Polytetramethylene glycol-modified polycyanurate matrices reinforced with nanoclays: synthesis and thermomechanical performance |
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Authors: | G I Anthoulis E Kontou A Fainleib I Bei |
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Institution: | (1) Department of Mechanics, National Technical University, Zografou Campus, 157 73 Athens, Greece;(2) Institute of Macromolecular Chemistry of National Academy of Sciences, 48, Kharkivs’ke shose, 02160 Kiev, Ukraine |
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Abstract: | The outstanding improvement in the physical properties of cyanate esters (CEs) compared with those of competitor resins, such
as epoxies, has attracted appreciable attention recently. Cyanate esters undergo thermal polycyclotrimerization to give polycyanurates
(PCNs). However, like most thermo setting resins, the main draw back of CEs is brittleness. To over come this disadvan tage,
CEs can be toughened by the introduction of polytetramethylene glycol (PTMG), a hydroxyl-terminated polyether. How ever, PTMG
has a detrimental impact on Young’s modulus. To simultaneously enhance both the ductility and the stiffness of CE, we added
PTMG and an organoclay (mont morillonite, MMT) to it. A series of PCN/PTMG/MMT nanocomposites with a constant PTMG weight
ratio was pre pared, and the resulting nanophase morphology, i.e., the degree of filler dispersion and distribution in the
composite and the thermomechanical properties, in terms of glass-transition behaviour, Young’s modulus, tensile strength,
and elongation at break, were examined using the scanning elec tron micros copy (SEM), a dynamic mechanical analysis (DMA),
and stress–strain measurements, re spectively. It was found that, at a content of MMT below 2 wt.%, MMT nanoparticles were
distributed uniformly in the matrix, suggesting a lower degree of agglomeration for these materials. In the glassy state,
the significant increase in the storage modulus revealed a great stiffening effect of MMT due to its high Young’s modulus.
The modification with PTMG led to a 233% greater elongation at break compared with that of neat PCN. The nanocomposites exhibited
an invariably higher Young’s modulus than PCN/PTMG for all the volume factors of organoclay examined, with the 2 wt.% material
displaying the most pronounced in crease in the modulus, in agreement with micros copy results.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 45, No. 2, pp. 255–268, March–April, 2009. |
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Keywords: | polycyanurate organoclay thermomechanical properties |
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