Effect of curing schedule

Table 2.10 Effect of cure schedule on Tg and CTE for an epoxy adhesive ...

The values of Poisson s ratio for some polymeric materials are shown in Table I. The stress-strain characteristics for several cured commercial structural adhesives were determined by Schjeldrup and Jones. These workers found that the modulus, at room temperature, for epoxy-based commercial adhesives varied in the range 322-375 ksi, while the ultimate stresses varied from 6,050 to 7,853 ksi and the ultimate strains varied from 2.4 to 15.6%. Sancaktar et al. investigated the effect of cure schedule on the tensile properties of a commercial structural adhesive. They found that the ultimate stress and modulus were higher for a longer, lower-temperature cure... 

Hamerton Ian, Tang Winnie, Anguita Jose V., and Silva S. Ravi P. Towards the rational design of polymers using molecular simulation Predicting the effect of cure schedule on thermo-mechanical properties for a cycloaliphatic amine-cured epoxy resin. React. Funct. Polym. 74 no. (2014) 1—15. 

Effect of Curing Time and Temperature on Tg and Degree of Cure. Samples having different H/R compositions were also cured with schedule B. The dependence of Tg on composition is shown in Figure 3 (open squares). The same samples were subsequently heated a second time in the calorimeter to determine the Tg s (closed squares) of the now fully cured samples (no measurable reaction enthalpy). The Tg s of these samples are the same as under schedule A (solid line). 

To determine the effect of the curing schedule upon the thermal stress development, a 0% excess MDA sample was made by first B-stage curing (2 hrs at 80°C) the sample, cutting it into the beam dimensions and then placing it in the apparatus. The deflection of the beam was measured during the remainder of the curing schedule (2 hrs at 150°C and 2 hrs at 180°C). 

The purpose of the study was a) to determine the effect of relative resin/hardener composition and ambient and elevated temperature curing schedules on the glass transition temperature, Tg, and on the degree of cure of the epoxy system, and b) to evaluate the agreement between the calculated degree of cure using the nth-order kinetic equation (1.1) (1, 2, 3) and the measured degree of cure. 

With the help of these phase diagrams, it is now possible to define different precuring and postcuring schedules. The effects of the curing process on the final morphologies are presented elsewhere (19). 

The mixing procedure, preparation conditions and cure schedule all have a profound effect on the mechanical properties of the adhesives and, consequently, will affect their durability [20, 73]. Because of this, expeditious on-site tests should be conducted to detect possible deficiencies. A number of test methods have been proposed by the CEN/TC193/SC1/WG11) in the pre-standard Adhesives for on-site assembling or restoration of timber structures — on-site acceptance testing . This... 

---