Triazine, cross-linked

Aromatic nitriles may be trimerized at moderate temperature and pressure with p-toluenesulfonic acid as catalyst. Studies were conducted to establish the effect of the reaction temperature, pressure, time, and catalyst concentration on yield of the trimerized product. Trimerization studies were also conducted to establish the effect of substituting electron donating or withdrawing groups on benzonitrile. Preliminary results of using the catalytic trimerization approach to prepare s-triazine cross-linked polyimide/graphite fiber composites are presented. 

TABLE n. - MECHANICAL PROPERTIES OF TRIARYL-S-TRIAZINE CROSS-LINKED PI/HMS FIBER COMPOSITES ... 

Melamine resins were introduced about ten years after the Beetle molding compound. They were very similar to those based on urea but had superior quaHties. Henkel in Germany was issued a patent for a melamine resin in 1936 (7). Melamine resins rapidly supplanted urea resins and were soon used in molding, laminating, and bonding formulations, as well as for textile and paper treatments. The remarkable stabiHty of the symmetrical triazine ring made these products resistant to chemical change once the resin had been cured to the insoluble, cross-linked state. 

Other amino resins besides MF resins are used to a lesser degree in coatings. Urea—formaldehyde resins are used in some coatings for wood furniture because these resins cross-link at lower temperatures than MF resins and the higher water resistance and exterior durabiUty that can be obtained using MF resins are not needed. Ethers of formaldehyde derivatives of 6-phenyl-l,3,5-triazine-2,4-diamine [91-76-9] (benzoguanamine resins) give... 

A polyvinyl alcohol is obtained by suspension polymerization of vinyl acetate and the cross-linking agent, triallyl isocyanurate, with a triazine ring followed by alkali hydrolysis. The polyvinyl alcohol gel is used as packing for gel-... 

Figure 5.17 Noncovalent cross-linking strategies of cyanuric acid functionalized poly-CA to form (a) poly-CA-triazine by using a diaminotriazine cross-linking agent or (b) poly-CA-wedge by using an isophthalamide cross-linking agent.

Figure 5.18 Cross-linking profile of poly-CA using the triazine-based cross-linking agent. Filled symbols denote the elastic modulus (G ) whereas empty symbols denote the loss modulus (G") at a strain value of 0.1. The percentage of the triazine-based cross-linking agent is based on the cyanuric acid groups attached to the polymer.

Cibacron Blue is a blue, polyaromatic, sulfonated dye (Fig. 6). It can be attached, as an affinity li nd, to solid matrix supjmrts (e.g. dextran, agarose) by the reaction of the triazine ring with free hydroxyl groups of the supports. The conditions of this triazine coupling method have been described by Bohme Such a dye affinity sorbent is also produced commercially, e.g. under trade name Blue Sepharose CL-6B (Cibacron Blue F3G-A covalently bound to the cross-linked agarose gel Sepharose CL-6B ) by Pharmacia, Sweden. 

An acetal-protected lithium initiator was used to polymerize styrene followed by linking with 1,3,5-triallyloxy-2,4,6-triazine to produce three-arm star polystyrenes.73 The protective acetal group was cleaved by weak acidic treatment in THF to give star polymers with terminal OH groups. These functional groups were coupled with toluene-2,4-diisocyanate to give randomly cross-linked products. Unfortunately, few characterization data were provided in this study. 

Triazine Ring Cross-linked Polyimides and Refractory Materials Derived from Them... 

The graphite fiber reinforced triaryl-s-triazine ring (TSTR) cross-linked polyimides with ring-chain structures have good mechanical properties at elevated temperatures. On pyrolysis, the TSTR cross-linked polyimides were converted to refractory type materials which are believed to be graphitic type ladder polymers containing some nitrogen in their cyclic structures. 

The polyimide class of polymers are known to possess a high degree of thermal stability. They decompose in an inert atmosphere around 500°C and in air about 400°C as indicated by thermo-gravimetric analysis (1). Because of the great thermal stability of 2,4,6-triphenyltriazine (2J (decomposes above 486°C), copolymerization of this compound with imides should lead to enhanced heat resistant materials in the form of triaryl-s-triazine ring (TSTR) cross-linked (XL) polyimides. 

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