Investigation And Application On The Friction And Wear Characteristics Of EVA/EPDM/SEBS Cross-linked And Foamed Material

The cross-linking and foaming material of ethylene-vinyl acetate copolymer (EVA) is applied to sport soles, and it is necessary to increase its overall performance. In this thesis, EVA as matrix material, both ethylene-propylene-diene terpolymer rubber (EPDM) and styrene-ethylene/butylene-styrene block copolymer (SEBS) as modified material, dicumyl peroxide (DCP) as a crosslinking agent to initiate the blends system to cross-link, and azodicarbonamide (AC) as a blowing agent thatis decomposited to produce gases filled in the cross-linked system to prepare uniform micro-cell and closed cell, the cross-linked and foamed material of EVA/EPDM, EVA/SEBS, and EVA/EPDM/SEBS blend system were prepared at a certain temperature and pressure. The universal testing machine and vulcameter are used to analyze their mechanical properties and crosslinking kinetics of crosslinking and foaming reactions. The friction and wear behaviors of cross-linked and foamed material are investigated with a DIN wear machine and the friction coefficient test instrument. The worn surfaces were examined by using Scanning Electron Microscope (SEM). Effect of loss angle tangent (tan?) of this kind of material on friction and wear characteristics are studied with dynamic mechanical thermal analysis.Experimental results showed that the mechanical properties of cross-linking and foaming material take a turn for the better with increasing of EPDM content in EVA/ EPDM blends. The real contact area increased because of the hardness reduced, the increase of elastic has enhanced adhesion, and it makes the friction coefficient increases. The increase of tensile strength and elongation at break of cross-linking and foaming material makes the abrasion resistance become better. Abrasive wear is the main wear form in the friction pair of cross-linking and foaming material with aluminum oxide cloth, but which also has mixed in adhesive wear. Both the blowing agent and cross-linking agent have a little effect on the friction coefficient. Both the mechanical property and friction coefficient increase with the increase of SEBS content in EVA/SEBS and EVA/EPDM/SEBS blends. The friction coefficient reaches a maximum at the SEBS mass fraction of 30% in EVA/SEBS blends and at the SEBS mass fraction of 40% in EVA/EPDM/SEBS blends. The wear volume increases with the increase of SEBS content in two blends. The friction force increases with the increase of tan?, the increase of real contact area and abrasion volume are relevanted to the reducement of storage modulus in EVA/EPDM/SEBS blends. The abrasion volume has a linear relationship with the reciprocal of its strain energy density so that it can be used to predict its wear resistance, and it also provides theoretical support for developing application and research for this kind of products.