In the present article, a practically applicable method was developed, by which the compositions of the grafted chains achieved by UV-irradiated photografting polymerization of vinyl acetate-maleic anhydride (VACMAH)/low density polyethylene (LDPE) film systems can be determined. By measuring FTIR spectra of the films containing known amounts of VAC and MAH, standard working plots of the relationship between the ratio of the absorption peak area of MAH to that of VAC and the ratio of the content of MAH to that of VAC were set up. If the characteristic absorption peak areas of MAH and VAC on the grafted film are calculated, then according to the standard working plots, the ratio of MAH content to VAC content can be determined. It is proved that this method was effective in wide range of MAH/VAC. Using this method, LDPE films containing different contents of MAH and VAC were characterized. The results show that the MAH content in the grafted film went up progressively, as the content of MAH in the monomer feed was raised; this phenomenon became more obvious when the total monomer concentration was increased, and the polymerization temperature was enhanced. These results should be attributed to the unique ability of MAH to abstract hydrogen when irradiated with UV light. (c) 2005 Wiley Periodicals, Inc.