Constructing highly oriented and condensed shish-kebab crystalline structure of HDPE/UHMWPE blends via intense stretching process：Achieving high mechanical properties and in-plane thermal conductivity

Abstract

Ultra-high molecular weight polyethylene (UHMWPE)had been widely discussed in terms of mechanical and wear-resisting performance, and gradually expanded to other functional fields. The key point was preserving and extending the disentangled UHMWPE chains, which could further obtain shish-kebab crystalline structure with highly orientation under extensional flow. In this paper, a designed intense stretching process was introduced to construct highly oriented and condensed shish-kebab crystalline structure for enhancing mechanical properties and in-plane thermal conductivity of HDPE/UHMWPE blends. The disentangled UHMWPE chains in gel state were firstly extended and better interacted with HDPE matrix through multistage stretching extrusion (MSE). After that, the condensed and highly oriented shish-kebab crystalline structure was constructed by MSE as well as uniaxial stretching, which also enlarged the long period, lamellar thickness, and retained high rate of lateral dimension. With the disentangled UHMWPE chains introduced and the designed intense stretching process, the tensile strength, Young's modulus and in-plane thermal conductivity increased to 237.8 MPa, 1312.8 MPas and 2.2 W/(m.K), respectively. This work could provide a new sight to the application of high-performance polyethylene blends.