Nowadays, increasing awareness of replacing synthetic fiber by glass fiber has emerged due to environmental problems and pollution. Automotive manufactures also seek new material especially biodegradable material to be used as non-load bearing application parts. This present work discusses the effect of silane treatments and fiber loadings on tensile properties of coir fiber reinforced polyester composites. From the experimental results, both silane treatments and fiber loadings increased the tensile properties. The presence of silane coupling agent on the fiber surfaces enhanced the compatibility between fiber and polymeric matrix. This compatibility promoted the capability of composites to sustain higher tensile loadings. From SEM observation pictured that longer fiber pull-out is a dominant factor for 5% fiber loading composites result lower tensile strength. Interfacial debonding also occurred for untreated fiber with silane coupling agent while silane treated fiber reinforced composites. Shorter pull-out fibers as observed and fibers are well gripped within the matrix showing betterinterfacial bonding and good tensile properties are achieved.
