【作者】 周洋；

【导师】 彭宗林；

【作者基本信息】 上海交通大学 ， 材料学， 2011， 硕士

【摘要】 天然橡胶是目前使用最广泛的通用橡胶。天然橡胶发泡材料是最早出现的发泡材料之一,目前已经在轮胎工业,抗冲减震,隔音保温,体育用品等各行各业得到充分应用。由于天然橡胶的软化温度和分解温度较低,因而通过各种手段将发泡剂的分解温度降低到合适的范围,使得天然橡胶的硫化过程和发泡过程相互匹配,对于天然橡胶发泡材料的制备和性能的提高有重要意义。本文以天然橡胶(NR)为基体聚合物,发泡剂H(N,N′-二亚硝基五次甲基四胺)、AC(偶氮二甲酰胺)和OBSH(4,4′-氧代双苯磺酰)为发泡剂,尿素(Urea)为活化剂,硫黄(S)为交联剂,系统研究了发泡剂H的尿素活化机理以及发泡剂AC、H和OBSH两两并用的分解特性,并在此基础上制备了天然橡胶发泡材料,研究了并用比例、类型和工艺条件对泡孔结构和发泡材料性能的影响。本文用差示扫描量热分析(DSC)、热重分析(TGA)和红外光谱分析(FTIR)等方法对发泡剂H与尿素的相互作用机理以及两者并用对天然橡胶硫化发泡的影响进行了定性和定量的表征。实验结果表明,发泡剂H与尿素并用的反应途径与它们单独分解不同,两者相互反应温度在130~180℃之间,峰值温度为150℃,发泡剂H和尿素的并用比例在等当量或尿素稍过量时效果最佳。发泡剂H和尿素对天然橡胶的硫化都有明显的促进作用,160℃发泡可以实现硫化过程和发泡过程的良好匹配。发泡材料的密度和硬度与并用比例和工艺条件有关,发泡体的泡孔均匀性与尿素的分散性密切相关,尿素分散均匀可以提高发泡材料泡孔均匀性。用差示扫描量热分析(DSC)、热重分析(TGA)对AC、H和OBSH的并用结果分析表明,AC/OBSH,H/OBSH并用后有较明显的协同作用,而AC/H并用后协同作用不明显。用无转子发泡硫化仪测试了不同温度下发泡剂两两并用的硫化曲线,160℃为发泡剂并用的最佳硫化发泡温度。AC/OBSH并用,H/OBSH并用后可以得到泡孔均匀的发泡材料,发泡材料的泡孔大小随着硫化发泡时间的增加而变大,泡孔数相应变少,泡壁变薄。天然橡胶发泡材料的压缩和吸能特性研究表明,其压缩应力应变曲线有两个阶段:线形弹性阶段,致密化阶段。随着发泡材料密度的减小,线形弹性区变宽,材料致密化应变εd出现推迟。密度小的天然橡胶发泡材料吸收能量较大。不同密度的发泡材料都有吸收能量最有效率的区间。随着密度的减小,材料吸能效率峰值提高,吸能曲线跨度变得更宽,表明密度较小的发泡材料在较宽的范围内均有良好的吸能效果。本论文的工作为研究聚合物基体中发泡剂的活化和并用特性提供了具有实用价值的基础,为天然橡胶发泡体系的选用提供了指导,为改善天然橡胶发泡材料的泡孔结构和性能提供了理论依据。更多还原

【Abstract】 Natural rubber (NR) foam is one of the earliest polymer foam materials, which has currently been used in plenties of industries. In the foaming technology, it is important to use various methods to decrease the decomposition temperature of blowing agents to a suitable range to make the curing process of NR could match well with foaming process. In this paper, we used NR as the polymer matrix, H (N,N′-dinitroso pentamethylene tetramine), AC (Azodicarbonamide), OBSH (p,p′-Oxybis Benzene Sulfonyl Hydrazide) as blowing agents, Urea as activator and Sulfur as crosslink agent. We systematicly studied the activation mechanism of blowing agent H with Urea, the decoposition characteristics of AC/OBSH, AC/H, H/OBSH compounds. We also studied the influence of blowing agents on curing and foaming process of NR. Finally, we prepared NR foam materials and studied the influences of blowing agents and process conditions to pore structure and compression performance of foam materials.Activation mechanism of blowing agent H with Urea in NR matrix was qualitatively and quantitatively characterized by DSC, TGA and FTIR analysis, and their effects on the foaming performance for NR were also investigated. The results show that the decomposition mechanism of blowing agent H and Urea mixture is different from their own decomposition reactions, they react at a temperature range from 130°C to 180°C, and the peak decomposition temperature is 150°C. The optimum ratio for the two compounds is at their equivalent weight or with a little excess of Urea. Both of blowing agent H and Urea show great accelerating effects on the cure of NR. The pore uniformity of NR foam is closely related to the dispersion of Urea.The DSC, TGA and FTIR analysis showed that the combination of AC/OBSH and H/OBSH had positive synergy effects and could made good pore structure, but the combination of AC/H had no obvious synergy effects. The optimum curing temperature of NR with blowing agent blends was about 160°C.The compressive behavior of NR foam through compressive stress-strain curves was also investigated by the means of energy absorption efficiency (E). Results show that foams with low density have better absorption efficiency in a wide range.In this paper, valuable parameters of the activation and blending characteristic of blowing agents in polymeric matrix were provided, which could give the guidance for blowing system selection and for the improvement of pore structure and performance of NR foams.更多还原