According to the preliminary experiment, natural rubber latex waste (WL) without treatment and polystyrene blend cannot gives good continuous films. Thus WL was treated with 20% by dry weight of natural rubber latex (20 g of dry NRL, 80 g of dry WL) referring to work by Rajalekshmi (2005) without curative. The treatment was done before blending with polystyrene. WL was heated in water bath at temperature of 50 °C and stirred with a mechanical stirrer for 5 minutes at a constant speed of 300 rpm. Then, NRL was added and continued stirred for 20 minutes. The treated waste natural rubber latex (TWL) was kept at ambient temperature for 24 hours before further use. 2.4