Synthesis and characterization of the polyols by air oxidation of soybean oil and its effect on the morphology and dynamic mechanical properties of poly(vinyl chloride) blends Pedro A. Ourique, 1 J  er ^ ome M. L. Gril, 2 Ga € elle W. Guillaume, 2 Cesar H. Wanke, 1 Sergio G. Echeverrigaray, 3 Ot  avio Bianchi 1 1 Materials Science Graduate Program (PGMAT) University of Caxias do Sul (UCS), Caxias do Sul, Brazil 2 Ecole Europ eenne d’Ing enieurs en G enie des Mat eriaux, Lorraine, France 3 Ceramic Materials Institute (IMC), University of Caxias do Sul (UCS), Bom Princıpio, Brazil Correspondence to: O. Bianchi (E - mail: otavio.bianchi@gmail.com) ABSTRACT: The use of natural additives, with low toxicity and good compatibility, for PVC is becoming increasingly attractive. In this study, soybean oil additives were prepared by air oxidation reactions and blending with PVC. The oxidation reaction produced a sig- nificant increase in the number of hydroxyl groups in soybean oil; however, this kind of reaction results in the formation of a hetero- geneous structure due to free radical reactions in the medium. The oxidized soybean oil improved the compatibility with PVC due to an increase in the number of polar groups, such as hydroxyls, and thus a reduction in the amount of atactic polymer was observed. Furthermore, an increase in the molecular weight of the oxidized oil, as well as large amounts of polar groups contributes to reducing the migration of oil in the PVC. Regarding the crystallinity of PVC, the use of pure and oxidized soybean oil causes small changes in the crystalline phase of the polymer. Oxidized soybean oil has great potential for usage as a secondary plasticizer for PVC. VC 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42102. KEYWORDS: biopolymers and renewable polymers; blends; poly(vinyl chloride); structure2property relations Received 7 November 2014; accepted 11 February 2015 DOI: 10.1002/app.42102 INTRODUCTION Poly(vinyl chloride), commonly abbreviated to PVC, is employed for a wide range of applications and is the third most widely produced polymer. It can be rigid or flexible and requires the addition of additives for further processing into products. Several additives are used such as plasticizers, stabil- izers, lubricants, anti-oxidants, processing aids, fillers, flame retardants, smoke suppressors, agents to improve tenacity and heat-and-form stability, optional pigments, and others. These additives facilitate the processing and determine the properties of the final products, allowing PVC to be used for a wide range of applications including rigid profiles, pipes and fittings, roof- ing membranes, rigid films and sheets, soft films for packaging, electrical cable insulations, imitation leather, signs, and inflata- ble products. 1,2 Among the additives, plasticizers and lubricants have received special attention in recent years. 3 Numerous efforts have been made to find a viable substitute for phthalates as a plasticizer for PVC. 1,2,4,5 The toxicity of low- molecular weight plasticizers, such as bis(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP) and benzyl butyl phthalate (BBP), is now well established. The European Union and the United States of America banned their use for some applica- tions, e.g., toys and childcare articles, 6,7 in 2005 and 2009, respectively. Manufacturers have increasingly been replacing low-molecular weight plasticizers with less toxic high-molecular weight plasticizers, such as diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP), and certain plasticizers have become important economically. Nontoxic plasticizers which could be used as alternatives to phthalates with similar effective- ness, compatibility and cost include polymer plasticizers based on polyol, adipic acid, adipates, terephthalates and 2,5-furandi- carboxylic acid (FDCA). 2,8–10 Plasticizers obtained from renew- able sources represent a good substitute due to their lower toxicity. Many studies have been focused on plasticizers origi- nating from vegetable oils. 11–15 The use of derivatives from corn oil, which is a widespread product, has been quite successful in such applications. 16 The literature shows that the mechanical properties and the thermal stability of plasticized PVC can been improved with the use of epoxidized oils. 17–19 The oil-based plasticizer diffusion can be controlled through selective reactions involving the polymer chain with the formation of covalent VC 2015 Wiley Periodicals, Inc. WWW.MATERIALSVIEWS.COM J. APPL. POLYM. SCI. 2015, DOI: 10.1002/APP.42102 42102 (1 of 8)