Phase behavior in blends of liquid crystalline poly(aryl ether ketone) (C-PAEK) and poly(aryl(ether) ketone) containing 4-methyl phenyl groups(T-PAEK) was investigated by differential scanning calorimetry(DSC),polarized light microscopy(PLM) and atomic force microscopy(AFM) techniques.In both(C-PAEK-rich) and T-PAEK-rich blends,the two components are molecular miscible in the melting state.For the 80/20 C-PAEK/T-PAEK blend,the bright core and rings are mainly composed of C-PAEK phase and dark rings consist of T-PAEK phase in the ring-banded spherulites.The development of the ring-banded spherulites in the C-PAEK/T-PAEK blends is a rhythmic growth process,and thus it is consistent with the structural discontinuity model proposed by Padden and Keith based on polyethylene spherulites.
Various morphologies of poly(trimethylene terephthalate) (PTT) solution-cast thin films at different crystallization temperatures were investigated by polarized light microscopy (PLM),atomic force microscopy (AFM) and transmitted electron microscopy (TEM).In the range of 110-150 oC,banded spherulite occurred and banding space gradually decreased along the radial direction from the primary nucleation site.Between 160 and 170 oC,normal non-banded spherulite was found.Above 170 oC,banded configuration occurred again.Lamellar growth direction of banded spherulite was determined to the crystal a-axis.
The effects of self-seeding nucleation on the crystallization behavior and properties of poly(trimethylene terephthalate) were studied.Differential scanning calorimetry(DSC) results indicated that the crystallization temperature of poly(trimethylene terephthalate) increased obviously(increased about 20℃) after the process of self-seeding nucleation.The results of polarized light microscopy(PLM) showed that the spherulite size decreased markedly from 40 μm to 8 μm.
The morphological structure of poly(trimethylene terephthalate)(PTT) thin films solution-cast at various temperatures was investigated by using polarized light microscopy and atomic force microscopy techniques. Different morphologies of the PTT films were observed at different crystallization temperatures (T c). In the temperature range of 363—403 K, banded spherulites occurred. When T c=413 K, the center location of the spherulite showed banded structure, while the outer region of the spherulite displayed a spherulite structure without ring-band. When T c≥423 K, the normal non-banded spherulite was found. The main reason for producing the ring-banded spherulite is the effect of residual solvent during the crystallization processs of the solution-cast films. At higher crystallization temperatures(≥423 K), no residual solvent exists during the crystallization of the films since the evaporation rate is higher at higher temperatures. So no banded structure is formed.
The crystalline syndiotactic 1,2-polybutadiene was synthesized with a catalytic system consisting of iron acetylacetonate , triisobutylaluminum and diethyl phosphite (DEP), and its single crystal structure was studied by transmission electron microscopy (TEM) and electron diffraction (ED) techniques. The polymer with melting point 179 ℃ was found to have 89.3% 1,2 content and 86.5% sydiotacticity based on 13C NMR measurement. The single crystals of the polymer were achieved by melt crystallization of the solution cast thin films at 150 ℃ for 2 h. Bright field electron micrograph shows that the single crystal exhibits a hexagonal prism shape with its long axis along the crystallographic b-axis, as revealed by the corresponding ED pattern. The strong (hk 0) reflections of the ED pattern indicate that the single crystal possesses a very good crystallographic orientation with the c-axis perpendicular to the film plane. According to the orthorhombic packing of the planar zigzag chains, all of the diffraction points can be indexed, and the unit cell parameters calculated from the ED result are a=1.102 nm and b=0.664 nm. In order to obtain the unit cell parameter c, α highly oriented thin film of the polymer was prepared with a special melt drawn technique. The TEM bright field image indicates that the melt drawn thin films contain highly oriented lamellae with their growing direction perpendicular to the drawing direction. The corresponding ED pattern reveals the molecular chains are highly oriented, with the c-axis parallel to the drawing direction. The unit cell parameter c is 0.513 nm, as calculated from the (hk 0) reflections.
The morphology of solution-cast thin films of isotactic poly(1-butene)(iPB-1) was investigated by using transmission electron microscopy(TEM) and electron diffraction techniques. The crystalline morphology of the solution-cast films of iPB-1 is greatly dependent on the preparation temperature. When the temperature is in the range of 90—100 ℃, metastable form Ⅱ spherulities are formed. Stable iPB-1 form Ⅰ crystals are achieved directly when the preparation temperature is higher(105—115 ℃).
We have reported the synthesis, morphological structure and single crystal structure of crystalline syndiotactic 1,2-polybutadiene. Now we want to study the effect of self-seeding nucleation on the crystallization behavior of it. In the report, the effects of self-seeding nucleation the crystallization behavior of syndiotactic 1,2-polybutadiene were studied by DSC and PLM techniques. The results indicated that the crystallization temperature of crystalline syndiotactic 1,2-polybutadiene increased obviously and the spherulite size decreased markedly after the process of self-seeding nucleation treatment.
The crystalline syndiotactic 1,2-polybutadiene was synthesized in a catalytic system consisting of iron acetylacetonate [Fe(acac) 3], triisobutylaluminum [Al(i-Bu) 3] and diethyl phosphite (DEP), and its morphological structure was investigated by transmission electron microscopy (TEM). The polymer with a melting point 179 ℃ was found to have 89.3% 1,2 polybutadiene and 86.5% syndiotacticity based on 13C NMR measurements. The bright field electron micrograph shows that the solution cast film of syndiotactic 1,2-polybutadiene consists of lamellae with lateral scale in micron size. It should be noted that the lamellae have no branching and they are almost parallel each other in localized areas. The lamellar growing direction is along b axis. Surprisingly, the electron diffraction pattern of the film only exhibits strong (hko) reflections, which indicate that the lamellae possess a single crystal-like orientation, i.e., with their c axis perpendicular to the film plane, while a and b axes in the film plane. According to the orthorhombic packing of plane zigzag chains, the cell parameters calculated from the electron diffraction pattern are a=1.102 nm, b=0.664 nm, respectively, which are completely consistent with the results reported by Natta et al..
