Electron-beam irradiation of low-density polyethylene in the presence of phenolic stabilizer, carboxylic acid stabilizer, or both



The effects of Irganox 1010 and citric acid as antioxidants and modifiers of the network structure and mechanical and thermal properties of low-density polyethylene (LDPE) during electron-beam crosslinking with different irradiation doses (up to 120 kGy) were investigated. The results showed that the addition of these stabilizers had a retarding effect on the gel fraction of LDPE within the investigated range of electron-beam-irradiation doses. However, a noticeable effect on the gel fraction was found for the LDPE formulations compounded with citric acid alone or with its mixture with Irganox 1010 (in an equal ratio), as illustrated by a study of the gel-fraction/dose relationships. Tensile testing measurements showed that the addition of both stabilizers caused a slight reduction in the stress at break and an increase in the strain at break. On the other hand, the thermal properties of the LDPE batches crosslinked with electron-beam irradiation were greatly improved as a result of the compounding with these stabilizers, as shown by thermogravimetric analysis studies. In this respect, the temperatures at different weight losses, the temperatures of the maximum rate of thermal decomposition, and the activation energies indicated that compounding with citric acid was more effective for stabilization against thermal decomposition than compounding with Irganox alone or a mixture. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1275–1286, 2005