Rheological Behavior of Raw Natural Rubber Coagulated by Microorganisms

Abstract

Abstract:Tests of the strain sweep, frequency sweep and stress relaxation for raw natural rubber coagulated by microorganisms (NR-m) and raw natural rubber coagulated by acid (NR-a) were carried out with the use of a rubber process analyzer (RPA). The results showed that the storage torque, complex viscosity of NR-m were higher than those of NR-a while the loss factor was lower. The effect of temperature on viscosity of raw NR was studied following the Arrhenious-Frenkel-Eyring model. The viscous flow behavior of NR-m was poorer than those of NR-a. Furthermore, stress relaxation measurements of raw NR showed a longer period of relaxation for NR-m.

The effect of mastication time on the physical properties and structure of natural rubber

“…Similar observations have also been reported in previous studies. 14,18 Figure 5 increases with increasing the frequency in all samples (see Figure 5(a)). This phenomenon is due to the fact that there is a sufficient time for rubber entanglement chains to recover from the deformation at low frequency but these entanglements do not have sufficient time to recover when the chains are deformed with high frequency and, thus, the modulus increases.…”

“…Such behavior is often found in rubber-based materials and is known as shear thinning. 14,18 With the shear rate held constant, the complex viscosity of the rubber decreased with increasing mastication time. This result can be explained by the fact that the mastication of the NR caused the M w to reduce due to chain breakage, which finally resulted in a reduction in the viscosity.…”

“…It can be seen that all the scattering profiles show a strong upturn at small q values, suggesting the presence of a heterogeneous structure in all the samples. [7][8][9][10][11][12][13][14][15][16][17][18][19][20] Thus, the distribution of the nonrubber component aggregations was heterogeneous. It is interesting that greater increases in the scattering intensity were observed when the rubber was masticated for longer times (5 and 10 min), while short mastication times showed lower increases compared to the sample without mastication.…”

Rheological properties and curing features of natural rubber compositions filled with fluoromica ME 100

“…Based on the obtained results the cure rheometric parameters point out to the 7 phr ME 100 composition as the most favorable, predicting the best possible interaction/distribution for this filler content with the elastomeric matrix [3,4,[6][7][8][9]22,26,27] .…”

“…Being polymers, the behavior of elastomeric compositions is intermediary between viscous and elastic states, the knowledge of the viscoelastic profile, which can be studied by rheology, being extremely important for the processing prediction as well as for the final properties of the vulcanized elastomer. In the elastomer field, the rheology is mainly studied with the aid of the following equipment: Oscillating Disc Rheometer, Mooney Viscometer and Rubber Processing Analyzer [1][2][3][4] .…”