Effect of Various Additives on the Physical Properties of Polyvinylchloride Resin

The compounding of Polyvinylchloride (PVC) with some additives was studied for the enhancement of physical and mechanical properties. Two categories of formulations (un-plasticized and plasticized PVC) were prepared with PVC (K value ranging from 60 to 70) taking as base polymer. Different additives generally categorized as plasticizers, fillers, stabilizers, pigments and processing aids, were mixed in the standard concentration unit “parts per hundred resins (phr)” with base polymer. Cable compound and shoe compound were prepared in plasticized-PVC category containing mainly plasticizing additives like diisooctyl phthalate (DIOP) (40 phr) and epoxidized soybean oil (2-3 phr) with general plasticizer (50-80 phr) respectively. Whereas the rigid pipe and sheet compounds were prepared as un-plasticized PVC category containing different fillers/stabilizers like tribasic lead sulphate (6 phr), lead stearate (1 phr), glyceryl monostearate (0.4 phr) in rigid pipe and butylin mercaptides (2-2.5 phr), fatty alcohol and fatty acid ester (0.5-0.8 phr) in rigid sheet compound. Experimental investigation was carried out for analyzing the mechanical properties like tensile strength, elongation at break, hardness and physical property i.e. specific gravity for the compounded samples. An appreciable increase was observed in tensile strength from 460 Kg/cm2 (base PVC-polymer) to a range of 550 Kg/cm2 for un-plasticized PVC compounds (rigid PVC-pipe and sheet) with little increase in elongation at break from 56% (base polymer) to 124.33% and 150% (for Pipe and Sheet compounds respectively). On the other side the elongation at break for plasticized PVC compounds was increased from 56% to 250.67% (for cable compound) and 351.33% (for shoe compound), where as the tensile strength was decreased from 460 Kg/cm2 to 150.33 Kg/cm2 (for cable compound) and 120.33 Kg/cm2 (for shoe compound). The hardness (shore A, D) was increased from 40 to 80 for all the compounds except shoe compound with hardness of 65.33. The impact of plasticizers was found in direct proportion on elongation at break but having inverse proportion on tensile strength.