A Study on the Abrasion Effect by 60 Co-γ ray Irradiation for Dental P.M.M.A. (Part Ⅰ)

Reported in this article are results of experiment in which diand tri-methacrylic acid esters and di- and tri-allyl compounds are used as cross linking monomer to coat P.M.M.A., irradiated with radioactivity to bring about linking reaction and improvement in linking density, so that the abrasion resistance of the dental P.M.M.A. can be improved. It was found that to add diallyl compound to unsaturated polyester and to coat the material with curing catalyzer as coating material added with M.E.K.P.O. and naphthenic acid cobalt and to irradiate with radioactivity to enrich cross linking density after hot press processing were very effective as a treatment to improve abrasion resistance of dental P.M.M.A .

A Study on the Abrasion Effect by 60 Co-γ ray Irradiation for Dental P.M.M.A. (Part Ⅰ)

Reported in this article are results of experiment in which diand tri-methacrylic acid esters and di- and tri-allyl compounds are used as cross linking monomer to coat P.M.M.A., irradiated with radioactivity to bring about linking reaction and improvement in linking density, so that the abrasion resistance of the dental P.M.M.A. can be improved. It was found that to add diallyl compound to unsaturated polyester and to coat the material with curing catalyzer as coating material added with M.E.K.P.O. and naphthenic acid cobalt and to irradiate with radioactivity to enrich cross linking density after hot press processing were very effective as a treatment to improve abrasion resistance of dental P.M.M.A .

Experimental study of 1 MW, 170 GHz gyrotron oscillator

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1997.Includes bibliographical references (p. 125-129).by Takuji Kimura.Ph.D

A Study on the Characteristics at Low Temperature of Welded Polycarbonate

In this study we investigated the tensile characteristics of welded polycarbonate at low temperature. This study intends to clarify the low temperature characteristics of welded part comparing with those of base material. The results of some measurements on the tensile properties from 20°C down to -70℃ are reported and the changes in tensile properties under low temperature atmosphere are discussed. Furthermore, notch and load velocity effects on the brittle fracture tendency are also discussed. Conclusions obtained in this study are summarized as follows; 1) Both welded part and base material of polycarbonate are strengthened at low temperature. 2) Welding joint efficiency of polycarbonate is very good even at low temperature. 3) Notch and load velocity effects are observed both on the base and the welded materials. 4) Correlations are observed between fracture surfaces and mechanical testing results

A Study on the Adhesion of the Composite Denture

In this paper we describe an experimental study, in the preceding article, authors reported about the abrasion for composite teeth, in this article are a composite denture which was newly made combining merits of the porcelain and the plastic teeth, a trial production of composite materials of the porcelain and the plastic teeth, and an experimental study of adhesion property of the composite tooth. The following summary can be made from the results of the present experiments. Adhesion of composite denture with filler of porcelain element in principal can be fully expected. In comparison with adhesion strength of P.M.M.A. to P.M.M.A., tensile joint efficiency adhered by P.M.M.A. of heat-cured type was 84-100%, while that of P.M.M.A. of low temperature cured type was 97-98%. Bending joint efficiency using the former adhesive was 87-94%, while that of the latter adhesive was 83-85%

A Study on the Thin Plate with Carbon Fiber Reinforced Hybrid Composite

In this paper we describe an experimental study, this article is to report fundamental data of constructions attained by carbon fiber reinforced hybrid composite of O.9mm in thickness whose resin base was reinforced. As a result of this series of test and experiments, it was found that; it is possible to attain reinforced resin base of hybrid composite of C.F.R.P. 16 times as much in rigidity against bending load as compared with that of single construction was observed with composite of O.9mm lamina. It was found that sandwich construction of C.F.R.P. is superior, while, in the case of canape construction, it was found necessary to have C.F.R.P. on the tension side. G.F.R.P. has possibility to be reinforced composite material, although it is considerably less superior to C.F.R.P

A Study on the Fatigue Characteristics of Polymethylmetacrylate Adherends

In this paper we describe an experimental study. Reported in this article are tensile fatigue characteristics of polymethylmetacrylate and its bonded material in relation to wave form of load, loading velocity and notch effect. In experiments, heat cured acrylic resin was used for base material, while heat cured and self-cured polymethylmetacrylate (Denture Acrylic SHOFU "Bio" Resin) were used as Adhesives. As a result of the research of test and experiments, it is found that; 1) Fatigue limits of the bonded materials using heat cured and self-cured P.M.M.A. are approximately 2/3 and 1/3 of that of the base material. 225 2) Two-fold property of S-N curve can be seen with dental P.M.M.A., and such property is partly attributable to temperature rise of the test piece. Fatigue limit drops as test velocity increases, and such drop is again partly attributably to temperature rise of the material. 3) Effect of notch is observed and it is noted that the notch causes deterioration in endurance limit by about 1/4

A Study on the Fatigue Characteristics of Polymethylmetacrylate Adherends

In this paper we describe an experimental study. Reported in this article are tensile fatigue characteristics of polymethylmetacrylate and its bonded material in relation to wave form of load, loading velocity and notch effect. In experiments, heat cured acrylic resin was used for base material, while heat cured and self-cured polymethylmetacrylate (Denture Acrylic SHOFU "Bio" Resin) were used as Adhesives. As a result of the research of test and experiments, it is found that; 1) Fatigue limits of the bonded materials using heat cured and self-cured P.M.M.A. are approximately 2/3 and 1/3 of that of the base material. 225 2) Two-fold property of S-N curve can be seen with dental P.M.M.A., and such property is partly attributable to temperature rise of the test piece. Fatigue limit drops as test velocity increases, and such drop is again partly attributably to temperature rise of the material. 3) Effect of notch is observed and it is noted that the notch causes deterioration in endurance limit by about 1/4

Synthesis of lamellar mesostructured calcium phosphates using n-alkylamines as structure-directing agents in alcohol/water mixed solvent systems

Lamellar mesostructured calcium phosphates constructed by ionic bonds were prepared by using n-alkylamines (n-C n H2n+1NH2, n = 8–18) at room temperature in the mixed solvent systems of aliphatic alcohol (C n H2n+1OH, n = 1–4) and water, and the synthetic conditions were investigated in detail. The mixed solvent systems suppressed the formation of crystalline calcium phosphates like brushite (CaHPO4·2H2O) and monetite (CaHPO4) at low temperatures, successfully affording pure lamellar mesostructured calcium phosphates. Other crystalline phases such as hydroxyapatite (Ca10(PO4)6(OH)2) were not formed under the conditions with the Ca/P molar ratios in the range of 0.7–1.0 in the starting mixtures. The Ca/P molar ratio of the lamellar mesostructured calcium phosphates was ca. 1.0, calculated by ICP and 31P MAS NMR data. Interestingly, the kind of alcohols strongly influenced the solubilities of calcium phosphate species and n-alkylamines, and then lamellar mesostructured phases were obtained with some morphological variation