Saovanee Kovuttikulrangsie and Jitladda T. Sakdapipanich

pp. 337 - 342

Abstract

NR-latex was tapped from different age and clone Hevea trees. The latex of virgin started from 3
years trees was transesterified to reduce the branching molecules. The molecular weight (MW) and molecular
weight distribution (MWD) of rubber molecules were measured using a gel-permeation chromatography
(GPC). It was found that variation in MW and MWD of natural rubber depended on the age and clone of
rubber tree. An increased age of rubber clone BPM 24 (3, 5 and 8 years) and KRS 156 (1, 15 and 25 years)
also increased the MW and MWD of rubber. Nine different clones of 8 months young virgin trees (NATAWE
208, AVROS 2037, RRIC 6, GT-1, PR 255, PR 261, KRS 156, BPM 24 and RRIM 600) showed a unimodal
distribution with a small variation in MW and narrow MWD. On the other hand, those regularly tapped
mature trees (NATAWE 208, AVROS 2037, RRIC 6, GT-1, PR 255, PR 261 and KRS 156) aged 25 years,
showed a great variation in MW and MWD. The Mw value of NR showed a great variation from about 10⁴
to 10⁶. The polydispersity ( Mw / Mn) was between 2 and 11.