ศศิประภา วิบูลกุล. Effect of the non-rubber parts on natural rubber properties. Master's Degree(Chemistry). King Mongkut's University of Technology Thonburi. KMUTT Library.. : King Mongkut's University of Technology Thonburi, 2009.
Effect of the non-rubber parts on natural rubber properties
Abstract:
In this research, the effect of non-rubber parts which are proteins and fatty acid
esters on the natural rubber properties was studied. The non-rubber parts were
removed with various methods, including centrifugation (CNR), acetone extraction
(AENR), hydrolysis reaction using protease (DPNR), fatty acid ester cleavage reaction
using phospholipase A2 (PLA2-NR), C (PLC-NR), A2 together with C (PLA2+C-NR)
and saponification reaction (SPNR). The removal of non-rubber constituents from NR
resulted in lowering molecular weights, nitrogen content, fatty acid ester content and gel
content. The molecular structures of PLA2-NR and PLC-NR were investigated by using
IH-NMR technique. The peak intensities at ? 4.09 and ? 4.17 ppm, which are related to
methylene proton (-CHz) linked between the rubber molecules and fatty acid esters,
were found to decrease. This confirmed the reduction of fatty acid ester contents.
Furthermore, SPNR was found to contain the lowest nitrogen and fatty acid ester
contents, resulting in the lowest gel content. Upon six-month storage, the gel content of
natural rubber and natural rubbers in which proteins and fatty acid esters were removed
was found to slightly increase. The processability study clarified that the molecules of
SPNR and silica-filled SPNR rubber composite flew easier than those of other rubbers
and rubber composites.