Study Of Synthesis And Application Of Quick-coagulant Of Natural Latex

Quick-coagulation is that liquid natural latex is coagulated by quick-coagulatant in a few minutes. The quick-coagulant is typically rapid and environmental, the synthesis and application research in quick-coagulatant of natural latex is rarely reported. In this study, emulsifier, oxidant A, oxidant B and octanol as a main raw material were used to preparing quick-coagulatant, which optimized the complex system of quick-coagulation. The effects of quick-coagulator on natural latex coagulation were studied, and the structure and variation properties of natural rubber coagulated by quick-coagulatant (NR-q) were investigated.Four factor such as octanol, emulsifier, oxidant A and oxidant B are selected. Orthogonal experimental method is adopted to design twenty-five experimens of different factors’level, the optimal combination is that the oxidant A is twenty-five grams, the oxidant B is five grams, octanol is about sixty percent, and the emulsifier is five grams.The quick-coagulant has a good effect on natural latex coagulation, in which the coagulation time is about20seconds, and the coagulated particles are much better. Furthermore, quick-coagulator can be recycled to save the cost of production. In addition, the dry rubber content has a great influence on the latex coagulation, the more the dry rubber content, the less the coagulation time.The raw rubber structures of NR-q are nearly the same as the raw rubber coagulated by acid (NR-a). IR spectrum has showed that, the NR-q has more obvious absorption peaks of protein in1540cm-1. Because the latex is coagulated very quickly, which slowing down the rate of loss of protein in latex. At the same time, the molecular weight and the distribution width index of molecular weight of NR-q are a little smaller than those of NR-a. And the impurity content, nitrogen content, ash content and volatile content are0.037percents,0.45percents,0.07percents,0.197percents respectively in raw rubber; initial plasticity (P0) is44and plasticity retention index (PRI) is86percents. All results achieve technical requirements of SCR-5.The vulcanized rubber of NR-q has better vulcanization characteristics and higher crosslinking densities compared with NR-a vulcanizate. The torque increase rate (VM) and cure rate index (Vc) are higher, and scorch time (t10) and vulcanization time (t90) are smaller. These indicate that the NR-q vulcanizate has higher vulcanization rate, but processing safety is poor. The crosslinking densities of NR-q detected by NMR are6.49×10-5mol/cm3, and the weight of network chain is higher while the free-ends and the transverse relaxation time are less.compared with NR-a, the compounds natural rubber of NR-q has better resistance deformation ability, and vulcanized rubber of NR-q has better physical and mechanical properties. In a certain period of time, the resistance deformation ability of NR-q will be better with the prolonging of ripening time. And The modulus, tensile strength, tearing strength of NR-q vulcanizate are higher than those of NR-a vulcanizate. And the tensile strength of NR-q vulcanizate is18.8MPa, and the tearing strength is27MPa.