Development of an extrusion system for producing fine‐celled HDPE/wood‐fiber composite foams using CO₂ as a blowing agent

Abstract

This paper presents an innovative design of a tandem extrusion system for fine-celled foaming of plastic/wood-fiber composites using a physical blowing agent (PBA). The plastic/wood-fiber composites utilize wood-fibers (WF) as a reinforcing filler in the plastic matrix and are known to be advantageous over the neat plastics in terms of the materials cost and some improved mechanical properties such as stiffness and strength. However, these improvements are usually accompanied by sacrifices in the ductility and impact resistance. These shortcomings can be reduced by inducing fine-celled or microcellular foaming in these composites, thereby creating a new class of materials with unique properties. An innovative tandem extrusion system with continuous on-line moisture removal and PBA injection was successfully developed. The foamed composites, produced on the tandem extrusion system, were compared with those produced on a single extruder system, and demonstrated significant improvement in cell morphology, resulting from EXTRUSION SYSTEM FOR PRODUCING FINE-CELLED HDPE/WOOD-FIBER COMPOSITE FOAMSuniform mixing and effective moisture removal. The effects of WF and coupling agent (CA) on the cell morphology were studied. An increase in the WF content had an adverse affect. The cell morphology and foam structures were improved when an appropriate CA was added. C

Injection Molding of Wood–Fiber/Plastic Composite Foams

“…798 Foaming technology presents such a possibility. This technology is a family of different processing methods that can produce wood-fiber/plastic composite parts with a lower density than solid parts due to numerous micron or millimeter-sized bubbles created by a blowing agent [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. However, it is not easy to obtain fine and uniform cell structures, which are critical to the maintenance of mechanical properties when the density is reduced.…”

“…However, it is not easy to obtain fine and uniform cell structures, which are critical to the maintenance of mechanical properties when the density is reduced. One major reason is the inherent moisture and volatiles in wood fiber, which are released at elevated temperatures during processing, causing significant deterioration of the foam cell morphology [2][3][4][5][6][7]. In addition, wood fiber is normally loaded at a high level (more than 40 wt% in certain applications).…”

The interaction of delignification and fiber characteristics on the mechanical properties of old corrugated container fiber/polypropylene composite

“…Wood fiber-reinforced composites are anisotropic and heterogeneous materials, which allow greater flexibility in engineering the composite properties to the requirements of the final use [4,5]. The processing of such composite material is flexible, economical, and ecological, and it is possible to use the same equipment used with either wood or plastics [6,7].…”

Properties of calcium carbonate filled and unfilled polystyrene foams prepared using supercritical carbon dioxide

“…Martini-Vvedensky et al 1 and Park et al 2 have pioneered to carry out continuous and batch foaming processes on a large scale basis for high impact polystyrene (HIPS) and polypropylene (PP) systems. Other foaming researches on polymers, including polyethylene (PE), 3,4 PP, [5][6][7] polyethylene terephthalate, 8 polycarbonate (PC), 9 polystyrene (PS), [10][11][12][13][14][15][16][17] and so forth, were also conducted to produce microcellular foams.…”