Mechanism of the green coagulation processes on the construction of raw rubber network structure

Abstract

Acid coagulation is the most traditional latex coagulation technology, but this coagulation process leads to delayed vulcanization, corrosiveness, and environmental pollution. Different coagulation processes significantly impact the raw rubber network structure, leading to differences in the properties of both raw rubber and rubber vulcanizates. Raw rubber was prepared by three acid‐free coagulation processes: freeze, microwave, and flash drying. The network density, molecular chain flexibility, molecular weight, processing fluidity, and plasticity retention of the raw rubber were characterized, and the vulcanization characteristics, viscoelasticity, mechanical properties, and dynamic mechanical properties of the cured rubber composites were investigated. Raw rubbers prepared by microwave drying and flash drying had higher crosslink density, more flexible molecular chains, larger molecular weight, and wider molecular weight distribution, thereby increasing the crosslink density of rubber vulcanizates. The crosslink density of the raw rubber prepared by microwave drying versus the acid coagulated raw rubber increased by 51% to 105.71 mol/m3, the tensile strength increased by 16% to reach 28.12 MPa, and the elastic modulus and rolling resistance under dynamic stress increased. This paper provides a new idea for analyzing the relationship between the raw rubber network structure and the properties of vulcanized rubber.Highlights Acid‐free raw rubbers are prepared by freeze, microwave, and flash drying. Coagulation processes significantly impact the raw rubber network structures. Effects of raw rubber network structures on properties are investigated. Crosslink density, plasticity retention, and tensile strength are improved.