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In order to reduce the dependency of resin synthesis on petroleum resources, vanillyl alcohol which is a renewable material that can be produced from lignin has been used to synthesize bioepoxy resin. Although it has been widely reported that the curing reaction and properties of the cured epoxies can be greatly affected by the molecular structure of the curing agents, the exact influence remains unknown for bioepoxies. In this study, four aliphatic amines with different molecular structures and amine functionalities, namely triethylenetetramine (TETA), Tris(2-aminoethyl)amine (TREN), diethylenetriamine (DETA), and ethylenediamine (EDA), were used to cure the synthesized vanillyl alcohol–based bioepoxy resin (VE). The curing reaction of VE and the physicochemical properties, especially the thermomechanical performance of the cured bioepoxies with different amine functionalities, were systematically investigated and compared using different characterization methods, such as DSC, ATR–FTIR, TGA, DMA, and tensile testing, etc. Despite a higher curing temperature needed in the VE–TETA resin system, the cured VE–TETA epoxy showed a better chemical resistance, particularly acidic resistance, as well as a lower swelling ratio than the others. The higher thermal decomposition temperature, storage modulus, and relaxation temperature of VE–TETA epoxy indicated its superior thermal stability and thermomechanical properties. Moreover, the tensile strength of VE cured by TETA was 1.4~2.6 times higher than those of other curing systems. In conclusion, TETA was shown to be the optimum epoxy curing agent for vanillyl alcohol–based bioepoxy resin.
Zhenyu Wang; Pitchaimari Gnanasekar; Sandeep Sudhakaran Nair; Songlin Yi; Ning Yan. Curing Behavior and Thermomechanical Performance of Bioepoxy Resin Synthesized from Vanillyl Alcohol: Effects of the Curing Agent. Polymers 2021, 13, 2891 .
AMA StyleZhenyu Wang, Pitchaimari Gnanasekar, Sandeep Sudhakaran Nair, Songlin Yi, Ning Yan. Curing Behavior and Thermomechanical Performance of Bioepoxy Resin Synthesized from Vanillyl Alcohol: Effects of the Curing Agent. Polymers. 2021; 13 (17):2891.
Chicago/Turabian StyleZhenyu Wang; Pitchaimari Gnanasekar; Sandeep Sudhakaran Nair; Songlin Yi; Ning Yan. 2021. "Curing Behavior and Thermomechanical Performance of Bioepoxy Resin Synthesized from Vanillyl Alcohol: Effects of the Curing Agent." Polymers 13, no. 17: 2891.
In this study, non-covalently functionalized graphene oxide (FGO) containing phosphorus and nitrogen was synthesized using dibenzyl N,N′-diethyl phosphoramidite (DDP) via a single step process. Meanwhile, novel bio-based phosphorus containing vanillin epoxy resin (VPE) was made via a two-step process and used as a flame-retardant adhesive. Subsequently, FGO was dispersed in the epoxy resin matrix at different weight ratios as reinforcement for improving mechanical, thermal and flame-retardant properties of the resultant composite systems. Curing behavior of the VPE and FGO mixtures with 4,4′-diaminodiphenylsulfone (DDS) as the crosslinker was investigated using a Differential Scanning Calorimeter (DSC). Thermal and flame-retardant properties of the cured VPE/FGO nanocomposites were systematically investigated by Thermogravimetric Analysis (TGA), Gas Chromatography – Mass Spectrometry (GC-MS), Limited Oxygen Index (LOI), vertical burning test (UL-94), and cone calorimeter test. Results indicated that all VPE/FGO nanocomposites exhibited excellent thermal and flame-retardant properties. In particular, VPE with 9 wt% of FGO achieved the highest LOI value (29.1%) and passed the V-0 rating in the UL-94 test. Furthermore, cone calorimetry test showed that flame retardancy performance of the VPE and VPE/FGO composites significantly improved compared to vanillin epoxy control resin without phosphorus. The gaseous and high boiling pyrolysis products of VPE cured by DDS were collected and characterized by GC/MS to reveal their formation mechanisms. The char layers of the cued VPE showed a high oxidation resistance with intumescent structures. The combined barrier and quenching effects of the char layer imparted VPE with excellent flame retardancy. This study illustrated a promising approach for synthesizing mechanically strong, thermally-stable and environmentally-friendly flame-retardant bio-based composite resins.
Pitchaimari Gnanasekar; Heyu Chen; Nicole Tratnik; Martin Feng; Ning Yan. Enhancing performance of phosphorus containing vanillin-based epoxy resins by P–N non-covalently functionalized graphene oxide nanofillers. Composites Part B: Engineering 2020, 207, 108585 .
AMA StylePitchaimari Gnanasekar, Heyu Chen, Nicole Tratnik, Martin Feng, Ning Yan. Enhancing performance of phosphorus containing vanillin-based epoxy resins by P–N non-covalently functionalized graphene oxide nanofillers. Composites Part B: Engineering. 2020; 207 ():108585.
Chicago/Turabian StylePitchaimari Gnanasekar; Heyu Chen; Nicole Tratnik; Martin Feng; Ning Yan. 2020. "Enhancing performance of phosphorus containing vanillin-based epoxy resins by P–N non-covalently functionalized graphene oxide nanofillers." Composites Part B: Engineering 207, no. : 108585.
Formaldehyde-free, water-resistant, and environmentally friendly wood adhesives were prepared from starches via a simple one-step epoxidation reaction followed by cross-linking using diethylenetriamine. This study focused on the effect of amylose/amylopectin ratio of starch (high amylose, low amylose, and amylopectin) on the epoxidation reaction and on the bonding performance of the prepared epoxidized starches. The epoxidation of starches altered the fluid behavior of the resins, from Newtonian for pristine epoxy to shear thinning, that corroborated the successful integration of starch chains as part of the epoxy resin. Epoxidized amylopectin had the highest viscosity, 114 Pa.s, and a high degree of substitution, 2.33 ± 0.10, among the starches that indicated that amylopectin is more favorable for the grafting of epoxy groups and for the integration of starch chains in epoxy resins compared to the starches with high amylose content. Bonding strengths were determined by lap shear tests on yellow birch specimens in dry, wet, and boiled conditions. High amylopectin epoxidized starch showed the highest lap shear bonding performance under wet conditions (5.50 ± 0.451 MPa). Under boiled conditions, all three epoxidized starches showed equally better performance than the unreacted starch-filled epoxy blends. This study provides fundamental insights into the effect of starch molecular structure on epoxidation reaction and adhesion properties and suggests a promising approach for developing strong formaldehyde-free sustainable biobased wood adhesives.
Nicole Tratnik; Pei-Yu Kuo; Nicolas R. Tanguy; Pitchaimari Gnanasekar; Ning Yan. Biobased Epoxidized Starch Wood Adhesives: Effect of Amylopectin and Amylose Content on Adhesion Properties. ACS Sustainable Chemistry & Engineering 2020, 8, 17997 -18005.
AMA StyleNicole Tratnik, Pei-Yu Kuo, Nicolas R. Tanguy, Pitchaimari Gnanasekar, Ning Yan. Biobased Epoxidized Starch Wood Adhesives: Effect of Amylopectin and Amylose Content on Adhesion Properties. ACS Sustainable Chemistry & Engineering. 2020; 8 (49):17997-18005.
Chicago/Turabian StyleNicole Tratnik; Pei-Yu Kuo; Nicolas R. Tanguy; Pitchaimari Gnanasekar; Ning Yan. 2020. "Biobased Epoxidized Starch Wood Adhesives: Effect of Amylopectin and Amylose Content on Adhesion Properties." ACS Sustainable Chemistry & Engineering 8, no. 49: 17997-18005.
A novel chemical architecture, vanillin-based phosphorus-containing flame-retardant building block (VP), was successfully synthesized as a sustainable platform biomolecule to be converted into fire-retardant epoxy (VPE) and polyurethane (VPU) resins for application as environmentally friendly adhesives. Structural characterizations confirmed the successful functionalization through their molecular structures. A series of VPU and VPE blends were prepared that showed excellent dry and wet bonding strengths and superior self-extinguishing flame retardancy. The highest bonding strengths, the maximum LOI value, and the lowest heat release rate in cone calorimetry tests were achieved by the VPE/VPU (80:20) blend due to the strong synergistic interpenetrating networks formed between the epoxy and PU macromolecules. The GC-MS analysis of the char residues indicated that the mechanisms for flame retardancy were a combination of the quenching effect from the phosphorus-containing free radicals and the diluting effect of the nonflammable gases in the gas phase, plus the formation of phosphorus-rich char layers in the condensed phase. This study showcased a highly promising approach to develop environmentally friendly high-performance flame-retardant chemicals using nontoxic vanillin as the starting material.
Pitchaimari Gnanasekar; Martin Feng; Ning Yan. Facile Synthesis of a Phosphorus-Containing Sustainable Biomolecular Platform from Vanillin for the Production of Mechanically Strong and Highly Flame-Retardant Resins. ACS Sustainable Chemistry & Engineering 2020, 8, 17417 -17426.
AMA StylePitchaimari Gnanasekar, Martin Feng, Ning Yan. Facile Synthesis of a Phosphorus-Containing Sustainable Biomolecular Platform from Vanillin for the Production of Mechanically Strong and Highly Flame-Retardant Resins. ACS Sustainable Chemistry & Engineering. 2020; 8 (47):17417-17426.
Chicago/Turabian StylePitchaimari Gnanasekar; Martin Feng; Ning Yan. 2020. "Facile Synthesis of a Phosphorus-Containing Sustainable Biomolecular Platform from Vanillin for the Production of Mechanically Strong and Highly Flame-Retardant Resins." ACS Sustainable Chemistry & Engineering 8, no. 47: 17417-17426.
A simple and rapid synthesis of bio-based epoxy resin derived from vanillyl alcohol was performed and its chemical structure was confirmed by FTIR, 1H and 13C NMR spectroscopy. Vanillin based epoxy resin (VE) was further reinforced by lignin-containing cellulose nanofibrils (LCNFs) with different weight ratios. Characteristics of the resin and the nanocomposites, including the curing process, chemical structure, morphology, mechanical performance, thermo-mechanical properties, and thermal degradation behavior were studied. A significant improvement in the mechanical performance of the nanocomposites was achieved with a low level of nanofibril addition. Tensile strength and toughness increased by 81% and 185%, respectively, when 1 wt% of LCNFs were used. The nanocomposite also showed an increase in thermo-mechanical properties as measured by dynamic mechanical analysis (DMA), and increased resistance to thermal degradation as shown by higher onset temperature and final char value in thermogravimetric analysis (TGA). This study showcased a promising approach to make environmental-friendly sustainable bio-based epoxy products with superior performance.
Zhenyu Wang; Pitchaimari Gnanasekar; Sandeep Sudhakaran Nair; Ramin R. Farnood; Songlin Yi; Ning Yan. Biobased Epoxy Synthesized from a Vanillin Derivative and Its Reinforcement Using Lignin-Containing Cellulose Nanofibrils. ACS Sustainable Chemistry & Engineering 2020, 8, 11215 -11223.
AMA StyleZhenyu Wang, Pitchaimari Gnanasekar, Sandeep Sudhakaran Nair, Ramin R. Farnood, Songlin Yi, Ning Yan. Biobased Epoxy Synthesized from a Vanillin Derivative and Its Reinforcement Using Lignin-Containing Cellulose Nanofibrils. ACS Sustainable Chemistry & Engineering. 2020; 8 (30):11215-11223.
Chicago/Turabian StyleZhenyu Wang; Pitchaimari Gnanasekar; Sandeep Sudhakaran Nair; Ramin R. Farnood; Songlin Yi; Ning Yan. 2020. "Biobased Epoxy Synthesized from a Vanillin Derivative and Its Reinforcement Using Lignin-Containing Cellulose Nanofibrils." ACS Sustainable Chemistry & Engineering 8, no. 30: 11215-11223.