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Abstract  

Specific heat capacity of boron nitride-filled polybenzoxazine has been investigated by using temperature-modulated differential scanning calorimetry, TMDSC, to study that it is a composite structure-insensitive property, i.e. independent of the degree of filler network formation. Many aspects of boron nitride filler such as particle size, particle surface area, particle shape, and filler loading are investigated. At the same filler loading, we observe insignificant change in composite specific heat capacity due to the effect of particle size, particle surface area, and particle shape. Filler loading is found to be the only aspect of filler that can change the specific heat capacity of this filled system. A linear relationship between the composite heat capacities and filler loading is observed and can be predicted by the rule of mixture with an error within ±1%. Within the temperature range betwen 0 and 80°C, the temperature dependent heat capacity of this composite can simply be expressed in the form of a linear equation: C p=A+BT.

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Abstract  

The low-temperature molar heat capacities of CoPc and CoTMPP were measured by temperature modulated differential scanning calorimetry (TMDSC) over the temperature range from 223 to 413 K for the first time. No phase transition or thermal anomaly was observed in the experimental temperature range for CoPc. However, a structural change was found to be nonreversible for CoTMPP in the temperature range of 368–403 K, which was further validated by the results of IR and XRD. The molar enthalpy ΔH m and entropy ΔS m of phase transition of the CoTMPP were determined to be 3.301 kJ mol−1 and 8.596 J K−1 mol−1, respectively. The thermodynamic parameters of CoPc and CoTMPP such as entropy and enthalpy relative to reference temperature 298.15 K were derived based on the above molar heat capacity data. Moreover, the thermal stability of these two compounds was further investigated through TG measurements. Three steps of mass loss were observed in the TG curve for CoPc and five steps for CoTMPP.

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Abstract  

Recycled poly(ethylene terephthalate) (R-PET) was chain extended with pyromellitic dianhydride (PMDA) in a commercial size twin-screw reactive extrusion system. Temperature-modulated differential scanning calorimetry (TMDSC) was used to evaluate the effect of the chain extension process on the thermal transitions and crystallinity of R-PET. Reactive extruded recycled PET (RER-PET) samples were tested based on different PMDA concentration and reactive extrusion residence times. The glass transition temperature (T g) did not show a significant change as a function of PMDA addition or the extrusion residence time. Melting temperature (T m) and crystallisation temperature (T c) decreased with increasing PMDA concentration and with increasing extrusion residence time. RER-PET samples showed double melting peaks, it is believed that different melting mechanism is the reason behind this phenomenon. The crystallinity of RER-PET samples is lower than that of R-PET. RER-PET samples at constant PMDA concentration showed a decrease in crystallinity with increasing extrusion residence time. Results suggest that the reactive extrusion process is more dependent on PMDA concentration rather than reactive extrusion process residence time.

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Abstract  

A three-phase model, comprising crystalline, mobile amorphous, and rigid amorphous fractions (χ c, χ MA, χ RA, respectively) has been applied in the study of semicrystalline Nylon-6. The samples studied were Nylon-6 alpha phase prepared by subsequent annealing of a parent sample slowly cooled from the melt. The treated samples were annealed at 110°C, then briefly heated to 136°C, then re-annealed at 110°C. Temperature-modulated differential scanning calorimetry (TMDSC) measurements allow the devitrification of the rigid amorphous fraction to be examined. We observe a lower endotherm, termed the ‘annealing’ peak in the non-reversing heat flow after annealing at 110°C. By brief heating above this lower endotherm and immediately quenching in LN2-cooled glass beads, the glass transition temperature and χ RA decrease substantially, χ MA increases, and the annealing peak disappears. The annealing peak corresponds to the point at which partial de-vitrification of the rigid amorphous fraction (RAF) occurs. Re-annealing at 110°C causes the glass transition and χ RA to increase, and χ MA to decrease. None of these treatments affected the measured degree of crystallinity, but it cannot be excluded that crystal reorganization or recrystallization may also occur at the annealing peak, contributing to the de-vitrification of the rigid amorphous fraction. Using a combined approach of thermal analysis with wide and small angle X-ray scattering, we analyze the location of the rigid amorphous and mobile amorphous fractions within the context of the Heterogeneous and Homogeneous Stack Models. Results show the homogeneous stack model is the correct one for Nylon-6. The cooperativity length (ξA) increases with a decrease of rigid amorphous fraction, or, increase of the mobile amorphous fraction. Devitrification of some of the RAF leads to the broadening of the glass transition region and shift of T g.

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Abstract  

A new method is presented to analyze the irreversible melting kinetics of polymer crystals with a temperature modulated differential scanning calorimetry (TMDSC). The method is based on an expression of the apparent heat capacity,
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\Delta \tilde C{e}^{---{i\alpha }} = mc_p + i(1/{\omega }F'_{T}$$ \end{document}
, with the true heat capacity, mcp, and the response of the kinetics,
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$F'_{\text{T}}$$ \end{document}
. The present paper experimentally examines the irreversible melting of nylon 6 crystals on heating. The real and imaginary parts of the apparent heat capacity showed a strong dependence on frequency and heating rate during the melting process. The dependence and the Cole-Cole plot could be fitted by the frequency response function of Debye's type with a characteristic time depending on heating rate. The characteristic time represents the time required for the melting of small crystallites which form the aggregates of polymer crystals. The heating rate dependence of the characteristic time differentiates the superheating dependence of the melting rate. Taking account of the relatively insensitive nature of crystallization to temperature modulation, it is argued that the ‘reversing’ heat flow extrapolated to ω → 0 is related to the endothermic heat flow of melting and the corresponding ‘non-reversing’ heat flow represents the exothermic heat flow of re-crystallization and re-organization. The extrapolated ‘reversing’ and ‘non-reversing’ heat flow indicates the melting and re-crystallization and/or re-organization of nylon 6 crystals at much lower temperature than the melting peak seen in the total heat flow.
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Journal of Thermal Analysis and Calorimetry
Authors: C. A. Gracia-Fernández, P. Davies, S. Gómez-Barreiro, Beceiro J. López, J. Tarrío-Saavedra, and R. Artiaga

. Swier , S , Mele , BV 1999 Reaction-induced phase separation in polyethersulfone-modified epoxy-amine systems studied by temperature modulated differential scanning calorimetry . Thermochim Acta 330 : 175 – 187 10.1016/S0040

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-isothermal temperature-modulated differential scanning calorimetry (TMDSC) for the separation of reversible and irreversible thermodynamic changes in glass transition and melting ranges of flexible macromolecules . Pure Appl Chem . 2009 ; 81 : 1931 – 1952 . 10

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-6031(98)00525-5 . 10. Wunderlich , B , Boller , A , Okazaki , I , Ishikiriyama , K , Chen , W , Pyda , M , Pak , J , Moon , I , Androsch , R . Temperature-modulated differential scanning calorimetry of reversible and

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. Xu , SX , Li , Y , Feng , YP . Numerical modeling and analysis of temperature modulated differential scanning calorimetry: on the separability of reversing heat flow from non- reversing heat flow . Thermochim Acta . 2000 ; 343 : 81 – 88 . 10

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temperature modulated differential scanning calorimetry . Themochim Acta. 388 : 343 – 354 . 44. Sbirrazzuoli , N , Vyazovkin , S , Mititelu , A , Sladic , C , Vincent , L . A study of

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