Development of environmentally friendly PVC compositions

Introduction. Polyvinyl chloride (PVC) is one of the most important polymers in the economy. Due to its versatility, this material is now found in a wide variety of products used in everyday life. A wide range of physical and mechanical properties is given to it by the use of additives, the main of which are plasticizers. The most common in terms of consumption are orthophthalic acid esters, in particular, dibutyl phthalate (DBP), dioctyl phthalate (DOP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP). Phthalates are well combined with polymers, give them high physical and mechanical properties, therefore plastic compounds based on them are widely used in the construction sector, engineering, as well as in agriculture and in everyday life. Numerous studies of products made from plasticized PVC, conducted in different countries, have established the adverse effects of DOP on human health, which led to the limitation of its areas of application. Legislative bans and growing consumer pressure are forcing PVC compound manufacturers to look for an environmentally friendly replacement for DOP. Methods and materials. In this research work, the possibility of creating more environmentally friendly PVC compounds using a mixture of plasticizers: industrial dioctyl phthalate and diisononyl phthalate and dibutoxyethyl phthalate (DBOEP) developed by us was studied. The choice of the plasticizers is based on the fact that DINP and DBOEP, in contrast to dioctyl phthalate, belong to the 3rd hazard class. Results and discussion. In the course of the correlation-regression analysis, a close functional relationship was obtained between the additives used and the characteristics of PVC, which was confirmed by the calculated coefficient of determination. Using the method of nonlinear programming applied to the constructed third-order polynomial dependencies, it was found that in the basic PVC composition formulation it is promising to replace up to 25 wt.h. DOP on DINP plasticizer. The joint use of industrial plasticizers DOP and DINP, as well as the developed DBOEP in the formulation of PVC compositions, indicates an increase in plasticity and manufacturability. This can probably be explained by the synergistic effect of the studied plasticizers. The dependence of the properties and content of plasticizers DBOEP and DINP in the form of a second-order surface was studied on the basis of the obtained experimental data, the level lines of the constructed function of two variables were studied, as a result of which it was found that the greatest effect is achieved at a dosage of: DOP – 25 wt.h., DINP – 5 wt.h. and DBOEF – 20 wt.h. Conclusion. The obtained research results show that the proposed formulation of the PVC composition makes it possible to reduce the toxicity of the plasticizers used by 50 % and improve the physical, mechanical and technological characteristics of the compounds.