Study On The Hydrophilic Modification Of Styrene-butadiene-styrene Triblock Copolymer

Styrene-butadiene-styrene(SBS)triblock copolymers have been widely used in bitumen modification in recent years.However,it is difficult to be compatible with the more polar materials,which limits its application.In this thesis,we aim to solve this problem by grafting polymers onto SBS in order to improve its hydrophilicity.Three monomers,namely Maleic Anhydride(MAH),Styrene(St)and Methyl Tetraglycol(MTG)were co-dissolved with SBS,respectively.Moreover,SBS was grafted and modified by the free radical polymerization.The Grafting Rate and hydrophilicity of modified SBS with different monomers or groups were investigated via visually optical Contact Angle measuring instruments,infrared spectrometers,nuclear magnetic resonance spectrographs and other instruments.In addition,Graft polymerization mechanism was discussed and reaction conditions were optimized when the Contact Angle was used as the reference.The three aspects are mainly considered as follows.1)Toluene and benzoyl peroxide(BPO)were used as solvent and initiator,respectively.The grafting polymerization between SBS and MAH was carried out under nitrogen atmosphere.The results show that with the increase of MAH content from 0.2 g to 2.4 g,the Grafting Rate increases at first and then decreases,while the Contact Angle showed an initial fall,after which it grew.the Grafting Rate was up to 6.06%and the Contact Angle is at least 89.20°.When the monomer WMAH=1.8 g(WMAH/WSBS=33.3%).As a result,the surface modification was effective and the polarity was the largest.2)Toluene and benzoyl peroxide(BPO)were used as solvent and initiator,respectively.The co-grafting polymerization between SBS,MAH and St was carried out under nitrogen atmosphere.The results showed that under the same conditions,the Grafting Rate of the polymer material obtained by adding the copolymerized monomer St increased,and the Contact Angle decreased.When the ratio of MAH to St was 1/1,the Grafting Rate was up to 6.43%.The Contact Angle is at least 86.20°;when the ratio of MAH and St substances is 1/1,increasing the reactant concentration,the Grafting Rate increases from 4.24%to 9.44%,and the Contact Angle decreases from 93.13° to 66.20°.Under the same conditions,The Grafting Rate initiated by AIBN is higher than that of BPO.3)Dioxane and water were used as solvent,the Methyl Tetraglycol(MTG)was grafted onto SBS,which was initiated by the cerium salt under nitrogen atmosphere.The influence of the amount of MTG on the Grafting Rate and Contact Angle of the reaction system was discussed.The results showed that the Grafting Rate is up to 13.61%and the Contact Angle is 60.25° as molar ratio of double bonds in SBS and MTG is 1/1.