Strategy To Produce Microcellular Foamed Poly(lactic acid)/Wood-Flour Composites in a Continuous Extrusion Process

Abstract

In microcellular foaming process of wood/plastic composites, the alterations in melt viscosity induced by the addition of wood-flour into the plastic matrix play an important role during the growth and stabilization of nucleated cells. This study examined the effects of wood-flour and low molecular weight rheology modifier addition levels on the melt flow index, shear viscosity, and extensional viscosity of PLA/wood-flour composites. From the results, an effective strategy is proposed to successfully and continuously produce microcellular foamed PLA/wood-flour composites with cellular structures similar to those achieved in neat PLA foams. It consists of matching the composites' melt index value (or melt viscosity) to that of neat PLA by using a rheology modifier. Lowering the melt index of the composites from the matching value resulted in unprocessable foaming conditions owing to the increased melt viscosity, whereas cell structures slightly deteriorated by increasing the melt index of the composite above its optimum value.

Mastering the structure of PLA foams made with extrusion assisted by supercritical CO2

“…The analyses were performed on Heat Only mode, from 10 to 200 8C with a heating ramp of 2 8C min 21 . An amplitude of 0.32 8C will be applied with a time period of 60 s.…”

“…with DH m the melting enthalpy, DH cc the cold crystallization enthalpy, and DH m1 the heat of fusion of PLA for a perfect crystal, known to be 93 J g 21 . 36 X-ray Diffraction.…”

“…The samples were exposed to an X-ray beam generated by a tube with a copper anticathode. The diffraction patterns were collected over an angular range (2u) between 5.58 and 45.08 with an incremental step of 0.0338 and a time of acquisition of 139.7 s dot 21 .…”

Improve the mechanical property and flame retardant efficiency of the composites of poly(lactic acid) and resorcinol di(phenyl phosphate) (RDP) with ZnO‐coated kenaf

“…Poly (lactic acid) (PLA), mainly produced from corns and potatoes, has attracted more and more attention among various kinds of biodegradable polymers because of its low cost and large production volume [1,2]. Because PLA can be made into film, foam, fiber, and molded parts, it can meet multiaspects of requirements [3][4][5][6][7]. With the rapid development of the PLA market, the application fields will be increasingly broadened.…”

The effect of processing parameters on cell structure and mechanical properties of extrusion‐foamed poly(vinyl chloride) sheets

“…To the solve the problem, microcellular foaming technology, through which microcellular plastics with a nominal cell size less than 10 µm and cell‐population density higher than 10 9 cells/cm 3 can be realized, was invented by researchers at the Massachusetts Institute of Technology . Interest in the microcellular plastics technology has been growing steadily since its invention, and research work on microcellular extrusion foaming of pure polymer materials such as polypropylene (PP) , polystyrene (PS) , polyethylene (PE) , polycarbonate (PC) , polylactic acid (PLA) , and blends such as PP/PE , PE/PS , PP/PS , PP/WOOD , PE/WOOD , PP/WGRT (waste ground rubber tire) , PVC/WOOD , PLA/WOOD , and so on, have been reported.…”