51315-5536-Compatibility of Polyethylene Grades with Biofuels and Biodiesel—Heating Oil Blends

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Product Number: 51315-5536-SG

ISBN: 5536 2015 CP

Author: Margit Weltschev

Publication Date: 2015

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Biofuels including ethanol and biodiesel (fatty acid methyl ester) represent an important renewable fuel alternative to petroleum-derived transport fuels. Increasing biofuels use would bring some benefits such as a reduction in oil demands and greenhouse gas emissions and an improvement in air quality.Materials compatibility is a major concern whenever the fuel composition is changed in a fuel system. The aim of this work is to study the interaction between high density polyethylene (HDPE) grades with and without polyamide permeation barrier and biofuels such as E85 (fuel with 85% ethanol) E10(fuel with 10% ethanol) premium fuel (with 5% ethanol) biodiesel and B10 (heating oil with 10% biodiesel). 10ljerricans made of two different polyethylene grades were filled with these fuels and exposed to temperatures of 20°C and 40°C for more than one year. Tensile properties (tensile strength breaking elongation and elasticity modulus) and Melt Flow Rate (MFR) were determined once a month and FTIR-spectroscopy was used to evaluate possible changes.The tensile properties of HDPE jerrican cuttings decreased but not significantly after immersion in premium fuel E10 E85 and biodiesel. In particular the elasticity modulus of the polyethylene grades was reduced after exposure to biodiesel.The tensile properties of HDPE jerrican cuttings with polyamide permeation barrier did not changed significantly after immersion in E85 and biodiesel after twoyears.The FTIR spectra of HDPE jerrican cuttings showed that the immersion tests for 14months with E85 at 20°C and 40°C only caused an increase in the peak of 1585cm-1 (C=C stretching vibrations) in the chemical structure of HDPE.The FTIR spectra of HDPE jerrican cuttings showed that immersion tests for 18months with biodiesel at 20°C and 40°C led to a broadening of the C=O peak of 1740 cm-1 and the appearance of the hydroxyl group at 3500 cm-1. Both features are explained by secondary degradation products of the polyethylene decomposition process caused by the temperature and unsaturated fatty acid content in the biodiesel since biodiesel decomposes quickly at elevated temperatures. The broadening of the C=O peak to 1740 cm-1 can be attributed to aldehyde carbonyl and ester carbonyl groups mutually overlapping.Measurements of the melt flow rate (MFR) showed an increase in the MFR with the immersion time in biodiesel due to the unsaturated fatty acid content.Diffusions of oxygen and rapeseed methyl ester increase the chemical impact on polyethylene grades.