Role of Divalent Metal Ions on the Basic Properties and Molecular Chains of Natural Rubber

Abstract

Metal ions are a kind of components that cannot be completely removed in natural latex, which have an important influence on the basic quality of natural rubber, such as ash, impurities, Wallace plasticity value, plasticity retention index, etc. The six kinds of common divalent metal ions in natural rubber including calcium ion, magnesium ion, copper ion, manganese ion, iron ion and zinc ion are targeted to explore their influence on the storage characteristics of natural rubber. The fresh latex was added the designed divalent ions, then became the raw natural rubber via some procedures such as solidification, drying. Based on divalent metal ion and their content, the storage characteristics of natural rubber and the microstructure of corresponding natural rubber sample were examined. Wallace plasticity value (P0), Plasticity retention index (PRI), accelerated storage-hardening number (ΔP) of the resultant samples were tested. The tensile strength, and rubber molecular weight were also determined to explore the effects of different divalent metals on the structural changes of natural rubber. In the experiment, the blank control group was designed. Through the contrast analysis with the blank control group, it was found that the storage stability of the raw rubber depends on not only the type but also the content of divalent metal ions.