Bio-based high performance epoxy-anhydride thermosets for structural composites: The effect of composition variables

Abstract

Please cite this article as: Adlina Paramarta, Dean C. Webster, Bio-based high performance epoxy-anhydride thermosets for structural composites: The effect of composition variables, (2016), AbstractThe structure-property relationships of a designed series of anhydride-cured epoxidized sucrose soyate (ESS) thermosets were studied. Epoxidized sucrose soyate is a novel bio-based epoxy resin derived from sucrose and soybean oil fatty acids, and it contains an average of 12 epoxy functional groups per molecule. This epoxy resin was crosslinked with methyl hexahydrophthalic anhydride to form polyester thermosets with high crosslink density, and a zinc-complex catalyst was used. In this study, the impact of composition variables-anhydrideto-epoxy molar ratio and catalyst amount-on the chemical, mechanical, and thermal properties of the thermosets were examined. All of the thermoset samples had very high gel fraction, which indicated excellent network connectivity. Samples made using an equimolar ratio of anhydrideto-epoxy groups had lower conversion of functional groups as shown by the somewhat lower gel fraction and higher moisture absorption. Analysis of the thermomechanical and tensile properties of the thermosets suggests that there is a factor interaction between anhydride-toepoxy molar ratio and catalyst amount. Furthermore, the results suggest that the molecular networks of the thermoset samples are fairly complex due to the simultaneous competing reactions between catalyst-initiated epoxy-anhydride, hydroxyl-initiated epoxy-anhydride, and epoxy homopolymerization.

Thermal and Flammability Characteristics of Blended Jatropha Bio-Epoxy as Matrix in Carbon Fiber–Reinforced Polymer

“…In addition, the width of the tan delta peak curvature might suggest the degree of homogeneity of the network. Paramarta et al and Pan et al also found the same pattern for bio-based thermosets, whereby a broader peak and a narrower peak was due to a higher catalyst amount in the blended polymer [2,34].…”

“…DMA revealed viscoelastic properties such as the glass transition temperature, the crosslink density, and the temperature dependence of the storage modulus, the loss modulus, and the tan delta of the epoxy and the jatropha bio-epoxy [2]. The graphs of the DMA test are shown in Figure 4 for Tan Delta, Figure 5 for Storage Modulus, and Figure 6 for Loss Modulus.…”

Cardanol‐Based Epoxy Monomers for High Thermal Properties Thermosets

“…The lower reactivity of internal epoxies compared to terminal ones are well‐known in the literature, however, anhydrides are known to easily open these epoxy moieties . This is the reason why the epoxies were cured with 4‐methylcyclohexane‐1,2‐dicarboxylic anhydride (MHHPA), which is a common anhydride used in epoxy‐anhydride thermosets (Scheme ) . MHHPA was also chosen for its liquid state at room temperature, as it allows for a homogeneous system, whereas most anhydrides are solids at room temperature and thus the mixing process is highly complicated.…”

“…However, all of these triglycerides exhibit similar structures with long flexible chains which provide low thermal or mechanical properties induced by a low crosslinking density and T g . Recently, Webster et al have described the sucrose soyate, a new bio‐based epoxy monomer which contains a sucrose backbone, inducing high rigidity and T g to the final thermosets . However, aromaticity is highly desired in epoxy networks in order to confer high thermal and mechanical properties to the final materials.…”

Vinyl Ester Resin Modified with Acrylated Epoxidised Soybean (AESO) and Linseed (AELO) Oils: Effect of Additional Urethane Crosslinking

“…According to NMR spectroscopic results the acryl/epoxy groups' ratio was at about 30/70% for both oils. It is noteworthy, that by contrast to epoxidation of plant oils, their subsequent acrylation is never complete 12,32 .…”