Mastication behavior of cis‐1,4‐polyisoprene as a model for natural rubber

Abstract

The mastication behavior of synthetic cis-1,4-polyisoprene (IR), deproteinized natural rubber (DPNR), and natural rubber (NR) in an internal mixer has been investigated at mixing temperatures from 88 to 186 C and different levels of mechanical energy, using Mooney viscosity and size exclusion chromatography (SEC). An envelope-shaped mastication efficiency curve and high similarity in the mastication behavior can be observed for IR and NR but not for DPNR. The minimum of the envelope-shaped curve shifts to lower temperatures when the mechanical energy is increased. Based on these findings, a mathematical description for the contribution of mechanical and thermo-oxidative mastication mechanisms has been established. Distinct statistical distribution of thermooxidative scission can only be observed in SEC measurements of materials masticated at high temperatures over 170 C.

Cellulose nanocrystals as nucleating agents for the strain induced crystallization in natural rubber

“…At an input temperature of 120 °C, the material temperature is expected to be higher due to self-heating induced by shearing forces during mixing (see discussion below). Hence at such temperatures thermo-oxidative mastication is generally expected, 52 which would have resulted in a decrease in the material viscosity during mixing, and a decrease in the elastic properties after vulcanization. Conversely, the elastic modulus of the material mixed at 120 °C is found to slightly increase that is likely due to a premature vulcanization during mixing ( cf.…”

Characterization of the molecular structure of masticated natural rubber using rheological techniques

“…The results may be because the region between 100 and 130 C is the least practical region for the chain-breakage effect, as the molecular chains transition from mechanical to thermal oxidative decomposition in this temperature interval. 13,19,20 3.3 | Characterization of molecular structural properties through RPA…”

“…This research focuses on the mastication of NR leading to changes in the molecular structure, which are mainly caused by degradation. [12][13][14] The changes in the rheological properties and molecular structure of the NR prepared at different mixing speeds were observed using the rubber processing analyzer (RPA). This method can rapidly compare the MW, MWD, degree of branching, and thermal stability of the raw NR at different masticating speeds while validating the results obtained in combination with GPC tests.…”

“…This research studied the changes in molecular structure, MW, degree of branching, and thermal stability of NR after mastication for 20 min at 35, 75, and 110 rpm, respectively. This research focuses on the mastication of NR leading to changes in the molecular structure, which are mainly caused by degradation 12–14 . The changes in the rheological properties and molecular structure of the NR prepared at different mixing speeds were observed using the rubber processing analyzer (RPA).…”

Preparation of bis‐epoxy end capped macromonomers through anionic orRAFTpolymerization

“…À60 C), good degradability and the presence of double-bond-rich composition that allows further chemical reactions after polymerization. 1 This makes it widely used in synthetic rubber, [2][3][4][5][6] polyurethane, 7 synthetic biosensors, 8 degrading bacteria, 9,10 biomedicine, 11 and so on. Isoprene polymers can be obtained from anionic, radical, coordination, and cationic polymerization, among which anionic polymerization was chose as the dominant technique for academia and industry.…”