Studies On Structure,Properties And Applications Of Wear And Oil Resistance Ethylene-vinyl Acetate Shoe Elastomer Composites

The soles are mainly of thermoplastic elastomer,synthetic rubber and plastic.Nowadays,the requirement of special shoe materials has been improved.The preparation of high-performance,light-weight and multi-functional composites is tendency of the special engineering soles in future.The EVA has excellent flexibility,elasticity and aging resistance.It is an important soles polymer material.However,the Va content has a great influence on the performance and application of the EVA.Currently,the EVA shoe materials are alwanys the EVA of Va content 15%²2%.It is difficult to meet the requirements of engineering soles in wear and oil resistance and so on.In this paper,two kinds of EVA foaming materials with different Va content were prepared by the mold chemical foaming,investigating the foaming behavior and properties of the two kinds of EVA.Then,the effects of silicone polymer?SP?on wear resistance,worn surfaces structure and mechanical properties of EVM?high Va EVA?/CB,EVM/CB/modified SiO₂ composites were studied.In addition,EVM/NBR composites with good compatibility were prepared by two-step blending method.The effects of NBR content on oil and wear resistance,vulcanization characteristics,dynamic mechanical properties and filler network of composites were systematically studied.Firstly,the foaming agent?AC?was activation treated by the metal oxide ZnO and organic acid salt ZnSA,obtaining the activation AC at decomposition temperature reduced from 230°C to 170°C.Optimizing the foaming and cross-linking temperature,foaming behavior and the principle of cell nucleation as well as as the effect of AC on foaming properties of EVA with two different Va content were investigated.The results showed that the density 0.18g/cm³,rebound rate 39%,cell density 1.74×10⁷cells/cm³,average cell diameter 79.35?m,good surface quality high foamed EVA2805 sole foaming material,was obtained when added 3 phr AC at 170°C by mold chemical foaming.The results showed that the density 1.03g/cm³,rebound rate 39%,cell density 2.09×10⁷ cells/cm³,average cell diameter 22.22?m,with good surface quality and mechanical properties low foamed EVM-500HV sole foaming material,was also obtained when added 2 phr AC and 30 phr filler at 175°C by mold chemical foaming.Compared the effect of different size CB on the wear resistance of EVM,the minimum size of N110 was the most obvious for reducing the abrasion volume of EVM.With the increase of the N110,the abrasion volume and the volume resistivity of EVM were reduced rapidly.The abrasion volume increased by 92.9%with volume resistivity 1.9×10⁷?·cm in 40 phr N110.The SP can significantly reduced the abrasion volume and Ra of EVM/CB composites,and effectively improved the structure and 3D optical profile of the worn surfaces.The abrasion volume decreased by 37.8%and Ra decreased by 39.0%in 8 phr SP.There was a modification to SiO₂ with different silane coupling agent KH550,KH560,KH570 and Si-69.Compared with the CB alone,the mechanical properties of EVM/CB composites were greatly improved by KH570 modified SiO₂.And the trouser and right angle tear strength increased by 21.1%and 48.4%,respectively.The analysis of RPA,SEM and 3D optical profilometer showed that the modified SiO₂ was better dispersion,and the abrasion volume and Ra were lower than that of the unmodified one.The micro-morphology and 3D optical profile of the worn surfaces were improved effectively.The EVM/NBR composites were prepared by a novel two-step blending method using BIPB as cross-linking agent.The wear and oil resistance of the composites were better than direct blending.The trend of oil and wear resistance of composites was analyzed by three-dimensional graph.With the increase of NBR content,the cross-linking density,wear and oil resistance of the composites were improved significantly in 30 phr filler.When NBR increased to 50 phr,the rate of volume and mass change decreased by 59.0%and 56.1%,and the contact angle decreased by 38.3%of the composites.The abrasion volume was 64mm³,and the Ra decreased by 54.1%.The microstructure of the worn surfaces were improved effectively.High wear and oil resistance sole materials were obtained.SEM showed that composites was mainly abrasive wear,accompaning by fatigue wear.DMA showed that there was only one Tg of EVM/NBR composites,indicating that the polymers with different polarity had excellent compatibility.The tan?peak value of the composites was lower than that of pure EVM with the increase of NBR content.SEM and TEM showed that the filler dispersed well in the matrix.