This objective of this research is to study the development of the pararubber tapping knife in order to determine the optimum of the edge and oblique angle and to compare the efficiency of the electrical motor and Je-Bong knife. The product was manufactured by iron steel carbon S45C and AISI 5160 with 75-90 degree edge knife and 0-45 degrees oblique angle. The results can be concluded that the optimum condition of the edge knife oblique knife and the cutting force were 75 degree 45 degree and 3.51-51.42 N respectively. It was found that the cutting force was straightly increased form 0-51.42 N and then gradually decreased. The energy consumption of timber cutting was 0.00370 J/mm3. The quality of the rubber tap using electrical motor was 72.07% which was higher than 2.8 of Je-Bong knife. As the results this product shows the average of rubber timber which is 2.22 mm. in 22.51 s.

This research work was to study the effect of surface treatment of natural fiber and the effects of type and content of natural fiber on the development of acoustic material from natural rubber foam /natural fiber composites. The surface treatment used for this research work was sodium hydroxide (NaOH) treatment. NaOH Concentrations and treatment times were varied from 0 to 15 %wt. and 0 to 30 min respectively. Natural fibers used for this work were bagasse fiber (BF) and oil palm fiber (OPF). The suitable condition for surface treatment was estimated by fiber length and diameter (L/D) ratio and morphology of natural fiber. The result suggested that L/D ratios tended to increase when NaOH concentrations and/or treatment times increased except for NaOH concentration of 15 %wt. L/D ratios of OPF after surface treatment were changed more than those of BF. The suitable conditions of NaOH treatment for BF and OPF were NaOH concentration of 10 %wt. and surface treatment times of 30 and 10 min respectively. The effects of fiber type and content on sound absorption properties of natural rubber foam /natural fiber composites were investigated by cell characteristics sound absorption coefficient DMA analysis and bulk density. Both treated BF and OPF with suitable treatment condition were varied from content of 0.0 to 10.0 %wt. The result showed that the cell size of composites tended to decrease with addition of natural fiber whereas number of foam cell per unit volume increased. After adding natural fiber more than 2.5 %wt. cell size of composite foam and number of foam cell per unit volume tended to change the inverse direction. Natural fiber in composites enhanced the sound absorption efficiency. Sound absorption coefficient of composites adding BF was more than that of composite adding OPF. The addition of natural fiber enhanced the elasticity of composites and that increased sound absorption efficiency. NaOH treatment led to creation of strong interfacial bonding between natural fiber and natural rubber and enhanced the sound absorption efficiency. Density of NR composite foam increased with increasing natural fiber content.