Preparation Of Styrene-sodium Acrylate Ionomer And Effect On The Crystallization Process Of PET

PET has been widely used in the industry, but its crystallization rate is very slow, which limits its application in engineering plastics. To enhance the crystallization rate of PET, adding nucleating agents is a easy and effective method. Ionomers nucleating agents can improve the crystallization of PET, and it cause slight molecular weight reduction of PET, therefore, it's very significative to study the properties of ionomers.Firstly, a series of styrene-acrylate acid copolymers with different molecular weight (Mw) and content of metal acrylate were synthesized. Then, neutralized the copolymers to styrene-sodium acrylate ionomers with NaOH/CH3OH. The TGA study showed that the ionomers have excellent thermal stability.Secondly, the effects of molecular weight (Mw), content of sodium acrylate and neutralization degree of styrene-sodium acrylate ionomers on the crystallization and morphology of PET were investigated. The results showed that the ionomers with lower content of sodium acrylate(5-10mol%) and lower molecular weight (Mw=2.0×103-3.0×104) have better nucleating effection. But compared with pure PET, all ionomers with kinds of molecular weight (Mw,), content of sodium acrylate can improve the crystallization of PET. As the degree of neutralization of styrene-sodium acrylate increased, the crystallizating rate of PET increased significantly, the best neutralization degree is 100%. The best ionomer in the stusy range is SAAg.2-Na, lwt%SAA8.2-Na can improve the Tmc of PET from 197.0℃to 213.9℃, and reduce the Tcc from 135.7℃to 122.6℃.The non-isothermal crystallization kinetics of PET modified by different ionomers was studied, the results shows that the Avrami index n increased with the addition of ionomers.Finally, The mechanical properties of PET modified by different ionomers was studied. The result showed that the mechanical properties of PET modified by different ionomers is improved. As the content of styrene-sodium acrylate ionomer increased from 0.1 wt%to 3wt%, the mechanical properties of PET increased firstly, and decreased afterwards, it reaches its maximum when the content is about 1wt%, improved the impact strength from 37.9 J/m to 42.9J/m, the tensile strength increased from 53MPa to 59.1MPa, and the flexural modulus increased from 2380.6MPa to 2586.2MPa.