Search

In our research on traditional clothing and accessories in the Ryukyu Islands of Japan, we have collected cloth fragments from traditional Ryukyuan costumes and other fabric products for radiocarbon (14C) dating. In this study, the cloth samples from historical costumes of noro priestesses (two samples), men and women from high-status families (five samples), and non-costume cloth products (seven samples), belonging to the traditional hereditary religious system of the ancient Ryukyu Kingdom, which lasted from approximately the 14th century AD to 1829 were analyzed. One extra sample originated from a silk shawl known as a Manila shawl. The oldest among the 15 samples dates back to the mid-15th century, but some newer ones belong to the unclear calibrated age range of AD 1650–1950. The measured dates are very consistent with the historical record, suggesting that acetone and acid-alkali-acid treatments are an adequate cleaning method for radiocarbon dating of silk and cotton samples produced in the late Middle Age and later.

Crosslinked polyurethane (PU) ionenes were prepared. NCO-terminated prepoly mer obtained from polyol blends of poly(oxytetramethylene)glycol (PTMG) and poly(oxyeth ylene)glycol (PEG) and 4,4'-methylenebis(phenylisocyanate) were made to react with 2- dimethylaminoethanol, resulting in amine-terminated (AT) prepolymer having isocyanurate ring in structure. By the reaction of AT-prepolymer with N,N,N' ,N'-tetramethyl-1,6-diaminohexane and 1,6-dibromohexane, crosslinked PU ionenes were obtained. Bound water existing in the hydrogel of crosslinked PU ionenes was determined by two methods. The amount of nonfreezing (bound) water determined by DSC was constant, ca. 9 water mol/[N+] mol, and not dependent upon the composition of PU ionenes. This type of water is considered to be the water strongly bound to [N+] ion site. On the other hand, the amount of bound water determined by drying measurement was greater than that determined by DSC measurement. In the drying mea surement, PU ionene containing larger amounts of PEG had larger amounts of bound water. The bound water determined by drying is considered to include water hydrated to polar ether [O] group in addition to nonfreezing water. 95 % of water existing in swollen hydrogel was free water, as in highly water-absorbing resin. Tensile properties of swollen gels were examined. It was suggested that the ionic aggregation that existed in dry state was destroyed in swollen state.

高い水膨潤性を持ち, かつ, 膨潤状態でも優れた力学特性を保持できるポリウレタン(PU)エラストマーを得る目的で, プレポリマー法により種々のPUアイオネンを合成した. まず, ポリ(オキシテトラメチレン)グリコール(PTMG)とポリ(オキシエチレン)グリコール(PEG)の混合ポリオールに, 4,4′-メチレンビス(フェニルイソシアナート)(MDI)をNCO/OH=2/1(モル)で反応させ, NCO基末端プレポリマーを合成した. 次いで, ジメチルアミノエタノールをNCO/OH=2/1(モル)で反応させ, アミノ基末端プレポリマーを得た. 最後に, N,N,N′,N′-テトラメチル-1,6-ジアミノヘキサン(THD)及び1,6-ジブロモヘキサン(DBH)を種々のモル比で反応させた. 純水に対する膨潤比とゲル分率の値より, PTMG/PEG=6/4及び7/3, THD/DBH=1/1.5の配合比のPUアイオネンが, 本目的に沿った. そこで, 6/4及び7/3のポリオールのブレンド比について, アイオネン含有量が異なる三種の試料を合成し, 広角X線回折, 偏光顕微鏡観察, 小角光散乱, 示差走査熱量測定, 動的粘弾性及び引張特性に基づいて物性に及ぼす構造の影響を検討した.