| 摘要 |
A method of enhancing the properties and appearance of polymeric substances is disclosed. The method involves treating a polymer so as to effect graft polymerization over the entire surface thereof in such a manner that variations in graft density occur across the surface of the polymer. This may be accomplished by forming chemically active species, e.g., ions or free radicals, in the polymer which vary in concentration across the surface of the latter and at least once contacting the surface of the polymer with a substance, for instance, a monomer such as a vinyl compound, which undergoes a graft polymerization reaction with the chemically active species. The chemically active species may be formed by irradiating the surface of the polymer with high energy radiation, for example, a beam of electrons. Different possibilities exist for achieving a varying concentration of the chemically active species across the surface of the polymer. One possibility resides in subjecting the surface of the polymer to both a homogeneous and a non-homogeneous irradiation. Another possibility resides in subjecting the surface of the polymer to a homogeneous irradiation and then eliminating at least some of the chemically active species in selected regions of the surface of the polymer. Still another possibility resides in directing a radiation beam at the surface of the polymer and varying the direction and/or the intensity of the beam. Numerous permutations within this framework exist.
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