Thesis (M.Sc.)--Chulalongkong University, 1999

Polymethylmethacrylate (PMMA) was used to improve the mechanical properties especially, Flexural strength (FS) and Hardness (HR) of ABS plastics. The composites were prepared by premixing various amounts of ABS, PMMA and all additives in high speed mixer and kneading all components by single screw extruder. Then, all composites were injected to be test specimens for mechanical property measurement. Differential scanning calorimeter (DSC) and scanning electron microscopy (SEM) were used to study melting temperature and dispersion of the composite, respectively. In the first study, PMMA had been added in different levels and observed that at high level of PMMA, the FS and HR could be increased while the impact property indicated significant loss. For recovery of impact property, the polymer modifier has been added. Unfortunately, it exhibited no improvement. Alternatively, the increasing of the rubber content and acrylonitrile content of the blend couldimprove the impact properties at the appropriate level. Furthermore, the addition of polyacrylonitrile-styrene polymer (SAN) could improve the miscibility of blended system. This allowed good property balance of the blended. For the best composite compatable in properties to those of the commercial resins composed of 25% wt. ABS, 20% wt. SAN, 55% wt. PMMA and additives at 2.0 phr. ethylene-bis-stearamide, 0.2 phr. calcium stearate and 0.1 phr. silicone oil.