Characterisation of zone 1 and zone 2 rubber particles in Hevea brasiliensis latex

Yeang H. Y., . and Yip Esah, . and Samsidar H., . Characterisation of zone 1 and zone 2 rubber particles in Hevea brasiliensis latex. pp. 108-123. ISSN 0127-7065

Rubber particles of Hevea brasiliensis latex separate into two main zones (Zone 1 and Zone 2) upon high speed centrifugation. Zone 2 rubber particles are small (0.35 um diameter and below) but numerous and they constitute about 94 of the total rubber particles with Zone 1 particles making up the remainder. Nevertheless the small numbers of Zone 1 rubber particles account for about 93 of the rubber volume and 70 of the total area of all rubber particles because of their greater size. The frequency distribution of rubber particle sizes indicate that Zone 1 rubber particles and Zone 2 rubber particles might be two separate populations. Zone 2 rubber particles are more sensitive than Zone 1 particles to destabilisation and electron microscope examination reveals that destabilised lutoids in the latex have small rubber particles of the Zone 2 variety adhering to their surfaces. Molecular characterisation of rubber reveals that both Zone 1 and Zone 2 particles have molecular -weights ranging from 104 to 10 . Zone 2particles contain rubber with higher average molecular weight. Examination of the molecular weight distribution curves show that the lower molecular weight of Zone 1 rubber is mainly due to the presence of a low molecular weight peak (approx. 10s) in its bimodal distribution. This peak is frequently indistinct in the largely unimodal Zone 2 rubber. A high molecular weight peak (approx. 1.1 106) is present in both Zone 1 and Zone 2 rubber. There is about twice as much total gel rubber in Zone 2 rubber (29) than in Zone 1 rubber (15). As a large proportion of the latex obtained from the rubber tree is derived from a very small number of Zone 1 rubber particles of exceptionally large size their prevalence in latex has an important bearing on the economic crop.

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Abstract

Rubber particles of Hevea brasiliensis latex separate into two main zones (Zone 1 and Zone 2) upon high speed centrifugation. Zone 2 rubber particles are small (0.35 um diameter and below) but numerous and they constitute about 94 of the total rubber particles with Zone 1 particles making up the remainder. Nevertheless the small numbers of Zone 1 rubber particles account for about 93 of the rubber volume and 70 of the total area of all rubber particles because of their greater size. The frequency distribution of rubber particle sizes indicate that Zone 1 rubber particles and Zone 2 rubber particles might be two separate populations. Zone 2 rubber particles are more sensitive than Zone 1 particles to destabilisation and electron microscope examination reveals that destabilised lutoids in the latex have small rubber particles of the Zone 2 variety adhering to their surfaces. Molecular characterisation of rubber reveals that both Zone 1 and Zone 2 particles have molecular -weights ranging from 104 to 10 . Zone 2particles contain rubber with higher average molecular weight. Examination of the molecular weight distribution curves show that the lower molecular weight of Zone 1 rubber is mainly due to the presence of a low molecular weight peak (approx. 10s) in its bimodal distribution. This peak is frequently indistinct in the largely unimodal Zone 2 rubber. A high molecular weight peak (approx. 1.1 106) is present in both Zone 1 and Zone 2 rubber. There is about twice as much total gel rubber in Zone 2 rubber (29) than in Zone 1 rubber (15). As a large proportion of the latex obtained from the rubber tree is derived from a very small number of Zone 1 rubber particles of exceptionally large size their prevalence in latex has an important bearing on the economic crop.

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Item Type:	Article
AGROVOC Term:	Hevea brasiliensis
AGROVOC Term:	Latex
AGROVOC Term:	Centrifugation
AGROVOC Term:	Electron microscopy
AGROVOC Term:	Molecular weight
AGROVOC Term:	Chilling
AGROVOC Term:	Particle size
Depositing User:	Ms. Suzila Mohamad Kasim
Last Modified:	24 Apr 2025 06:28
URI:	http://webagris.upm.edu.my/id/eprint/23386

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