www.tjprc.org SCOPUS Indexed Journal editor@tjprc.org WATER ABSORPTION AND THERMAL PROPERTIES OF PMMA REINFORCED BY NATURAL FIBERS FOR DENTURE APPLICATIONS JAWAD K. OLEIWI, SIHAMA I. SALIH & HWAZEN S. FADHIL Department of Materials Engineering, University of Technology, Baghdad, Iraq ABSTRACT The water absorption and thermal conductivity of denture base materials are important properties due to effect on dimensional stability and sensory of food during mastication. This paper discusses the effect of two natural fibers (siwak and bamboo) which used as reinforcement for properties (water absorption and thermal conductivity) of PMMA. The two kinds of fibers used in three different lengths (2, 6 and 12mm) and three concentrations (3, 6 and 9 wt. %). The results showed that the percent water absorption, thermal conductivity and thermal diffusivity increased with increase fiber length and weight fraction. The highest values of water absorption for bamboo specimens and siwak specimens (6.21 % and 7.21 % respectively) at (9wt.%) and (12mm) fiber length. The maximum values of thermal conductivity and thermal diffusivity for bamboo specimens (0.2216 W/m 0 K and 0.1628 mm 2 /sec), while for siwak specimens (0.2408 W/m 0 K and0.1747mm 2 /sec), respectively at optimum condition of (9wt. %) and (12mm) fiber length. KEYWORDS: Thermal Properties, Water Absorption, Natural Fibers, PMMA & Denture Received: Apr 24, 2018; Accepted: May 15, 2018; Published: Jun 19, 2018; Paper Id.: IJMPERDJUN2018115 INTRODUCTION Recently natural fibers have attracted the care of researcher and scientists due to the benefits of these fibers over conventional synthetic fibers. These natural fibers are cheap, light weight, high specific properties, available, biodegradable and non-abrasive, different from other fibers. On the other hand, there are certain disadvantages of these fibers such as incompatiblewith the matrix (polymer), and poor resistance to moisture to the highest degree decrease the potential of natural fibers to be utilized as reinforcement in matrix [1]. The bonding between the natural fiber and the matrix (polymer) can be increased by altering the fiber surface. Chemical treatment enhances the adhesion by removing the organic residue from a surface of the fiber and those, enable an interlocking mechanism with the matrix [2]. R. K. Durkan [3] estimate the effect of the different dental fiber system on heat and microwave polymerized denture base resins. The results show that the value of water absorption of denture base polymers is higher when the specimens are reinforced with the fiber systems. X. Zhang [4] studied the effect of Salinized aluminum borate whiskers (ABWs) on PMMA properties (flexural strength, surface hardness, and thermal stability) by varying the content of (ABWs) from 1 to 20 wt.%. The result showed that the (ABWs) improve the properties of PMMA and 5% provided the highest reinforcement. Hanan Abdul et. al [5] determined the influence of adding siwak micro powder on the certain mechanical properties of acrylic resin. The results showed that the addition of (7 %) siwak powder to the acrylic resin revealed a Original Article International Journal of Mechanical and Production Engineering Research and Development (IJMPERD) ISSN (P): 2249-6890; ISSN (E): 2249-8001 Vol. 8, Issue 3, Jun 2018, 1105-1116 © TJPRC Pvt. Ltd.