Epoxidized novolac

The composition of an epoxide moulding material will greatly depend on the specific application, and this has been discussed at length. ". The resin may be of the epoxide novolac type and there will also be present hardeners, fillers (such as silica), a silane coupling agent, pigment, flame retardant and a wax release agent. 

Void-free phenolic networks can be prepared by crosslinking novolacs with epoxies instead of HMTA. A variety of difunctional and multifunctional epoxy reagents can be used to generate networks with excellent dielectric properties.2 One example of epoxy reagents used in diis manner is the epoxidized novolac (Fig. 7.34) derived from the reaction of novolac oligomers with an excess of epichlorohydrin. 

Figure 7.34 Reaction of phenol and epichlorohydrin to form epoxidized novolacs.

Epoxidized novolacs, 411 Epoxy -phenol networks, 411-416 properties of, 413-416 Epoxy-phenolic reaction kinetics of, 413 mechanism of, 411-412 Epoxy structures, 414 e-Caprolactam, 174... 

Figure 4.9 shows the lit of experimental results obtained for the epoxidized novolac DDS system, using Eq. (4.12) with X = 0.15 (Oyanguren et al., 1993b). As Acpmax could not be determined with enough precision, X was used as an adjustable coefficient. 

Figure 4.9 Tg as a function of conversion for an epoxidized novolac-DDS system (xmax = 0.80). The dashed line is the curve predicted using Eq. (4.12) with X =0.15 (Oyanguren and Williams, 1993b - Copyright 2001 - Reprinted by permission of John Wiley Sons, Inc.)...

BET Brunauer-Emmett-Teller method PEN-1 Soviet grade of epoxide-novolac... 

Generally these compositions contain an epoxy-novolac, a hardener, a catalyst, silica fillers, and an internal lubricant/mold release compound. Brom-inated epoxies and antimony trioxide are included to provide the required flame retardant characteristics. Other, unspecified additives are used to promote adhesion or to reduce corrosion rates. Because of their superior thermal capabilities and electrical properties, epoxidized novolacs are preferred over epoxy homopolymers. Near stoichiometric amounts of hardeners such as novolacs (Equation 1), anhydrides, and primary amines can be used to cure the resins in the presence of a catalyst. The linkages which are formed include ethers, esters, or secondary amines, respectively. 

Almost all of the early initiators absorbed well below 200 nm. It was Schle-singer who prepared diazonium salts with an extended spectral range, and with them, was able to polymerize various mono- and bifunctional epoxy monomers, furans, dioxycyclopentadiene, and oxycyclohexene, as well as oligomers and epoxidized novolacs. Dose sensitivities on the order of 15-30 mJ/cm have... 

The epoxy novolacs synthesized by reaction of novolacs with chloromethyloxiiane may contain traces of hydrolyzable and nonhydrolyzable organically boimd chlorine as impurities, which reduce not only the functionality of the epoxidized novolac but negatively affects the properties of the crosslinked products. Furthermore, traces of chloride and alkali metal ions also need to be carefully removed. In contrast to this, epoxy novolacs obtained by epoxidation of allylphenol are fiee of chloride and alkali metal ions. 

APTMOS 3-amino-propyl-trimethoxysilane, AuHFA fluoroalcohol-coated gold nanospheres, BBCB bisbenzocy-clobutene, BCB benzocyclobutene, CA cellulose acetate, CAB cellulose acetate-butyrate, CEE chloroethyl ether, DIMP diisopropyl methylphosphonate, DMMP dimethyl methylphosphonate, EPR epoxidized novolac, IPA isopropanol, OV-225 cyanopropyl methyl phenylmethyl silicone, OV-275 dicyanoallyl sihcone, PAAM polyallylamine hydrochloride, PAPPS propylaminopropyl polysiloxane, PDMS poly(dimethylsiloxane), PECH polyepichlorohydrin, PEG polyethylene glycol, PEI polyethyleneimine, PEO polyethylene oxide, PEVA polyethylene-co-vinyl acetate, PEUT poly(ether urethane), PHEMA poly(2-hydroxyethyl methacrylate), PIB polyisobutylene, PMMA poly(methyl methacrylate), PTMOS propyltrimethoxysilane, PVA polyvinyl alcohol, PVP polyvinylpyrrolidone, SXFA siloxanefluoroalcohol... 

For some highly crosslinked thermosetting polymers with rigid backbones, topological restrictions limit the maximum attainable conversion. For the reaction between epoxidized novolacs and cresol-based novolacs, a maximum conversion, Xmax= 0.80 was reported (Hale et al., 1991). A similar value of x ,ax was reported for the cure of an epoxidized novolac with 4,4 -diaminodiphenylsulfone (DDS) (Oyanguren and WilKams, 1993a). In these cases, partially reacted networks may be modeled as a random solution of reacted functionalities with a concentration equal to x/x ax... 

An example relating some of the features of nonisothermal cure discussed here is provided by Patel et al. (1989). These authors describe the dynamic mechanical behavior at constant heating rate of an epoxidized Novolac-anhydride system both uncured and at various stages of cure. The different degrees of cure were imparted by curing isothermaUy at the temperatures indicated on each curve. Samples coated on a wire-mesh support were char-... 

Figure 5.49. DMA data for an epoxidized novolac-anhydride system on wire mesh at 5 °C/min heating rate. Curves in (a) are resonant frequency or relative storage modulus. Curves in (b) are damping or relative loss tangent. [From Patel et al. (1989) reprinted with permission of the North American Thermal Analysis Society.]...

One of the most commonly used groups of epoxide resins is that comprised of the diglycidyl ethers, and these are made by reacting epichlorohydrin with a bisphenol such as bisphenol A. The preparation of the diglycidyl ether of bisphenol A has already been illustrated, but many other glycidyl ether type epoxides are of considerable importance. The preparation of an epoxide novolac type resin is shown below ... 

The diglycidylether of Bisphenol A (DGEBA) is where n = 0. With increasing n, the viscosity of the epoxy resin increased imtil it becomes a solid epoxy. At high molecular weight, the structure is basically the polyhydroxyether of Bisphenol A termed Phenoxy (PHE). Epoxidized novolacs (phenol-formaldehyde resins) are also employed in epoxy thermosetting systems. Epoxies are typically crosslinked with di- (or higher) amines (either aliphatic or aromatic). 

An important reaction for epichlorohydrin is the reaction between it and bisphenol A, 4,4 -isopropylidinediphenol, to produce the highly important epoxides that are usually referred to as the diglycidyl ethers of bisphenol A to distinguish them as a class from the cycloaliphatic epoxides, Novolac epoxides, and so on. 

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