The Efficiency of Cellulosic Fillers in Common Thermoplastics. Part II. Filling with Processing Aids and Coupling Agents

Abstract

This paper reports on the effect of additives on the properties of injection moulded composites based on polypropylene (PP) and high density polyethylene (HOPE) filled with wood and cellulose flour. Three types of additives were studied: dispersion aids, elastomeric additives, and adhesion promoting agents. Some of the dispersion aids were found to improve the filler dispersion and the impact strength. The modulus remained relatively undected while the strength was lowered. The high molecular weight elastomeric additives increased the impact strength and ductility, while the stiffness was reduced. An adhesion promotor based on a maleic anhydride modified polypropylene was found to behave as a true coupling agent, i.e. the strength and ductility increased, the melt strength was improved, and also the hot water resistance was raised. The experimentally determined composite moduli are found to agree relatively well with theoretical predictions. The effect of processing on the shape and size of the filler particles is evaluated using automatic image analysis.

Eigenschaften von extrudierten Holz-Kunststoff-Werkstoffen auf Basis von Refiner-(TMP-)Fasern und Hanffasern

“…Overall, the use of MAPP resulted in improved flexural strength compared to uncoupled formulations (Figure 7) which is a well-known effect (Woodhams et al 1984, Dalväg et al 1985, Felix et al 1993, Stark and Rowlands 2003. Flexural strength due to application of MAPP was improved by 126 % for the hemp fibrebased WPC, by 109 % for the wood fibre-based WPC and by 88 % for the wood flour-based WPC.…”

Recycled Newspaper Fibers as Reinforcing Fillers in Thermoplastics: Part I-Analysis of Tensile and Impact Properties in Polypropylene

“…K2 has a maximum value of 0.5. If the fibers are equal to or longer than lc, K2 varies between 0.5 and 1.0, and the fibers can fail by fracture and, (4) In this case the composite failure is assumed to be at the failure strain of the fibers and sm is the stress taken up by the matrix at the failure strain of the composite, K2 [Equations (3) and (4)] thus accounts for the fiber-matrix adhesion and the fiber length present in the system.…”

“…uniformity of dispersion of the fibers in the matrix, and the ability of the interface to transfer stress to the fiber are some of the important fac tors that need to be studied to optimize composite properties. Several studies aimed at improving dispersion of the lignocellulosic fibers in the non-polar matrix and increasing the stress transfer efficiency of the interface have been con ducted in various laboratories [1,[4][5][6][7][8][9].…”

Effects of Alkali Treated Nano-kenaf Fiber in Polypropylene Composite upon Mechanical Property Changes

“…[4][5][6][7] Cellulose is a linear, stereo-regular polysaccharide connected with repeated D-glucopyranose units linked by 1,4-β-glucoside bonds. Calculated elongation modulus of nanocellulose is 137 GPa.…”