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Functionalization of graphene nanoplatelets using sugar azide for graphene/epoxy nanocomposites
Saswata Bose,Lawrence T. Drzal 한국탄소학회 2015 Carbon Letters Vol.16 No.2
We report a covalent functionalization of graphene nanoparticles (GnPs) employing 2,3,4-Tri-O-acetyl-β-D-xylopyranosyl azide followed by fabrication of an epoxy/functionalized graphene nanocomposite and an evaluation of its thermo-mechanical performance. Successful functionalization of GnP was confirmed via thermal and spectroscopic study. Raman spectroscopy indicated that the functionalization was on the edge of the graphene sheets; the basal plane was not perturbed as a result of the functionalization. The epoxy/functionalized GnP composite system exhibited an increase in flexural modulus (~18%) and glass transition temperature (~10°C) compared to an un-functionalized GnP based epoxy composite.
Donghwan Cho,Lawrence T. Drzal 한국탄소학회 2016 Carbon Letters Vol.19 No.-
In efforts to characterize and understand the properties and processing of phenylethynylterminated imide (LaRC PETI-5, simply referred to as PETI-5) oligomers and polymers as a high-temperature sizing material for carbon fiber-reinforced polymer matrix composites, PETI-5 imidization and thermal curing behaviors have been extensively investigated based on the phenylethynyl end-group reaction. These studies are reviewed here. In addition, the use of PETI-5 to enhance interfacial adhesion between carbon fibers and a bismaleimide (BMI) matrix, as well as the dynamic mechanical properties of carbon/BMI composites, are discussed. Reports on the thermal expansion behavior of intercalated graphite flake, and the effects of exfoliated graphite nanoplatelets (xGnP) on the properties of PETI-5 matrix composites are also reviewed. The dynamic mechanical and thermal properties and the electrical resistivity of xGnP/PETI-5 composites are characterized. The effect of liquid rubber amine-terminated poly(butadiene-co-acrylonitrile) (ATBN)-coated xGnP particles incorporated into epoxy resin on the toughness of xGnP/epoxy composites is examined in terms of its impact on Izod strength. This paper provides an extensive overview from fundamental studies on PETI-5 and xGnP, as well as applied studies on relevant composite materials.
Kim, Sumin,Do, Inhwan,Drzal, Lawrence T. Wiley Subscription Services, Inc., A Wiley Company 2010 Polymer composites Vol.31 No.5
<P>The objective of this research was to investigate thermal stability and dynamic mechanical behavior of Exfoliated graphite nanoplatelets (xGnP™)-Linear Low-Density Poly Ethylene (LLDPE) nanocomposites with different xGnP loading content. The xGnP-LLDPE nanocomposites were fabricated by solution and melt mixing in various screw rotating systems such as co-, counter-, and modified-corotating. The storage modulus (E′) of the composites at the starting point of −50°C increased as xGnP contents increased. E′ of the nanocomposite with only 7 wt% of xGnP was 2.5 times higher than that of the control LLDPE. Thermal expansion and the coefficient of thermal expansion of xGnP-loaded composites were much lower than those of the control LLDPE in the range of 45–80°C (299.8 × 10<SUP>−6</SUP>/°C) and 85–100°C (365.3 × 10<SUP>−6</SUP>/°C). Thermal stability of the composites was also affected by xGnP dispersion in LLDPE matrix. The xGnP-LLDPE nanocomposites by counter-rotating screw system showed higher thermal stability than ones by co-rotating and modified-co-rotating system at 5 wt% and 12 wt% of xGnP. xGnP had a great effect on high thermal stability of xGnP-LLDPE composites to be applied as tube and film for electrical materials. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers</P>
지상규,Lawrence T. Drzal,조동환 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.102 No.-
In the present study, exfoliated graphite nanoplatelets (EGN) were chemically modified with carboxylterminatedpoly(butadiene-co-acrylonitrile) (CTBN) liquid rubber via carboxylation, acylation, and subsequentlyesterification. Multiple characterizations by means of attenuated total reflectance-Fourier transforminfrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray diffractionspectroscopy, thermogravimetric analysis, and scanning electron microscopy demonstrated the chemicalmodification. For comparison, neat vinyl ester resin (VE), EGN/VE and CTBN-EGN/VE composites wereprepared by using a free-standing Teflon mold to avoid pressure during curing. The amounts of EGNand CTBN-grafted EGN containing in EGN/VE and CTBN-EGN/VE composites were 1, 3, and 5 wt%, respectively. The impact strength of EGN/VE and CTBN-EGN/VE composites was strongly dependent upon theCTBN-grafted EGN concentration incorporated into neat VE. It was remarkably enhanced up to 220–240% even with low contents (5 wt%) of CTBN-grafted EGN in comparison to neat VE and unmodifiedEGN/VE. The result revealed that a small amount of EGN chemically modified with liquid rubber CTBNplayed an important role in increasing the impact toughness of thermosetting resin.