝固后，用透射电镜观察形貌。发现DPNR-聚苯乙烯接枝共聚物（DPNR-graft- ps）具有纳米基体结构，其中平均直径约为1 um的天然橡胶分散体在厚度为10 ~ 60 nm的聚苯乙烯纳米基体中分散良好。在30℃时，具有纳米基体结构的DPNR-接枝- ps的存储模量约为DPNR的10-100倍，而具有岛状基体结构的DPNR-接枝- ps的存储模量约为1-3倍。存储模量提高10-100倍是纳米基质结构的显著优势。当纳米基质中PS纳米颗粒尺寸约为5 nm和60 nm时，具有纳米基质结构的dpnr -接枝PS的损耗正切值分别约为0.15和0.08，且与频率无关。具有纳米矩阵结构的DPNR-接枝- ps的频率无关损耗正切与DPNR本身的频率无关损耗正切相区别。结果表明，将纳米粒子密集分布在纳米基体中，可以制备出具有频率无关损耗切线的新型材料。少

Effect of physical interaction such as entanglement on the mechanical properties was investigated, in order to elucidate the origin of outstanding mechanical properties of rubbers with nanometrix structure. The nanomatrix structure was formed by graft-copolymerization of styrene onto natural rubber in latex stage followed by coagulation of the resulting latexd; so that, the dispersoid of natural rubber of about 1 um in average diameter was well dispersed in the nanomatrix of polystyrene of 10-60 nm in thickness. The polystyrene nano-particles of about 5 nm in average diameter were dispersed in the nanomatrix, in which natural rubber existed between the polystyrene nano-particles. The effect of the polystyrene nano-particles and natural rubber present in the nanomatrix was assessed with an Anton Paar MCR 302 RheometerThe sample used in the present work is commercial high ammonia natural rubber (HANR) latex. The HANR latex was subjected to deproteinization with urea and sodium dodecyl su … More lfate in order to prepare deproteinized natural rubber (DPNR). The graft-copolymerization of styrene onto natural rubber was carried out in latex stage with tert-butyl hydroperoxide with tetra ethylene pentamine. After coagulation of the grafted latex, morphology was observed by transmission electron microscopy.The nanomatrix structure was found for graft-copolymer of DPNR and polystyrene (DPNR-graft-PS), in which the dispersoid of natural rubber of about 1 um in average diameter was well dispersed in the nanomatrix of polystyrene of 10-60 nm in thickness.Value of storage modulus of DPNR-graft-PS with the nanomatrix structure was about10-100 times as high as that of DPNR at 30 OC, whereas the value of DPNR-graft-PS with the island-matrix structure was about 1-3 times. The 10-100 times higher value of the storage moduluswas remarkable advantage of the nanomatrix structure. When the size of PS nano-particle in the nanomatrix was about 5 nm and 60 nm, value of loss tangent of the DPNR-graft-PS with the nanomatrix structure was about 0.15 and 0.08, respectively, which were independent of frequency. The frequency independent loss tangent of the DPNR-graft-PS with the nanomatrix structure was distinguished from that of DPNR, itself. Consequently, it is concluded that a novel material, which possesses frequency independent loss tangent, is prepared by densely distributed the nano-particles into the nanomatrix. Less