Poly polarizing optical microscopy

POM Polarized optical microscopy PPDX Poly(p-dioxanone)... 

The monomers XXIV-m-n were polymerized with initiator 4 in a monomer to initiator ratio of about 50. Table 16 summarizes the physico-chemical data for these polymers. Poly-(XXIV-m-n) exhibited smectic C mesophases, but these phases were only observed over a small temperature range and isotropization occurred shortly after the glass transition. It was not possible to identify the mesophase by polarized optical microscopy, but the smectic phase was confirmed by X-ray scattering experiments. Transition temperatures increased with the length of the carbon segments (n) but decreased with increasing siloxane segment (m). 

PTT/poly(butylene succinate) Melt blended at 270 °C for various times or for 2 h. at various temperatures/mechanical properties/DSC/morphology/polarized optical microscopy Zhou et al. 2012... 

In the literature many differences can be found in the temperature range used for the study of the crystalUzation and melting processes of PEO and PCL based AB diblock and ABA triblock copolymers. When the studies are performed above room temperature, an important fraction of the blocks may remain amorphous [8-11, 14, 16] however, most authors report that when the study is extended at temperatures below Tg, both blocks can crystallize [13-15,17]. In the case of ABA triblock copolymers, it has been found that the B-block remains amorphous when its content is lower than 10%, or its molecular weight is very low. Piao et al. [17] and He et al. [18,19] synthesized either poly(e-caprolactone)-6-poly(ethylene oxide)-6-poly(e-caprolactone) ABA triblock copolymers, as well as poly(ethylene oxide)-6-poly(e-caprolactone) AB diblock copolymers. They used poly(ethylene glycol) (PEG) as precursor and a calcium catalyst. Then, they characterized the materials by using NMR, DSC, WAXS and Polarized Optical Microscopy (POM). Cooling DSC scans carried out by He et al. [18] in AB diblock copolymers of different compositions are presented in Fig. 13.1. 

Figure 3.2 shows crystallization of poly(lactic acid) under different conditions. If PLA does not contain nucleating agents, crystallization is slow and produces only a few spherulites. If too small amount Figure 3.2. Polarized optical microscopy photographs of of nucleating agent is added, crystallization (a), pla containing 0.05 wt% hydrazide...

The formation of liquid crystalline phases with thermochromic properties in a poly(fl-peptide) was reported in Reference 13. The color changes were observed by using polarizing optical microscopy. However, this method was not found to be suitable for determining thermochromism. 

In this work, the structure, morphology and crystallization behavior of a semi-crystalline polymer, poly(ethylene oxide), PEO, when mixed with natural montmorillonite (Na -MMT) are studied [9]. The structure of the hybrids was investigated by X-ray diffraction (XRD), the thermal properties by Differential Scanning Calorimetry (DSC) and the kinetics of crystallization by isothermal Polarized Optical Microscopy (POM) and isothermal DSC. It is known that for PEO /... 

Polarized optical microscopy (POM) was performed to confirm the transition temperatures obtained by DSC studies and to find out the type of mesophases present in the synthesized polymers, the crystal phase to nematic phase transition temperature (Cr-N), and nematic phase to isotropic phase (N-1) temperature. It was found that the transition temperatures of the polymers are almost the same as those obtained in DSC. The POM results revealed that the poly(azomethine esters) 3(b-d) exhibit nematic liquid crystal phases and the images were shown in Fig. 12.5. 

Figure 6 Spherulites of isotactic poly-l-butene (a, during growth) and of polyethylene (b, after completion) by optical microscopy (OM) under crossed polars. Reproduced from Ref. [3] with permission of John Wiley Sons, Inc.

Fig. 2 Optical microscopy image of a small section of a poly(ethylene oxide) (PEO) droplet dispersion sample, see text (1000-mm wide) obtained at Tc = - 2.6 °C. Amorphous droplets appear dark and semicrystalline droplets appear white under nearly crossed polarizers. The plot shows the fraction of crystallized droplets as a function of temperature upon cooling (0.4 °C min-1) for homogeneous nucleation. (Reprinted with permission from [84], Copyright 2004 by the American Physical Society)...

---