Roles of slip agents in blown film extrusion of linear low density polyethylene (LLDPE) (In collaboration with petronas chemicals polyethylene Sdn Bhd)
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Date
2017-07
Authors
Nur Haslina Nasirah Binti Abdul Hadi
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Abstract
Slip agents are low viscosity additives, which are added to modify the surface properties of Linear Low Density Polyethylene (LLDPE) films to reduce the coefficient of friction (COF) of the films. In this work, the effects of different type of slip agents on the mechanical, optical and surface characteristics of LLDPE blown films were investigated. Slip agent A and B were used in this project and the concentration of slip agent B was varied between zero to 1500 parts per million (ppm) while concentration of slip agent A is 1200 ppm. The LLDPE powder was first pre-mixed with the additives (neutralizer, processing aid, slip agent, antioxidant, antiblock) by using rotating rollers for homogenizing and subsequently compounded using twin screw extruder. The film was then prepared using blown film extrusion. The slip agents were found to adversely effect the film properties particularly the COF, tensile strength and tear strength. The values of COF decreased with increasing concentration of slip agents. This could be explained due to increasing of amide migration to the surface of the bulk matrix. The slip agents decreased the tensile strength and young’s modulus while the elongation at break increased for all the samples in both machine direction and transverse direction. This could be attributed to the presence of the microvoids left in the matrix and remaining slip agents in the blown film sample. The LLDPE film with slip agent B and concentration of 800 ppm shows the better results in mechanical, optical and surface characteristic of blown film.