Study of Processability of Poly(vinyl chloride): Effects of Acrylic and Chlorinated Polyethylene Impact Modifiers, Oil Palm Empty Fruit Bunch Fiber, and Mixing Temperature Aznizam Abu Bakar, 1 Azman Hassan, 1 Ahmad Fuad Mohd Yusof 2 1 Department of Polymer Engineering, Faculty of Chemical and Natural Resources Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia 2 Plastics Technology Centre, SIRIM Bhd. Shah Alam, P.O. Box 7035, 40911 Malaysia The influence of acrylic impact modifier, chlorinated polyethylene (CPE) impact modifier, oil palm empty fruit bunch (OPEFB) fiber, and mixing temperature on the processability of poly(vinyl chloride) (PVC) com- pounds was investigated. The acrylic impact modifier was the most efficient additive in reducing the fusion time of the PVC, followed by the OPEFB fiber and the CPE impact modifier, whereas OPEFB was the most efficient in decreasing the melt viscosity of the com- pounds, followed by CPE and acrylic. A PVC compound containing 9 phr of CPE and 40 phr of OPEFB had high values of fusion time and end torque. The fusion time and melt viscosity of all of the PVC compounds decreased with increasing mixing temperature. J. VINYL ADDIT. TECHNOL., 14:204–210, 2008. ª 2008 Society of Plastics Engineers INTRODUCTION Fusion characteristics of poly(vinyl chloride) (PVC) such as fusion time and torque at the equilibrium stage (end torque), which are obtained from the fusion curve, are used to elucidate the processability of the studied PVC compound. Fusion transforms the PVC grains from the solid into the liquid phase (PVC melt). Benjamin [1] and Portingell [2] defined the fusion of PVC as the pro- cess of removing the boundaries between base particles whereby a continuous mass that results has a homogene- ous molecular structure. The grains are broken down into the so-called primary particles. Further breakdown of the primary particles into the subprimary particles takes place if sufficient energy is applied. This destruction process is accomplished by the combined action of heat, pressure, and shear during processing. Besides that, the additives used in the PVC formulation, such as external and inter- nal lubricants, processing aids, impact modifiers, and fill- ers are also able to affect the fusion rate of the PVC within the processing equipment. As the properties of PVC products depend on the mor- phology and the degree of fusion, additives that control the rate of fusion within the processing equipment become important ingredients in a successful formulation. Many studies have shown that external lubricants delay the fusion time of PVC compounds and that internal lubricants decrease the fusion time [3–6]. However, Lind- ner reported that the synergistic interaction between oxidized polyethylene (external lubricant) and calcium stearate (internal lubricant) can be used to accelerate the fusion time of PVC blends significantly [7]. Processing aids used to improve the processing properties of PVC have been recognized as fusion promoters. According to other researchers, processing aids have increased the rate of fusion by increasing the friction between the particles [8, 9], which increases melt temperature and encourages PVC entanglement. Impact modifiers have also been used extensively as additives in commercial PVC formulations to improve the toughness properties of PVC products. Chlorinated poly- ethylene (CPE) is commonly used as an impact modifier of PVC. At low contents of CPE (less than 10 phr), the fusion time of CPE-impact-modified PVC compound has been delayed, whereas the fusion process has been promoted as the CPE content was increased. Thus, CPE has dual functions, i.e., as an external lubricant or Correspondence to: Aznizam Abu Bakar; e-mail: aznizam@fkkksa. utm.my Contract grant sponsor: Ministry of Science, Technology, and Environ- ment of Malaysia; contract grant number: Vot 72197. DOI 10.1002/vnl.20167 Published online in Wiley InterScience (www.interscience.wiley.com). Ó 2008 Society of Plastics Engineers JOURNAL OF VINYL & ADDITIVE TECHNOLOGY——2008