Linear Low-Density Polyethylene/(Soya Powder) Blends Containing Polyethylene-g-(Maleic Anhydride) as a Compatibilizer S.T. Sam, H. Ismail, Z. Ahmad Polymer Engineering Division, School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Nibong Tebal, 14300 Penang, Malaysia Blends were made from linear low-density polyethylene (LLDPE) and various amounts of soya powder. The soya powder content was varied from 5 to 20 wt%. Polyethylene-g-(maleic anhydride) (PE-g-MA) was used as a compatibilizer. Tensile strength and elongation at break (EB) decreased with increasing soya powder content. However, Young’s modulus increased with the incorporation of soya powder. The addition of PE-g-MA as a compatibilizer increased the tensile strength, EB, and modulus of the blends. The interfacial adhesion between soya powder and LLDPE was improved by the incorporation of PE-g-MA, as demonstrated by scan- ning electron microscopy. Increasing the content of soya powder reduced the crystallinity of the LLDPE phase. The addition of PE-g-MA had no significant effect on melting temperature, but the degree of crys- tallinity of the LLDPE was increased. The thermal sta- bility of the blends was determined by using thermog- ravimetric analysis. Thermal stability decreased with increasing soya powder loading. However, the addition of PE-g-MA slightly increased the thermal stability of LLDPE/(soya powder) blends. J. VINYL ADDIT. TECHNOL., 15:252–259, 2009. ª 2009 Society of Plastics Engineers INTRODUCTION Polyethylene is one of the important types of polymers in usage, and its annual consumption volume is on the rise. Therefore, polyethylene is one of the major components of the plastic waste in the world. In term of degradability, this type of polymer is highly resistant to biodegradation, photooxidation and thermal oxidation. The degradation of polyethylene can be accelerated by incorporating a degradable additive into the plastic. Various types of additives have been added into the plas- tic matrix, such as corn starch [1], cassava starch [2, 3], sago starch [4, 5] and potato starch [6–8]. All of these biomaterials have proven to meet the requirements of minimum effect on flow properties and minimum disturb- ance of products [9]. There is not much work which makes use of soya products as degradable fillers in plastic. Most of the appli- cations of soya products were well-established in the food sciences. Soya products include soya powder, and soya concentrate and are commercially available. Soya powder contains about 56% of protein and 34.9% of carbohydrate. However, the composition may vary with processing tech- nique and the product application. Soya products are one of the biomaterials that is abundantly available. Therefore, they are potential degradable fillers in plastic matrices [10]. Thus the investigation of the performance of soya products as degradable fillers is a worthwhile effort. In this work, an attempt to incorporate soya powder into LLDPE has been made. A commercially available compatibilizer, polyethylene-grafted maleic anhydride (PE-g-MA), has been added to LLDPE/(soya powder) blends. The effects of PE-g-MA on processing behavior, tensile properties, morphology, chemical structure and thermal properties were studied. EXPERIMENTAL Materials Soya powder was obtained from Hasrat Bestari (M) Sdn. Bhd. The moisture content was 3.12%. The granular size was in the range of 50–100 nm with an average granular size of 80 nm. The protein content was 44.2%. Pellet form linear low-density polyethylene (LLDPE) (ETILINAS LL0209SA) was obtained from Polyethylene Malaysia Sdn. Bhd. The melting point was 1228C. A PE-g-MA with an appropriate 3 wt% grafted level was supplied by Aldrich Chemical Company, Inc. (Milwaukee, WI). Sample Preparation Soya powder was melt-blended with LLDPE at 1508C in a Haake Reodrive 5000 internal mixer for 10 min at Correspondence to: H. Ismail; e-mail: hanafi@eng.usm.my DOI 10.1002/vnl.20197 Published online in Wiley InterScience (www.interscience.wiley. com). Ó 2009 Society of Plastics Engineers JOURNAL OF VINYL & ADDITIVE TECHNOLOGY——2009