Insight on natural rubber’s relationship with coagulation methods and some of its properties during storage

The changes in the structure, such as molecular weight, crosslinking density, and gel content, could influence the stability and the processing performance of natural rubber (NR) during storage. Previous works showed that temperature and humidity influence storage performances. Here, we found different coagulation methods could also affect storage behaviors of natural rubber, since coagulation methods could affect the content of non-rubber components. In this article, natural rubber latex was coagulated by three different coagulation methods. Under storage conditions, the content of some non-rubber components, namely the gel content, Mooney viscosity, Wallace initial plasticity (P0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$P_{0}$$\end{document}), plasticity retention index (PRI), molecular weight, tensile strength, and crosslinking density of natural rubber were compared and analyzed. The results showed that properties (PRI, Mooney viscosity, and green strength) of NR were higher than that of NR-Salt and NR-Acid after storage; at the same time, PRI, Mooney viscosity, and green strength of NR-Salt were higher than that of NR-Acid after storage. Mooney viscosity and green strength of NR-Salt and NR-Acid showed a tendency for increase in the begin and then decrease. According to the changes before and after storage, we can choose suitable coagulation methods and rubber based on what we need.