Fabrication of oriented UHMWPE films using low solvent concentration. (5th February 2017) - Maksimkin, A.V.
Abstract: The method of oriented films fabrication from the ultrahigh molecular weight polyethylene (UHMWPE) and small amount of solvent (1.6 ml of solvent per 1 g of UHMWPE) is described. This method excludes UHMWPE solution because the solvent acts as a plasticity agent. The UHMWPE structure formed due to plasticization favoured to drawability increase. Multi-stage hot orientation method with a draw ratio up to 35 was used to fabricate UHMWPE films. The reactor powders and fabricated films were tested by SEM, DSC and XRD. The degree of crystallinity was increased up to 94% determined by DSC and 93% determined by XRD for films with draw ratio 26 and 35. The achieved tensile strength and modulus was 0.9 GPa and 35 GPa respectively for films with draw ratio 35. Orientation of the films proceeded via two different mechanisms: (i) macromolecules deployment and their crystallization below draw ratio 26 and (ii) slipping of the fibrils above draw ratio 26. Slipping of the fibrils results in a taut tie molecules amount increase and consequently favour the tensile strength and especially modulus increase. Graphical abstract: Highlights: A new method to fabricate ultra-high molecular weight polyethylene films is described; Prepared films have a very high crystallinity (up to 94%); The tensile strength and modulus of films was 0.9 GPa and 35 GPa; Orientation of the films proceeded via (1) unfolding and recrystallization of macromolecules and (2) slipping of the fibrils;