Epoxy resin Conventional

Sufficient titanate leads to a fully hardened polymer. Using only enough titanate to react with free hydroxyls, the resin may subsequently be cured at lower cost with conventional cross-linking agents. The titanated epoxy resin has a low power factor, which is important in electrical appHcations, eg, potting components and insulation (see Embedding). Titanates improve adhesion of metals to epoxies. 

The bisphenol A-derived epoxy resins are most frequendy cured with anhydrides, aUphatic amines, or polyamides, depending on desired end properties. Some of the outstanding properties are superior electrical properties, chemical resistance, heat resistance, and adhesion. Conventional epoxy resins range from low viscosity Hquids to soHd resins. 

Bisphenol F Resin. Bisphenol F [2467-02-9] epoxy resin is of the same general stmcture as the epoxy phenol novolaks. Bisphenol F is 2,2Emethylene bisphenol. Whereas the epoxy phenol novolaks vary from viscous Hquids to soHd materials, the bisphenol F resin has a low viscosity (ca 4 Pa-s (40 P)) and 165 epoxy equivalent weight. Its n value (degree of polymerization) is about 0.15 and crystallization, often a problem with low viscosity conventional bisphenol A resins, is reduced with the bisphenol F resin. 

Owing to relatively low viscosity, these resins offer advantages for 100% soHds (solvent-free) systems. Higher filler levels are possible because of the low viscosity. Faster bubble release is also achieved. Higher epoxy content and functionaHty of bisphenol F epoxy resins can provide improved chemical resistance compared to conventional epoxies. 

In recent years, proprietary catalysts for advancement have been incorporated in precataly2ed Hquid resins. Thus only the addition of bisphenol A is needed to produce soHd epoxy resins. Use of the catalysts is claimed to provide resins free from branching which can occur in conventional fusion processes (10). Additionally, use of the catalysts results in rapid chain-extension reactions because of the high amount of heat generated in the processing. 

The higher molecular-weight soHd epoxy resins are used in formulations that usually consist of a resin, hardener, reinforcing filler, pigments, flow control agents, and other modifiers. In addition to using conventional hardeners in these formulations, epoxy resins can also be hardened with other resins, ie, acryhcs or polyesters. 

RPLC-PDA is frequently used for quality control, such as the determination of free Irganox 1098 in PA4.6 (at 278 nm after dissolution/precipitation), of free Irganox 1010/1076 in PP (at 278 nm after extraction with MTBE, thus avoiding dissolution of polymer waxes), of Luperco 802 in PP (at 218 nm, after extraction with HCC13), and of Tinuvin 122 in HDPE (at 225 nm as diol). The advantages of the use of HSLC over conventional LC in QC of plastics and additives have been demonstrated, e.g. for AOs in PE, mixed phthalate esters and residual terephthalic acid in PET and partially cured epoxy resins [557],... 

B-AP pyrolants made with CTPB are cured with epoxy resin as in the case of conventional AP-CTPB composite propellants. The mixture ratio of large-sized AP particles (200 pm in diameter) and small-sized particles (20 pm in diameter) is 0.30/ 0.70. The mass fraction of boron is variously 0.010, 0.050, 0.075, or 0.150, and the diameter of the boron particles, d, is either 0.5 pm, 2.7 pm, or 9 pm. 

This structure has superior water-resistant properties in comparison to conventional polyols used for PU synthesis. Room temperature cures are easily obtained with typical urethane catalysts. Short chain diols, fillers and plasticizers may also be used in their formulations in order to vary physical properties. Formulations usually with NCO/OH ratio of 1.05 are used for this purpose. Such urethanes are reported to be flexible down to about -70 °C. HTPB is regarded as a work horse binder for composite propellants and PBXs. HTPB also successfully competes with widely used room temperature vulcanizing (RTV) silicones and special epoxy resins for the encapsulation of electronic components. HTPB-based PUs are superior in this respect as epoxy resins change their mechanical properties widely with temperature. 

Commercial cylindrical quartz cells can be adapted for gas-phase work as illustrated in Fig. 9.18. Such a cell finds use in the near infrared for the determination of overtone vibrational frequencies, and also in visible and ultraviolet spectroscopy. A much less expensive cell which is adequate for most gases may be constructed from Pyrex along the lines of the cell shown in Fig. 9.18. Quartz windows may then be attached by epoxy resin. A cell which is filled from a conventional vacuum line will generally contain mercury vapor which absorbs at 2537 A. Once the origin of this absorption is recognized, it causes little difficulty because of its narrow bandwidth. 

A rare example of cationic polymerization of emulsified epoxy resins has been reported by Walker et al.973 Polymerization of water emulsion of epoxy resins with a variety of superacids (triflic acid, HCIO4, HBF4, HPF6) results in polyols with two glycidyl units (294) in contrast to commercial epoxy resins with one unit separating the aromatic moieties. The level of residual glycidyl ether and Bisphenol-A units is also much lower than in conventional epoxy resins. 

Schartel B, WeiB A, Mohr F, Kleemeier M, Hartwig A, Braun U. Flame retarded epoxy resins by adding layered silicate in combination with the conventional protection layer building flame retardants melamine borate and ammonium polyphosphate. J. Appl. Polym. Sci., 2009, submitted. 

---