SYNOPSISMethacrylic acid (MAA) was grafted onto polyethylene ( P E ) surfaces by simultaneous irradiation with UV rays in the liquid phase to estimate hydrophilic and mechanical properties for MAA-grafted PE plates. The amount of grafted MAA increased sigmoidally with UV irradiation time, and the higher grafted amount was obtained at higher monomer concentrations. With an increase in grafting of MAA, the wettabilities from the contact angles of water were enhanced and the refractive indices from the ellipsometry decreased. Though the contact angles remained constant above the grafted amount of 0.02 mmol/cm2, the refractive indices approached the value of PMAA around 0.009 mmol/cm2, indicating that the PE surfaces were fully covered with grafted PMAA chains. Then, at a fixed grafted amount, the grafted layer can absorb more water and the grafted P E plates possessed higher tensile shear adhesive strength, in case grafting was carried out at lower monomer concentrations. Surface properties depended on the density of carboxyl group at the surfaces of grafted layers, whereas adhesive properties depended on the structural properties of grafted chains as well as on the density of carboxyl group of the whole grafted layers.
I NTRO DU CTlO NPolyolefins such as polyethylene ( P E ) and polypropylene (PP) have good mechanical properties, but their surfaces are inert or hydrophobic. Such surfaces will result in poor adhesivities or wettabilities. Therefore, in some cases, the addition of new properties to such polymer substrates is required while concurrently leaving their bulk properties unchanged. Several techniques such as photo-, radiation-, and plasma-initiated graftings are available for modifying polyolefins, of which the photografting is expected to be the most convenient technique. An advantage of this technique is that the location of grafting can be restricted to the polymer surfaces without affecting any bulk properties because of the lower energy of the used UV rays. Many studies have been carried out for the hydrophilization of polymer