Enthalpy relaxation of the glass of poly (l-lactic acid) of different d-isomer content and its effect on mechanical properties

Insertion‐Crystallization‐Induced Low‐Temperature Annealing Peaks in Melt‐Crystallized Poly(l‐Lactic Acid)

“…Though using an even higher heating rate is advantageous for increasing the signal/noise ratio, it is detrimental regarding thermal‐lag effects, quantified elsewhere for the used instrument. [ 67–69 ] Data obtained on samples annealed at 140 °C for less than about 100 s reveal on subsequent heating the glass transition at around 68 °C, being slightly higher than typically observed in conventional differential scanning calorimetry (DSC) experiments, [ 70,71 ] due the higher heating rate, [ 72–74 ] and no further events. Annealing the sample longer than about 100 s permits crystallization as indicated with the melting event at temperatures close to 200 °C and the decrease of the heat‐capacity step at T g due to the reduced liquid fraction.…”

Kinetics of homogeneous crystal nucleation of polyamide 11 near the glass transition temperature

“…Here, depending on the component geometry/wall thickness and molding parameters, cooling rates up to several 100 K/s may be observed, [45][46][47] perhaps suppressing crystallization but permitting formation of nuclei which might grow to crystals over long time, causing, for example, aging/ change of properties. 48,49 Classical enthalpy relaxation of the glass has been treated in a separate study 44 lubricant, and is designed for processing by extrusion. 50 The melt-flow volume index, mass-average molar mass, and polydispersity are 1 cm 3 /10 min (235 C, 2.16 kg), 50 17.2 kg/mol, and 2, 51 respectively.…”

“…Such thermal profiles, that is, fast cooling of the melt followed by annealing the glass slightly below T g is often observed in industrial processing of this material, for example injection molding. Here, depending on the component geometry/wall thickness and molding parameters, cooling rates up to several 100 K/s may be observed, 45–47 perhaps suppressing crystallization but permitting formation of nuclei which might grow to crystals over long time, causing, for example, aging/change of properties 48,49 . Classical enthalpy relaxation of the glass has been treated in a separate study 44 and crystal formation below T g has been proven for another representative of the polyamide family, namely PA 6 36 …”

Physical aging of the 62.5GeS2-12.5Sb2S3-25CsCl chalcogenide glass: Assessing the mechanisms of equilibration and crystallization

“…In a previous work [20], the authors had evidenced a glass transition temperature at the onset point of 280°C, and a crystallization peak with a maximum around 478°C during heating scans. Since physical aging can influence the material performances 13,21,22 it is important to study and give a better understanding of this phenomenon. Moreover, the way by which a glass reaches (or not) its equilibrium state after a certain aging time is still matter of debate in the scientific community 16 .…”