ABSTRACT:To get more information on the structure of iodinated poly(vinyl alcohol) (PVA), thermal analyses of unoriented and oriented PVA films were conducted. Unoriented and oriented PVA films iodinated with aqueous solutions at selected concentrations were carried out by thermogravimetry (TG) and differential scanning calorimetry (DSC). The TG curves for the iodinated film shows four or five weight-loss zones associated with degradation and evaporation of excess I 2 molecules and I 2 molecules from I 5 Ϫ , partial OH side groups on PVA, and I 2 from I 3 Ϫ , the remaining OH groups and the partial main chains, the remaining main chains, and a very small amount of residue from PVA. The char of KI salts remained. By investigating the TG results, it was identified that the amount of I 3 Ϫ ions increased with increasing I 2 /KI up to 65%, but above that weight gain, the rate of increase diminished and the amount of I 5 Ϫ ions from the I 3 Ϫ ions increased. The TG curve for the oriented film was very similar to that for the unoriented film except for its greater weight loss at zone I due to narrow space in amorphous region. The DSC thermogram of iodinated films indicated two peaks at 145°C and 160 -170°C, corresponding to the melting of crystals and the degradations of OH groups and main chains, respectively. The maximum temperatures of peaks were much lower than that of the untreated one.

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ABSTRACT:To examine the possibility of applying the iodination of nylon 6 to forming, a new type of nylon 6 -iodine complex films iodinated before forming (IBF film) and the old type of films iodinated after forming (IAF film) were prepared and their structures were investigated and compared with each other. The IBF films from iodinated nylon 6 powders could be obtained by a melt press at 185°C, which is much lower than the melt-press temperature of pure nylon 6 (250°C). It was ascertained that the structure of IAF films is similar to that reported by Lee et al. but the structure of IBF films is very different. The distinctive features of the IBF films compared with the IAF films are as follows: The IBF films have no excess iodine molecules (I 2 ) to form a complex with nylon 6 chains because those molecules in the iodinated powders have been evaporated through the melt press. The IBF films have a practically amorphous structure but only a few crystalline portions with a relaxed state which may have been created with iodide-ion-free segments of nylon 6 molecules through the procedure of film forming.

Four types of polyvinyl alcohol (PVA)/iodine complex films were made using different boric acid treatments to prepare polarizing films having high durability under humid and warm atmospheres and to identify the effects of the boric acid treatment method on the formation of the PVA/iodine polarizing film. The four types of films were a PVA iodinated film(I), a PVA film that was iodinated and then treated with boric acid(I-B), a PVA film that was treated with boric acid and then iodinated(B-I), and a PVA film that was simultaneously treated with iodine and boric acid(IþB). The concentrations of I 2 /KI were 0.03, 0.05, and 0.07 mol/L, and the concentrations of boric acid were 0.1, 0.3, and 0.5 mol/L. Comparing four type films treated with 0.05 mol/L I 2 /KI and 0.5 mol/L boric acid, the conformation of PVA/iodine complexes for I-B film were larger than the others. The degrees of polarization (q) of all of the films increased to very high levels (99.9%:). The durability of I-B was superior to B-I or IþB, and the change in the q was below 5% because the boric acid treated after iodine treatment reduced the molecular mobility of the PVA/ iodine complex chains through intracrosslinking, so that the PVA/iodine complex could not easily collapse.

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