Ming-Chao Luo

A rheological study on non-rubber component networks in natural rubber

Phospholipids and proteins were separately removed as the main non-rubber components to individually study their effect on the structure and properties of the rubber. Fourier Transform Infrared Spectroscopy (FTIR) and 1H nuclear magnetic resonance spectroscopy (1H-NMR) were used to characterize the chemical structure and the residual non-rubber component. A rheology study and stress relaxation measurements were used to study the role that non-rubber components play in natural networks. A rheological study showed that natural rubber (NR) and deproteinized natural rubber (DPNR) exhibited similar dynamic modulus at 170 °C. The lack of superposition in van Gurp–Palmen (vGP) curves at different temperatures for NR and DPNR, together with the shape of vGP curves, proved that long chain branching was mainly constructed by phospholipids. Stress relaxation measurements at room temperature were fitted with the Maxwell model and showed that the NR relaxation curve underwent a quick decrease and then came to an equilibrium stress retention of 58%, which is about 3 times higher than that of DPNR, indicating that proteins in NR contributed to the network structure at room temperature. Combining molecular dynamic studies, the interaction of proteins and phospholipids in non-rubber networks was proposed.

Synergistic effect of CB and GO/CNT hybrid fillers on the mechanical properties and fatigue behavior of NR composites

In this paper, graphene oxide (GO) and carbon nanotube (CNT) hybrid fillers were used to replace partial carbon black (CB), and GO/CNT/CB/NR composites were prepared with excellent crack growth resistance, low heat build-up and superior mechanical properties. Mechanical testing revealed a significant synergistic reinforcement between GO/CNT and CB in NR composites. The improved dispersion of GO/CNT hybrid fillers and CB in the NR matrix was characterized by transmission electron microscopy (TEM). Through the fatigue test, the GO/CNT/CB/NR composites showed excellent fatigue crack growth resistance and low heat build-up compared to CB/NR composites. These properties provide the NR composites with better applications in industry.