Performance Optimization Of Elastomer Toughening Of Pvc

The stiffness and toughness of polymers are very important for their practical applications. Toughening of plastics is still a focus of polymer material science. Poly (Vinyl chloride) (PVC) is an important thermoplastics and the toughening of PVC has important academic and applied values. PVC belongs to notch sensitive materials, so the notched impact strength is very low. Elastomer can act as impact modifiers to overcome the notch sensitivity of PVC and improve their notched impact strength.The core-shell modifier used is Methyl methacrylate-butadiene-styrene (MBS) copolymer and butadiene-styrene-n-butyl acrylate (SBR/BA/St) copolymer in our work. The main research work and conclusions are as follows:Seeded emulsion polymerization was adopted to prepare MBS with different grafting efficiency and core-shell ratio. The influences of grafting efficiency and core-shell ratio of MBS on the toughness of PVC were studied. MBS with different grafting efficency were obtained through changing cross-linking degree (DVB) content of MBS. The impact strength of PVC/MBS blends increased with grafting degree. When core-shell ratio of MBS is 50-50, PVC/MBS blends fractured in ductile mode. For PVC blends toughened by MBS with small particle sizes, the toughening mechanism was the shear yielding of PVC matrix. In the progress of SBR was grafted by St and MMA, St monomer was easy to penetrate to the inner of SBR and form the microphase of PSt. The inclusion of St increased with increasing amount of droped St.MBS with a little inclusion of St was favor to toughening PVC.SBR/BA/St tercopolymer was sysnethsized by emulsion polymerization. With increasing amount of BA in modifier, the dispersion morphology of modifiers in PVC matrix became well, the impact strength of PVC blends enhanced significantly and the yielding strength decreased. From TEM, The toughening mechanism was the debonding between modifier and the shear yielding of PVC matrix.