Kinetic investigation of eggshell powders as biobased epoxy catalyzer

Degradation kinetics of epoxidized soybean oil composites filled with sisal fiber

“…TG plots at the heating rates 5, 10, 15, and 20°C and the deconvoluted peaks are displayed in Figure 7. The first stage of weight loss is associated with the degradation of unreacted MTHPA and DEH35 corresponding to 14% of the weight, being observed in the temperature range of ~115–220°C, these are low molecular weight compounds with lower thermal stability 37 . Sisal degradation occurs in the second stage of weight loss and it is divided into two phases: in the temperature range between ~220 and 320°C, attributed to the thermal decomposition of hemicellulose and lignin; and in the ~315–400°C range, attributed to the decomposition of cellulose and carbonaceous residue.…”

“…In the composites ESO/MTHPA/DEH35/S10 and ESO/MTHPA/DEH35/S30, the band at 900 cm À1 disappears at 200 C. In the investigated compounds, it is believed that the oxirane group reacted with zwitterions generated from the curing agent (MTHPA), promoting the ring opening and generating a reticulated network, a reaction scheme is shown in Figure 4. 9,[37][38][39] The gradual decrease of the absorbance bands at 1851 and 1772 cm À1 (attributed to the C-O anhydride bonds) characteristic of MTHPA is also observed, suggesting that the anhydride groups were opened, which shows that MTHPA reacted with the ESO epoxide group. The band intensity at 1707 cm À1 of ester carbonyl stretching gradually increases, due to the C-O bond between the anhydride and epoxy, there is also an increase in the band at 1161 cm À1 corresponding to C-O-C bonds of ester formed during the crosslinking process.…”

“…The first stage of weight loss is associated with the degradation of unreacted MTHPA and DEH35 corresponding to 14% of the weight, being observed in the temperature range of $115-220 C, these are low molecular weight compounds with lower thermal stability. 37 Sisal degradation occurs in the second stage of weight loss and it is divided into two phases: in the temperature range between $220 and 320 C, attributed to the thermal decomposition of hemicellulose and lignin; and in the $315-400 C range, attributed to the decomposition of cellulose and carbonaceous residue. The third stage of thermal degradation corresponds to ESO, and takes place in the range of 300-475 C. 45,46 Thermal degradation trends similar to these of the investigated composites in the present work were previously reported by Senthilkumar et al 34 and Benítez-Guerrero et al, 47 who analyzed biobased epoxy composites (SR greenpoxy 56) and sisal/hemp fibers, and composites with sisal (and also hot washed sisal fiber), respectively, a 3-stage thermal decomposition was reported and the sisal fiber decomposed in two stages.…”

Tailoring sustainable compounds using eggshell membrane as biobased epoxy catalyst

“…Nevertheless, it is worth of mention adding the eggshell membrane the epoxy curing develops completely, occurs below 300 °C, and no degradation phenomena due to the MTHPA decomposition are verified. Therefore, may be assumed that the eggshell membrane properly acted as epoxy catalyst, as well as suggested that the curing initiation occurs through the amines and carboxyl present in the membrane proteins, as illustrated in Figure 2 [17] .…”

“…Nevertheless, using membrane as a catalyst is still scarcely explored. Jaques et al [17] investigated the curing kinetics of epoxies adding eggshell (E) or membrane (M) as curing catalysts, it was applied Ozawa, Kissinger, Friedman isoconversional, Friedman model based and Málek to model the curing. The results showed that only the membrane presented potential application as cross-linking performer.…”