minutes the grafted nonwoven substrate was then washed by sonication in thf and methanol to remove unreacted and unattached compounds fig1 shows that conformal grafting has been formed on the nylon fiber even though the surface energy of nylon is very different from pp the same technique can generate conformal grafting for both materials a specimen of polybutylene terephthalate pbt nonwoven 160 u03bcm thick and of dimension 2 u00d7 4 cm was exposed to uv of 150 to 300 nm and intensity 50 mw cm 2 for 15 minutes another specimen was not pre treated at all both substrates were then soaked with 20 glycidyl methacrylate and benzophenone i m 1 25 in butanol solution the substrate was sandwiched between two glass slides coated with frekote u00ae and then exposed to uv of 300 to 450 nm and intensity 4 mw cm 2 for 15 minutes the grafted nonwoven substrate was then washed by sonication in thf and methanol to remove unreacted and unattached compounds fig1 shows that pbt fibers on the nonowoven have been grafted with high density and conformal pgma graft without pre treatment conformal grafting can still be formed on the pbt fibers this is due to the fact that pbt is more polar than pp and dipole dipole interactions between benzophenone and pbt improve its adsorption as a result a high density of initiator can be obtained even without pre treatment a specimen of polypropylene nonwoven 250 u03bcm thick and of dimension 2 u00d7 4 cm was soaked in 100 mm benzophenone u2212 2 in methanol for 18 hours immediately after soaking it was sandwiched between two.