A composite films which exhibit low oxygen transmission rates. The film comprises a silane resin coated on a plastic substrate then cured by ultraviolet radiation. For the silane coating, this invention relies on a class of organosilicon compounds derived from 1) organohydrogensilanes or organohydrogensiloxanes and 2) propargyl esters of carboxylic acids containing a terminal aromatic hydrocarbon radical, where the carbopropynoxy group of the ester and the aromatic hydrocarbon radical are separated by at least two adjacent ethylenically unsaturated carbon atoms. If more than two of these carbon atoms are present they form a sequence of conjugated ethylenic double bonds which allows the polymer to cross-link upon exposure to ultraviolet radiation.