Fourier transform infrared analysis of polycarbonate/epoxy mixtures cured with an aromatic amine

Abstract

ABSTRACT:In our previous article, we established that polycarbonate (PC) can react with the diglycidyl ether of bisphenol-A (DGEBA) at 200ЊC through transesterification and addition reactions, resulting in degraded PC chains with phenolic end groups and also in PC/DGEBA copolymers. However, these reactions can be minimized or eliminated at lower temperatures, below 160ЊC. In this article, Fourier transform infrared analysis (FTIR) was used to study the curing kinetics of epoxies in the presence of PC. The curing agent was an aromatic amine, diaminodiphenyl methane (DDM). FTIR results showed that the presence of a small amount of PC promoted the amineepoxide reactions, probably due to the catalytic effect of the phenolic end groups in the PC chains. However, the PC did not alter the epoxy cure reaction mechanism. Two different blending processes were used to premix the PC and DGEBA, namely, solutionblending and melt-blending processes, in order to give different extents of prereactions. If a solution-blending process was used, PC tended to undergo crystallization during an early stage of cure. When a melt-blending process was used, no melting peak was observed in the thermograms of the differential scanning calorimeter (DSC) for the modified epoxies; PC chains bonded to DGEBA during prereaction at 200ЊC, thus inhibiting the crystallization of PC during cure.

Investigation of Cure Reaction, Rheology, Volume Shrinkage and Thermomechanical Properties of Nano-TiO2 Filled Epoxy/DDS Composites

“…On the other hand, the strong absorbances at 1625 and 3367 cm −1 of the NH 2 groups from the DDS also reduce with curing time and almost disappear after 90 minutes, again indicating the time for complete epoxy/amine conversion. However, an evaluation of the curing kinetics is difficult since during polymerization the spectrum between 3100 and 3600 becomes complex; the unreacted amines and hydroxyl groups overlap to a broad band and the absorbance at 1625 cm −1 forms after short curing time a shoulder to the strong absorption at 1594 cm −1 caused by phenyl ring [40]. Therefore, the rate of epoxy/amine polymerization was estimated only by following the loss of epoxide band intensity with respect to cure time.…”

Effective enhancement of poly(bisphenol-A carbonate) crystallinity with polyamide-66 ionized nucleation through ion-dipole interactions coupled with plasticization

“…For instance, common PC plasticizers include organic solvents such as acetone [20][21][22], carbon tetrachloride [23,24], tetrahydrofuran [24,25], ethyl acetate [26], chloroform [27], and supercritical CO 2 (SCCO 2 ) [28,29] can enhance the free volume and movement of PC molecular chains, and promote the ordering of molecular chanis into regular helica segments, which serve as crystal nuclie to initiate PC crystalization. Similarlly, flexible polymers such as polycaprolactone [30,31], polyethylene glycol [32], epoxy resins [33], esters such as diallyl phthalate [34], tributyl citrate [35,36], and small molecule liquid crystals such as cholesterol nonanoate (CN) [37,38] enhance the flexibility of PC to alevate the crystal growth. In addition, plasticizers are coupled with nucleating agents to achieve the modification in a greener, efficient, and environmentally friendly way.…”