| Poly(vinyl chloride)(PVC) is the second-largest general resin in the world and one ofthe prioritizing new function materials during the twelfth five. PVC has extraordinaryproperties, making it widely used in many important fields. However, PVC also have somestructural defects wich resulting in its poor stability. Therefore, a amount of thermal stabilizeris needed to be added in fabricating PVC to improve its thermal stability and relieve itsthermal degradation. In practice, however, many of the commercial thermal stabilizers aretoxic, expensive or cause environmental problems. Making it a urgent to research the novelthermal stabilizer which is safety, non-toxic, green and efficient. As is known to all, plan oilis not only abundant resources, safety, environmental-friendly, but also renewable,whichmaking it a unique resource that the others cannot be compared. This paper is devoted tostudy on research and complex application of novel modified castor oil-based thermalstabilizer.First of all, castor oil-based binary acids were synthesis by the mono-esterification ofdifferent anhydride with ricinoleic acid，so some functional groups which have thermalstability were successfully introduced to castor oil-based binary acid. And the novelcalcium/zinc soap of castor oil-based binary acids were also prepared. Contrast withtraditional oil based thermal stabilizer of calcium isooctanoate (IA-Ca) and zinc isooctanoate(IA-Zn), the reasons of differences of thermal stability and mechanism of the castor oil-basedmetal soaps were also researched. Experiment showed that five kinds of castor oil-basedbinary acids can improve the thermal stability of PVC. The stabilizing efficiency is attributedto the Diels-Alder reaction can take place between castor oil-based binary acids and theconjugated double bond of PVC, which can be appropriately inhibit the growth of theconjugated double bond and the release of HCl. The thermal stability of castor oil-basedmetal soaps was also investigated. Zinc carboxylate of ricinoleic acid maleate (RAM-Zn) andzinc carboxylate of ricinoleic acid hexahydrophthalate (RAH-Zn) exhibited better thermalstabilization efficiency to PVC than IA-Zn. The results also suggested that calciumcarboxylates of ricinoleic acid maleate and ricinoleic acid hexahydrophthalate (RAM-Ca,RAH-Ca) can acted as a long-term thermal stabilizer like IA-Ca. What’s more, there was asynergistic stabilization effect between RAM-Zn/IA-Ca and RAH-Zn/IA-Ca. And the bestsynergistic effect were achieved when the ratio of calcium/zinc ion content is1.67/1.00and1.92/1.00, respectively. Moreover, the thermal stability of RAM-Zn/IA-Ca system andRAH-Zn/IA-Ca system has been significantly improved by the combination of epoxidized soybean oil, phosphite ester, β-diketone and antioxidant with certain ratios.Secondly, three kinds of castor oil-based acids intercalated hydrotalcites were preparedaccording to “memory effect” and notes as LDHs-RA, LDHs-RAM and LDHs-RAH,respectively. When added these castor oil-based acids intercalated hydrotalcites with calciumstearate/zinc stearate (CaSt2/ZnSt2) to PVC resin could significantly enhanced the thermalstability of PVC resin than carbonic acid root intercalated hydrotalcites (LDHs-CO3).Moreover LDHs-RA, LDHs-RAM and LDH-RAH have better thermal stability than CaSt2and its thermal stability time are87.7min,68.4min and53.6min, in180℃, respectively, it isfar higher than CaSt2which thermal stability time is37.9min only. ZnSt2, LDHs-CO3,antioxidant and other co-thermal stabilizer were added to this novel hydrotalcites in order toimprove its stabilizing efficiency. And get the thermal stabilizer formulations with industrialapplication prospect.Novel castor oil-based thermal stabilizers were studied in this paper. From raw materialsto products they have the advantages of safety, environmental friendly, non-toxic andnon-polluting. The research of castor oil-based thermal stabilizers can not only full use of theabundant resources of ricinoleic acid in our country, but also provide a new way for thedevelopment and application of new environmental protection plastic additives. |
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