Preparation of PBS/ cotton stalk cellulose materials with wood-like microstructure by using supercritical CO 2 extrusion foaming combined with solid-state stretch

Abstract

It is an efficient method to prepare polymer materials with wood-like microstructure by using supercritical CO₂ foaming combined with solid-state stretch. In this study, PBS/cotton stalk cellulose (CSC) biodegradable microcellular foam was prepared via supercritical CO₂ extrusion foaming, yielding a fully degradable material with 3-4-fold expansion. Subsequently, forced solid-state stretching above the glass transition temperature (Tg) but below the melting temperature (Tm) of PBS deformed spherical cells into “tubular pore structures”. SEM imaging confirmed transformation from quasi-spherical pores to tubular structures aligned with the stretching direction (aspect ratio: 13.12:1 at 500% stretching); additionally, fluorescence staining with Calcofluor White (CFW) demonstrated oriented alignment of cellulose along the stretching direction post-stretching. The results showed that the tensile strength and tensile modulus of materials reached 47.31 MP and 503.13 MPa respectively, markedly surpassing pure PBS foam performance, similar to the performance of poplar.