Effects of water-soluble polymers upon some properties of natural rubber latex
An investigation of the effects of various water-soluble polymers upon some properties of natural rubber latex has been carried out. All the polymers, which were of two principal types, distinguished according to the rate of addition of polymerisation reactants, were prepared by free-radical initiated solution polymerisation. Two types of monomers, namely, ionisable hydrophilic monomers and hydrophobic monomers were used in the preparation of polymers. Both types of polymers, referred to as Type 1 and Type 2, were principally characterised by viscometry, hydrophilicity assessment and infra-red analyses. It has been found that such characteristics of these polymers as molecular weight, composition distribution and hydrophilicity are dependent upon the method used for their preparation. Explanations which have been suggested for this dependence accord with theoretical predictions. It has also been found that certain properties of natural rubber (NR) latex such as mechanical stability (MST), viscosity, zinc-oxide thickening, heat-sensitivity and creaming can be modified with the addition of water-soluble polymers and that the extent to which each of these properties is modified depends upon the characteristics of the added polymer. The extent of the modification of MST and viscosity of NR latex greatly depended upon both the molecular weight and composition of the added polymer. The influence of composition of the added polymer in modifying zinc-oxide thickening was found to be more important than that of molecular weight. Even though the effects of polymers of Type 1 and Type 2 upon the properties of NR latex were generally similar it has not been able to make proper comparisons between the effects of these two types of polymers as their characteristics were different.
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