Preparation, Structure And Properties Of HIPS/BR Thermoplastic Vulcanizates And HIPS/WGRT Thermoplastic Elastomers

Thermoplastic vulcanizate (TPV) based on high impact polystyrene (HIPS)/cis-1,3-butadiene rubber (BR) blends and thermoplastic elastomer (TPE) based onhigh impact polystyrene (HIPS)/waste ground rubber tire (WGRT) blends wereprepared by dynamic vulcanization, the influence of composition ratios, interracialcompatibilization, preparing technique on the morphology and mechanical propertiesof HIPS/BR TPV and HIPS/WGRT TPE were researched, the dynamic viscoelasticbehavior of the prepared HIPS/BR TPV and HIPS/WGRT TPE were alsoinvestigated systematically. The results were as follows:(1) The dynamically vulcanized HIPS/BR blends were prepared by differentfeeding methods, considering the mechanical properties of the prepared blends,masterbatch method was the most appropriate process method. A series of blendswere prepared by changing the composition and species of raw materials, themechanical properties and microstructure were researched. The dynamicallyvulcanized HIPS/BR blends did not show the elastomer behavior when the HIPS/BRblend ratio ranged from30/70to70/30. The tensile strength and tearing strengthdecreased slightly due to the addition of EVA, but the processability of theHIPS/EVA/BR TPV were improved obviously.(2) The dynamically vulcanized HIPS/EVA/BR blends compatibilizing withSBS showed the obvious elastomer behavior when the dosage of SBS was4phrabove. Considering the proper elasticity, strength and low hardness, the SBS contentshould range from812phr. The fracture surface morphology of the compatibilizingHIPS/EVA/BR TPV was relatively smooth. There was no obvious micro-phaseseparation. BR particles were dispersed evenly in the etched surfaces of theHIPS/EVA/SBS/BR TPV and the dimension of the BR dispersed particles was in therange of310μm. A rubber process analyzer revealed that the storage modulus decreased significantly with increasing strain and the incorporation of compatibilizerSBS in the HIPS/EVA/BR TPV weakened Payne effect apparently, the loss modulusshowed a typical peak at10%strain and the tanδ increased continuously withincreasing strain.(3) The series dynamically vulcanized HIPS/EVA/SBS/BR TPV showed theelastomer behavior when the carbon black content was in the range of080phr inthe BR pahse. With the increasing of carbon black content, the tensile strength,tearing strength and Shore A hardness were increased obviously and the elongationat break was decreased, while the tension set at break remained unchanged. Thefracture surface of unfilled HIPS/EVA/SBS/BR TPV showed the well interfaceinteraction; the fracture surface of HIPS/EVA/SBS/BR TPV filled by carbon blackshowed the smooth fracture and the strong elasticity.(4) The Shore A hardness and tensile set at break of the HIPS/EVA/SBS/BRTPV were decreased obviously when the aromatic oil was filled in the HIPS resinphase, the elongation at break was increased apparently. The fracture surfacemorphology of the HIPS/EVA/SBS/BR TPV was smooth, indicating the strongdeformation recovery ability. The vulcanized BR particles were dispersed evenly onthe etched surface of the HIPS/EVA/SBS/BR TPV and the dimension of the BRdispersed particles was in the range of540μm. A rubber process analyzer revealedthat storage modulus decreased rapidly where the loss modulus curves showed atypical peak. Loss peak was appeared near the transition temperature (Tg) of HIPS.The tan and the dynamic viscosity decreased notablely with the increasing ofaromatic oil.(5) For the HIPS/EVA/WGRT blends with different HIPS/WGRT ratios, theHIPS/EVA/WGRT blends showed the performance of elastic deformation when thedosage of HIPS was less than35wt.%, the tensile strength and tear strengthincreased, while the elongation at break decreased substantially; however, when thedosage of HIPS was40wt.%above, the HIPS/EVA/WGRT blends showed the rigidwhich was similar to the mechanical buhavior of plastic. The elongation at breakreached the maximum value at WGRT content of45phr.(6) Experimental results indicated that SBS had a good compatibilization effecton the HIPS/EVA/WGRT blends. Compared with HIPS/EVA/WGRT blends, thetensile strength and the elongation at break went through maximum values at acompatibilizer resin content of12phr respectively. Morphology study showed that the interface interaction was strong in the HIPS/EVA/WGRT blends compatibilizedby SBS, which contributed to the significantly improved mechanical properties.Payne effect could be found in the strain sweep of HIPS/EVA/SBS/WGRT blends,which was related to the variation of interface interaction. The increasing dosage ofSBS compatibilizer in the HIPS/EVA/WGRT blends weakened the Payne effect andled to the slow decrease of storage modulus, indicating that the Payne effect couldcharacterize the variation of interface interaction.