Preparation and Properties of High-Performance Biobased Polyurea Fiber via Reactive Extrusion

Biobased fibers have gradually gained attention with the development of fiber industry due to the characteristics of renewability and environmentally friendliness. For polyureas derived from urea and biobased diamine, the excellent properties such as high strength, high toughness, and rapid crystallization, offer them great potential in the construction and application of fiber materials. It is in this work aiming at constructing high-performance polyurea fibers, taking the problems of poor pulverizability and high melt viscosity into account. A three-step process, including prepolymerization, reactive extrusion, and drawing, was proposed and accomplished to conduct fiber formation for the polyurea. Prepolymerization was carried out via melting polycondensation from urea and 1,10-diaminodecane. The oligomer obtained was then able to be crushed into particles for extrusion. The reactive extrusion in which chain extension took place was conducive to increasing the molecular weight ( M n = 23.2 kg/mol). The obtained fiber was then further drawn at 160°C to increase the crystallinity and as a result, to increase the strength. A reorganization of crystal structure for the drawn yarn can be observed and improved crystallinity was detected. The tensile strength is found to be increased from 45 to 600 MPa after drawing, while the modulus is found to be from 1.1 to 5.9 GPa. It is concluded that the difficulties in the processing and formation of polyurea fiber have been solved in this study. Such technique developed here expands the application fields of polyurea materials and provides a new option for the development of high-performance biobased fibers.