The Role of Non-Rubber Components on Molecular Network of Natural Rubber during Accelerated Storage.

Huifeng Zhang,Fuchun Zhao,Shuangquan Liao,Xu Chen,Mingchao Luo,Lu Zhang,Yueqiong Wang

doi:10.3390/polym12122880

Abstract

Though the non-rubber components have long been recognized to be a vital factor affecting the network of natural rubber (NR), the authentic role of non-rubber components on the network during accelerated storage has not been fully illuminated. This work attempts to clarify the impact of non-rubber components on the network for NR during accelerated storage. A natural network model for NR was proposed based on the gel content, crosslinking density, and the non-rubber components distribution for NR before and after centrifugation. Furthermore, the effect of non-rubber components on the network was investigated during accelerated storage. The results show that terminal crosslinking induced by non-rubber components and entanglements are primary factors affecting the network formation during accelerated storage. By applying the tube model to analyze the stress-strain curves of NR, we found that the contribution of the entanglements to the network formation is larger than that of terminal crosslinking during accelerated storage. The work highlights the role of non-rubber components on the network during accelerated storage, which is essential for understanding the storage hardening mechanism of NR.

Highlights

Natural rubber (NR) from Hevea brasiliensis consists of 94% cis-1, 4-polyisoprene and 6% non-rubber components, such as proteins, lipids, metal ion, and so on [1,2,3,4,5]
The centrifugation treatment apparently decreases the content of non-rubber components in natural rubber (NR), which provides a convenient and versatile method to analyses network structure in comparison with traditional enzymatic or chemical approaches
The natural network structure model of NR is established by the change in the protein, ester content, metal ions, gel content, and crosslinking density before and after centrifugation

Summary

Introduction

Natural rubber (NR) from Hevea brasiliensis consists of 94% cis-1, 4-polyisoprene and 6% non-rubber components, such as proteins, lipids, metal ion, and so on [1,2,3,4,5]. The research studies show that the non-rubber components in NR are connected with main chain through α-terminal, ω-terminal, and metal ions to form network structure [12,13,14,15]. Sakdapipanich et al verified the existence of the non-rubber components in the natural network based on the crystallization behaviors. Guo et al demonstrated the natural network linked by protein-based ω-terminal and phospholipids-based α-terminal [16].

Objectives

Methods

Results

Conclusion