Study On The Refinement Of AC Foaming Agent And EVA/AC Foaming Material

Compared with ordinary EVA(ethylene vinyl acetate copolymer),foaming materials have disadvantages such as low mechanical strength,large material shape variable,etc.The EVA foaming materials with smaller pore size or even reach microcellular level can improve their mechanical strength and resilience,etc.,which expands the application field of EVA foaming materials.In this paper,a superfine AC(azodicarbonamide)foaming agent with an average particle diameter of less than 1?m was synthesized by a bubble liquid membrane method.Then,EVA foaming materials were prepared using self-made superfine AC foaming agent and marketed AC foaming agent respectively.The cell size,foaming ratio,resilience performance and mechanical properties of EVA foamed materials prepared by two kinds of AC foaming agent with different size were compared under optimal conditions.The main results were as follows:1.The optimal preparation conditions of AC foaming agent were as follows:the concentration of sodium bromide was 20 g/L,the concentration of ferric chloride was 5 g/L,the concentration of sulfuric acid was 1 mol/L,the ratio of hydrogen peroxide to water was 1:1.6,the dropping speed rate of hydrogen peroxide was 0.66 mL/min.The reaction temperature was 50?and the reaction time was 5 h.A superfine AC foaming agent could be obtained under these condition.Its decomposition temperature was 210.86?,which decressed by 30?than the AC foaming agent before fining.2.EVA2 was determined as the foaming matrix for subsequent experiments through rheological test and preliminary test.The optimal foaming conditions of two kinds of AC foaming agents were obtained by a single factor experiment.The best foaming conditions of maketed AC foaming agent was as follows:foaming temperature was 200?,foaming pressure was 10 MPa,and foaming time was 10 min.The best foaming conditions of self-made superfine AC foaming agent was as follows:foaming temperature was 190?,foaming pressure was 11 MPa,and foaming time was 10 min.3.The best foaming formula for commercial AC was as follows:EVA resin 100 phr,foaming agent 8 phr,DCP crosslinking agent 1.4 phr,nano calcium carbonate 2 phr.The best foaming formula for refined AC was as follows:EVA resin 100 phr,foaming agent 4 phr,DCP crosslinking agent 1.2 phr,nano calcium carbonate 1 phr.4.Under the optimal conditions,for commercial AC foaming EVA,the cell size distribution was 100-150?m,the bibulous rate was 12.5%,the rebound rate was 94.8%,The permanent compression deformation was 6.2%,the tensile strength was 1.03 MPa/(g/cm~3),the breaking elongation was 95.43%,the young's modulus was 2.16 MPa,and the yield strength was 1.95 MPa;for refined AC foaming EVA,the cell size distribution was 10-20?m,the bibulous rate was 1.02%,the rebound rate was 97.4%,The permanent compression deformation was 2.7%,the tensile strength was 5.44 MPa/(g/cm~3),the breaking elongation was153.66%,the young's modulus was 7.53 MPa,and the yield strength was7.55 MPa.The cell size of EVA foaming material prepared by refined AC foaming agent is significantly smaller than that of the marketed AC.Due to the differences in the size and structure of the cells,the properties of the foaming material prepared by refined AC are significantly better than that of the marketed AC.