Purpose: The purpose of this study is to evaluate the influence of natural sisal fibers on mechanical properties of polymethyl methacrylate (PMMA). Materials and Method: In total, 90 specimens are prepared to be used in the study. The specimens are divided into three main groups, 30 specimens of heat cure PMMA without additives (control) and experimental groups of 60 specimens of heat cure PMMA with salinized sisal fibers with two different weight percentages (5% and 10%) wt. Three point bending test is performed to evaluate the flexural strength of the specimens, while the impact strength is done by impact testing Charpy's machine and tensile test is performed according to ASTM D‐638. Analysis of variance (ANOVA) test is used for statistical analysis. Results: Impact test results indicate a highly significant in the reinforced specimens when compare with control specimens. Tensile strength significantly increases after reinforcement with fibers. Nonsignificant difference is detected in flexural strength among the reinforced groups and control group. Conclusion: Reinforcement of the heat cured acrylic resin with natural sisal fibers significantly increases its impact strength and tensile strength with nonsignificant in flexural strength.

Materials and Methods: In total, 90 specimens were prepared to be used in the study. The specimens were divided into (3) main groups depended on the presence of sisal fibers powder, first group (30) specimens of heat cure PMMA without additives (control), second and third experimental groups of 60 specimens of heat cure PMMA with salinized sisal fibers powder with two different weight percentages (1 and 3%) wt. Three point bending test was used to measure the flexural strength of the specimens, while the impact strength was done by impact testing Charpy’s machine and tensile test was performed according to ASTM (D-638). Data analysis was performed using (ANOVA) test. The results of this study refer to a highly significant in the flexural strength and tensile strength of specimens reinforced with sisal fibers powder compared with control specimens. Non-significant difference was detected in impact strength among the reinforced groups and control gro. Reinforcement of acrylic resin with natural sisal fibers powder affects its flexural strength and tensile strength with non-significant in impact strength.

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