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- Title
Pressure and temperature influence on the friction coefficient of granular polymeric materials on the metal surfaces.
- Authors
Vytvytskyi, Viktor; Mikulionok, Ihor; Sokolskyi, Oleksandr; Gavva, Oleksandr
- Abstract
Introduction. The research is carried out to determine the friction coefficients (FR) of granulated polymeric material on a metal surface, in particular, to describe the principles of their movement in the feeding zone of a screw extruder. Materials and methods. To study the movement of polymer granules in the channel of an extruder the four types of granules are used: high density polyethylene (PE), ethylene-vinyl acetate copolymer (EVA), polystyrene (PS) and polyvinylchloride (PVC). The FR are defined using a plane-parallel model of the extrusion process. Results and discussion. Analysis of the results showed a general decrease of FR with the increasing pressure, but upon the reaching the maximum values at almost all curves is a transition through a minimum, after which values of FR begin to rise. For the PE the FR decreases from 0.35 to 0.26 in a load 200 Pa and from 0.23 to 0.17 in 2000–2200 Pa, with the increasing of a channel depth from 7 to 23 mm. For the EVA the FR increases from 0.15 to 0.44 in 200 PA and from 0.15 to 0.17 in 1900–2100 Pa. For the PS the FR changes from 0.6 in 200 Pa to 0.3 in 2100 Pa and doesn't depend on the changes a channel depth. For the PVC the FR increases from 0.3 to 0.7 in 200 Pa and from 0.22 to 0.43 in 1900–2100 Pa. With the increasing of a temperature of a working surface to 90 °C the FR of the PE becomes independent on the changes a channel depth and acquires medium values to 0.3 in 200 Pa and to 0.2 in 2100 Pa. For the EVA in 80 °C the FR for each depth increases and reaches values from 0.25 to 0.4 in 200 Pa and from 0.19 to 0.23 in 1600–1700 Pa. For the PS in 100 °C the FR decreases to 0.5 in 200 Pa and to 0.2 in 2100 Pa. For the PVC the FR doesn't depend on the heating of the working surface. The difference between the described dependencies for four researched types of polymer is explained by the different mechanical properties of investigated polymers, including the values of strength, FR and deformation at different temperatures. Conclusions. The obtained results allow to improve the process of extrusion, increase its productivity and reduce its energy consumption by increasing the accuracy of calculations.
- Subjects
METALLIC surfaces; POLYVINYL chloride; POLYETHYLENE
- Publication
Ukrainian Food Journal, 2017, Vol 6, Issue 3, p543
- ISSN
2304-974X
- Publication type
Article
- DOI
10.24263/2304-974X-2017-6-3-14