Release of dithiocarbamates into artificial sweat from latex vulcanizates: Effects of the accelerator type and storage time

Effect of Latex Purification and Accelerator Types on Rubber Allergens Prevalent in Sulphur Prevulcanized Natural Rubber Latex: Potential Application for Allergy-Free Natural Rubber Gloves

Natural rubber (NR) gloves manufactured from NR latex are widely utilized in various applications as a personal protective device due to their exceptional barrier characteristics in infection control. However, the use of NR gloves was associated with concerns on NR protein allergy. With comprehensive leaching procedures now a common practice in NR latex glove factories to eliminate latent rubber proteins and chemical allergens, occurrences and complaints of protein allergy from medical glove users have decreased drastically over the past two decades. The present work aims to eliminate further the residual rubber allergens in NR latex through effective purification of the NR latex and compounding the thus purified latex with an established formulation for allergy-free NR for glove applications. NR latex was purified by deproteinization and saponification, respectively. Several analytical techniques were used to verify rubber allergens eliminated in the purified latexes. Saponified NR (SPNR) latex was the purified NR latex of choice since it is devoid of allergenic proteins and poses the lowest risk of Type I allergy. The purified NR latex was compounded with zinc diethyldithiocarbamate (ZDEC), zinc dibutyldithiocarbamate (ZDBC), and zinc 2-mercaptobenzothiazole (ZMBT), respectively, for glove dipping. Among the investigated accelerators, only ZDBC was not detected in the artificial sweat that came into contact with the dipped articles. Thus, it is deduced that ZDBC poses the lowest risk of Type IV allergy to consumers. Additionally, the morphological and physical properties of dipped articles were assessed. It was revealed that the dipped film from the SPNR latex compounded with ZDBC provided thinner and less yellow products with a more uniform internal structure and a tensile strength comparable to those of commercial NR gloves.

Chitosan and Natural Rubber Latex Biocomposite Prepared by Incorporating Negatively Charged Chitosan Dispersion

Generally, natural rubber/chitosan (NR/CT) biocomposites could be prepared by either mixing natural rubber latex (NRL) with CT acid solution or mixing dry NR with CT powder on mixing equipment. In the present work, a new mixing method has been proposed and properties of the obtained NR/CT biocomposites are investigated. CT particles were prepared to have a negative charge that could be dispersed in water by using a ball mill before mixing with NRL. The effects of CT loading varied from 0 to 8 phr on latex properties and physical properties of NR/CT biocomposite films were focused. The results showed that the viscosity of NRL increased with increasing CT loading. With increasing CT loading from 0 to 8 phr, 300% modulus of the NR/CT biocomposite film increased, whereas the opposite trend was found for elongation at break. Additionally, the presence of CT in the biocomposite resulted in an increased elastic modulus (E') in conjunction with enhanced antibacterial activity against Staphylococcus aureus (S. aureus).