Low protein natural rubber latices

A comparative study of the latex concentrate properties and properties of latex dipped films prepared from low protein (LP) latices was carried out. Besides the basic latex properties, the extractable protein (EP), antigenic and allergenic protein (AP) contents of the latex concentrates and latex dipped films were also examined. In addition, the physical properties such as tensile, tear and cuff rupture strength and coefficients of friction of the latex dipped films were compared. The biocompatibility and barrier performance of these films were also evaluated. The majority of the coagulant dipped films prepared from LP latices, that were wet-gel leached for 5 min at 50°C, showed low levels of allergenic and antigenic protein (AgP) contents. However, only a few of these films showed EP content of less than 200 /jg/dm2. There was a considerable variation in the nitrogen contents ofLP latices (0.04% - 0.21%) andprevulcanised LP latices (0.09% - 0.24%). In view of the relatively wide range of nitrogen contents and the expectation that product prepared from a LP latex ought to contain low levels of EP, AP and AgP contents, it was proposed that maximum limits for nitrogen content of the latex and maximum limits for EP, AP and AgP contents of the dipped vulcanised latex films prepared under standard conditions be established in order to characterise and define the term ‘low protein latices’. The determinations of dry rubber contents and mechanical stabilities of some of the LP latex concentrates were found to be problematic due to the difficulty with coagulation and excessive foaming, respectively. For a majority of LP latex concentrates, extended maturation times were found to be necessary to achieve precure and tensile properties comparable to a normal high-ammonia centrifuged latex. Minimal problems were observed during the preparation of dipped films from the LP latices. The biocompatibility and barrier characteristics of dipped films prepared from LP latices were rather similar to those prepared from normal latex concentrate.