Study On The Synthesis,Synergism And Application Of A Kind Of Rare-earth As Thermal Stabilizer For PVC

In Polyvinyl chloride （PVC） applications has a main drawback or limitation that iteasily undergoes severe thermal degradation at a relatively low temperature, so, properamount of stabilizers need be added so as to restrict the degradation of PVC during thethermal processing. In recent years, majority research works have mainly focused oneither improving the compatibility of rare earth stearate and PVC by adding additives orforming a new compound by introducing a special functional group. Here, with thesecond thought we present a circular rare earth cyanurate synthesized via a simplereaction between organic weak acids and rare earth compound.Lanthanum cyanurate was synthesized from cyanuric acid, lanthanum nitrate andsodium hydroxide. In order to determine the reasonable process conditions, theorthogonal experiment method has been used to explore the various related factor’sinfluence within the lanthanum cyanurate synthesis reaction. The synthesized productwas characterized by FTIR and element analysis. The effect of lanthanum cyanuric onthermal stabilization and discoloration of PVC was studied by Congo red test, and alsocompared with lanthanum stearate, calcium stearate, zinc stearate. The effect oflanthanum cyanurate on Plasticizing effect of PVC was studied on a torque rheometer,and in comparison with other heat stabilizers, including lanthanum stearate, calciumstearate and zinc stearate, lanthanum cyanurate. The synergy which lanthanumcyanurate respectively with calcium stearate, zinc stearate, pentaerythritol, beta diketonehave showed in PVC thermal stability was investigated through the Congo red test.Based on synergy, three groups of composite stabilizer has been made, and researchedtheir thermal stability, discoloration experiment. In addition, the effect of compositestabilizer on Plasticizing effect of PVC was studied on a torque rheometer.The results show those the best synthesis process of Lanthanum cyanurate isA2B3C3D2(Temperature70℃， NaOH concentration1.2mol·L^-1， response time60min， pH=7). There is coordination effect between cyanuric acidic group andlanthanum ion, which imparts excellent thermal stability for lanthanum cyanurate; when lanthanum cyanurate content is2.5%of PVC, the thermal stabilization time of PVC is80min; The max torque of lanthanum stearate is slightly less than lanthanum cyanurate,so, when they are used for PVC thermal stabilizers, the power of lanthanum stearatewhich required in machining process would beless than lanthanum cyanurate. However,balancing torque decided the production power consumption of the processingequipment. Balancing torque of lanthanum cyanurate is slightly less than lanthanumstearate, so, when they are used for PVC thermal stabilizers, lanthanum cyanurateproduction power consumption of the processing equipment would be less thanlanthanum stearate. Both rare earth cyanurate stabilizer and rare earth stearate stabilizerin plasticizing experiments respectively have disadvantage and advantage, if combinedtogether, it will be very promising. Lanthanum cyanurate respectively with the calciumstearate, zinc stearate, pentaerythritol have obvious synergy, but was not obvious withbeta diketone. The effect of composite stabilizers（Ⅰ） is better than the other two groupsin thermal stability testing, however, the effect of composite stabilizers（Ⅲ） is betterthan the other two groups in discoloration situation.