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Impact of Intensive Mixing and Shearing Elements on the Effectiveness of Extrusion of Wood Polypropylene Composites

100%

Głogowska K. , Sikora J. W. , Ludziak K.

Advances in Science and Technology. Research Journal

2021

tom Vol. 15, no 4

231--242

The objective of this study was to determine the effect of various design solutions for intensive mixing and shearing elements located at the end of a single-screw plasticizing system on the effectiveness of wood polypropylene composite extrusion. Four types of such elements were used in the study: a pineapple mixer, a Maddock mixer, a ring mixer, and a helical mixer. For the purpose of the study, 4 blends were prepared containing 5, 10, 15 and 20% of wood fibre, respectively. Direct and indirect resulting factors as well as variable, constant and disturbing factors were investigated. The effectiveness of extrusion of wood polypropylene composites was determined based on results of parameters characterizing this process, such as extrudate temperature, unit consumption of energy supplied to the extruder, mass flow rate, and extrusion speed. It has been shown that the effectiveness of the extrusion process can be improved by using different mixing and shearing elements. Such screw design solutions make it possible to affect rheological phenomena occurring during melt flow in the plasticizing system, without modifying the extrusion process parameters such as screw rotation speed and polymer temperature. The literature review shows that there exist very few and general studies investigating the effect of screw design geometry, especially that of mixing and shearing elements, on the efficiency of extruding and mixing wood polypropylene materials.

Effect of mould speed on selected properties of moulded parts and energy consumption in rotational moulding

100%

Głogowska K. , Longwic F. , Ludziak K.

Bulletin of the Polish Academy of Sciences. Technical Sciences

2022

tom Vol. 70, nr 5

art. no. e143106

This paper deals with rotational moulding. The relationship between mould speed and wall thickness in the upper, middle and lower areas of rotational moulded parts is investigated. Young’s modulus of moulded parts is determined via static tensile testing. A static compression test is performed to determine the maximum compressive force causing strain. The test is conducted on the wall of moulded parts, parallel to the main axis of rotation. Also, energy consumption in rotational moulding is investigated for different rotational speeds of the mould. Moulded parts are made of DOWLEX®2629UE linear low-density polyethylene (LLDPE). Experimental results are statistically analysed using STATISTICA 13. Non-parametric statistical tests are used for results analysis. The ANOVA method is employed to determine if there are any significant differences between obtained results. The statistical tests show that the range is much narrower for a speed ratio of 4:1. The narrowest range value is obtained for 12\3 rpm. The highest Young’s modulus values are obtained for the parts moulded at 12\3 rpm (1263.33 MPa) and 16\4 rpm (1263.67 MPa). The highest maximum compressive force is obtained for the parts moulded at 12\3 rpm (10 400 N). An analysis of the results demonstrates that the part moulded at 12\3 rpm has the most advantageous properties. For this mould speed, the power consumption amounts to 8.28 kWh. Experimental results and statistical analyses demonstrate that mould speed affects both moulded part quality and energy consumption in the rotational moulding process.