Optimal design of Celuka microporous foaming extrusion device and its bubble deformation induction mechanism

Abstract Aiming at the technical challenges existing in the current microbubble foaming process of wood–plastic composites, a continuous microporous foaming extrusion platform suitable for this material was built by optimizing the screw geometry and foaming mold. The internal bubble structure characteristics of samples under different processing conditions are observed to reveal the gas bubble derivation behavior and morphological evolution law during the extrusion process, which is aimed to achieve effective size parameter control. The results indicate that the adaptation of Celuka foaming mold, enhancement of screw mixing ability, and series connection of cavity transfer dynamic mixer can help obtain the desired pressure drop parameters to realize the microcellularization of wood–plastic composite materials in the foaming process. In addition, affected by the melt flow state, the bubbles undergo certain deformation behavior during growth, and the enhanced melt strength contributes to improve the structural stability of bubbles. Meanwhile, by adjusting the foaming temperature from 190 °C to 210 °C, the bubble size and distribution density were optimized to 87.6 μm and 2.3 × 10 4 cells/cm 3 , respectively.