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: Cp=A+BT.
Authors:Yanni Qi, Jian Zhang, Shujun Qiu, Lixian Sun, Fen Xu, Min Zhu, Liuzhang Ouyang, and Dalin Sun
Polyaniline/NiO (PANI/NiO) composites were synthesized by in situ polymerization at the presence of HCl (as dopant). FTIR,
TEM and XRD were used to characterize the composites. Thermogravimetry (TG)–mass spectrometer (MS) and temperature modulated
differential scanning calorimetry (TMDSC) were used to study the thermal stability, decomposition and glass transition temperature
(Tg) of the composites, respectively. FTIR and XRD results showed that NiO nanoparticles connected with PANI chains in the PANI/NiO
composites. TEM results exhibited that the morphologies of PANI/NiO composites were mostly spherical, which were different
from the wirelike PANI. TG–MS curves indicated that the products for oxidative degradation of both PANI and PANI/NiO composite
were H2O, CO2, NO and NO2. TG curves showed that with NiO contents increased in PANI/NiO composites, thermal stability of PANI/NiO composites increased
firstly and then decreased when the NiO content was higher than 66.2 wt%. Tg of PANI/NiO composites also increased from 163.19 to 252.36 °C with NiO content increasing from 0 to 50 wt%, and then decreased
with NiO content increasing continuously.
Authors:F. Awaja, F. Daver, E. Kosior, and F. Cser
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 (Tg) did not show a significant change as a function of PMDA addition or the extrusion residence time. Melting temperature (Tm) and crystallisation temperature (Tc) 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.
A three-phase model, comprising crystalline, mobile amorphous, and rigid amorphous fractions (χc, χMA, χRA, 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 χRA decrease substantially, χMA 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 χRA to increase, and χMA 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
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 Tg.
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,
. 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.
-isothermal temperature-modulateddifferentialscanningcalorimetry (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
Wunderlich , B , Boller , A , Okazaki , I , Ishikiriyama , K , Chen , W , Pyda , M , Pak , J , Moon , I , Androsch , R . Temperature-modulateddifferentialscanningcalorimetry of reversible and