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

Abstract

Non-rubber components, mainly indicating phospholipid and protein, were separately removed from natural rubber to individually study their effect on structure and properties of the rubber. Fourier Transform Infrared Spectroscopy (FTIR) and 1 H nuclear magnetic resonance ( 1 H NMR) were applied to characterize the chemical structure and the non-rubber component residual. Rheology study and stress relaxation measurement were adopted to study the role non-rubbers played in natural networks. Rheological study of natural rubber (NR) and deproteinized natural rubber (DPNR) exhibited similar dynamic modulus at 170 o C. The lack of superposition in van Gurp Palmen (vGP) curves at different temperature for NR and DPNR, together with the shape of vGP curves proved that long chain branching was mainly constructed by phospholipid. Stress relaxation measurement at room temperature was fitted with Maxwell model and showed that NR relaxation curve underwent a quick decrease and then come to 58% equilibrium stress retention, about 3 times higher than that of DPNR, indicating that protein in NR contributed to the network structure at room temperature. Combined the chemical with molecule dynamic study, the interaction between protein and phospholipid in non-rubber component network was proposed.

Effect of treated mica on rheological, cure, mechanical, and dielectric properties of ethylene propylene diene monomer (EPDM)/barium titanate (BaTiO3)/mica

“…The loss phase angle δ versus the absolute value of the complex modulus | G *| is plotted in Figure (C), known as Van Gurp curves . It is shown that at the same phase angle, the trend of | G *| is consistent with that of complex viscosity, meaning that the length of molecular chains of coupling agents can influence the interaction between treated mica and matrix.…”

“…The G ′/ G ′′ curve is often used to illustrate the liquid‐like and solid‐like behavior of polymer composites . It is found that G ′/ G ′′ of samples all exceeds 1, meaning that there is no rheological transition from liquid‐like behavior to solid‐like behavior for these samples.…”

Influence of nonrubber components on properties of unvulcanized natural rubber

“…In addition, it is clearly seen that ADS samples from the three H brasiliensis genotypes showed the highest peak A. This might be due to large networks in ADS enabling high SIC at low temperature . Furthermore, it is noteworthy that the peak A disappeared for the LPNR and AENR samples from all H brasiliensis genotypes.…”

“…This might be due to large networks in ADS enabling high SIC at low temperature. 52 Furthermore, it is noteworthy that the peak A disappeared for the LPNR and AENR samples from all H brasiliensis genotypes. This confirms that the spontaneous SIC in NR indicated by peak A in the relaxation spectra was associated with the total content of proteins and lipids together with macrogels.…”

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

“…It can be confirmed that the more relaxation units in NR-24 h are obviously confined by the network with abundant non-rubber components. Furthermore, the Maxwell model is used to understand the stress relaxation curves [51][52][53].…”