Properties Of Polyvinyl Alcohol Research Articles

Some electrophysical properties of polyvinyl alcohol and its chelates

Some electrophysical properties of polyvinyl alcohol and its chelates

THE RELATIONSHIP BETWEEN MANUFACTURING CONDITIONS OF POLYVINYL ALCOHOL AND THE PROPERTIES POLYVINYL ALCOHOL FIBERS

Vinyl acetate (VAc) was polymerized at temperature ranging from -30°C to +60°C in the presence of catalysts prepared from tri-n-butyl boron (BBu3) and a, a′-azo-bisisobutylonitrile (AIBN).In addition, polymerization of VAc was carried out at 30°C using BBu3 as catalyst in methanol (MeOH) and in methylacetate (MeOAc), and also carried out at 60°C in MeOH using three kinds of catalysts, (1) AIBN, (2) BBu3 and (3) AIBN-BBu3 mixtures.These polyvinyl acetates thus obtained were saponified to polyvinyl alcohol (PVA) and further deesterified.From the viewpoint of crystallinity and stereoregularity, the PVA prepared at the lower polymerization temperature has better qualities and the PVA (A) derived from polymerization in MeOH has much higher crystallinity and regularity than the PVA (B) derived from polymerization in MeOAc.Heat treated and not formalized PVA fibers derived from PVAc polymerized temperature below 10°C, neither dissolves nor shrinks in hot water up to 115°C. These fibers have very good resitance to hot water but their properties, such as tenacity, elongation and elastic recovery are not influenced by the polymerization temperature.Heat treated fibers prepared from PVA (A) have much better resistance to hot water at 110°C than those prepared from PVA (B), but other properties do not differ between (A) and (B).The properties of PVA and the fibers obtained from it are not influenced by the kinds of catalysts, when the polymerization temperature is same.

PVAの性質に及ぼす母体ポリ酢酸ビニルの重合温度および重合率の効果

母体ポリ酢酸ビニルの重合温度の上昇とともに, ポリビニルアルコールの40%含水ジメチルスルホオキサイド溶液で認められる濁り速度は小になり, 水中膨潤度は増加し, また赤外線吸収スペクトルにみられる結晶性パンド, 8.7μの吸光度は低下することを認めた. また塊状重合の場合は, 重合率によっても濁り速度, 膨潤度が変ることを認めた.

Effects of Ionizing Radiation on Polyvinyl Alcohol II. Changes of Physical Properties of the Irradiated Specimen Caused by Heat Treatment

The physical Properties of polyvinyl alcohol irradiated by deuterons or gamma rays were found to change remarkably by heat treatment. Irradiation causes the decrease of the molecular weight and the increase of the carbonyl groups. When these specimens are heated above 120°C, however, the solubility diminishes considerably and even gel formation occurs for highly irradiated ones. Infrared absorption spectra revealed that the number of carbonyl groups formed by the irradiation decreased greatly as a result of heat treatment. Some discussion are given on the process of gel formation.