Polymer isocyanurate

Another use is of minor proportions of polyfunctional aHyl esters, eg, diaHyl maleate, ttiaHyl cyanurate, and ttiaHyl isocyanurate, for cross-linking or curing preformed vinyl-type polymers such as polyethylene and vinyl chlotide copolymers. These reactions ate examples of graft copolymerization in which specific added peroxides or high energy radiation achieve optimum cross-linking (see Copolymers). 

Urethane network polymers are also formed by trimerization of part of the isocyanate groups. This approach is used in the formation of rigid polyurethane-modified isocyanurate (PUIR) foams (3). 

Modification of cellular polymers by incorporating amide, imide, oxa2ohdinone, or carbodiimide groups has been attempted but only the urethane-modified isocyanurate foams are produced in the 1990s. PUIR foams often do not require added fire retardants to meet most regulatory requirements (34). A typical PUIR foam formulation is shown in Table 6. 

FD-MS by itself provides only limited chemical information. Lattimer et al. [92] have also compared the analysis of extracted rubber vulcanisates by means of FD-MS and FAB-MS, using the aforementioned EI/FD/FT/FAB ion source. The systems investigated were neoprene/DOPPD, EPDM/(DOP, PBNA, paraffin wax), neoprene-SBR blend/(DOP, DOPPD, TDBHI). Certain compounds were observed by FD but not by FAB (wax, oil, isocyanurate antioxidant TDBHI). In FAB conditions some polymer additives suppress... 

In an acetone extract from a neoprene/SBR hose compound, Lattimer et al. [92] distinguished dioctylph-thalate (m/z 390), di(r-octyl)diphenylamine (m/z 393), 1,3,5-tris(3,5-di-f-butyl-4-hydroxybenzyl)-isocyanurate m/z 783), hydrocarbon oil and a paraffin wax (numerous molecular ions in the m/z range of 200-500) by means of FD-MS. Since cross-linked rubbers are insoluble, more complex extraction procedures must be carried out (Chapter 2). The method of Dinsmore and Smith [257], or a modification thereof, is normally used. Mass spectrometry (and other analytical techniques) is then used to characterise the various rubber fractions. The mass-spectral identification of numerous antioxidants (hindered phenols and aromatic amines, e.g. phenyl-/ -naphthyl-amine, 6-dodecyl-2,2,4-trimethyl-l,2-dihydroquinoline, butylated bisphenol-A, HPPD, poly-TMDQ, di-(t-octyl)diphenylamine) in rubber extracts by means of direct probe EI-MS with programmed heating, has been reported [252]. The main problem reported consisted of the numerous ions arising from hydrocarbon oil in the recipe. In older work, mass spectrometry has been used to qualitatively identify volatile AOs in sheet samples of SBR and rubber-type vulcanisates after extraction of the polymer with acetone [51,246]. 

Chlorinated fluorocarbons (CFCs), 21 591 Chlorinated glycolurils, 73 109-110 Chlorinated hydantoins, 13 110 Chlorinated hydrocarbons (CHC) contamination by, 23 111—112 for PVC polymers, 25 674 Chlorinated isocyanurates end use of chlorine, 6 135t as pool sanitizers, 26 175-176 Chlorinated methanes... 

The polycyclotrimerization of difunctional isocyanates (or NCO-terminated prepolymers) produces polymer networks containing heterocyclic, thermostable per-hydro-1,3,5-triazine-2,4,6-trione (isocyanurate) rings as crosslinks ... 

URETHANE POLYMERS] (Vol 24) PUIR foams. See Polyurethane-modified isocyanurate. 

Risch et al. have reported on the reaction of l,3-diazetidine-2,4-diones, which are used in the preparation of polymers and advanced materials <1999JPR616>. With the help of special catalysts it was possible to dimerize or trimerize diisocyanate to give l,3-diazetidine-2,4-diones 183 or isocyanurates 184 (Scheme 25). 

A series of compounded flame retardants, based on finally divided insoluble ammonium phosphate together with char-forming nitrogenous resins, has been developed for thermoplastics.23 These compounds are particularly useful as intumescent flame-retardant additives for polyolefins, ethylene-vinyl acetate, and urethane elastomers. The char-forming resin can be, for example, an ethyle-neurea-formaldehyde condensation polymer, a hydroxyethyl isocyanurate, or a piperazine-triazine resin. Commercial leach-resistant flame-retardant treatments for wood have also been developed based on a reaction product of phosphoric acid with urea-formaldehyde and dicyandiamide resins. 

With regard to reactive flame-retardants, two routes can be followed to improve thermal stability and fire behavior of PU foams use of brominated or phosphorus-containing polyol or, for rigid foams, the introduction inside polymer backbone of more thermally stable structure than urethane, mainly isocyanurate, but also uretidione rings or carbodiimide.19... 

Dicyanates react with diisocyanates. The poly addition results in the formation of crosslinked polymers with cyanurate and isocyanurate rings [32]. The polymers have high deformation and decomposition temperature in the case of a crosslinked copolymer from 9,9-bis(4-cyanatophenyl)fluorene the corresponding values are 480 °C and 440 °C (in air), respectively. 

Ni H, Aaserud DJ, Simonsick WJ Jr., Soucek MD. (2000) Preparation and characterization of alkoxysilane functionalized isocyanurates Polymer 41 57-71. 

Modification of poly(carbodiimide) foams with polyols afford hybride foams containing urethane sections. However, the thermal stabilities of the poly (urethane carbodiimide) foams are lower. Using isocyanate trimerization catalysts, such as l,3,5-tris(3-dimethylaminopropyl)hexahydro-s-triazine, in combination with the phospholene oxide catalyst gives poly(isocyanurate carbodiimide) foams with improved high temperature properties. The cellular poly(carbodiimide) foams derived from PMDI incorporate six-membered ring structures in their network polymer structure. ... 

In contrast, the isocyanurate linkage is thermally stable, as determined by TGA, as shown by a model compound study (58) and produces less combustible gases. Accordingly, unmodified isocyanurate-based polymers, e.g., resins and foams, are thermally stable, and therefore, temperature- and flame-resistant. In other words, the unmodified polyisocyanurates decompose at higher temperatures than the polyurethanes, and generate lower amounts of combustible gases than polyurethanes. 

Synthesis and Properties of Imide and Isocyanurate-Linked Fluorocarbon Polymers... 

Isocyanurate-linked polymers can be formed by cyclotrimerization of diisocyanate intermediates under moderate temperature conditions (14). Compounds V and VI cyclotrimerize readily at room temperature upon addition of catalytic quantities of W,W,AT,N -tetramethyl-l,3-butane-diamine and allyl glycidyl ether, provided that atmospheric moisture is rigorously excluded. 

Figure 1. Thermo gravimetric analysis of isocyanurate-linked fluorocarbon polymers, heating rate 2.7° C/minute in air.

Polymerizations. Isocyanurate polymer formation was catalyzed by the addition of N,N,N, N -tetramethyl-l,3-butanediamine and allyl glycidyl ether (redistilled) 1% (by weight) of each catalyst was used. Polymerization occurred at 25° to 50°C under anhydrous conditions although temperatures of 100° to 150° C were needed to complete the reaction with the short chain diisocyanate intermediates used. 

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