In recent years, PET (polyethylene terephthalate) fabrics has been widely used in many fields, such as industrial field and clothes, based on the excellent mechanical characteristics and chemical resistance. On the other hand, to introduce the new functions, the modification of these fibers and textiles by radiation induced graft polymerization has been studied. However, it is not easy to graft functional polymer chains onto PET fibers, because PET fibers possess high chemical resistance and thermal stability, as well as the relatively high resistance to radiation.
We have adapted the new method of electron beam grafting using the film bag which can be vacuumed and sealed by heating the film bag to avoid exposure. This method can read to high degree of grafting by preventing the decrease of generated radicals in polymer. Emulsion grafting was tried by this film bag method. When the molecular weight ratio between the GMA (glycidyl methacrylate) conc. and the activator conc. was 180 or more, the degree of grafting was greatly improved.
This phenomenon is considered as follows. At high surfactant concentrations in aqueous solution, GMA is sufficiently emulsified, and is the droplet of the stable hydrophilic surface. However, at low surfactant concentrations in aqueous solution, droplets of GMA canʼt be completely emulsified, it becomes unstable hydrophobic surface, and increase the GMA dissolved in the aqueous solution. Accordingly, it was considered that the degree of grafting was increased by the high sorption of GMA to the hydrophobic PET fibers.
Also, PET film could get the high degree of grafting compared with polyethylene (PE) for the material of the film bag used as a reaction container. Because the film-bag made of polyethylene is easily generated the polymer radicals by irradiation, and therefore, the degree of grafting on fiber decrease by the monomer consumption on the films.
As a result, 27％ of grafting degree was obtained at the 20 wt％ GMA emulsion with 0.3 wt％ Span 20 under the low 100 kGy dose by the vacuum sealed method using the PET film-bag.
