Anthony Maiorana

Thermoset bio-based diglycidyl ether of diphenolate esters (DGEDP) exhibit comparable mechanical properties as petroleum-derived diglycidyl ether of bisphenol A (DGEBA), while DGEDP is derived from levulinic acid, a safe and readily renewable feedstock. To determine the potential replacement of DGEBA as dielectric materials, a series of DGEDP-esters (i.e. methyl, ethyl, propyl and butyl esters) were synthesized and studied. Broadband dielectric spectroscopy revealed that DGEDP-propyl has the… Show more

Thermoset bio-based diglycidyl ether of diphenolate esters (DGEDP) exhibit comparable mechanical properties as petroleum-derived diglycidyl ether of bisphenol A (DGEBA), while DGEDP is derived from levulinic acid, a safe and readily renewable feedstock. To determine the potential replacement of DGEBA as dielectric materials, a series of DGEDP-esters (i.e. methyl, ethyl, propyl and butyl esters) were synthesized and studied. Broadband dielectric spectroscopy revealed that DGEDP-propyl has the highest dielectric constant in the series, comparable to DGEBA. Differences in the dielectric properties of DGEDP-esters is attributed to the interplay of segmental, small local, and side-chain motions on one hand and free volume and steric hindrance on the other. Show less

Herein a unique strategy for cellulose nanocrystal functionalization is presented in the form of surface functionalization of cellulose nanocrystals. Cellulose nanocrystals were prepared from acid hydrolysis of ramie fibers and then further subjected to amine functionalization with an amino trimethoxy silane (APTMS). The introduction of surface amine functionality to the cellulose nanocrystal allowed for an additional reaction with a biobased epoxy resin derived from diphenolic acid. The… Show more

Herein a unique strategy for cellulose nanocrystal functionalization is presented in the form of surface functionalization of cellulose nanocrystals. Cellulose nanocrystals were prepared from acid hydrolysis of ramie fibers and then further subjected to amine functionalization with an amino trimethoxy silane (APTMS). The introduction of surface amine functionality to the cellulose nanocrystal allowed for an additional reaction with a biobased epoxy resin derived from diphenolic acid. The resulting thermomechanical properties of epoxy nanocomposites with amine functionalized cellulose nanocrystal were on average more than 7 times improved. Specifically, the storage modulus at 160 °C increased from 19.5 MPa for the neat resin to 151.5 MPa for the composite with 10wt% APTMS modified CNC. The results reported herein demonstrate that amine functionalized cellulose nanocrystals provide excellent dispersion in epoxy resin systems and are a viable route to utilization of both biobased nanofillers and biobased epoxy resins.
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Abstract Biobased diglycidyl ethers of diphenolate (DGEDP) and monoglycidyl ether of
eugenol (GE) were synthesized and formulated as new type of biobased epoxy resins for
vacuum infusion processing with glass fiber mats. The processablity of these new biobased
formulations were benchmarked against two diglycidyl ether bisphenol A (DGEBA)
petroleum based resins. Compositions with 15wt% GE and 85wt% of either DGEDP-ethyl or
pentyl esters resulted in suitably viscosity and… Show more

Abstract Biobased diglycidyl ethers of diphenolate (DGEDP) and monoglycidyl ether of
eugenol (GE) were synthesized and formulated as new type of biobased epoxy resins for
vacuum infusion processing with glass fiber mats. The processablity of these new biobased
formulations were benchmarked against two diglycidyl ether bisphenol A (DGEBA)
petroleum based resins. Compositions with 15wt% GE and 85wt% of either DGEDP-ethyl or
pentyl esters resulted in suitably viscosity and gelation time for composite vacuum infusion molding. Show less

Modified cellulose nanocrystals were decorated with silver nanoparticles using a one-pot reduction method. In contrast to a quasi-uniform distribution of silver nanoparticles, we report on the interactions of non-contact nanoparticle clusters with significant line broadening and red shifts in the extinction spectra. The particle size and cluster distributions were examined using a transmission electron microscope. Monte Carlo random walk (MCRW) simulations of the extinction spectrum show that… Show more

Modified cellulose nanocrystals were decorated with silver nanoparticles using a one-pot reduction method. In contrast to a quasi-uniform distribution of silver nanoparticles, we report on the interactions of non-contact nanoparticle clusters with significant line broadening and red shifts in the extinction spectra. The particle size and cluster distributions were examined using a transmission electron microscope. Monte Carlo random walk (MCRW) simulations of the extinction spectrum show that the interacting silver nanospheres are organized in small, non-contact clusters. We observed that the MCRW optimization using the first-order iterative approximation to the self-consistent dipole field equations quickly approaches the observed localized clusters. Show less

Biobased epoxy nano-composites composed of untreated multi-wall-carbon-nanotubes (MWCNT) and diphenolic acid-derived biobased epoxy: diglycidyl ether of diphenolate n-butyl ester (DGEDP-Bu), were fabricated. Electrical, rheological, and mechanical percolation thresholds were compared between biobased and commercial bisphenol A (DGEBA) epoxy composites. For both epoxies, nanocomposites loaded with 0.05–0.2 wt % MWCNT's exhibited electrical and rheological percolation at 0.05 wt % and 0.2 wt %… Show more

Biobased epoxy nano-composites composed of untreated multi-wall-carbon-nanotubes (MWCNT) and diphenolic acid-derived biobased epoxy: diglycidyl ether of diphenolate n-butyl ester (DGEDP-Bu), were fabricated. Electrical, rheological, and mechanical percolation thresholds were compared between biobased and commercial bisphenol A (DGEBA) epoxy composites. For both epoxies, nanocomposites loaded with 0.05–0.2 wt % MWCNT's exhibited electrical and rheological percolation at 0.05 wt % and 0.2 wt % respectively. DMA and tensile results revealed that DGEDP-Bu composites exhibited equivalent or superior properties to DGEBA composites. With 0.2 wt % MWCNT's, DGEDP-Bu nanocomposites exhibited 68% higher electrical conductivity and a three-fold higher rheological yield stress than those made from DGEBA. Rheological characterization corroborated that continuous MWCNT networks are formed within epoxies between 0.1 and 0.2 wt % MWCNT's. Moreover, upon MWCNT loading, DGEDP-Bu demonstrates equal mechanical performance and better electrical conductivity than DGEBA. Show less

The curing kinetics of a family of biobased epoxies derived from n-alkyl diphenolate esters differing in ester side chain length were compared with diglycidyl ether of bisphenol A (DGEBA). Isothermal isoconversional analysis and Kamal–Sourour model fitting by differential scanning calorimetry (DSC) were utilized to obtain reaction constants. The biobased epoxides and DGEBA have reaction orders that are comparable while the autocatalytic rate constant of DGEBA was larger than those of the… Show more

The curing kinetics of a family of biobased epoxies derived from n-alkyl diphenolate esters differing in ester side chain length were compared with diglycidyl ether of bisphenol A (DGEBA). Isothermal isoconversional analysis and Kamal–Sourour model fitting by differential scanning calorimetry (DSC) were utilized to obtain reaction constants. The biobased epoxides and DGEBA have reaction orders that are comparable while the autocatalytic rate constant of DGEBA was larger than those of the biobased epoxies. As the n-alkyl side chain length of diphenolate esters increased, the autocatalytic rate constant decreased. Furthermore, the non-autocatalytic rate constant for DGEBA is smaller than that of the biobased epoxies. The cause for the difference in rate constants is discussed, and applications are assigned to the epoxies based on curing kinetics. Show less

In this work, a series of bio-based chemically recyclable epoxy resins were synthesized from n-alkyl bisferulate esters that do not activate human estrogen receptor alpha (ERα). Viscosities of corresponding glycidyl ether n-alkyl bisferulate resins, determined by steady shear rheology, range from 12–9.4 Pa s. Activation energies of flow range from 83–96 kJ mol−1 and are similar to the diglycidyl ether bisphenol A (DGEBA). Thermomechanical properties of diglycidyl ether n-alkyl bisferulate… Show more

In this work, a series of bio-based chemically recyclable epoxy resins were synthesized from n-alkyl bisferulate esters that do not activate human estrogen receptor alpha (ERα). Viscosities of corresponding glycidyl ether n-alkyl bisferulate resins, determined by steady shear rheology, range from 12–9.4 Pa s. Activation energies of flow range from 83–96 kJ mol−1 and are similar to the diglycidyl ether bisphenol A (DGEBA). Thermomechanical properties of diglycidyl ether n-alkyl bisferulate resins cured with isophorone diamine were governed by the length of α,ω-diols that link glycidyl ether ferulate units. That is, the glassy phase modulus and alpha transition temperatures range from 3400–2400 MPa (at 25 °C) and 40–53 °C (peak of E′′), respectively. Furthermore, the onset of thermal degradation (Td5%) varied from 331–300 °C. Chemical recycling of cured epoxy resins was performed by static immersion in 10 w/w sodium hydroxide aqueous solutions at 60 °C. Times required for complete conversion of cured resins to water-soluble degradation products was also α,ω-diol length dependent and varied from 5 to 65 h. Thus, diglycidyl ether of n-alkyl bisferulate resins provides a viable biobased alternative to BPA epoxy resins as well as the option of chemical degradability and recovery of fillers in composite applications. Show less

Adipic acid, a highly abundant chemical that can be produced from biomass, was used to prepare an aromatic-free epoxy resin. Synthesis of the diglycidyl adipate was performed by a one-step process using epichlorohydrin and by a two-step process comprising allylation and epoxidation. The viscosity of diglycidyl adipate is 25 mPa·s, which is 99% lower than the diglycidyl ether of bisphenol A (DGEBA). The storage modulus at 25 °C for cured diglycidyl adipate and DGEBA is 2000 and 3200 MPa… Show more

Adipic acid, a highly abundant chemical that can be produced from biomass, was used to prepare an aromatic-free epoxy resin. Synthesis of the diglycidyl adipate was performed by a one-step process using epichlorohydrin and by a two-step process comprising allylation and epoxidation. The viscosity of diglycidyl adipate is 25 mPa·s, which is 99% lower than the diglycidyl ether of bisphenol A (DGEBA). The storage modulus at 25 °C for cured diglycidyl adipate and DGEBA is 2000 and 3200 MPa, respectively. The alpha transition temperature through peak of the loss modulus and the peak of tan(δ), are 77 °C and 90 °C, respectively. Low-viscosity epoxy applications are discussed herein.
© 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016. Show less

The monofunctional glycidyl ether of eugenol (GE) was used as a reactive diluent for the diglycidyl ether of diphenolate n-pentyl ester (DGEDP-Pe). Viscosities of GE and DGEDP-Pe are 25 mPa.s and 11 Pa.s, respectively. Compositions GE/DGEDP-Pe epoxy resins with 5, 10, 15, 20, and 30 wt % GE were analyzed for viscosity reductions and, subsequently, cured with isophorone diamine. The glassy modulus of cured GE/DGEDP-Pe epoxy resins remained between 2000 and 3000 MPa. The glass transition… Show more

The monofunctional glycidyl ether of eugenol (GE) was used as a reactive diluent for the diglycidyl ether of diphenolate n-pentyl ester (DGEDP-Pe). Viscosities of GE and DGEDP-Pe are 25 mPa.s and 11 Pa.s, respectively. Compositions GE/DGEDP-Pe epoxy resins with 5, 10, 15, 20, and 30 wt % GE were analyzed for viscosity reductions and, subsequently, cured with isophorone diamine. The glassy modulus of cured GE/DGEDP-Pe epoxy resins remained between 2000 and 3000 MPa. The glass transition temperature decreased linearly, from 92 °C for neat DGEDP-Pe, with progressively higher loadings of GE to 53 °C at the highest GE loading of 30 wt %. The thermal stability decreased as GE loading increased with a maximum of 30 °C loss in the onset of degradation at 5 wt % mass loss. The role of GE as a reactive diluent is discussed and a range of loadings was determined to be suitable for a vacuum infusion epoxy resin system. Show less

A series of nanocomposites were prepared from graphene
platelets (GPL) and a flexible biobased epoxy thermoset matrix derived from
cashew nut shell liquid. The loading of GPL in the biobased thermoset matrix
ranged from 0.1 to 0.8 wt % and resulted in increased tensile strength and
Young’s modulus (17 to 33 MPa and 474 to 1700 MPa, respectively). Increases
in mode I fracture toughness for KIC and GIC ranged from 0.6 to 1.9 MPa·m1/2
and 906 to 1734 J/m2, respectively… Show more

A series of nanocomposites were prepared from graphene
platelets (GPL) and a flexible biobased epoxy thermoset matrix derived from
cashew nut shell liquid. The loading of GPL in the biobased thermoset matrix
ranged from 0.1 to 0.8 wt % and resulted in increased tensile strength and
Young’s modulus (17 to 33 MPa and 474 to 1700 MPa, respectively). Increases
in mode I fracture toughness for KIC and GIC ranged from 0.6 to 1.9 MPa·m1/2
and 906 to 1734 J/m2, respectively. Furthermore, dynamic mechanical analysis
revealed that GPL incorporation resulted in increases in the α-transition
temperature (peak of the loss modulus) from 27 to 50 °C and increases the
storage modulus from 1000 to 2000 MPa. Also, introduction of GPL increased
the onset of degradation (Td3%) for the biobased thermoset matrix by 30 °C.
Results of this work demonstrate that incorporation of graphene platelets
enhances all measured physical and thermal properties of the cashew nut shell
derived epoxy resin and enables higher performance applications. Show less

Cellulose nanocrystals (CNCs) were modified with natural di- and tricarboxylic acids using two concurrent acid-catalyzed reactions including hydrolysis of amorphous cellulose segments and Fischer esterification, resulting in the introduction of free carboxylic acid functionality onto CNC surfaces. CNC esterification was characterized by Fourier transform infrared spectroscopy, 13C solid state magic-angle spinning (MAS), and conductometric titration experiments. Average degree of substitution… Show more

Cellulose nanocrystals (CNCs) were modified with natural di- and tricarboxylic acids using two concurrent acid-catalyzed reactions including hydrolysis of amorphous cellulose segments and Fischer esterification, resulting in the introduction of free carboxylic acid functionality onto CNC surfaces. CNC esterification was characterized by Fourier transform infrared spectroscopy, 13C solid state magic-angle spinning (MAS), and conductometric titration experiments. Average degree of substitution values for malonate, malate, and citrate CNCs are 0.16, 0.22, and 0.18, respectively. Despite differences in organic acid pKa, optimal HCl cocatalyst concentrations were similar for malonic, malic, and citric acids. After isolation of modified CNCs, residual cellulose coproducts were identified that are similar to microcrystalline cellulose based on SEM and XRD analysis. As proof of concept, recycling experiments were carried to increase the yield of citrate CNCs. The byproduct was then recycled by subsequent citric acid/HCl treatments that resulted in 55% total yield of citrate CNCs. The crystallinity, morphology, and substitution of citrate CNCs from recycled cellulose coproduct is similar to modified citrate CNCs formed in the first reaction cycle. Thermal stability of all modified CNCs under air and nitrogen resulted in T10% and T50% values above 256 and 323 °C, respectively. Thus, they can be used for melt-processing operations performed at moderately high temperatures without thermal decomposition. Nanocomposites of poly(vinyl alcohol) with modified CNCs (1 wt % malonate, malate, citrate, and unmodified CNCs) were prepared. An increase in the thermal decomposition temperature by almost 40 °C was obtained for PVOH-citrate-modified CNC nanocomposites. Show less