Cold crystallization temperature

Fig. 4.8.7. Typical DSC curves of a crystalline polymer melting temperature (T, ), crystallization temperature (7V), glass transition temperature (Tg), and cold crystallization temperature (T )...

A similar result for PPE/PET blends has been reported by Liang and Pan [1994]. The authors found the cold crystallization temperature, T in the dispersed PET phase to be markedly lower than that of the virgin PET, indicating that PPE may partly act as nucleating agent to promote the nucleation of the PET component. 

Bulk crystallization temperature upon cooling from the melt Tf Crystallization temperature of the bulk homopolymer Fc,coid Cold crystallization temperature T c,hom Homogeneous crystallization temperature... 

The cold crystallization temperature shifts to the low-temperature side with increasing spinning speed. In contrast, the melting peak temperature shifts to the high-temperature side with increasing spinning speed. 

At low draw ratios, the fibers are largely amorphous and exhibit a significant crystallization exotherm at the cold crystallization temperature. 

Figure 7.20 DSC curves for poly(p-phenylene sulfide) (PPS) fibers [19]. 1, Heating curve of as-spun fiber 2, cooling curve 3, heating curve of the sample cooled from the molten state at 20 "C min 4, heating curve of the sample quenched from a temperature between the glass transition temperature and the cold crystallization temperature . 3, heating curve of the. sample cooled from the glassy state...

The transition behaviour of the blend can be evaluated by differential scanning calorimetry (DSQ. As shown in Figure 16.5, there is no significant change in glass transition temperature (Tg) of PLA with NR content (57.7-59.4 °C), which confirms the immiscible character of brittle and elastic polymers. However, a cold crystallization exothermic peak is observed. The cold crystallization temperatures (Jcc) are 127.6 °C for PLA/NR (90/10) and 123.5 °C for PLA/NR (80/20), respectively. The presence of cold crystallization suggests that the addition of NR may increase the crystallization rate of PLA, and the observed activities could result from the nucleating effect of NR. 

Epoxidizedsoybean oil (ESO) is produced via conversion of the double bonds of soybean oil with peracids or peroxides, resulting in more reactive oxirane or epoxide moieties, promoting chemical reactions [230-232]. ESO is normally used to plasticize and/or stabilize poly(vinyl chloride) (PVC), chlorinated rubber, and PVOH emulsions [231, 232]. The effects of ESO as a PLA plasticizer were reported elsewhere [230, 233, 234]. In summary, ESO lowered Tg, cold crystallization temperature Tm. enthalpy of cold crystallization (AHcc), tensile strength, and tensile... 

Sun et al. [23] studied the crystallization kinetics of PET oriented by solid-state coextrusion. The cold crystallization temperature was found to decrease with the increase in the extrusion draw ratio for samples extruded at various temperatures. This suggested presence of more amorphous chains containing the trans conformation isomer than the gauche conformation isomer. Because the trans isomer can be packed into crystal lattice more... 

Table II. Glass transition temperatures (Tg), cold crystallization temperatures ...

Figure 10.21 shows the DSC thermograms of the quenched samples of the copolymers. The composition dependencies of and for the copolymers are shown in Table 10.11. The values increase with increasing the content of the naphthalene moieties. When the molar fraction of DHN is over 0.3, the peaks corresponding to the clear cold-crystallization temperature (T ) and cannot be detected. For the synthesized copolymers with a DHN molar fraction being less than 0.3, the decreases with increasing the content of the naphthalene moieties, while T shows a reverse... 

Cold-crystallization temperature measured from DSC traces at a heating rate of 10 °C/min. 

It has also been noticed that within some temperature interval around the transition points and NI the two neighbouring phases are not strictly homogeneous, but each phase contains embryos of the other phase. The relative amount of the phase existing in an embryonic form remains very small up to temperatures very close to the transition point, but it is detectable by NMR. Figure 1 shows several proton NMR spectra of DDA9-L representative of (A) the isotropic phase with a small nematic fraction, (B) nematic phase with a small isotropic fraction (1-2 %), (C) pure nematic phase homogeneously oriented, (D) unoriented nematic phase, or solid phase above the cold crystallization temperature, (E) solid phase with some nematic fraction, and (F) solid phase near room temperature. It is interesting to note that the sharp peak at the centre of spectrum B, which could not be obtained in the line shape simulation procedure reported in... 

Besides the composite proton NMR line shape which is observed just below on cooling (Fig. 1(E)), we can observe at least three different line shapes in the solid state of the polymer DDA9 namely, one below Tg, and two others, particularly meaningful, between and the cold crystallization temperature and above this temperature, respectively. The cold crystallization temperature, of DDA9 occurs about 50 °C below The proton NMR spectra observed between and have a super-Lorentzian shape, i.e. one in which the wings spread out more than in the true Lorentzian, and consequently the ratio he line widths... 

Fig. 7.17 Illustration of a DSC thermogram during the heating scan for a polymer sample. T, glass transition T, cold-crystallization temperature T, melting temperature.

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