Diisocyanates, modified

Figure 1. Infrared spectra for a toluene diisocyanate modified hydantoin epoxy/2-ethyl-l,3-hexanediol oligomer showing the OH and NH bands of the oligomer as a function of temperature in uncatalyzed and catalyzed formulations.

Table III. Shear Strength of Diisocyanate-Modified Lignin Adhesive...

In Table V, the mechanical properties of particleboard bonded with nonemulsifiable diisocyanate modified with maize starch are given. The extender content for the diisocyanate was up to 20%. However, with increasing extender content, the internal bond of the boards decreased, and the thickness swelling increased the boards had V100 quality. First tests with adhesives of diisocyanates and starch were encouraging, and more attempts in developing new glue formulations... 

The fourth type of composition is exemplified by unsaturated polyester prepolymers combined with a photoinitiator 1. A mixture of a tolylene diisocyanate-modified maleic anhydride-phthalic anhydride-propylene... 

Research efforts on filled polymer blends have been more focused on nanopartide-filled systems [42, 43]. One usual observation is the same as those with microscopic fillers - polar nanofillers localize in more polar phases [44—53]. In cases where both phases are polar or nonpolar, the filler particles have been observed to be expelled from both phases in the blend [54—56]. Selective localization of nano-sized partides has been an interesting topic of research. We discuss some of the results here. Gahleitner et al. [57] observed a preferential localization of clay particles in PA6 droplets in PA6/PP blends. Recall that day, espedally montmorillonite, is highly polar in both its pristine and various organically modified forms [58-62]. Similarly, Wang et al. [63] reported selective localization of clay particles in maleic anhydride grafted ethylene-propylene-diene (EPDM-MA) rubber droplets in poly(trimethylene terephthalate)/EPDM-MA blends. Selective localization of fillers other than clay particles has also been reported. Eor instance, Ou and Li [64] observed that toluene diisocyanate modified titania particles selectively localized in PA6 droplets in PP/ PA6/titania blends. 

From these, prepolymers are prepared where the diisocyanates may be completely reacted as in the case of the urethane oils which resemble the oil-modified alkyds but have urethane (—NHCOO—) links in place of the ester (—COO—) links of the alkyds, or where one only of the isocyanate groups is combined, leaving the other to participate in crosslinking reactions. Such a reactive prepolymer is the biuret that may be prepared from hexamethylene diisocyanate, has the following structure ... 

Di-hydroxyl end-capped PPG (18) is an intermediate in the formation of a common polyurethane prepolymer (20). End group functionality of this intermediate is important, as this hydroxyl functionality is modified to form the prepolymer. Any different end group structures could lead to the presence of prepolymer that will not form polyurethane of the desired structure. The desired reaction of the intermediate (18) to form the prepolymer (20) is described in Figure 21. Reaction of one unit of the intermediate (18) and two units of methylene diphenyl 4,4 -diisocyanate (MDI) results in the formation (nominally) of the prepolymer (20). 

Chain Extendable Urethane Modified Epoxy Oligomer. The chain extendable urethane modified oligomers were prepared by combining equimolar amounts of epoxy-diol adduct and half-blocked diisocyanates, and heating the resulting mixture at 80°C for 4-6 hours until the isocyanate Infrared band disappeared. 

Guevera, R., and Moslem , A.A. (1983). Hygroexpansive and sorptive behaviour of wood modified with propylene oxide and oligomeric diisocyanate. Journal of Wood Chemistry and Technology, 3(1), 95-114. 

Lutomski, K. (1975). Resistance of beechwood modified with styrene, methyl methacrylate, and diisocyanate against the action of fungi. Material und Organismen, 10(4), 255-262. 

When polymerization proceeds in the presence of modifiers, the mechanochemical process enhances cross-linking and, correspondingly, improves the physicochemical properties of final plastics. For example, mechanochemical treatment of acrylonitrile butadiene styrene (ABS) plastic in the presence of tolnene diisocyanate improves thermal oxidative stability of the plastic (Chetverikov et al. 2002). 

The purpose of this ehapter is to deseribe the analytieal methods that are available for deteeting, and/or measuring, and/or monitoring hexamethylene diisoeyanate, its metabolites, and other biomarkers of exposure and effeet to hexamethylene diisocyanate. The intent is not to provide an exhaustive list of analytieal methods. Rather, the intention is to identify well-established methods that are used as the standard methods of analysis. Many of the analytieal methods used for environmental samples are the methods approved by federal agencies and organizations such as EPA and the National Institute for Occupational Safety and Health (NIOSH). Other methods presented in this chapter are those that are approved by groups such as the Association of Official Analytical Chemists (AOAC) and the American Public Health Assoeiation (APHA). Additionally, analytical methods are included that modify previously used methods to obtain lower deteetion limits, and/or to improve aeeuraey and precision. 

Alexandersson R, Hedenstiema G, Plato N, et al. 1987. Exposure, lung funetion, and symptoms in car painters exposed to hexamethylene diisocyanate and biuret modified hexamethylendiisoeyanate. Areh Environ Health 42(6) 3 67-3 73. 

To address this concern uretonimine-modified isocyanates with improved low-temperature properties were prepared using 4,4 -diphenylmethane diisocyanate catalyzed with 3-methyl-l-phenyl-3-phospholene-l-oxide. The formation of uretonimine was consistently higher than uretdione formation using this catalyst. The uretonimine-modified isocyanate can be stored at temperatures substantially lower than ambient temperature while still remaining liquid. In addition it is soluble in melted 4,4 -diphenylmethane diisocyanate. 

TABLE 1. Scoping Reactions for Preparation of Urctonimine-Modified Isocyanate Using 93.80% 4,4 -Diphenylmethane Diisocyanate Containing 6.20% 2,4 -Diphenylmethane Diisocyanate Conducted at 105-108°C Using 3-Methyl-l-phenyl-3-phosphoIene-l-oxide as Catalyst... 

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