Mechanical Properties of Talc- and (Calcium carbonate)-Filled Poly(vinyl chloride) Hybrid Composites Bee Soo Tuen, Azman Hassan, Aznizam Abu Bakar Department of Polymer Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia The main objective of this study was to investigate and compare the mechanical properties of poly(vinyl chlo- ride) (PVC) composites filled with calcium carbonate (CaCO 3 ), talc, and talc/CaCO 3 . Talc and CaCO 3 with dif- ferent grades were incorporated into the PVC matrix. To produce the composites, the PVC resin, fillers, and other additives were first dry-blended by using a labo- ratory mixer before being milled into sheets in a two- roll mill. Test specimens were prepared by compres- sion molding, after which the mechanical properties of the composites were determined. Single and hybrid fil- ler loadings used were fixed at 30 phr (parts per hun- dred parts of resin). Talc-filled composite showed the highest flexural modulus and the lowest impact strength, whereas uncoated, ground, 1-lm CaCO 3 (SM 90) showed optimum properties in terms of impact strength and flexural modulus among all grades of CaCO 3 . It was selected to combine with talc at differ- ent ratios in the hybrid composites. The impact strength of the hybrid composites gradually increased with increasing SM 90 content, but the flexural and tensile properties showed an opposite behavior. Hybrid (10 phr talc):(20 phr SM 90)-filled PVC composite reached a synergistic hybridization with balanced properties in impact strength, as well as flexural and tensile properties. J. VINYL ADDIT. TECHNOL., 00:000–000, 2012. ª 2012 Society of Plastics Engineers INTRODUCTION Poly(vinyl chloride) (PVC) is a commodity thermo- plastic that has been widely used in many industrial appli- cations, such as pipes, electric wires, window profiles, siding, etc. Its versatility for accepting numerous addi- tives, extraordinary stability to weathering, and competi- tive price are the reasons for the success of PVC. How- ever, low impact strength and thermal stability cause restrictions on its application which indicate a need for additional research on PVC. Recently, rigid particle fillers have been extensively used in creating polymer composites with good modulus, strength, rigidity, durability, and hardness. However, these property enhancements are usually accompanied by a severe decrease in impact strength. Therefore, researchers are constantly investigating ways to produce the polymer composites with balanced mechanical properties at a rea- sonable production cost. One of the common ways is by incorporating low-cost mineral fillers into the PVC ma- trix. This way facilitates the competition of new materials with the conventional ones. However, the high-quality performance of new materials and significant cost reduc- tion can be achieved if the role of fillers in the polymer matrix is well-understood. Many studies have been reported on various properties of (single mineral)-filled thermoplastic composites. The common mineral fillers used in the PVC formulations are calcium carbonate (CaCO 3 ) and talc. CaCO 3 is able to perform in two ways in such formulations, depending on the particle size. A submicron CaCO 3 can be used as an impact modifier, while CaCO 3 can detract from, rather than enhance, impact performance if CaCO 3 that is too coarse is used. Sun et al. [1] reported that the tensile strength and impact strength of CaCO 3 /PVC greatly increased with decreasing CaCO 3 particle size, a result which was attributed to the enhancement of interfacial ad- hesion between CaCO 3 particles and the PVC matrix. Xie et al. [2] showed that CaCO 3 nanoparticles are able to stiffen and toughen the PVC matrix simultaneously. They also found that CaCO 3 nanoparticles acted as stress con- centrators leading to interface debonding or voiding and matrix deformation. These mechanisms lead to the tough- ening of nanocomposites. The stiffness and strength of the PVC matrix can be enhanced by the incorporation of talc filler into the PVC formulation. However, there is still some degree of decre- ment in impact strength. This decrement becomes less as the particle size of the talc decreases. As the particle size is reduced the ability of the talc to increase stiffness does not change if its particle shape remains the same [3]. According to Wiebking [3], the particle shape influenced the modulus, whereas the particle size influenced the The authors thank the Ministry of Science, Technology and the Environ- ment of Malaysia for funding this work under IRPA Project (Vot. 78044). Correspondence to: A. Abu Bakar; e-mail: aznizam@cheme.utm.my DOI 10.1002/vnl.20280 Published online in Wiley Online Library (wileyonlinelibrary. com). Ó 2012 Society of Plastics Engineers JOURNAL OF VINYL & ADDITIVE TECHNOLOGY——2012