碱式柠檬酸镧作为PVC热稳定剂的研究

Study on Alkali Type Lanthanum Citrate as a Heat Stabilizer of PVC

PVC在生产中会因为温度升高而降解,通常添加热稳定剂来抑制PVC的降解。在碱性条件下,用柠檬酸和硝酸镧所制备碱式柠檬酸镧作为PVC热稳定剂。用红外光谱、元素分析以及差热分析仪对产物进行表征。通过刚果红实验和变色性能测试对PVC进行稳定性测试。结果显示,185℃条件下碱式柠檬酸镧对PVC的热稳定时间达到57 min,有较好的长期抗变色能力。为了改善其对PVC的初期抗变色能力,引入硬脂酸锌和季戊四醇,制备复合稳定剂。复合稳定剂对PVC的热稳定能力得到提高,且对PVC的初期着色有了较大的改善。碱式柠檬酸镧在提高镧含量的基础上增加了活性羟基,从而使其对PVC降解起到抑制作用。

PVC was degraded with the elevating of temperature in production, stabilizers was usually added to PVC to suppress the degradation of PVC. In this paper, Alkali type lanthanum citrate was prepared by citric acid, NaOH and lantha- num nitrate under alkaline conditions. It was analyzed by elemental analyzer, FTIR and differential thermal analyzer. Thermostability of PVC was analyzed by Congo red test and heat aging test. The experiment shown that the stabilization time of alkali type lanthanum citrate was 57 minutes and it has a good effect under 185 ℃. Alkali type lanthanum citrate is good for long - term anti - tarnishing capability of PVC. In order to improve its initial thermal stability, zinc stearate and pentaerythritol were used in experiment to prepare compound stabilizer. Thermal stability of compound stabilizer is better than alkali type lanthanum citrate, and the stabilizer obviously improves the initial coloring of PVC. Alkali type lanthanum citrate increases active hydroxyl on high content of lanthanum basis, thus thermal stability of Alkali type lanthanum citrate is greatly improved.