Preparation of acrylic acid grafted polypropylene nonwoven fabric by photoinduced graft polymerization with preabsorption of monomer solution

Abstract

We improved photoinduced graft polymerization by absorbing the monomer solution onto the substrate (Ab-type) instead of immersing the substrate in the monomer solution (Im-type) before photoirradiation to yield a more practical and effective grafting system. With this system, acrylic acid (AA) was effectively grafted onto polypropylene (PP) nonwoven fabric. The maximum degree of grafting obtainable was restricted by the amount of monomer preabsorbed onto the PP fabric. However, we effectively enhanced the degree of grafting by increasing the monomer concentration, adding trimethylolpropane triacrylate (TMPTA) to the monomer solution, and repeating the photoirradiation with supplementation of the monomer solution. The net availability of the monomer for graft polymerization was 50% or greater; this increased to 90% or greater with the addition of TMPTA and was much higher than for conventional Im-type photografting ( 13%). Fourier transform infrared spectra, scanning electron microscopy morphology observations, and the adsorption-regeneration properties confirmed that the PP-g-AA fabric prepared by the improved Ab-type photografting method had comparable qualities to those of fabric prepared by conventional Im-type photografting. Thus, the improved Ab-type photografting system provides potential for the preparation of graft adsorbents on a large scale at a competitive cost with a continuous reactor, such as a conveyer belt system, instead of a batch reactor.

A Review of Polymeric Refabrication Techniques to Modify Polymer Properties for Biomedical and Drug Delivery Applications

“…Generation of radicals by direct irradiation via UV/ microwaves (40,41) Direct radical generation eliminates need of initiators and washout steps (42,43) Irradiation is non-penetrative and only allows surface modification (42,43) Enzymatic grafting…”

“…It is a rather simplistic and effortless process requiring only a limited number of steps to accomplish a graft product as depicted in Fig. 4 where ethyl cellulose is affected by electromagnetic radiation to generate a free radical capable of reacting with acrylonitrile (31,42,43,61). The photo-initiated grafting process can advance via two different approaches, either by employment or devoid of a photosensitizer depending on the properties of the polymer in question (36,43,62,63).…”

“…The same steps and conditions are required as with any electromagnetic radiation technique. However, as with any radical-based grafting system, the same complications regarding homopolymerization and isomerization apply, and to complicate homopolymerization further, the grafting process only occurs at the point of incidence of photons (42). Areas where the incident radiation was absent, monomer cannot attach to the polymer resulting in further synthesis of homopolymer (42).…”

“…However, as with any radical-based grafting system, the same complications regarding homopolymerization and isomerization apply, and to complicate homopolymerization further, the grafting process only occurs at the point of incidence of photons (42). Areas where the incident radiation was absent, monomer cannot attach to the polymer resulting in further synthesis of homopolymer (42). In addition, photo-systems do not have a great penetration depth; therefore, perplexities are encountered when considerable magnitudes of polymer need to be grafted corresponding to industrial amounts (31,42,43,61).…”

“…Areas where the incident radiation was absent, monomer cannot attach to the polymer resulting in further synthesis of homopolymer (42). In addition, photo-systems do not have a great penetration depth; therefore, perplexities are encountered when considerable magnitudes of polymer need to be grafted corresponding to industrial amounts (31,42,43,61).…”