Study On The Synthesis And Structure-property Relationship Of Woody Oil-based Plasticizer For PVC

Plasticizer is one of the most widely used additives in plastic processing and manufacturing industry.At present,the majority of plasticizers are Dioctyl-Phthalate(DOP)and Dibutyl-phthalate(DBP).However,these phthalate plasticizers have teratogenic,carcinogenic and other risks,which are difficult to meet the requirements of REACH176.Environmental-friendly plasticizers are welcome in the market.Oil plasticizers have received worldwide attention because of their low toxicity,renewable raw materials,biodegradability,etc.Now,the oil plasticizers are mainly from edible oil,such as soybean oil.However,these edible oil based plasticizers lacks variety and multi-performance,which is difficult to meet the growing demand for high-quality plasticizers in the plastic industry.Based on this,in this study,the plasticizing performance and structure-properties relationship of epoxy fatty acid ester and oil-based polybasic acid ester plasticizers were explored,the internal relationship between the plasticizer structure and the plasticizing effect were studied,modeled the relationship between plasticizing effect and structure was modeled by mathematics,two kinds of plasticizers with excellent migration properties were synthesized and the properties of plasticizer products were analyzed and tested comprehensively.These results may offer a theoretical foundation for the further application of woody oil-based epoxy plasticizer.The specific research contents and conclusions are as follows:1.Study on the synthesis and properties of plasticizer:Woody oils(stillingia oil and tung oil)were chosen as raw materials.By saponification,esterification,epoxidation and Diels-Alder reaction,woody oils were transferred to epoxy oil-based plasticizers(four kinds of epoxy fatty acid ester plasticizers and five kinds of“six-membered ring" C₂2-tribasic ester structure plasticizers).The properties of these plasticizers with different structures were studied by the IR analysis,X-ray diffraction,thermogravimetry,tensile test,dynamic thermodynamics,scanning electron microscopy,and extraction test.The experimental results show that the Tg(glass-transition temperature)of PVC plasticized by the epoxy fatty acid ester plasticizer is 30.5?,which is significantly lower than the PVC plasticized by the DOP(37.64?);the tensile strength is about 24MPa,similar to DOP(26.22MPa);the elongation at break is above 385%,which is higher than DOP(360.64%);the thermogravimetric analysis shows that the loss rate of PVC plasticized by epoxy plasticizer at 300? is significantly lower than that by DOP,and the residual of PVC plasticized by epoxy plasticizer was greater than that by DOP.All of these show that epoxy fatty acid ester has a very strong plasticizing property and thermal stability.For "six-membered ring" C₂2-tribasic ester structure plasticizers,four plasticizers[Trimethyl C₂2-tribasate(TM111),C₂2-tribasic methyl diethyl ester(TM122),C₂2-tribasic methyl dibutyl ester(TM144),C₂2-tribasic methyl dioctyl ester(TM188)]have favorable plasticizing effect and the same physical and chemical properties as the DOP.However,the thermal stability of PVC with these plasticizers are superior to those of the DOP.Among the four plasticizers,the volatilization of TM111,TM122 and TM144 plasticized PVC film is 4.08%,3.92%and 2.83%,respectively,which is less then 5.54%of DOP plasticized PVC film.The tensile strength of PVC film plasticized by TM111 and TM122 is 25.24MPa and 22.74MPa,respectively,which is higher than the PVC film plasticized by DOP(22.32MPa).The elongation at break of PVC film plasticized by TM111 is 2.5%,higher than that plasticized by DOP.Therefore,TM111 has the most excellent plasticizing property.2.Study on the relationship between structures and properties:The structure-property relationship of oil-based plasticizers was constructed based on the structure-property relationship of epoxy fatty acid ester and C₂2-tribasic ester.The structure of oil-based plasticizer is mainly devided into two parts:polar group and non-polar group.For plasticizers,the polar groups should be at the periphery of the molecule of the plasticizer to facilitate their contact with the molecular chain of PVC and increase compatibility;the number and length of non-polar groups should be appropriate.So,they cannot block the polar groups.And they should interact with the molecular chain of PVC and block the interaction between the molecular chains of PVC to reduce the interaction between the molecular chains of PVC.Thus,thet play a role of lubricating(plasticizing).On this basis,in order to predict the plasticizing effect of the oil-based plasticizer,an empirical formula for calculating the plasticizing index is proposed in this study.3.Verification test:According to structure-property relationship and plasticizing index(Ip),two kinds of compounds with different structures-Epoxy acetyl glyceride(ELCO)and C₂2-tribasic ethyl dimethyl ester(TM211)]were synthesized.The results show that the Tg of ELCO is-0.77?,which is lower than 6.13?,the elongation at break of ELCO plasticized PVC is 370.56%,which is higher than that of epoxy soybean oil(ESO)plasticized PVC(321.11%).Compared with the epoxy fatty acid methyl ester(flash point:178?),it has a higher flash point(204?),less heat loss and better thermal stability.For TM211,XRD shows that the product can effectively destroy the crystallinity of PVC;DMA shows that the Tg(46.37?)of TM211 plasticized PVC is lower than TM188 plasticized PVC(52.1?);Tensile test and SEM of the cross-sectional fracture surfaces show that it has the same plasticizing performance as the DOP,but it can improve the tensile strength of the material;The resistance to extraction in five solvents(such as water,ethanol,ether,etc.)and the volatility of TM211 are better than DOP;TGA and pyrolysis activation energies show that TM211 can effectively improve the thermal stability of PVC materials.Therefore,ELCO and TM211 are both new plasticizers with excellent properties.The successful synthesis of these two plasticizers shows that the formula of structure-property relationship and plasticizing index(Ip)proposed in this study is feasible to some extent.