A facile solvent-less approach to toughen epoxy thermosets by means of a bio-based resin, that is, poly(furfuryl alcohol) (PFA; furan resin) is reported. The bio-resin PFA was firstly synthesized through polycondensation reaction of furfuryl alcohol as a bio-monomer and maleic anhydride as a catalyst. Different amounts of PFA were blended with diglycidyl ether of bisphenol A epoxy resin and cured by diethylenetriamine as a hardener, which simultaneously cross-linked both of the epoxy and PFA resins. The curing process was studied by Furrier transform infrared spectroscopy and differential scanning calorimetry. Scanning electron microscopy of the chemically cured blends revealed no phase separation. It was found remarkable increase in flexural modulus and strength of the neat and modified epoxies with increasing PFA content up to around 15%. Moreover, in comparison with neat epoxy, the epoxy-PFA thermosets showed 60% increase in critical stress intensity factor and 123% increase in critical strain energy release rate. In fact, chemical reaction of PFA-incorporated epoxy could toughen the epoxy matrix without sacrificing the flexural strength and modulus. Toughening was obtained through cross-link density reduction. As exhibited by dynamic mechanical thermal analysis, Tan δ and magnitude of β-relaxation were also increased for the epoxy-PFA alloys. Overall, this green, simple, concise and cost-effective approach was suggested for being considered to produce toughened epoxy thermosets in industrial scale.
ChenSChenBFanJ. Exploring the application of sustainable poly(propylene carbonate) copolymer in toughening epoxy thermosets. ACS Sustain Chem Eng2015; 3: 2077–2083.
2.
NaguibMSangermanoMCapozziLC. Non-reactive and reactive block copolymers for toughening of UV-cured epoxy coating. Prog Org Coat2015; 85: 178–188.
3.
Parameswaran PillaiJPionteckJHäßlerR. Effect of cure conditions on the generated morphology and viscoelastic properties of a poly(acrylonitrile–butadiene–styrene) modified epoxy–amine system. Ind Eng Chem Res2012; 51: 2586–2595.
4.
FengHWangXWuD. Fabrication of spirocyclic phosphazene epoxy-based nanocomposites with graphene via exfoliation of graphite platelets and thermal curing for enhancement of mechanical and conductive properties. Ind Eng Chem Res2013; 52: 10160–10171.
5.
FanMLiXZhangJ. Curing kinetics and shape-memory behavior of an intrinsically toughened epoxy resin system. J Therm Anal Calorim2015; 119: 537–546.
6.
SahooSKMohantySNayakSK. Toughened bio-based epoxy blend network modified with transesterified epoxidized soybean oil: synthesis and characterization. RSC Adv2015; 5: 13674–13691.
7.
RatnaD.Handbook of thermoset resins. Shawbury, Shrewsbury: iSmithers, 2009.
8.
LevitaGDe PetrisSMarchettiA. Crosslink density and fracture toughness of epoxy resins. J Mater Sci1991; 26: 2348–2352.
9.
KongJTangYZhangX. Synergic effect of acrylate liquid rubber and bisphenol A on toughness of epoxy resins. Polym Bull2008; 60: 229–236.
10.
CardwellBJYeeAF. Rate and temperature effects on the fracture toughness of a rubber-modified epoxy. Polymer1993; 34: 1695–1701.
11.
DomunNHadaviniaHZhangT. Improving the fracture toughness and the strength of epoxy using nanomaterials – a review of the current status. Nanoscale2015; 7: 10294–10329.
12.
PearsonRAYeeAF. Toughening mechanisms in thermoplastic-modified epoxies: 1. Modification using poly(phenylene oxide). Polymer1993; 34: 3658–3670.
13.
LiuWZhouRGohHLS. From waste to functional additive: toughening epoxy resin with lignin. ACS Appl Mater Interfaces2014; 6: 5810–5817
14.
McCarronA.A synergistic approach to modeling crack propagation in nanoreinforced polymer composites 2008. Amherst: University of Massachusetts.
NagarajaBMKumarVSShasikalaV. A highly efficient Cu/MgO catalyst for vapour phase hydrogenation of furfural to furfuryl alcohol. Catal Commun2003; 4: 287–293.
18.
PinJ-MGuigoNMijaA. Valorization of biorefinery side-stream products: combination of humins with polyfurfuryl alcohol for composite elaboration. ACS Sustain Chem Eng2014; 2: 2182–2190.
19.
SariMGRamezanzadehBShahbaziM. Influence of nanoclay particles modification by polyester-amide hyperbranched polymer on the corrosion protective performance of the epoxy nanocomposite. Corros Sci2015; 92: 162–172.
20.
ConleyRTMetilI. A study of the oxidative degradation of furfuryl alcohol polycondensates by infrared spectroscopy. J Appl Polym Sci1963; 7: 1083–1091.
21.
ConleyRTMetilI. An investigation of the structure of furfuryl alcohol polycondensates with infrared spectroscopy. J Appl Polym Sci1963; 7: 37–52.
22.
HayatyMHonarkarHBeheshtyMH. Curing behavior of dicyandiamide/epoxy resin system using different accelerators. Iran Polym J2013; 22: 591–598.
23.
KarayannidouEGAchiliasDSSideridouID. Cure kinetics of epoxy–amine resins used in the restoration of works of art from glass or ceramic. Eur Polym J2006; 42: 3311–3323.
24.
BobrowskiAGrabowskaB. The impact of temperature on furan resin and binders structure. Metall Foundry Eng2012; 38: 73–80.
25.
DekaHMisraMMohantyA. Renewable resource based “all green composites” from kenaf biofiber and poly (furfuryl alcohol) bioresin. Ind Crops Prod2013; 41: 94–101.
26.
ChouraMBelgacemNMGandiniA. Acid-catalyzed polycondensation of furfuryl alcohol: mechanisms of chromophore formation and cross-linking. Macromolecules1996; 29: 3839–3850.
27.
De VergaraULSarrionandiaMGondraK. Polymerization and curing kinetics of furan resins under conventional and microwave heating. Thermochim Acta2014; 581: 92–99.
28.
MacielGEChuangI-SMyersGE. Carbon-13 NMR study of cured furfuryl alcohol resins using cross polarization and magic-angle spinning. Macromolecules1982; 15: 1218–1220.
29.
VeisiHAzadbakhtREzadifarM. An efficient and green procedure for synthesis of pyrrole derivatives by paal–knorr condensation using sodium dodecyl sulfate in aqueous micellar. J Heterocyclic Chem2013; 50: E241.
30.
ChenJ-XLiuM-CYangX-L. Indium (III)-catalyzed synthesis of N-substituted pyrroles under solvent-free conditions. J Braz Chem Soc2008; 19: 877–883.
WuSGuoQPengS. Toughening epoxy thermosets with block ionomer complexes: a nanostructure–mechanical property correlation. Macromolecules2012; 45: 3829–3840.
34.
ThomasRYumeiDYuelongH. Miscibility, morphology, thermal, and mechanical properties of a DGEBA based epoxy resin toughened with a liquid rubber. Polymer2008; 49: 278–294.
35.
MenardKP. Dynamic mechanical analysis: a practical introduction. New York: CRC press2008, pp. 91–121.
36.
El HomranyMMaaroufiABenaventeR. Improvement of mechanical performance of epoxy resins filled with cobalt and chromium powders. J Appl Polym Sci2010; 118: 3701–3706.
37.
KoleskeJV.Paint and coating testing manual, the Gardner-Sward handbook; Paint Testing Manual. 14th ed. Philadelphia: Wiley, 1995, pp. 534–547.
38.
KyritsisAVikelisGMaroulasP. Polymer dynamics in epoxy/alumina nanocomposites studied by various techniques. J Appl Polym Sci2011; 121: 3613–3627.
39.
OishiSSRezendeMCOrigoFD. Viscosity, pH, and moisture effect in the porosity of poly (furfuryl alcohol). J Appl Polym Sci2013; 128: 1680–1686.
40.
PrincipeMOrtizPMartínezR. An NMR study of poly(furfuryl alcohol) prepared with p-toluenesulphonic acid. Polym Int1999; 48: 637–641.
41.
KalakkunnathS. Viscoelastic relaxation characteristics of rubbery polymer networks and engineering polyesters, PhD Dessertation, University of Kentucky, USA, 2007.
MustoPRagostaGAbbateM. Photo-oxidation of high performance epoxy networks: correlation between the molecular mechanisms of degradation and the viscoelastic and mechanical response. Macromolecules2008; 41: 5729–5743.
44.
LachRGrellmannW. Time-and temperature-dependent fracture mechanics of polymers: general aspects at monotonic quasi-static and impact loading conditions. Macromol Mater Eng2008; 293: 555–567.
45.
Fernández-GarcíaMde la FuenteJLCerradaML. Preparation of poly (tert-butyl acrylate-g-styrene) as precursors of amphiphilic graft copolymers. 1. Kinetic study and thermal properties. Polymer2002; 43: 3173–3179.
46.
ThomasRSinturelCPionteckJ. In-situ cure and cure kinetic analysis of a liquid rubber modified epoxy resin. Ind Eng Chem Res2012; 51: 12178–12191.
47.
ShuklaSKSrivastavaD. Blends of modified epoxy resin and carboxyl-terminated polybutadiene. I. J Appl Polym Sci2006; 100: 1802–1808.
48.
YangGFuS-YYangJ-P. Preparation and mechanical properties of modified epoxy resins with flexible diamines. Polymer2007; 48: 302–310.
49.
XiaoXLuSQiB. Enhancing the thermal and mechanical properties of epoxy resins by addition of a hyperbranched aromatic polyamide grown on microcrystalline cellulose fibers. RSC Adv2014; 4: 14928–14935.
50.
DadfarMRGhadamiF. Effect of rubber modification on fracture toughness properties of glass reinforced hot cured epoxy composites. Mater Des2013; 47: 16–20.
51.
ShermanCLZeiglerRCVergheseNE. Structure–property relationships of controlled epoxy networks with quantified levels of excess epoxy etherification. Polymer2008; 49: 1164–1172.
52.
ZhouCGuALiangG. Tough silica-hybridized epoxy resin/anhydride system with good corona resistance and thermal stability for permanent magnet synchronous wind-driven generators through vacuum pressure impregnation. Ind Eng Chem Res2015; 54: 7102–7112.
53.
MathewVSSinturelCGeorgeSC. Epoxy resin/liquid natural rubber system: secondary phase separation and its impact on mechanical properties. J Mater Sci2010; 45: 1769–1781.
54.
BoeslB.Fracture toughening mechanisms in nanoparticle and micro-particle reinforced epoxy systems using multi-scale analysis. PhD Dessertation, University of Florida, USA
55.
BuilesDHHernandezHMondragonI. Relationship between the morphology of nanostructured unsaturated polyesters modified with PEO-b-PPO-b-PEO triblock copolymer and their optical and mechanical properties. J Phys Chem C2013; 117: 3563–3571.
