STUDY ON RHEOLOGICAL AND THERMAL PROPERTIES OF TREATED WASTE NATURAL RUBBER LATEX/POLYSTYRENE BLEND AS REDUCTANT

Abstract

The waste natural rubber latex (WNRL) was treated by natural rubber latex (NRL) to improve the properties. The treatment was done prior to blending with polystyrene (PS). The preparation of treated waste natural rubber latex (TWNRL)/PS was conducted with ratio of 70/30 using internal Haake mixer at 140ºC with speed of 60 rpm. The WNRL/PS blend was prepared in a similar way for comparison purpose. The mixing torque was recorded during blending, while storage modulus and tan_delta were investigated using Rheometer. The thermal gravimetry (TG) and difference scanning calorimeter (DSC) were also studied. The results showed that TWNRL/PS blend gave lower mixing torque compared to WNRL/PS blend. Thus, it reveals that the treatment of WNRNL by NRL could improve the processibility. The storage modulus of TWNRL/PS blend showed lower value compared to WNRL/PS blend. This could be due to that the TWNRL/PS blend contains lower cross-linked molecules which have lower resistance to chains mobility. A study using DSC implied that TWNRL and PS are immiscible (two-phase system). This can be proven by the presence of two glass transition. In comparison, the Tg from DSC and tan_delta observed for TWNRL/PS and WNRL/PS blends showed no significant difference. However, the degradation temperature of TWNL/PS blend was slightly lower than that of WNRL/PS blend due to the requirement of energy for breaking the network molecule was lower.