Kinetics of Temperature‐induced and Reaction‐induced Phase Separation Studied by Modulated Temperature DSC

Pieters, Ronny; Miltner, Hans; Assche, Guy Van; Mele, Bruno Van

doi:10.1002/masy.200690026

Cited by 8 publications

(15 citation statements)

References 15 publications

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“…Moreover, the viscosity of the resin increases significantly when nanoparticles are added. The toughness of a matrix can also be improved by incorporation of rubber particles or embedding thermoplastic inclusions [15,16]. But again, a homogeneous dispersion of the particles in the matrix is hard to obtain.…”

Section: Introductionmentioning

confidence: 99%

Effect of electrospun polyamide 6 nanofibres on the mechanical properties of a glass fibre/epoxy composite

et al. 2013

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Recently, several types of nanoparticles are frequently incorporated in reinforced epoxy resin composites. A homogeneous dispersion of these nanoparticles is still a problem.Thermoplastic nanofibrous structures can tackle this dispersion issue. Therefore, this paper investigated the effect of electrospun polyamide 6 nanofibrous structures on the mechanical properties of a glass fibre/epoxy composite. The nanofibres were incorporated in the glass fibre/epoxy composite as stand-alone interlayered structures and directly spun on the glass fibre reinforcement. Both ways of nanofibre incorporation have no negative effect on the impregnation of the epoxy. Moreover, the nanofibres remain well dispersed within the matrix. Incorporation of nanofibres increases the stress at failure in the 0°-direction, the best results are obtained when the nanofibres are directly electrospun on the glass fibres. Optical microscopic images also demonstrate that nanofibres prevent delamination when a 90° crack reaches a neighbouring 0° ply. Furthermore, mode I tests showed a small improvement when a thin nanofibrous structure is deposited directly onto the glass fibres. When the composites are loaded under 45°, it is proven that, for an identical stress, the glass fibre composite with deposited nanofibres has less cracks than when interlayered nanofibrous structures are incorporated. Generally, it can be concluded that the addition of polyamide 6 nanofibres improves some mechanical characteristics of a glass fibre/epoxy composite.

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Section: Introductionmentioning

confidence: 99%

Effect of electrospun polyamide 6 nanofibres on the mechanical properties of a glass fibre/epoxy composite

et al. 2013

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“…27,28 A complete description of the extraction of the heat capacity and other MTDSC signals can be found in the literature. [29][30][31][32] MTDSC turns out to be very valuable for the study of the kinetics and chemorheology in reacting systems, [33][34][35] melting/ crystallization, 26,[36][37][38][39] temperature-induced phase separation in blends, [40][41][42] and solutions, [42][43][44][45][46][47][48][49][50][51] and reaction-induced phase separation in reacting systems. 32,52 As heat effects caused by fast processes following the modulated heating rate contribute to the heat capacity (c p ) signal, the c p signal is therefore called the apparent (specific) heat capacity (c app p ).…”

Section: Introductionmentioning

confidence: 99%

Phase behavior of PCBM blends with different conjugated polymers

Zhao

Bertho

Vandenbergh

et al. 2011

Phys. Chem. Chem. Phys.

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In this work the phase behavior of [6,6]-phenyl C(61)-butyric acid methyl ester (PCBM) blends with different poly(phenylene vinylene) (PPV) samples is investigated by means of standard and modulated temperature differential scanning calorimetry (DSC and MTDSC) and rapid heat-cool calorimetry (RHC). The PPV conjugated polymers include poly(2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene) (MDMO-PPV), High T(g)-PPV which is a copolymer, and poly((2-methoxy-5-phenethoxy)-1,4-phenylene vinylene) (MPE-PPV). Comparisons of these PPV:PCBM blends with regioregular poly(3-hexyl thiophene) (P3HT):PCBM blends are made to see the different component miscibilities among different blends. The occurrence of liquid-liquid phase separation in the molten state of MDMO-PPV:PCBM and High T(g)-PPV:PCBM blends is indicated by the coexistence of double glass transitions for blends with a PCBM weight fraction of around 80 wt%. This is in contrast to the P3HT:PCBM blends where no phase separation is observed. Due to its high cooling rate (about 2000 K min(-1)), RHC proves to be a useful tool to investigate the phase separation in PPV:PCBM blends through the glass transition of these crystallizable blends. P3HT is found to have much higher thermal stability than the PPV samples.

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“…In fact, analysis of the c p app data of the individual quasi-isothermal sections shows that a statistically significant positive slope is already observed at −18 °C. The presence of an excess heat capacity resulting from (reversible) demixing and remixing induced by the temperature modulation was evidenced before in polymer−water solutions, ,, hydrogels, and polymer blends. , The gradual increase in c p excess can be attributed to a gradual increase in the interfacial contact area between the coexisting phases. , Unfortunately, the observed slow increase of c p app does not allow distinguishing between a nucleation and growth or spinodal decomposition (plus coarsening) mechanism.…”

Section: Resultsmentioning

confidence: 93%

Adjacent UCST Phase Behavior in Aqueous Solutions of Poly(vinyl methyl ether): Detection of a Narrow Low Temperature UCST in the Lower Concentration Range

Assche

Mele

et al. 2011

Macromolecules

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We provide the first experimental evidence for the existence of a low concentration narrow UCST miscibility gap, which is the second of two narrow miscibility gaps constituting together adjacent UCST phase behavior. The existence of adjacent UCST miscibility phase behavior in aqueous polymer solutions has been theoretically predicted, but so far escaped experimental verification. We have been able to determine the low concentration narrow UCST miscibility gaps from the changes in apparent heat capacity observed in stepwise isothermal cooling modulated temperature differential scanning calorimetry (MTDSC) experiments. In wide-angle X-ray diffraction (WAXD) experiments it was unambiguously demonstrated that the MTDSC heat capacity changes are not due to crystallization. Together with earlier experimental results on the high concentration narrow UCST miscibility gap, the bimodal LCST miscibility gap and the sigmoidal melting line of ice the experimental results reported in this work complete the full experimental verification of the predicted complex phase behavior of aqueous solutions of PVME. As far as the authors are aware, this is the first system where adjacent UCST phase behavior is found. On the basis of the theoretical predictions the observed phase behavior could be more general and other systems may exist where similar behavior can be observed.

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Kinetics of Temperature‐induced and Reaction‐induced Phase Separation Studied by Modulated Temperature DSC

Cited by 8 publications

References 15 publications

Effect of electrospun polyamide 6 nanofibres on the mechanical properties of a glass fibre/epoxy composite

Effect of electrospun polyamide 6 nanofibres on the mechanical properties of a glass fibre/epoxy composite

Phase behavior of PCBM blends with different conjugated polymers

Adjacent UCST Phase Behavior in Aqueous Solutions of Poly(vinyl methyl ether): Detection of a Narrow Low Temperature UCST in the Lower Concentration Range

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