Polarizing microscopy spherulites observed

A dispersion of spherulitic liquid crystalline particles in brine exists between 0.8 gm/dl NaCl (Figure 2(a), first sample on the left) and 1.2 gm/dl. As the salinity is increased to about 1.4 gm/dl NaCl, the amount of liquid crystals as well as the birefringence increase, and the texture observed using PLS is intermediate between those of the spherulite (S) and lamellar (L) structures. The aqueous solution is a homogeneous lamellar phase between 1.6 and 1.8 gm/dl NaCl. The surfactant molecules form bilayers with their polar heads toward the brine. Figure 3(a) shows the lamellar structure as observed by polarized microscopy at 1.6 gm/dl salt and without any polymer. The bands represent "oily streaks" in a planar background. 

Okabe et al. [341] observed the presence of spherulites in LLDPE gels by polarizing microscopy. They also studied the influence of the kind of comonomers in LLDPE gels it appeared that the gel temperature increases by... 

Presence of TCL changes the properties of crystalline matrix. Transcrystallization of isotactic polypropylene in the presence of different fibers has been thoroughly analyzed. Gray as the first one provided detailed description of isotactic polypropylene behavior in the presence of wood fibers using polarized light microscopy. He observed that when melted polymer is cooled down, it crystallizes in spherulite forms in nonisothermal and isothermal conditions, creating additionally a TCL. 

Only minor effects were found on the equilibrium melting temperature and degree of crystallinity. Polarized optical microscopy observations revealed that the spherulites size decrease and the number increase with attapulgite content (Figure 12.14). 

The simples method involves observation of crystal growth by polarized optical microscopy. In the case of a neat PPLA no crystal appeared in the first 6 min. of crystallization but when 2.5 wt% of organic bisurea was added many crystals were observed right from the beginning of crystallization. Also, large spherulites were formed in neat PPLA and small in the nucleated PLLA. ... 

In some cases, the enzymatic polymerization afforded spherulites of artificial cellulose II, composed of single crystals with the molecular axis orientated perpendicular to the plane (29). Both positive- and negative-type spherulites were observed by polarization optical microscopy. By changing the reaction parameters. 

The random arrangement of adjacent crystals in the fringed-micelle model (see Fig. 2.4), does not accord with evidence obtained from microscopy. The electron microscope shows the crystals in polyethylene to be very thin twisted lamellae laid one upon another (Fig. 1.7). The lamellae are too small to be observed with the light microscope. Light microscopic examination of thin films or sections between crossed polarizers reveals complex polyhedral objects known as spherulites (see Fig. 2.5). They are in fact a complex ordered aggregation of the sub-microscopic crystals. In polyethylene the crystal lamellae are about 10 nm thick. They are separated one from another by thin lamellae of amorphous polymer of about the same thickness. The lateral... 

With increasing neat PVAc content, the heat of fusion decreases and die melting peaks shift to lower temperature in PLA/PVAc blends. The interaction parameters exhibit negative values for up to 10% hydrolyzed PVAc copolymer, but the values increase to positive ones with increasing the degree of hydrolysis. SAXS analysis and polarized optical microscopy observation indicate that a considerable amoimt of PVAc components is located in the interlamellar region. But P(VAc-co-VA) component is expelled out of the interfibrillar regions of the PLA spherulites in PLA/P (VAc-co-VA) blends. 

Spherulites. As the term implies, these are spherically shaped crystalline bodies (sometimes called supermolecular structures ) are aggregates smaller fibrillar, lamellar, or needlelike crystallites. The spherulites are well known to most polymer chemists from polarization optical microscopy observations. It should be mentioned that, although spherulites are birefringent, they are not 100% crystals, they do contain considerable concentrations of amorphous regions. 

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