Study On Preparation And Properties Of Rubber-based Lightweight Materials

Polymer-based lightweight materials have wide application prospects in daily life,ocean engineering,space exploration,and other fields.With the needs of development,under the premise of ensuring that the relevant performance loss is not large,there is a trend of decreasing density to improve operational efficiency and reduce costs.In this paper,cis-1,4-polybutadiene rubber/polystyrene-butadiene rubber(BR/SBR)blends were used as the matrix to carry out lightweight research by foaming process and filling lightweight filler process respectively.First,BR/SBR blended rubber foam with an internal gradient cell size structure was prepared by using supercritical fluid foaming technology and N₂ as the physical foaming agent through the"Three-step"process of pre-sulfurization,supercritical foaming,and secondary sulfurization.The effect of BR/SBR blended rubber pre-vulcanization time on the internal cellular structure,foaming properties,mechanical properties,abrasion resistance and friction behavior of BR/SBR blend rubber foam was studied.The apparent density of BR/SBR rubber foam material decreases first and then increases with the extension of the pre-vulcanization time from 10 min to 18 min.When the pre-vulcanization time is 14 min,the foam size of BR/SBR rubber foam material is larger,the inner wall of the bubble is thinner,and a better foaming effect is achieved.At the same time,with the extension of pre-vulcanization time,the tensile strength and elongation at break of BR/SBR rubber foam material decreased first and then increased,while the resilience decreased slightly,and the shore C hardness increased significantly,indicating that the dimensional stability of BR/SBR rubber foam material became better.Using SEM to observe the BR/SBR rubber foam materials surface solid layer,found that with the increase of the pre-vulcanization time,the solid layer located on the foam surface gradually thickens,and the internal structure is more and more obvious gradient cell size of holes.This is related to the escape of the foaming agent from the rubber matrix and the vulcanization process of the matrix during the secondary vulcanization of the material.The research on abrasion resistance of BR/SBR rubber foam materials shows that with the extension of pre-vulcanization time,although the apparent density of the foam material increases from 0.50 g·cm^-3 to 0.81 g·cm^-3,however,its DIN relative volume loss are significantly smaller,indicating that the abrasion resistance of the foam material is getting better and better,which is caused by the thickening of the solid layer thickness on the surface of the BR/SBR rubber foam material,and the gradient cell size structure inside the foam material provides the abrasion resistance.Second,BR/SBR blended rubber was filled with inorganic lightweight filler hollow glass microspheres(HGM)to prepare rubber-based lightweight composite materials.To improve the compatibility between HGM and rubber matrix,chemical copper plating was carried out on the surface of HGM by using the catalytic copper plating process of HGM modified by polydopamine(PDA)and Ag nanoparticles:the surface of HGM was first coated with dopamine that can undergo auto-oxidative polymerization under mild conditions and adhere to various organic/inorganic surfaces,and a nanometer-thick PDA layer is formed on the surface of HGM,it provides a secondary reaction platform for its further modification.During the subsequent activation of HGM/PDA microspheres with silver nitrate,Ag⁺can be reduced in situ by the reducibility of catechol in the molecular structure of PDA and is reduced on the surface of PDA in the form of Ag nanoparticles.In the process of further electroless copper plating,Ag nanoparticles can be used as catalytic crystal nuclei to become the reduction center of Cu²⁺.Finally,the Ag nanoparticles are used as the center to reduce the Cu element on the surface of HGM,and the reduced Cu element catalyzes the subsequent reduction of Cu²⁺by autocatalysis.After reduction,the Cu element is finally connected to form a copper layer with uniform thickness and dense quality.The effect of electroless copper plating was evaluated by SEM,EDS,FTIR,and XRD.Filter paper experiment,EDS,and XPS were used to simulate and analyze the bonding mechanism between copper-plated HGM and rubber.The results show that the redox reaction between the reactive sulfur in rubber matrix and Cu on the surface of copper-plated HGM can be successfully carried out at high temperature through thin filter paper,and the bond between the two phases can be established in the form of the chemical bond.The bonding behavior of copper-plated HGM and rubber and the influence of the content of copper-plated HGM in the HGM-rubber composite on the physical and mechanical properties and abrasion resistance of the lightweight polymer composite were studied.The results show that the compatibility between HGM and rubber matrix is improved obviously after copper plating,and the physical and mechanical properties/abrasion resistance of composite are improved significantly.