Catalysts crosslinking

Table 3. Least-Squares Analysis 2000-1400 cm 1 of 1 1 Stoichiometry Anhydride Epoxide Mixtures (0.5% wt BDMA Catalyst) Crosslinked at 90 °C...

The IPNs prepared were composed of a rubbery polyurethane and a glassy epoxy component. For the polyurethane portion, a carbodiimide-modified diphenyl-methane diisocyanate (Isonate 143L) was used with a polycaprolactone glycol (TONE polyol 0230) and a dibutyltin dilaurate catalyst (T-12). For the epoxy, a bisphenol-A epichlorohydrin (DER 330) was used with a Lewis acid catalyst system (BF -etherate). The catalysts crosslink via a ring-opening mechanism and were intentionally selected to provide minimum grafting with any of the polyurethane components. The urethane/epoxy ratio was maintained constant at 50/50. A number of fillers were included in the IPN formulations. The materials used are shown in Table I. 

The resins can be crosslinked by heating with Friedel-Crafts catalysts. It is assumed that the nitrile groups are forming triazines by heating. Even without Friedel-Crafts catalysts crosslinking is possible however, the reaction proceeds slowly. The materials are intended for use as laminating... 

Storage May develop pressure vent bottle periodically Uses Polymerization initiator/catalyst/crosslinking agent for cure of unsaturated polyester resins in gel coats to eliminate or reduce porosity mfg. of acrylic resins hardener for fiberglass-reinforced plastics catalyst in food-contact crosslinked polyesters Regulatory FDA 21 CFR 177.2420... 

Hazardous Decomp. Prods. Heated to decomp., emits toxic fumes of Cr Uses Catalyst, crosslinking agent used for curing heat-vulcanized silicone rubbers, food-contact rubber articles Manuf./Distrib. Gelest http //www.geiest.com Trade Name Synonyms Aztec DCLBP-50-PSI [Aztec Peroxides] Perkadox PD t[Flexsys http //www. fiexsys. com]... 

Uses Catalyst, crosslinking agent for heated curing of unsat. polyester resin systems polymerization initiator for acrylates, PE, PS Trade Name Synonyms Aztec DHPEH f[Aztec Peroxides] Trigonox 141 f[Akzo Nobel http //www.akzonobel.com], USP -245 t[Crom pto n http //www. cromptoncorp. com]... 

Dabco, Amine and tin catalysts, crosslinkers and silicone surfactants. Air Products and Chemicals, Inc. 

Furfural reacts with ketones to form strong, crosslinked resins of technical interest in the former Soviet Union the U.S. Air Force has also shown some interest (42,43). The so-called furfurylidene acetone monomer, a mixture of 2-furfurylidene methyl ketone [623-15-4] (1 )> bis-(2-furfurylidene) ketone [886-77-1] (14), mesityl oxide, and other oligomers, is obtained by condensation of furfural and acetone under basic conditions (44,45). Treatment of the "monomer" with an acidic catalyst leads initially to polymer of low molecular weight and ultimately to cross-linked, black, insoluble, heat-resistant resin (46). 

This is also known as Bulk Moulding Compound (BMC). It is blended through a mix of unsaturated polyester resin, crosslinking monomer, catalyst, mineral fillers and short-length fibrous reinforcement materials such as chopped glass fibre, usually in lengths of 6-25 mm. They are all mixed in different proportions to obtain the required electromechanical properties. The mix is processed and cured for a specific time, under a prescribed pressure and temperature, to obtain the DMC. 

Hydrosilation silicones or addition cure systems utilize a hydride functional crosslinker with a vinyl functional base polymer and a noble metal catalyst. While the cure can be initiated with UV [48,49], thermal cure versions dominate the commercial market [23,50]. In thermal cure systems, inhibitors are necessary for processing and anchorage additives are common. 

The UV cure system contains an epoxy or a vinyl ether functionalized PDMS polymer and a photo catalyst [36]. This latter, a diaryliodonium salt is photolyti-cally decomposed to form an active acid that polymerizes the epoxy or vinyl ether groups and crosslinks the network. 

The term novolac refers to the early use of phenolic to replace expensive shellac-based coatings. Novolacs are now those resins made at formaldehyde-to-phenol molar ratios of less than one-to-one. They are generally, though not always, manufactured under acidic conditions. Sulfuric or oxalic acids are most often chosen as catalyst though aromatic sulfonic acids and phosphoric acid are also quite common. Many other acids are used for special purposes. The finished novolac resin is incapable of further polymerization or crosslinking and therefore... 

The autocatalytic hardening of tannins without addition of formaldehyde or another aldehyde as crosslinker is possible, if small traces of alkaline Si02 are present as catalyst and also a high pH is used, or with certain tannins just by the catalytic action induced by the wood surface [152-160]. 

Aryl-5-oxo-1,2,3,5-tetrahydropyrido[ 1,2,3-i/e]quinoxaline-6-carboxy-mides were prepared from 7-chloro derivatives and arylboronic acids in the presence of Na2C03, diphenylphosphinated divinylbenzene-crosslinked polystyrene and Pd(PPh3)4 catalyst. 7-Chloro derivatives were obtained from 7-hydroxy derivatives by heating in POCI3 at 50°C for 3 h (01MIP12). 

A new type of rigid polymer of 1,1-binaphthols was developed recently [41-43]. The 3,3 -crosslinked polymeric binaphthol ligand 18 in combination with AlMe3 was applied as the catalyst for the 1,3-dipolar cydoaddition (Scheme 6.16) [44]. Very high selectivities were obtained when the aluminum catalyst of 18 (20 mol%) was applied to the 1,3-dipolar cydoaddition reaction between nitrone la and al-kene 8a. The only observable diastereomer resulting from the reactions was exo-9a... 

Modified PS by use of BF3-OEt2 catalyst had better properties comparised with virgin PS and other modified polymers. High thermostability and photosensitivity of modified PS compared with virgin PS are explained by the crosslinked structure of macromolecules formed during the processes of thermo- and phototreatment. 

Guo et al. [70,71,73] recently attempted to hydrogenate NBR in emulsion form using Ru-PCy complexes. However, successful hydrogenation can only be obtained when the emulsion is dissolved in a ketone solvent (2-butanone). A variety of Ru-phosphine complexes have been studied. Crosslinking of the polymer could not be avoided during the reaction. The use of carboxylic acids or first row transition metal salts as additives minimized the gel formation. The reactions under these conditions require a very high catalyst concentration for a desirable rate of hydrogenation. 

At the downstream of the extrusion process a suitable reaction catalyst, reactive diluent, e.g., crosslinking monomer, is fed into the molten polymer mix. 

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