Kaoru Kawase

Preparation of delaminated clay having a narrow micropore distribution in the presence of hydroxyaluminum cations and polyvinyl alcohol

The pillaring of Na-montmorillonite with cationic oligomers of hydroxyaluminum (COHA) in the presence of an aqueous solution of polyvinyl alcohol resulted in the formation of a clay having a large surface area and pore volume. The pore-size distribution determined from a N2 adsorption/desorption hysteresis was narrow and centered at about 25 Å. The peak width at half height in the distribution curve was < 5 Å. As a result of delamination, the layer structure of the prepared clay was found from X-ray powder diffraction measurements to be lost. Short-range ordering, however, still existed in this delaminated clay, because exchangeable cations in the montmorillonite completely exchanged with Al3+, a requisite step for pillaring.The order of adding the starting materials (Na-montmorillonite, polyvinyl alcohol, and COHA) greatly affected the surface area and the pore volume of the delaminated clay. Two orders of addition (Namontmorillonite, then COHA, then polyvinyl alcohol; and COHA, then Na-montmorillonite, then polyvinyl alcohol) gave no measurable surface area and pore volume. Two other orders of addition (polyvinyl alcohol, then COHA, then Na-montmorillonite; and polyvinyl alcohol, then Na-montmorillonite, then COHA) gave surface areas of 107 and 160 m2/g and pore volumes of 0.13 and 0.29 cm3/g, respectively. The amounts of the COHA solution and polyvinyl alcohol added greatly influenced the surface area and pore volume of the delaminated clay. Both properties increased monotonically with increasing amount of added polyvinyl alcohol, and increased to a maximum and then decreased with increasing amount of added COHA solution. The maximum surface area of the prepared delaminated clay was 330 m2/g.

Radiation-Induced Graft Copolymerization of Alkyl Methacrylates onto Polypropylene

KAWASE, KAORU, AND HAYAKAWA, KIYOSHI. Radiation-Induced Graft Copolymerization of Alkyl Methacrylates onto Polypropylene. Radiation Res. 30, pp. 116-128 (1967). Six alkyl methacrylates have been grafted onto polypropylene fibers by y-irradiation by two techniques. In the grafting in which backbone polymer was dipped into liquid monomer (liquid-phase grafting), large differences in the extent of grafting were observed with the monomers, together with a remarkable acceleration of grafting rates. Monomers such as n-butyl and n-propyl methacrylates grafted to a very high extent, but the efficiencies of the grafting of isobutyl and isopropyl methacrylates were very low. From investigations on the homopolymerization occurring together with the grafting, bulk polymerization, and the swelling capability of grafted products, the differences in the grafting with monomers are explained in terms of differences in the relative concentration of monomers in the fibers. In the grafting in which the backbone polymer was suspended in the vapor of the monomer (gas-phase grafting), the rate of grafting was linear with the vapor pressure of the monomer. Results of grafting at a constant vapor pressure showed that the differences in extent of grafting and in the gel effect were much less, compared with those in the liquid phase, and in general the results were similar to those for bulk polymerization of methacrylates.

Radiation resistivity of polyacenaphthylene-grafted polyethylene

Abstract Thin poly (ethylene-g-acenaphthylene) films prepared by the vapor-phase grafting method were subjected to the γ-irradiation in air, and various changes in tensile and structural properties of the film were investigated by comparing with those of the untreated or crosslinked polyethylene film. Polyethylene got to lose its inherent necking property by oxidative degradation and to be brittle-fractured by the irradiation dose less than 100 Mrad in air. The polyacenaphthylene-grafted polyethylenes (extent of grafting, ∼ 54 by 100( P-P ° ) P ° ), however, kept their ductility up to 200 Mrad or more, and the rate of increase in elastic modulus as well as yield strength with the increasing irradiation dose was considerably lower than that of untreated or crosslinked polyethylene. The effect of the grafting extent, and that of the irradiation dose-rate on the fracture energy were also examined. The weight increase of polyethylene due to the oxygen consumption and the resulting formation of carbonyl group which proceeded proportionally with the irradiation dose were remarkably suppressed by the grafting, whereas the double bond formation seemed to be unaffected by it. The grafted film held the original content of gel fraction unchanged during the irradiation in air, but the average molecular weight of the sol fraction decreased gradually. Meanwhile, the gel fraction of the crosslinked polyethylene was degenerated by a small dose of irradiation. The analysis of gaseous products revealed the formation of water, methanol, acetaldehyde and so forth from the irradiated grafted film. The grafting procedure and the subsequent irradiation of the grafted film did not affect the degree of crystallinity of the backbone polyethylene. The role played by the grafted polyacenaphthylene for endowing the radiation resistivity to polyethylene and its inherent limitation in effect were discussed from the structural point of view of the grafted film.

Radiation graft polymerization of solid monomers by vapor-phase method

Abstract Radiation graft polymerization proceeding in the sublimation vapors of solid monomers exhibits a peculiar feature differed from that of the ordinary liquid-phase graft polymerization, and also from that of the vapor-phase graft polymerization utilizing gaseous monomers or vapors of liquid monomers. In this experiment, polyethylene and poly(ethylene-co-vinyl acetate) films were irradiated with the γ-rays in the atmosphere of α,β-disubstituted ethylenic solid monomer such as maleimide, maleic anhydride, or acenaphthylene, or in that of the binary solid comonomers. Graft polymerization was characterized by little occluded homopolymer formation and high efficiency of grafting. When the monomer vapor was not sorbed into the polymer film, the reaction took place on the surface of film with the formation of fine granules of the grafted polymer. The oxygen gas coexisting with the monomer vapor did not inhibit the grafting reaction, but merely retarded it to the same extent as nitrogen. Thus the graft polymerization of unsorbed polar monomer as maleimide or maleic anhydride onto polyethylene was considered to proceed on the surface by a solid-state polymerization mechanism. When the monomer was sorbed and dispersed monomolecularly into the backbone polymer film, the grafting reaction seemed to proceed mainly in the inner part of the film. Grafting of copolymer took place when a film was exposed under γ-rays to a combined vapor of binary solid monomers chosen as an electron donor-acceptor combination, and in some cases nearly-alternating copolymer grafting was achieved even if one of the binary comonomers could not be sorbed into the film. The effects of the affinity of film to monomers on the rate of grafting and on the composition of grafted copolymer were also investigated by adopting poly(ethylene-co-vinyl acetate) films of various compositions and their surface-modified ones.

Vapor-Phase Graft Copolymerization of Fluoroalkyl Acrylates onto Cotton Cloth by Ultraviolet Irradiation:

The cotton cloth (# 20, bleached plain fabric) was desized with Biotex P (# 2S0), then scoured with dilute sodium hydroxide solution, followed by rinsing in running tal water, air-dried at room temperature, and kept over phosphorus pentoxide. The monomers were: 1, I-dihydropertluorohuty I acrylate (HhI3.3) [2J, 1,1-dihydroperfluoropropyl acrylate (PFPA) E2]; 1,1,3-trihydropernuoropropy! acrylate (TIvI’~), bp 50°C/29

Studies on controlled pores of polyethylene pore materials. V. Control of layer-like pores of polyethylene and paraffin mixtures intercalated with two guest particles.

高結晶性ポリエチレン (PE) 及び液体パラフィン (Pa) 混合物に少量のポリオキシエチレンステアリルエーテル (POS) あるいはステアリン酸カルシウム (SCa) を加えて種々の倍率に圧延し, Paを有機溶剤により抽出し, PE層間に微細孔を形成させた. その多孔体の微細孔構造を見掛けの比容, 小角X線及び窒素ガス吸着後の脱離による表面積測定により検討した. この多孔フィルムはPaとの混合比 (C) が0.50～1.00, 圧延温度115℃の条件で3から15倍に圧延すると, 圧延方向に層状の空孔が形成した. そのうちCが0.67と1.00で圧延倍率が7～12倍の条件では167～212m2/gの大きい表面積が得られた. POS及びSCaはPa中で異なった大きさのミセル粒子 (ゲスト) を作り, それがPE配向層 (ホスト) にインターカレーションして支柱を形成すると推察された. 最も微細な層状の多孔体では65Åのホストと45Åのゲストが多量に積み重なった構造であった.

Unique pore structure formed in montmorillonite in the presence of polyvinyl alcohol and aluminium chlorohydroxide

Porous montmorillonite, having a sharp pore size distribution (most abundant pore size ca. 30 A), was prepared by the ion exchange of Na–montmorillonite with aluminium chlorohydroxy oligomers in the presence of polyvinyl alcohol.

X-ray diffraction and DSC measurements of frozen sodium-montmorillonite. Amount of the unfrozen water and its location.

未焼成および種々の温度で焼成したナトリウム-モンモリロナイト(Na-Mt)について含水量の異なる試料を-73℃ で凍結させて,X線小角散乱法により底面間隔(d(001))を測定した。焼成温度が600℃ 以下ではNa-Mtは水により膨潤するが,700℃ 以上の温度で焼成するともはや膨潤し得なかった。これらの試料について示差走査熱量計(DSC)により融解熱を測定したところ,膨潤可能なNa-Mt中には0.459-Water/g-Clayの未凍結水が認められた。膨潤能を失なったNa-Mt中にはこのような未凍結水は存在しないので,未凍結水はNa-Mt粒子群が構成する粒子間隙に存在するのではなく,層内空間に存在することが結論された。未凍結水量と層内空間容積から凍結モンモリロナイト中の未凍結水の密度(2.0g/cm3)が推算された。

EFFECT OF IMMOBILIZED PHOTOSENSITIZERS ON PHOTOISOMERIZATION OF NORBORNADIENE

ABSTRACT Novel immobilized photosensitizers were prepared and the effect of them on the photoisomerization of norbornadiene(NBD) to quadricyclene(QC) was studied in the heterogeneous phase. Chloromethylstyrene(ClMeST) was graft-polymerized by γ-ray irradiation onto polyethylene(PE) powders or crosslinked PE sponges which had been prepared so as to possess large surface areas. Then aromatic ketocarboxylic acids were combined on the grafted PE by ester linkage. The resultant insoluble photosensitizers were very effective for photoisomerization of NBD. When immobilized photosensitizers were used, the dependency of quantum yield for QC formation and byproduct formation on the wavelength was comparable to that obtained by low molecular weight aromatic ketones as homogeneous photosensitizers. The effect of the quantity of immobilized photosensitizers, the agitation technique, etc. on the quantum yield were also investigated.

Gamma-Ray Induced Graft Copolymerization

空気中前照射によるポリエチレンフィルムへのメタクリル酸のγ 線グラフト共重合について検討した。低圧法ポリエチレンでのグラフト反応は捕捉ラジカルとパーオキサイドから起こり, 照射ポリマーを空気中25℃ で長時間保存すると, 捕捉ラジカルが消滅してパーオキサイドに由来する反応だけになる。また空気中100℃ で熱処理すると, 捕捉ラジカルに続いてハイドロパーオキサイドの消滅することが推定された。照射直後のグラフト (捕捉ラジカルとパーオキサイドによる反応) は照射線量と直線関係はないが, 放置後のグラフト (パーオキサイドによる反応) は照射線量とほぼ比例関係にあった。照射直後のグラフト量は照射温度の低いほど多い。放置後のグラフト量は照射温度に依存しなくて, -78-0℃ における前者のグラフト量は後者の4-5倍に達するが, 約40℃ 以上のときは両者の差はほとんどない。放置後のグラフト反応速度は重合温度の高いほど早く, 見かけの活性化エネルギーは22kcal/mo1であった。低圧法と高圧法ポリエチレンについて, 照射後空気中保存によるゲラフト量の減衰の比較から, 高圧法ポリエチレンでは捕捉ラジカルに由来するグラフト反応はほとんど認められなかった。