Research Of EVA Modified By Blending

Ethylene-vinyl acetate(EVA) is a rubber-like elastic plastic, and it is a non-toxic, odorless, and transparent thermoplastic. It has good flexibility, impact resistance, transparency, adhesion, etc., but its low mechanical strength, poor thermal stability and resistance, limit its application. Linear low density polyethylene(LLDPE) is short branched polymer, and it has good tensile strength, tear strength, abrasion resistance, thermal stability etc. At the same time, the better compatibility of LLDPE and EVA can make up the deficiencies in performance. This paper will adopt the method of melt blending, using the blend of EVA、LLDPE as the basic, Nano-silica and Silicone powder were used filler, to produce EVA/LLDPE composite. Firstly, the experiment investigated the effect of LLDPE to the performance of EVA; and then studied the effect of the dosage of modified Nano-silica, and the dosage of adding method on mechanical properties, surface property, rheological property, thermal stability, thermal oxygen aging resistance etc. Finally, the influence of EVA and MAH grafted material (EVA-g-MAH) was studied. And ulteriorly the effect of filler on EVA/LLDPE composite performance, and the different filler dispersive situation in EVA/LLDPE basic and the interface between filler with basic were analyzied. This work will lay foundation for the study of "heat-and scratch-resistant EVA film". The results show:(1) The blending of EVA/LLDPE has improved than pure EVA to some extent in thermal stability and thermal aging resistance. In this blending system, with the increase of LLDPE percentage, the tensile strength and tear strength continuously increased; the surface friction coefficient of the composite materials continuously decreased, the scratch resistance of material improved, but the melt fluidity became poor.(2) The Nano-silica pretreated by silane coupling agent KH560, was added to EVA/LLDPE(80/20) basic. The results found that:the same dosage of modified Nano-silica has more enhancement effect than unmodified Nano-silica, wherein, when the content of modied Nano-silica was10.0phr, the tensile strength compared to that of pure EVA/LLDPE was improved by37.8%. Tear strength of the composite was increased with the increase of Nano-silica dosage; With the increase of modified Nano-silica, the friction coefficient of material surface decreased continuously, and the scratch resistance of composite material surface was impoved. However, the fluidity became poor. Using SEM analysis of tensile section, it was found that the dispersion of KH560modified Nano-silica in the basic has been improved.(3) The filling of the Silicone powder by direct powder addition and masterbatch addition into EVA/LLDPE(80/20), found that:the latter had a higher tensile strength. When the masterbatch powder content was6.0phr, the composite had the largest tensile strength, about37.2%higher than that of pure EVA/LLDPE. When the dosage of Silicone powder was4.0phr, the two ways both reached the maximum tear strength. With the increase of the dosage of Silicone powder, the surface friction decreased continuously, the scratch resistance of material surface was impoved. The fluidity of complex system has also been enhanced; Using SEM analysis of composites tensile section, it was found that the dispersion of Silicone powder by masterbatch method was improved.(4) Using EVA-g-MAH as impregnant of the composite system, it was found that:for the Nano-silica composite system (Nano-silica dosage was10.0phr), when the dosage of EVA-g-MAH was8.0-12.0phr, it showed the best result. When the dosage of EVA-g-MAH was12.0phr, the tensile strength of modified Nano-silica composites were compared with pure EVA/LLDPE and they were increased by about52.4%. When the dosage was8.0phr, the composite had the maximum tear strength. For the Silicone powder composite system(4.0phr Silicone powder, masterbatch way to add6.0phr Silicone powder), when the dosage of EVA-g-MAH was4.0phr, the way of adding Silicone powder composite materials showed tensile strength about46.7%higher than that of pure EVA/LLDPE, while, when the dosage of EVA-g-MAH was6.0phr, the masterbatch added method increased by about51.9%compared to pure EVA/LLDPE. When the dosage was2.0phr, the two ways both reached the maximum tear strength. EVA-g-MAH can improve the scratch resistance, thermal stability, thermal aging resistance of EVA/LLDPE composite material. Using SEM analysis of composite tensile section, it was found that adding EVA-g-MAH in composite system, the dispersion of filler in the basic was further improved.