Structural and kinetic modification of aqueous hydroxypropylmethylcellulose (HPMC) induced by electron beam irradiation

✍ Scribed by Kazuya Furusawa; Toshiaki Dobashi; Satoshi Morishita; Mikio Oyama; Tadashi Hashimoto; Naoki Shinyashiki; Shin Yagihara; Naotsugu Nagasawa

• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 310 KB
• Volume: 353
• Category: Article
• ISSN: 0378-4371
• DOI: 10.1016/j.physa.2004.12.068

✦ Synopsis

Aqueous solutions of 10 and 20 wt% hydroxypropylmethylcellulose (HPMC) were irradiated with different doses to make gel films. The gel fraction of the film increased sharply above a critical dose upon increase of the dose and then decreased gradually after passing a maximum. The scission/cross-linking ratio and the critical dose were determined with the aid of Charlesby-Rosiak equation as 0.52 and 9 kGy for the 10 wt% gel and 0.43 and 14 kGy for the 20 wt% gel, respectively. The gel fraction for the 20 wt% HPMC film was lower at low dose and higher at high dose than that for the 10 wt% film. The behavior of the swelling ratio of the gel film was just opposite to that of the gel fraction. The cross-linking density of the gel estimated from the Flory theory increased linearly with the irradiation dose at low dose, passed through a maximum around 100 and 160 kGy for 10% and 20% films, respectively, and decreased at high dose. These results suggest a competition of scission and cross-linking induced by the indirect effect of irradiation. Dielectric-relaxation measurements