• Journal of the Korean Applied Science and Technology
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• v.5 no.1
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• pp.41-51
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• 1988

Aliphatic aldehyde polyoxyethylene glycol acetals were synthesised through the reaction of aliphatic aldehydes such as caproic aldehyde, capryl aldehyde, capric aldehyde and lauric aldehyde with excess diethylene glycol, triethylene glycol and tetraethylene glycol, respectively. The acetal formation, in which water was azeotropically distilled by adding benzene to the reaction system, was gained a good yield of acetal type compounds. This reaction is found pseudo first order reaction at various temperatures such 70, 80, 90 and $97^{\circ}C$. Also these activation energies of reaction of acetal type products such as caproic aldehyde diethylene glycol acetal, capryl aldehyde diethylene glycol acetal, capric aldehyde diethylene glycol acetal, lauric aldehyde diethylene glycol acetal, caproic aldehyde triethylene glycol acetal and caproic aldehyde tetraethylene acetal were 17.3, 19.6, 21.2, 21.6, 15.5 and 14.7 Kcal/mole.

• Journal of the Korean Chemical Society
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• v.28 no.5
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• pp.335-341
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• 1984

Acetals of ${\alpha},{\beta}$-unsaturated aldehydes reacted readily with aryl bromides in the presence of palladium catalyst and triethylamine to form aryl conjugated enals. Acrolein diethyl acetal and methacrolein diethyl acetal were reacted with phenyl bromides with substituents such as methyl and isopropyl groups at $100^{\circ}C$. The reaction products yields except the reaction of o-bromotoluene with methacrolein diethyl acetal. The products were identified by proton nuclear magnetic resonance and infrared spectroscopy. In the reverse combination of reactants to prepare aliphatic 2,4-dienals in good yield of above 50%, 3-bromopropenal dimethyl acetal and (E)-3-bromo-2-methylpropenal diethyl acetal were used as vinylic halide reactants and 1-alkenes and ethyl acrylate as olefin reactants.

• Rapid Communication in Photoscience
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• v.2 no.3
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• pp.76-78
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• 2013

Photoaddition reactions of aromatic carbonyl compounds with silyl thioketene acetals have been explored. The results of this study show that the acetonphenone react with dimethyl substituted silyl thioketene acetal competitively via either single electron transfer (SET)-desilylation or [2+2]-cycloaddition pathways to produce b-hydroxyester and oxetanes. In contrast, photochemical reactions of the benzaldehyde with dimethyl substituted silyl thioketene acetal mainly lead to the formation of oxetanes arising by [2+2] cycloaddition. A comparison of the results with those of silyl ketene acetal revealed that replacement of sulfur atom in ${\alpha}$-silyl donor substrate bring about dramatic changes in chemoselectivities as well as excited state reaction mechanism.

• Tribology and Lubricants
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• v.16 no.1
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• pp.1-8
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• 2000

Friction and wear tests have been performed on nylon, acetal resin, and PTFE (polytetrafluoroethylene), in reciprocating dry sliding conditions against steel discs. According to the results, acetal resin showed the lowest wear rates and PTFE exhibited the lowest friction coefficient. The prominent wear mechanisms found were adhesion and abrasion.

• Journal of Technologic Dentistry
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• v.23 no.1
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• pp.107-114
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• 2001

R.P.D fabrication can be made if the skills already is properly used in the manufacturing press. You may feel extremely comfortable to wear it. The material used has high elasticity that it can endure the hole process of Acetal Wax pattern casting without any deformation moreover its adaptability is not bad. Because of the poor financial condition of patterns and health insurance, Acetal R.P.D Framework can be one of the best alternatives used for setting clasp partial denture cheaply. R.P.D Framework is aesthetically excellent. The color caused by saliva is so similar to that of the rest of teeth that even dentists as well as patients can not recognize clasp arm. Clasp also helps to secure prosthesis ideally without damaging teeth due to its deep position downward. Since dentists and patients have a good reaction to clasp so far, we are encouraged to apply it to other technical fields.

• Bulletin of the Korean Chemical Society
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• v.23 no.1
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• pp.154-156
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• 2002

• Bulletin of the Korean Chemical Society
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• v.19 no.8
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• pp.862-868
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• 1998

The Lewis acid mediated intramolecular additions of allylsilanes to acetal substrates are described. Excellent regio- and diastereoselectivity are achieved by boron trifluoride promoted cyclization of allysilane-acetals 5 and 8 derived from hydroxy allysilances 3. Cyclizations occur in moderate to high yields, providing directr routes to cis-2, 6-disubstituted 4-methylenetetrahydropyrans 6 and 9.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2387-2396
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• 2000

Wear and operation characteristics of Nylon and Acetal pinion against steel gear were studied to gain a better understanding of their tribological and mechanical behavior. Tests were conducted with power circulating gear test rig under unlubricated conditions. Specific wear rates were measured as a function of applied load and total revolution. The worn tooth surfaces were examined with a profile projector and camera. Nylon pinion showed lower specific wear rates than Acetal pinion, but it revealed breakage at high load. Principal wear depths were developed at tooth tip and below the pitch line of pinion. Life estimation for the Nylon pinion was made by taking into account steel gear equivalent Hertz stress and average sliding velocity. The dominant wear mechanisms were adhesion and abrasion.

• Tribology and Lubricants
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• v.8 no.1
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• pp.48-55
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• 1992

The friction characteristic of plastics (PTFE, Nylon, Acetal and phenolic) was studied on the lubricated condition with a pin on disk machine. Mineral oil without additive (base oil) and water were used as liquid lubricants at the controlled temperature. From the experimental work, it was found out that the coefficient of friction of plastics was controlled by the mechanical properities of plastic more than that of liquid for various load and temperature. Viscosity of liquid has affected on the friction only at low temperature under lighb load. Among the tested plastics, the coefficient of friction of PTFE was the lowest under light load and at low temperature while Nylon at medium load and temperature, and Acetal at heavy load and high temperature. The coefficient of friction of soft plastics like PTFE and Nylon were increased as the load and temperature were increased, while that of hard plastic (Acetal) was decreased and that of thermo setting plastic (phenolic) was mixed. Also for soft plastics, the coefficient of friction under heavy load was always higher than that under light load, while hard plastic was vice versa.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1720-1729
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• 2001

Wear characteristics of Nylon and acetal pinions against steel gears for different pitch line velocities was studied with a power circulating gear test rig under unlubricated condition. Specific wear rate was measured as a function of tooth number, module, tooth width and total revolution. The worn tooth surfaces were examined with a profile projector. The Nylon pinion showed lower specific wear rate than the acetal pinion. However, the Nylon pinion was fractured at high tooth loads, whereas the acetal pinion exhibited a steady wear behavior. The wear characteristics of Nylon pinion varied significantly with the Pitch line velocity. Wear occurred most severely at the tooth tip and the region immediately below the pitch line of pinion. The dominant wear mechanisms were adhesion and abrasion.