Effect of filler on the total protein content and mechanical properties of natural rubber latex films at different filler loadings

Abstract

Calcium carbonate (CaCO3) is an important filler, widely used rubber industries, particularly in natural rubber latex dipped such as gloves. The main advantages are cost reduction and product improvement. With the development of technology in superfine filler production, the use of CaCO3 as a non-reinforcing filler has gained much attention as it could help to improve natural rubber (NR) product properties. In this study, mixed clones of natural rubber field latex (MCFL) were prepared before further processing into mixed clones’ natural rubber latex concentrate (MCLC). The properties of MCLC were evaluated before compounds with CaCO3 and other rubber chemicals. The MCLC films were prepared from the MCLC added with CaCO3 varied from 10 to 40 parts per hundred rubber (pphr) and rubber chemicals. The total protein contents for unaged and aged latex films before and after acetone extraction was determined, respectively, according to total nitrogen (N) and extractable protein (EP) contents. The content of CaCO3 in MCLC films at different loadings was characterised by a Thermogravimetric analyser (TGA). Meanwhile, mechanical properties such as tensile and tear strengths were also determined. It was found that the total protein contents for the unaged MCLC films at different filler loadings were higher as compared to the aged samples. It is also proposed that the chemicals’ interference for MCLC films have occurred from 25 pphr until 40 pphr filler loadings. The tensile strength of MCLC films decreased as the filler loading increased. However, the tear strength of MCLC films increased as the filler loading increased.