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Performance and Durability Testing
Published in Rose A. Ryntz, Philip V. Yaneff, Coatings Of Polymers And Plastics, 2003
For automotive applications, both low-bake (80 to 90°C) and high-bake (120 to 130°C) 2K clearcoats are in use today. Most 2K coatings for plastics use aliphatic hexamethylene diisocyanate (HDI) as its film properties exhibit a good combination of flexibility and durability, and reasonably fast reactivity. For some applications, blending in some isophorone diisocyanate (IPDI) or biuret is used to increase surface hardness or produce softer, more flexible films. The choice of catalyst, temperature, and alcohol can dramatically influence the composition of the final product, especially when IPDI is used (97). There is little use of aromatic diioscyanates such as toluene diisocyanate (TDI) or methane diphenyl diisocyanate (MDI) due to their high contribution of yellowing. In general, the addition of a small amount of catalyst is enough to induce cure of the high-bake coating at lower temperature. The strongest catalysts are materials such as mercuric compounds, tin (IV) compounds, zinc (II) carboxylates, tertiary amines, and carboxylic acids (98). In cases where the resin does not cure fast enough, more reactive, faster curing materials can be used.
Hierarchy analysis of different cross-linkers used for the preparation of cross-linked cyclodextrin as drug nanocarriers
Published in Chemical Engineering Communications, 2018
R. Pushpalatha, S. Selvamuthukumar, D. Kilimozhi
Cyclodextrins when reacted with cross-linkers like hexamethylene diisocyanate and toluene diisocyanate result in carbomate-bonded nanosponges. The cross-linkers are used with cyclodextrin in the molar ratio of 1:2 to 1:8. These nanosponges can be prepared by solvent method at temperature ranging from room temperature to 70°C under anhydrous/nitrogen atmosphere. Residual solvent can be removed using acetone. These nanosponges are initially developed for purification of water, including removal of nitrophenol, dissolved organic carbon. Recent research focuses on preparing molecular-imprinted nanosponges using these diisocyanate cross-linkers for encapsulation of dextromethorphan, steroids, dyes, and naringin (Takayuki Hishiya et al., 1999; Roche et al., 2009; Ma et al., 2011; Kyzas et al., 2013; Swaminathan et al., 2013).
Molecular design of supramolecular polymers with chelated units and their application as functional materials
Published in Journal of Coordination Chemistry, 2018
Igor E. Uflyand, Gulzhian I. Dzhardimalieva
The ruthenium-based photolabile complex, [Ru(bpy)2(L)2](PF6)2, (L = 4-(aminomethyl)pyridine), was introduced into polyurea organogels and hydrogels through reactive amine fragments on photocleavable L ligands (Scheme 20) [199]. The chain extension was achieved with Jeffamine ED-2003 and as the cross-linker poly (hexamethylene diisocyanate), with about 40% of the isocyanate groups introduced by a crosslinking agent. Featuring long-term stability in the dark, the cleavage of the pyridine–ruthenium bond upon irradiation with visible or near-infrared radiation (in a two-photon process) leads to a rapid de-gelation of the supramolecular gels.
Glove permeation of chemicals: The state of the art of current practice—Part 2. Research emphases on high boiling point compounds and simulating the donned glove environment
Published in Journal of Occupational and Environmental Hygiene, 2020
A novel permeation panel was developed (Ceballos et al. 2011, 2014a) to test the permeation of sprayed monomers and oligomers of 1,6-hexamethylene diisocyanate and isophorone diisocyanate against 0.010–0.013 cm latex gloves. Monomers but not oligomers permeated immediately at 0.0029 µg/cm2/min as shown by direct indicating Swypes and fiberglass filters impregnated with 1-(2-pyridyl)-piperazine whose derivatization products were analyzed by LC-UVD with a sensitivity of 0.1 µg. Butyl gloves (0.033 cm) showed no permeation unlike nitrile (0.013 cm) and natural rubber latex (0.013 cm), with latex permeating fastest.