Studies On The LDHs-Re-Zn Complex Heat Stability System Applied In PVC

This thesis involved the synthesis of a series of LDHs, zinc soaps and rare earth soaps and the research work of RZL complex stabilizing system. The synergism effect of these complex heat stabilizers was also studied. RZL complex stabilizing system possessed excellent thermal stability and it hasn't been reported at home and abroad.Following the synthesis principle of the innocuity and good effect, firstly, several kinds of zinc soaps and rare earth soaps were synthesized. Then, acrylic zinc and glycin zinc were studied. The reaction conditions were optimized through tests. The experimental results showed that for acrylic zinc the mole ratio is n (CH2=CHCOOH): n (zn(CH3coo)2) =1: 6, the temperature is 80℃ and the optium zinc salt is acetic zinc, the yield of the production is 96.5%;for glycin zinc the mole ratio is n (NH2cH2cooH) ' n(znco3)=l .' 3 , the temperature is 100℃ and the optium zinc salt is zinc carbonate.The yield of the product is 92.8%. These productions were tested by IR technic, TGA technic etc. It showed that for acrylic zinc ,the zinc content is 30.6%, the stretching vibration of O-H at 3400cm"1 disappears in IR, the melting point is 139~142℃;for glycin zinc ,the zinc content is 28.5 % , the stretching vibration of O-H at 3400 cm"1 disappears in IR. And the melting point is 282~284℃.In order to reduce the cost, LDHs was prepared and It was characterized by XRD, TGA, IR etc.. These test results proved that the LDHs was prepared successfully.The thermal stabilities of RZL were characterized through cango red test paper, aging oven, etc.. The experimental results showed that the product possessesed excellent thermal stability for PVC resin,it can obtain good thermal stability while added 2.4phr of RZL in PVC. Furthermore, the RZL were compared with organic tin stabilizer, organic antimony stabilizer, Ca/Zn stabilizer , rare earth stabilizer. It showed that RZL have better thermal stability than Ca/Zn stabilizer and rare earth stabilizer, it almost has the similar thermal stability as the organic tin stabilizer.ABSTRACTIn the end, the heat stability mechanism of RZL serial heat stabilizers for PVC had been studied. Through FT-IR technic, the C-CI bond stretching vibration frequency of samples were compared. It show that RZL complex stabilizing system react with C1 of the PVC chain.Therefore this research work is important for improvement of the heat stabilizing effect of rare earth and development of our plastics additives industry.