Study Of The Novel Glyceryl Ca/Zn Thermal Stabilizer For Poly(Vinyl Chloride)

Poly(vinyl chloride)(PVC), as one of five synthetic resins, has become the third largest demand material in the world and the first largest in China. PVC has many advantages such as lower cost, corrosion resistant, insulation and high mechanical strength. However, PVC material has some structural defects because of the current polymerization technology, which lead to the degradation of PVC. To solve this problem, thermal stabilizers must be added into PVC. The commonly used thermal stabilizers are lead salts, metal soaps, organotin, rare earth and other co-stabilizers. Lead salts and organotin stabilizers are restricted used due to their strong toxicity and high cost. Calcium and zinc soap thermal stabilizer, considered as a non-toxic and environmental-friendly stabilizer, is becoming the most promising one.In this paper, firstly, PVC thermal degradation mechanism is discussed and the development of the PVC thermal stabilizers at present is clarified. Combining with the excess of the byproduct of biodiesel-glycerol, the study of glyceryl thermal stabilizers is focused on. Zinc glycerolate(ZnGly) and calcium glycerolate(CaGly) are synthesized with glycerol, zinc oxide and calcium oxide. The synthesis conditions are discussed and the best synthetic technology is determined. Products are confirmed by infrared spectrum, elementary analysis, X-ray diffraction and thermogravimetric analysis. Polyadipate glycerides(PAG) is synthesized with glycerol and adipic acid. The synthesis conditions are discussed and the best synthetic technology is determined. Products are confirmed by infrared spectrum, mass spectrometry and thermogravimetric analysis.The thermal aging oven method and Congo red method are used to measure the effect of products on thermal stability of PVC. ZnGly and CaGly have better effect on thermal stability comparing to the traditional thermal stabilizers, and when the mass ratio of ZnGly and CaGly is 1/3, the best performance is obtained. As a co-stabilizer, PAG has little effect with PVC when used alone. However, the addition of β-diketone, dipentaerythritol(DPER) and PAG with ZnGly/CaGly obviously increase the thermal stability. Comparing with the traditional co-stabilizers, PAG has better performance than DPER and is not as good as β-diketone. And the effect increases with the amount of PAG. When the mass ratio of PAG, ZnGly and CaGly is 0.5/0.5/1.5, the best performance is obtained.Finally, the novel Ca/Zn thermal stabilizer is obtained, when the PAG/ZnGly/CaGly=0.5/0.5/1.5. PVC with the addition of this thermal stabilizer has a excellent inhibitory effect of pre-colored, and has excellent long-term thermal stability.