Molecular modification of slightly cross-linked HDPE

The aim of this study is to investigate the changes in molecular structure of high density polyethylene after slightly cross-linking with either electron beam irradiation or chemically with the peroxide method, by examining both the gel and sol parts of the polymer. Melt flow index and dynamic mechanical thermal analysis tests verify the cross-linking process after each treatment method. Differential scanning calorimetry and Fourier transformed infrared tests, together with rheology and viscometry tests, show that the cross-linking process has resulted in not only cross-linking long chains but also chain scission of short chains, thus broadening the molecular weight distribution. Because these created short chains act like lubricants, cross-linked chains flow easier. Therefore, the polymer remains processable according to the melt flow index test, and this will make the usage of slightly cross-linked high density polyethylene in injection molding processes possible.