Abstract: H-and Y-crosslinks formed by photoinitiated crosslinking of dodecane,squalane,isooctane and 1-hexene as the model compounds of low density polyethylene in the presence of benzophenone as photoinitiator have been studied for the first time by solution state ¹³C NMR spectroscopy. The quantitative studies show that the types of crosslinks depend on the sorts of the model compounds.H-and Y-links are both formed for photo crosslinked dodecane and isooctane samples Whereas only H-links were detected for the crosslinked squalane.On the other hand,the double bond of unsaturated hydrocarbons such as 1-hexene can be opened to form Y-link by the reaction between a terminal vinyl group and an alkyl radical.These results are in good agreement with those obtained from low density polyethylene and give new evidence for elucidating the formation of the crosslinks in the photo cosslinked polyethylene.

Key words: ¹³C NMR, Low density polyethylene, Model compounds, Photoinitiated crosslinks