• Journal of Adhesion and Interface
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• v.17 no.2
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• pp.67-71
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• 2016

In this study, low-viscosity polyurethane hot-melt were synthesized with polyether polyol / polyester polyol, 4,4-dicyclohexylmethane diisocyanate ($H_{12}MDI$), 2-butanone oxime (MEKO) to improve the properties and peel strength. The properties of the synthesized low-viscosity polyurethane hot-melt was evaluated through FT-IR, viscosity meter and UTM. When the content of the reactive diluent increases and the NCO-blocked prepolymer decreases, the viscosity of low-viscosity polyurethane hot-melt adhesive was increased. When the ratio of OH-terminated oligomer, NCO-blocked prepolymer and content of reactive diluent is 1 : 0.5 : 0.5, low-viscosity polyurethane hot-melt showed 1.1 kgf/cm peel strength.

• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.46-51
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• 2010

Polyorganosiloxane modified polyurethane (PDMS-PU) polymers were prepared from copolymerization of ${\alpha}$,${\omega}$-hydroxypropyl terminated polyorganosiloxane with isophorone diisocyanate (IPDI), polypropylene glycol (PPG), and 2,2-bis(hydroxymethyl) propionic acid (DMPA). Hydrophobic polyorganosiloxane was introduced in polyurethane main chain as soft segment block unit. The isocyanate groups in PDMS-PU block copolymer was blocked with 2-butanon oxime and obtained PDMS-PU dispersions in water by neutralizing with triethylamine (TEA). The deblocking temperature of PDMS-PU polymer was measured from thermal analysis. The good stability of the PDMS-PU dispersion was obtained by dispersing into water. PDMS-PU prepolymers were prepared with various contents of DMPA under [NCO]/[OH] = 1.12~1.53 equivalent ratio. Increasing DMPA from 7.2, 13.4, and 18.7 mole% in preparation of PDMS-PU polymer, particle sizes were decreased from 156, 100, 65 dnm. Also contact angle and adhesive strength were measured.

• Macromolecular Research
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• v.13 no.5
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• pp.427-434
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• 2005

To improve the performance and reduce raw material costs, blocked isocyanates were prepared with mixture of blocking agents in many industries. Three blocked isocyanates (adducts) namely $\varepsilon$-caprolactam/benzotriazole-blocked 4,4'-diphenylmethane diisocyanate (MDI), toluene-2,4-diisocyanate (TDI) and 4,4'-dicyclohexyl-methane diisocyanate ($H_{12}$MDI) were synthesized. Six reference adducts were also prepared by blocking MDI, TDI, and $H_{12}$MDI with $\varepsilon$-caprolactam ($\varepsilon$-CL) or benzotriazole. The reactions were carried out in acetone medium and dibutyltin dilaurate (DBTDL) was used as a catalyst. The progress of the blocking reaction was monitored by IR spectroscopy. De-blocking temperatures (dissociation temperatures) of these adducts were studied using DSC and TGA and the results were correlated. As expected, the thermal analysis data showed that de-blocking temperature of blocked aromatic isocyanates was lower than that of the blocked aliphatic isocyanates. The low de-blocking temperature of blocked aromatic isocyanate could be due to electron withdrawing benzene ring present in the blocked isocyanates. It was also found that benzotriazole-blocked adducts de-blocked at higher temperature compared with $\varepsilon$-CL-blocked adducts.

• Polymer(Korea)
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• v.37 no.2
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• pp.232-239
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• 2013

A series of novel imidazole-blocked diisocyanate bioadhesives (IBAs) were synthesized from reaction of toluene 2, 4-diisocyanate (TDI), isophorone diisocyanate (IPDI), hydroxyl-terminated polylactide (HO-PLA-OH), 1,1,1-trimethylolpropane (TMP), and imidazole. Synthesis of IBAs was confirmed by Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). Differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) revealed that the TDI-based IBA had lower thermal dissociation temperature and a faster deblocking rate than IBA based on IPDI. Hydroxyl-terminated polyurethane (HPU) was introduced to study the adhesive effect of the synthesized IBAs. Improvement on elastic modulus, tensile strength and water resistance of IBA-modified HPU in comparison with neat HPU suggested the good adhesive effect of IBA due to the strong chemical reaction between released NCO groups from IBA and hydroxyl groups from HPU.