Synthesis Of Multifunctional Poly-cardanol And Its Application In SBR

Styrene butadiene rubber（SBR）is widely used in shoe materials,tyres,tapes and conveyor belts due to its excellent properties such as low cost,high elasticity,abrasion resistance and chemical resistance.However,the widespread use of SBR will consume petrochemical resources and rubber processing requires the use of additives as plasticizers and coupling agents to improve processing properties and interfacial interactions.In this paper,the Friedel-Crafts alkylation reaction was used to the bulk polymerization of cardanol in the absence of solvent to obtain poly-cardanol（PCA）,which was used to partially replace SBR.Meanwhile,the effect of PCA on the processing performance of SBR and the interfacial properties on silica-enhanced SBR were investigated.Details are as follows.（1）PCA resin synthesized by the bulk polymerization of cardanol in the solvent-free condition was evaluated using Mooney viscosity,gel permeation chromatography（GPC）,Fourier transform infrared（FTIR）analysis,liquid nuclear magnetic resonance（NMR）,and ultraviolet spectroscopy（UV）.PCA was blended with the different proportions of LIR and then the mechanical properties and the thermal stability of blends were studied.Results showed that the optima Friedel-Crafts alkylation reactive condition was at a temperature of 100°C for 2 h and at the catalyst of 5%of p-toluenesulfonic acid.The chemical structure of PCA were verified by the weakening of the peak in 3009 cm^-1,1263 cm^-1and 1154 cm^-1in IR spectra,the blue shift of the UV absorption and the new absorption protons peaks in ¹H-NMR spectra.During the co-crosslinking of PCA and LIR,PCA induces the crystallization of the long chain segments of LIR.PCA has flexible alkyl chains and hydrophilic phenolic hydroxyl groups,so it is hope to be used as a plasticizer just like LIR and also as a compatibilizer.（2）The substitution and plasticizing effects of PCA on SBR were investigated by partial substitution.Results showed that the phenolic hydroxyl group of PCA had a stabilizing effect on the sulfur radicals and thus delayed the normal sulphation time.PCA exhibited a low T_gvalue.PCA increased the free volume of the alkyl chain segments of the blends so the activity scope and the freedom degree range of polymer chain segments increased accordingly.This is beneficial for blends to absorb external forces and prevent the growth of cracks.The rigid benzene ring in PCA can strengthen the material.When PCA was increased from 10phr to 30phr,the tensile strength of SBR/PCA increased by98.5%,103.8%and 147.7%and the elongation at break increased by 41%,138%and373%respectively.Similar to SBR,PCA has excellent thermal stability properties.（3）The dispersion of silica in silica-reinforced PCA/SBR composites was better than that in silica-reinforced SBR attributing to the hydrogen bonds of hydroxyl groups between PCA and Si O₂and theπ-πstacking interaction between PCA and SBR,together with the entanglement of alkyl chains.Due to the perfect three-dimensional network structure of silica,the silica-reinforced PCA/SBR composites showed more obvious Payne effect,shorter positive vulcanization time and scorch time than without PCA.The SBR/PCA/Si O₂vulcanized rubber possessed higher crosslinking density and lower swelling ratio in toluene than SBR/Si O₂vulcanized rubber because of the good dispersion of Si O₂and the high double bond density in the presence of PCA.PCA as a rubber substitute,plasticizer and compatibilizer provides a simple and green route for the application of natural products in the rubber industry.