Semi-Interpenetrating Novolac-Epoxy Thermoset Polymer Networks Derived from Plant Biomass (original) (raw)
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Polymer Engineering & Science, 2017
Fast pyrolysis bio‐oil was employed as a source of phenolic compounds in the production of a bio‐based polymeric network. The bio‐oil was reacted with epichlorohydrin in alkaline medium using benzyltriethylammonium chloride as a phase transfer catalyst. The amount of free phenolic hydroxyl groups before and after modification was quantified through 31P‐NMR spectroscopy; and the epoxy content of the bio‐oil upon the chemical functionalization was measured by means of a titration using HBr in acetic acid solution. Grafting of epoxy functions onto the monomer`s structure was studied by FTIR. Likewise, α‐resorcylic acid was also modified with reactive epoxy moieties, and used as low molecular weight comonomer. The epoxidized derivatives of the bio‐oil were cured in epoxy polymers with 4‐dimethylaminopyridine. Thermo‐mechanical characterization showed that the obtained materials behave as thermoset amorphous polymers, exhibiting modulus values ranging from approximately 1.5–3.4 GPa at ro...
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Epoxy is the most prevalent thermosetting resin in the field of polymer composite materials. There has been a growing interest in the development of bio-based epoxy resins as a sustainable alternative to conventional petrochemical epoxy resins. Advances in this field in recent years have included the use of various renewable resources, such as vegetable oils, lignin, and sugars, as direct precursors to produce bio-based epoxy resins. In the meantime, bio-oils have been produced via the decomposition of biomass through thermochemical conversion and mainly being used as renewable liquid fuels. It is noteworthy that bio-oils can be used as a sustainable resource to produce epoxy resins. This review addresses research progress in producing bio-oil-based epoxy resins from thermochemical processing techniques including organic solvent liquefaction, fast pyrolysis, and hydrothermal liquefaction. The production of bio-oil from thermochemical processing and its use to inject sustainability i...
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Journal of Polymers and the Environment, 2021
The direct conversion of natural products to useful engineering materials is desirable from both economic and environmental considerations. We are describing the synthesis and properties of 100 % oil-based epoxy resins generated from three epoxidized oils. The catalyst, tris(pentafluorophenyl)borane (B(C6F5)3) in toluene, allowed for controlled cationic polymerization at a very low concentration. Epoxidized oils (derived from triolein, soybean, and linseed oil) had varying epoxy content, rendering resins of different cross-link density. The polymerization was carried out at room temperature followed by post-curing at elevated temperature to speed up conversion. Epoxy resins were amorphous transparent glasses with glass transitions below glass transitions and hard rubbers above. Despite their high cross-link density, these materials show relatively low Tg's reflecting the aliphatic nature of fatty acids and the presence of plasticizing "dangling" chains. The structure of the triglyceride starting oils influenced the properties of the resulting materials: the more regular structure of triolein compared to the very heterogeneous structures of soybean and linseed oils seemed to have enhanced some properties of the polymer networks. These epoxy polymers are potentially useful as encapsulating and potting compounds for electronic applications.
Bio-Based Aromatic Epoxy Monomers for Thermoset Materials
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The synthesis of polymers from renewable resources is a burning issue that is actively investigated. Polyepoxide networks constitute a major class of thermosetting polymers and are extensively used as coatings, electronic materials, adhesives. Owing to their outstanding mechanical and electrical properties, chemical resistance, adhesion, and minimal shrinkage after curing, they are used in structural applications as well. Most of these thermosets are industrially manufactured from bisphenol A (BPA), a substance that was initially synthesized as a chemical estrogen. The awareness on BPA toxicity combined with the limited availability and volatile cost of fossil resources and the non-recyclability of thermosets implies necessary changes in the field of epoxy networks. Thus, substitution of BPA has witnessed an increasing number of studies both from the academic and industrial sides. This review proposes to give an overview of the reported aromatic multifunctional epoxide building blocks synthesized from biomass or from molecules that could be obtained from transformed biomass. After a reminder of the main glycidylation routes and mechanisms and the recent knowledge on BPA toxicity and legal issues, this review will provide a brief description of the main natural sources of aromatic molecules. The different epoxy prepolymers will then be organized from simple, mono-aromatic di-epoxy, to mono-aromatic poly-epoxy, to di-aromatic di-epoxy compounds, and finally to derivatives possessing numerous aromatic rings and epoxy groups.
Frontiers in Chemistry
One-hundred percent renewable triphenol-GTF-(glycerol trihydroferulate) and novel bisphenols-GDF x-(glycerol dihydroferulate) were prepared from lignocellulose-derived ferulic acid and vegetal oil components (fatty acids and glycerol) using highly selective lipase-catalyzed transesterifications. Estrogenic activity tests revealed no endocrine disruption for GDF x bisphenols. Triethyl-benzyl-ammonium chloride (TEBAC) mediated glycidylation of all bis/triphenols, afforded innocuous bio-based epoxy precursors GDF x EPO and GTF-EPO. GDF x EPO were then cured with conventional and renewable diamines, and some of them in presence of GTF-EPO. Thermo-mechanical analyses (TGA, DSC, and DMA) and degradation studies in acidic aqueous solutions of the resulting epoxy-amine resins showed excellent thermal stabilities (T d 5% = 282-310 • C), glass transition temperatures (T g) ranging from 3 to 62 • C, tunable tan α, and tunable degradability, respectively. It has been shown that the thermo-mechanical properties, wettability, and degradability of these epoxy-amine resins, can be finely tailored by judiciously selecting the diamine nature, the GTF-EPO content, and the fatty acid chain length.
Polymers for Advanced Technologies, 2018
Bio-based epoxy resins were synthesized from nonedible resources like linseed oil and castor oil. Both the oils were epoxidized through in situ method and characterized via Fourier transform infrared and 1 H-NMR. These epoxidized oils were crosslinked with citric acid without using any catalyst and their properties compared with diglycidyl ether of bisphenol A-epoxy. The tensile strength and modulus of epoxidized linseed oil (ELO) were found to be more than those of epoxidized castor oil (ECO)-based network. However, elongation at break of ECO was significantly higher than that of both ELO and epoxy, which reveals its improved flexibility and toughened nature. Thermogravimetric analysis revealed that the thermal degradation of ELO-based network is similar to that of petro-based epoxy. Dynamic mechanical analysis revealed moderate storage modulus and broader loss tangent curve of bio-based epoxies confirming superior damping properties. Bioepoxies exhibit nearly similar contact angle as epoxy and display good chemical resistant. The preparation method does not involve the use of any toxic catalyst and more hazardous solvents, thus being eco-friendly.
Journal of Materials Processing Technology, 2008
In the earlier study about polymer network of phenolic and epoxies resins mixed with linseed oil, only Phencat 15 was used as the catalyst for the phenolic resin. In this study, Phencat 382 and UH (a urea hydrochloride solution based on a 1 : 1 mole ratio of urea : hydrochloric acid 32%) will be used as catalysts to study their effects on the polymer network of phenolic and epoxy resins mixed with epoxidized linseed oil (ELO) (58%). The effect of each one of these catalysts on the curing and the properties of the formed network were investigated. It was discovered that Phencat 382 was the best catalyst for the composites. It was also discovered that ELO can play its role as plasticiser in the blends of epoxy and phenolic resins and does improve the flexural strength and other mechanical properties of the prepared resins. The storage modulus, flexural modulus, stress at peak and glass transition temperature decreased with increasing percentage by weight of ELO added irrespective of the catalysts used, while the strain yield increased. The cross-link density decreased with the increasing amount of ELO in the resins. The best properties were obtained for the 80/20 epoxy/phenolic resin blends after post-curing for 4 hours.