Phenolic-Epoxy Blends

Aging site Epoxy novolac Nitrile phenolic Vinyl phenolic Epoxy phenolic 

Strength retention (%) after 6 years for aluminum double-overlap joints. Stress level 20% (vinyl phenolic 15%). 

---

Applications of NBR adhesives can be divided in three groups (1) solely nitrile rubber (2) nitrile rubber/phenolic blends (3) nitrile rubber/epoxy blends. 

Heat resistant resin compositions based on BMI/aminophenol-Epoxy blends are achieved by reacting a BMI/p-aminophenol 1 1 adduct with epoxy resin (62). Both the secondary amine and phenol functionality may react with the epoxy resin and subsequently cure through an imidazole catalyst. Imidazole catalysts promote both the epoxy/phenol reaction and the anionic maleimide crosslinking. The formation of a 1 2 BMI/aminophenol adduct, as in Fig. 20, is claimed in a patent (63). The hydroxy terminated BMI/aminophenol adduct is an advantageous curing agent for epoxy resins when high temperature performance is desired. 

Alloyed blends consisting of epoxy-phenolic, epoxy-nylon, and epoxy-polysulfide adhesives... 

Typically tape or film epoxy adhesives are modified with synthetic thermoplastic polymers to improve flexibility in the uncured film and toughness in the cured adhesive. Epoxy resins can also be blended with phenolic resins for higher heat resistance. The most common hybrid systems include epoxy-phenolics, epoxy-nylon, epoxy-nitrile, and epoxy-vinyl hybrids. These hybrid film adhesives are summarized in Table 13.2, and structural properties are shown in Table 13.3. 

Keywords. Cyanate ester, Polycyanurates, Phenolic-triazine, Polymer matrix composite, Cure kinetics, Polymer blends, Cyanate-epoxy blend, Bismaleimide-triazine resins, Aerospace structure... 

A second generation of phenolic dispersions, patented by J. S. Fry (33). involved the post dispersion of phenolic resins in a mixture of water and water-miscible solvents. To conform with air pollution regulations, the solvent was held to 20 volume %, or less, of the volatiles. A heat-reactive phenolic resin dispersion (34) and a phenolic-epoxy codispersion have become commercially available based on the above technology. Supplied at 40-45% solids, these products, which have a small particle size (0.75-1.0 ym), are better film formers than the earlier dispersions. Used alone or in blends with other waterborne materials, corrosion-resistant baking coatings may be formulated for coil coating primers, dip primers, spray primer-surfacers, and chemically resistant one-coat systems. Products of this type are also tackifiers for acrylic latexes, and such systems have been employed as contact, heat seal, and laminating adhesives for diverse substrates. 

In this section, the future developments will be discussed that might be expected in commercial polymer blends comprising at least one of the constituents from the class of commodity polymers. Generally, the commodity polymers considered include polyethylene (and variants LDPE, HOPE, LLDPE, VLDPE and ethylene copolymers), polypropylene (PP), ethylene-propylene rubber (EPR and EPDM), polyvinylchloride (PVC), polystyrene (PS), ABS, and poly(methyl methacrylate) (PMMA). Elastomeric polymers commonly used in tire and associated applications are important in polymer blends as many tire component constructions employ polymer blends to maximize performance. However, these will not be considered here. Thermosetting polymers which could be classified as commodity polymers (urethane, phenolics, epoxies) will also not be covered, but will be mentioned in a later section discussing new polymer blends designed for specific applications (e.g., water based coatings). 

Resins with improved flame-retarding properties were obtained from BMI containing phosphorus cured with different kinds of agents (Tsai et al. 2009) or by blending a commercial phenolic epoxy resin containing phosphorous and melamine phenol formaldehyde novolac with various amounts of BMI (Chiang et al. 2013). 

Laminates contain different reinforcement materials (woven/non-woven glass/organic fibers, expanded PTFE, etc.), resin types (phenolic, epoxy, cyanate ester, polyimide, BT, etc.), resin formulations (blended, functionality, etc.), hardeners (dicyanodiamide [dicy],phenol-novolak, cresol-novolak, p-aminophenol, isocyanurate, etc.), and sometimes fUler particles (ceramic or organic). The ratio of aU of these individual components can vary widely.To define a test strategy for laminates, it is important to understand the different main components of the materials as well as the conditions during manufacturing, as these wiU have a large influence on their properties and quality. 

Various types of polymeric modifiers have been researched as possible candidates to impart impact resistance of epoxy resins. Sometimes, properties other than impact resistance are to be modified. For example, for adhesive applications, the main focus is usually on improving shear and peel strength. In these cases, epoxies blended with elastomeric nitrile rubbers (Hycar CTBN, B.F. Goodrich), phenolics, nylons (soluble types such as DuPont Zytel-61), and pol5nirethanes are commonly used. For impact modification, there are several approaches, as discussed below. 

These relatively expensive adhesives account for only a small fraction of the current usage of structural adhesives. They are used primarily for military applications designed for service between 149 °C and 260 °C. Epoxy-phenolics are blends of thermosetting phenolic and epoxy resins. They are supplied as viscous liquids, which may contain solvents, or as glass-cloth or fabric-supported films or tapes. They are often modified with fillers and thermal stabilizers. 

Benzene, toluene, and xylene are made mosdy from catalytic reforming of naphthas with units similar to those already discussed. As a gross mixture, these aromatics are the backbone of gasoline blending for high octane numbers. However, there are many chemicals derived from these same aromatics thus many aromatic petrochemicals have their beginning by selective extraction from naphtha or gas—oil reformate. Benzene and cyclohexane are responsible for products such as nylon and polyester fibers, polystyrene, epoxy resins (qv), phenolic resins (qv), and polyurethanes (see Fibers Styrene plastics Urethane POLYiffiRs). 

The most commonly used stabilizers are barium, cadmium, zinc, calcium and cobalt salts of stearic acid phosphorous acid esters epoxy compounds and phenol derivatives. Using stabilizers can improve the heat and UV light resistance of the polymer blends, but these are only two aspects. The processing temperature, time, and the blending equipment also have effects on the stability of the products. The same raw materials and compositions with different blending methods resulted in products with different heat stabilities. Therefore, a thorough search for the optimal processing conditions must be done in conjunction with a search for the best composition to get the best results. 

The production test showed that the epoxy phenolic enamel was the preferred enamel for coating tinplate containers used in packaging irradiation-sterilized ham and beef. The preferred end-sealing compound for the same application was the blend of cured and uncured isobutylene-isoprene copolymer. 

The evaluation of the components of the tinplate container showed that the preferred enamel for irradiation processing was the epoxy phenolic the preferred end-sealing compound was the blend of cured and uncured isobutylene—isoprene copolymer. Component testing of tinplate and solder for possible changes in mechanical properties, microstructure, and corrosion resistance indicated that the radiation caused... 

A variety of polymers, both thermosets as well as thermoplastics, can be blended and coreacted with epoxy resins to provide for a specific set of desired properties. The most common of these are nitrile, phenolic, nylon, poly sulfide, and polyurethane resins. At high levels of additions these additives result in hybrid or alloyed systems with epoxy resins rather than just modifiers. They differ from reactive diluents in that they are higher-molecular weight-materials, are used at higher concentrations, and generally have less deleterious effect on the cured properties of the epoxy resin. 

Epoxy-phenolic adhesives are made by blending epoxy resins with phenolic resins to improve the high-temperature capabilities of the standard epoxy resins. Developed in the early 1950s, they were the first high-temperature epoxy adhesives to become commercially available.2,3... 

These adhesives are generally based on blends of solid epoxy resins with resole-type phenolic resin. The epoxy resin component is often not the predominant component in the blend, depending on the end properties required. Phenolics are compatible with epoxy resins and will react through the phenolic hydroxyl group. The amount of phenolic resin used is generally much greater than that required to crosslink with the epoxy, so one can debate whether (1) the epoxy toughens the phenolic adhesive or (2) the phenolic increases the heat resistance of the epoxy. 

Several hybrid epoxy emulsions have been commercially prepared. An epoxy emulsion blended with waterborne aliphatic urethanes exhibited peel strength on aluminum of 10 lb/in—1.5 times greater than with the polyurethane itself. The optimum concentration of urethane in the final emulsion was about 50 percent by weight.13 Epoxy-phenolic dispersions have also been developed to provide waterborne adhesive systems with high glass transition temperature and chemical resistance. 

Epoxy resin Poly-(diallyl-phthalate) ABS PC-ABS blend Brominated bisphenol A Dechlorane Plus Octabromodiphenyl oxide Brominated phenol, triphenyl phosphate 0.5 mg sample at 950°C DB-5 fused silica capillary, 30 m x 0.25 mm i.d., 1.0-pm film 40°C for 4 min, ramp at 10°C/min to 320°C, hold for 18 min MS (El, 15-650 mass range) Injector T = 300°C detector T = 300°C 30/1 injection spUt [49]a,e... 

The curing behavior of an epoxy system was investigated by dynamic differential scanning calorimetry (DSC). The epoxy resin (R) was a blend of bisphenol-A-diglycidylether (90%) and a monoepoxide (10%). The hardener (H) was a triethylene-tetramine-phenol-formaldehyde adduct containing 2% free phenol. 

---