MICROCOMPOUNDING OF SMALL SAMPLES OF NATURAL RUBBER
We describe a microcompounding method that can be used to characterize and compare cured small natural rubber samples. First, commercial Hevea and dried guayule (Parthenium argentatum) latex samples were microcompounded to validate the method. Latex was then extracted from the ground branches of six greenhouse shrubs of different ages and genotypes of wild type and transgenic guayule and coagulated into rubber samples. Size exclusion chromatography showed that the samples had different molecular weights and oligomer content. Little variation in physical properties was found between rubber extracted from shrubs of different age within a genotype, but a larger variation among genotypes was found. The new method allows testing of cured rubber samples from experimental variants and early screening out of genotypes to assess the impact of variations in cultivation practices or lab-scale processing conditions on rubber quality.ABSTRACT
Test dumbbell.
SEC MALS (red) and dRI (blue) traces of (a) guayule and (b) Hevea brasiliensis.
Stress-strain plots for guayule (solid) and Hevea (dashed) controls.
SEC MALS (red) and dRI (blue) traces of the rubber samples. (a) AOO young, (b) AOO old, (c) G1-2 young, (d) G1-2 old, (e) G1-4 young, and (f) G1-4 old.
Stress-strain plots of all transgenic samples.
(a) Tensile strength at break, (b) modulus at 100% elongation, and (c) elongation at break of samples from three different genotypes and two ages. Solid columns are the old, and striped columns are the young plants. The number of replicates is listed in Table III. Standard error bars are plotted.
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