Comparative study of the elasticity and permeability of vulcanized films made with skim and cream natural rubber latex

Abstract

The purpose of this study was to gain a clearer picture of the structure and properties of vulcanized films made with skim and cream latex from Hevea brasiliensis. The two properties targeted for this study were the elasticity of the films and their permeability to acetone. Surface characterization by atomic force microscopy revealed that vulcanization substantially modified the structure of the films compared to unvulcanized films. Unlike unvulcanized films, particle identity was retained in the vulcanized films made with cream latex, even after 4 weeks of aging. In addition, skim latex gave vulcanized films with greater elasticity than those obtained with cream latex. On the basis of the structural characterization carried out on the latex and films and information from the literature, the greater elasticity of the skim films arose from more entanglements between polyisoprene chains and associations between proteins. Despite differences in the structure, the acetone permeability was very similar for skim and cream vulcanized films.

Preparation of core-shell particle of disinfectant agent nanocapsules-skim rubber particles by the heterocoagulation technique

“…In contrast, the particle contours of non-crosslinked skim particles disappeared, resulting in blurred spots. 20 The result also agreed with the internal morphology of prevulcanised latex particles examined by the phase transfer/bulk polymerisation/TEM technique which revealed the uniform crosslink structure of SPVS particles. 7 Analysis of CHD-PMA Nanocapsules.…”

Pre‐Vulcanization of Large and Small Natural Rubber Latex Particles: Film‐Forming Behavior and Mechanical Properties

“…Finally, rubber molecules from neighboring RPs are crosslinked (inter‐particle crosslinked network) by residual curing agents at high temperature known as post‐vulcanization process, where eventually all the RPs lost their identities and coalesced into a continuous film. However, it was previously reported that the vulcanization structure mostly occurred during pre‐vulcanization followed by the post‐vulcanization in film‐forming period . For example, in concentrated NR (CNR) latex film, the morphology of the RPs was dependent upon the level of crosslinking in that the RP identity was retained over long aging periods for highly crosslinked particles, creating rough surface .…”

“…However, it was previously reported that the vulcanization structure mostly occurred during pre‐vulcanization followed by the post‐vulcanization in film‐forming period . For example, in concentrated NR (CNR) latex film, the morphology of the RPs was dependent upon the level of crosslinking in that the RP identity was retained over long aging periods for highly crosslinked particles, creating rough surface . On the other hand, pre‐vulcanized latex film surface made from skim NR latex was smooth and contours of RPs were no longer discernible, leading to greater elasticity than that of the CNR latex film .…”

“…For example, in concentrated NR (CNR) latex film, the morphology of the RPs was dependent upon the level of crosslinking in that the RP identity was retained over long aging periods for highly crosslinked particles, creating rough surface . On the other hand, pre‐vulcanized latex film surface made from skim NR latex was smooth and contours of RPs were no longer discernible, leading to greater elasticity than that of the CNR latex film . While the above two‐stage curing process is practiced in the dipping industry, the fine‐tuning of the pre‐ to post‐vulcanization to obtain the desired properties is still very much a trial and error exercise.…”

“…[29,32] On the other hand, pre-vulcanized latex film surface made from skim NR latex was smooth and contours of RPs were no longer discernible, leading to greater elasticity than that of the CNR latex film. [32] While the above two-stage curing process is practiced in the dipping industry, the fine-tuning of the pre-to postvulcanization to obtain the desired properties is still very much a trial and error exercise.…”