Incorporation into epoxy resins

Ghutta, N.K., Treatment of Spent Ion Exchange Resins by Incorporation into Epoxy Resins, Middle Eastern Regional Radio Isotope Centre for Arab Countries, Cairo (1997)... 

Oligomeric phosphoric/phosphonic anhydrides can be incorporated into epoxy resins to make prepolymers or used as curing agents (184-186). 

Selenium-75 121 days 0.14, 0.27, 0.28 2.0 0.19 + Medium Frigerio and Eisler lower (1%8) Incorporated into epoxy resin for tag or implant. 

Branched copolymers of PDMS and poly(caprolactone) have been prepared as shown in equation 13. They were incorporated into epoxy resin via reaction at the terminal hydroxy groups and acted as toughening agents, with a three-fold increase in impact strength being observed with 5 wt% of 36 present. The siloxane phases were in the range of 10-20 mn, resulting in an optically clear material ... 

Commercial epoxy adhesives are composed primarily of an epoxy resin and a curing agent. Various additives and modifiers are added to the formulation to provide specific properties. Example trade names and suppliers of these ingredients are included in App. A. The curing agent may be incorporated into the resin to provide a single-component adhesive, or else it may be provided in a separate container to be mixed into the resin immediately prior to application. 

Over the past several decades, significant advances have been made in developing epoxy-based adhesives having improved performance over these early adhesive systems. These improvements were made possible by (1) the incorporation of toughening additives into epoxy resin formulations and (2) the use of multifunctional epoxy resins primarily for high-temperature applications. These innovations are discussed in later chapters. 

It is made by dimerizing cyanamide in basic aqueous solution, and is a colorless solid melting at 208°C. Dicyandiamide is soluble in polar solvents, but at room temperature is insoluble in bisphenol A epoxy resins. It can be made into a very fine powder and milled into epoxy resins to form stable dispersions. Because the dicy is insoluble in the epoxy, the only possible reaction sites are at the particle surfaces. Although some reaction certainly occurs over a short time, the adhesives easily can have a useful shelf life of six months. On heating to about 150°C, the dicyandiamide becomes soluble in the epoxy resin, and the adhesive polymerizes rapidly. Cure can be accelerated by incorporation of tertiary aromatic amines or substituted ureas. 

Incorporation of monofunctional epoxy POSS into an amine-cured epoxy network increased and broadened the Tg without changing the crosslink density and enhanced the thermal properties. Additionally, it was found that the thermal and thermal-mechanical properties of resultant styrene-POSS vinylester resin nanocomposites were dependent on the percentage of POSS incorporated into the resin [171]. Over a range of POSS incorporations, the Tg of the copolymers changed very little, but the flexural modulus increased with increasing POSS content. 

Incorporation of the above m-brominated phenolics into epoxy resin was accomplished either by the thermally catalyzed phenolic hydroxyl - epoxy reaction or by the caustic catalyzed reaction (U). The reactions are depicted as follows ... 

Although the m-bromo phenol containing epoxy resin exhibits unusual stability, the chemistry for the incorporation of these phenolics into epoxy resin involves opening of the epoxy ring which eventually reduces the epoxy content of the final resin. Reduction of the glass transition temperature by 15-20° C was observed. 

The incorporation of elastomers into epoxy resins has been an active area of research over the past decade (1-11). The primary reason for this interest has been the improved toughness of the modified materials. We have limited our work to the carboxy-terminated butadiene-acrylonitrile copolymers (CTBN) produced by... 

It is a Lewis acid t e catalyst, which initiates the homopolymerization of epoxy resins that predominantly form ether linkages [25]. The complexes are normally used at 3-5 phr and when used as an accelerator in systems involving anhydrides or amines, 1 phr or less. At room temperature, it is stable when mixed into epoxies, resin soluble salt that has essentially no catalytic activity. Due to this latency, most resin systems incorporating BF3MEA can be stored at room temperature for several months without any appreciable change in viscosity. The effect of BF3MEA on the gel time of an 828/DDS resin system at different temperatures is shown in Figure 13.3. 

Jash and Wilkie [86] reported that even when the fraction of clay was as low as 0.1 wt% the PBQiR in a cone calorimeter was lowered by 40 %. Lee et al. [87] demonstrated that incorporation of 6, 8 and 10 wt% of MMT into epoxy resin increased linearly the char yield firom 9.1 to 15.4 % reducing the thermal degradation of the epoxy matrix. Nazare et al. [88] studied the flammability properties of unsaturated polyester resin with nanoclays using cone calorimetry. The authors verified that the incorporation of 5 wt% of nanoclays reduces the PHRR by 23-27 % and THR values by 4-11 %. While incorporation of condensed-phase flame retardants (such as ammonium polyphosphate, melamine phosphate and alumina trihydrate) reduce the PHRR and THR values of polyester resin, the inclusion of small amounts of nanoclay (5 % w/w) in combination with these char promoting flame retardants causes total reductions of the PHRR of polyester resin in the range 60-70 %. Ammonium polyphosphate, in particular and in combination with polyester-nanoclay hybrids show the best results compared to other flame retardants. 

Novolac resins have been widely used in many applications such as adhesives, coatings, construction, and composite matrices in the aerospace and electronic industries. This is due to their high strength, excellent flameretardant, low cost, good chemical and corrosion resistance and good dimensional stability [19-21]. Elastomeric and thermoplastic modifiers have been successfully incorporated into epoxy networks to improve their fracture energies and impact strengths [22],... 

The thermal expansion of plastics can be increased by the incorporation of reinforcing agents or fillers into the formulation. Thns, the incorporation of ceramic powder filler into polytetraflnroethylene (PTFE) rednces the coefficient of thermal expansion. On the other hand, the incorporation of 20% glass fiber into epoxy resins will increase the coefficient of cubical expansion from 0.5 mn/mn/°C x 10" to 2.0 mn/mn/°C x 10. Reinforcanent of perfluoroalkoxyethylene improved the heat distortion temperature at 0.45 MPa from 24 C to lOO C and at 1.8 MPa from 30°C to 58°C. This was accompanied by a nominal increase in tensile strength. 

The incorporation of glass fiber into epoxy resins improves the tensile strength from as low as 34 to 68 MPa (Table 3.1), accompanied by a reduction of flexural modulus from 3 to 1.1 GPa (Table 3.2). 

Kaya et al. [138] found that the incorporation of organically modified clay into epoxy resins improved mechanical properties of the nanocomposites. 

The incorporation of silica into epoxy resins has little effect on tensile strength. The tensile strength of reinforced epoxy resin is 30-84 MPa, compared to values of 68-72 MPa for silica-reinforced polymer. The flexnral modulus falls from 80 GPa for the unreinforced polymer to 15 GPa for the reinforced polymerm while elongation at break remains virtually unchanged. 

Popovics et showed that the incorporation of epoxy resin into... 

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