MODIFIED BY WOOD FILLERS RECYCLEDPOLYETHYLENE FOR EUROPALLETS APPLICATION

摘要

One of the possibilities of reinforcement of polyolefines is adding diverse fillers likeglass or carbon fibers (but they are rather expensive) and natural fillers like wood, plants and others.It’s especially important for wasted of low density polyethylene which has low modulus. For the testsit was used waste polyethylene (LDPE) from industrial and consumption films and as reinforcement itwas used wood fibers LIGNOCEL CB 120 supplied by J. Rettenmaier & S?hne GmbH+Co. This filleris made of coniferous soft trees, it has fibrous structure and it particle size is 70 – 150 μm. For the testsit was prepared three kinds of composite materials with 10% (PE1), 20% (PE2) and 30% (PE3) ofwood fibers. Besides for comparison it was tested original polyethylene (PE0) and next was testedspecimens cut out from produced europallets (with 15% of wood fibers). It was tested mechanicalproperties all prepared composite materials like tensile strength, stress and bending e-modulus, impactstrength, Brinell hardness and processing properties like melt flow, Vicat point and additionallydensity (balance of liquid method), water absorption and photos on optical and SEM microscope.Tests of mechanical properties during tension and bending show that properties connected withincreasing of straight and stiffness like e-modulus, tensile strength, hardness grow along with contentof wood fibers. However properties like strain at break or impact strength low with increase of amountof fillers. The Vicat point of tested composite materials was on the level about 98 – 100 0C and itdoesn’t change with increase of amount of fillers. Results of melt flow presents fall of processingproperties along with increase content of wood fibers. Using image analyzes it was shown distributionof wooden fibers for all tested composite materials. After comparison of all tests’ results we proposedone composite with 15% of wood fibers and reclaimed LDPE that to process pre-production batch ofeuropallet produced by Becker GmbH (extraction with pressing). Besides it distribution of stresses anddeflections of europallets was analyzed having various amount of wood fibers (by means of FEM -finite elements method) that to estimate their strength (HMH hypothesis) and reduction cost ofmaterial processing. Geometric and numeric models of analyzed pallets and bitch files prepared bymeans of Femap 7.1, calculations and postprocesing by Ansys 5.7. The low-filler reclaimedpolyethylene can be use on such products like wood decks, boxes, flower pots, automotive parts andothers building and building parts. On the base of done tests and numerical calculation it seems thatfilling of reclaimed LDPE by wood fibers has to be on the level 15 – 20% for optimal processing andproperties.