Preparation Of Multifunctional Polyol Ester-based Rare Earth Metal Alkols And Their Application As Additives For PVC

As the earliest functional plastic put into industrial production in the world,polyvinyl chloride（PVC）is widely used in industrial and agricultural production and life because of its excellent corrosion resistance,plasticity,insulation,high strength and low cost.However,in the production of PVC products,it is susceptible to thermal aging decomposition by high temperature,which not only affects the beauty of PVC,but also affects the quality of PVC products.Therefore,it is necessary to consider adding heat stabilizers to improve this defect of PVC in the production process,Therefore,it is necessary to consider adding heat stabilizers to improve this defect of PVC in the production process,among which,lead salts,metal soaps,organic tin and rare earths are common heat stabilizers.Most of these heat stabilizers suffer from various deficiencies and have a single function.The paper prepared a series of polyol ester-based rare earth metal alcohol salt heat stabilizers with good improvement of PVC thermal stability,in addition to excellent antibacterial,plasticizing and UV resistance properties.Therefore,the paper is a good reference for studying the preparation and application of rare earth metal alcohol salts.Firstly,the mannitol fumarate-based rare earth lanthanum metal alkoxide（MFE-La）was synthesized using fumaric acid,mannitol and lanthanum acetate as raw materials.The mannitol fumarate was synthesized by esterification reaction using p-toluenesulfonic acid as the catalyst and cyclohexane as the water-carrying agent.Then the polyol ester was reacted with lanthanum acetate in the ethanol environment to obtain the MFE-La.The structure and physical properties of rare earth metal alkoxides were characterized by Fourier transform infrared spectroscopy（FTIR）,X-ray photoelectron spectroscopy（XPS）and thermogravimetric analysis（TG）.The thermal stability of MFE-La to PVC was investigated by oven aging experiment and conductivity experiment.It was found that the thermal stability was the best when the molar ratio of MFE to La elements was 2:1,and the thermal stability was the best when the ratio of MFE to zinc stearate was Zn:La=1:3.The antibacterial properties of MFE-La were tested by surface antibacterial experiment and optical density（OD）method,and the highest antibacterial rates against S.aureus and E.coli were over99.5%.The biocompatibility of metal alkoxides was studied by hemolysis experiment.The results showed that the hemolysis rate of MFE-La was less than 5%and met the biocompatibility criteria.Rare earth metal alkoxide（PHE-La）based on pentaerythritol p-hydroxybenzoate was synthesized.The structure and physical properties of PHE-La were characterized,and the thermal stability and antibacterial properties of PHE-La on PVC were explored.The results showed that when PHE-La was added,the molar ratio of PHE to La was 2:1,and the thermal stability was the best when it was compounded with zinc stearate at the ratio of Zn:La=1:3.On the other hand,when the hemolysis rate of PHE-La is within the standard value,the antibacterial ability of PHE-LA against S.aureus and E.coli is above 99.5%.Carbon dots-supported Ti O₂ complex（Ti O₂@CQDS）was prepared by hydrothermal method and characterized in detail.And the effects and mechanisms of Ti O₂@CQDs on the UV degradation resistance of PHE-La/Zn St₂ stabilized PVC were investigated from both experimental and DFT theoretical calculations.The experimental results show that the use of Ti O2@CQDs can obviously slow down the photodegradation of PVC and improve the thermal stability of PVC to some extent.The calculation results of DFT theory show that CQDs belongs to local excitation,and photogenerated electrons and holes are easy to recombine,so that CQDs can convert ultraviolet light into visible light and improve the ultraviolet degradation resistance of PVC.The rich carboxyl carbonyl oxygen and ketone carbonyl oxygen on CQDs can fix HCl produced by PVC degradation by forming hydrogen bonds.And the hydroxyl group on CQDs can be complexed with Zn Cl₂ produced by Zn St₂stabilized PVC,thus inhibiting“zinc burning”.Therefore,Ti O₂@CQDs is a multifunctional light stabilizer for PVC,which can be used as the assistant for light and heat stability of PHE-La.