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An advanced analytic method, based mainly on thermorheological analysis of standard frequency sweeps at several temperatures, is introduced which can determine a host of rheological indicators for long-chain branched polyethylenes and other materials with an Arrhenius-type temperature dependence. The method can be used to classify and categorize unknown samples to material types (tubular and autoclave low density polyethylene, long-chain branched metallocene polyethylene). For long-chain branched metallocene polyethylenes, it is, furthermore, possible to determine molar mass and branching degree using established relations with rheological behavior. It is, therefore, possible to gain a rather comprehensive picture of the molecular structure of long-chain branched polyethylenes using only a relatively simple set of rheological experiments. An automated analysis routine facilitates the evaluation.

Summary: Impact poly(propylene) copolymers (IPC) having various ethylene-propylene rubber (EPR) compositions were prepared using a high activity Ziegler-Natta catalyst. EPR composition was characterized by temperature rising elution fractionation (TREF) analysis and FT-IR spectroscopy. Effect of EPR composition on the morphology and surface properties of IPC was investigated by scanning electron microscopy (SEM), 3D profiler, and gloss meter. Composition and amount of amorphous and crystalline EPR were quantified by TREF and found to be dependent on the ethylene content in EPR. From the SEM result, it was found EPR composition has a strong influence on its shape and size. IPCs containing propylene-rich EPR exhibited a finer dispersion of EPR phase. The surface roughness decreased with decreasing ethylene content in EPR. The comparison of EPR composition and morphology and surface properties exhibited strong correlations.

Summary: Effect of high density polyethylene (HDPE) addition on the morphology of heterophasic poly(propylene) copolymer (HPC) was investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Stress whitening developed upon dart impact was evaluated using Gardner-type impact tester. In the TEM study of HPC/HDPE blends, a core-shell morphology was observed of HDPE encapsulated by ethylene-propylene rubber (EPR). At low HDPE weight fractions (95/5 and 90/10 HPC/HDPE), the size of dispersed phase increased compared to pure HPC. However, further increase in HDPE leads to a decrease in domain size. The impact strength reached a maximum at 90/10 HPC/HDPE blend, and then decreased with further increase in HDPE content. The stress whitening of HPC was decreased with addition of HDPE. This decrease is attributed to the difference in the shrinkage between HPC and HPC/HDPE blends. The pressure-volume-temperature relationship supports that an additional volume contraction of HDPE can reduce the stress whitening of HPC.

Sulfonated poly(ether ketone ketone) ionomers (SPEKK) with ion-exchange capacities (IEC) between 0.2 and 3.4 meq/g were prepared by sulfonating PEKK with a mixture of concentrated and fuming sulfuric acids. Sulfonation occurs only on the phenyl rings attached to ether and ketone groups. The glass transition temperature of the dry SPEKK ionomers increased linearly with increasing IEC, and the ionomers were thermally stable to 250°C, above which desulfonation occurred. Waterswollen ionomers exhibited microphase separated morphologies, and the average correlation length determined by small angle X-ray scattering increased with increasing IEC. The proton conductivity of hydrated SPEKK membranes measured by impedance spectroscopy ranged from 10 –3 to 10 –1 S/cm as the IEC increased from 1.0 to 2.4 meq/g. Single cell performance curves on membrane-electrode assemblies (MEA) indicated that the SPEKK membranes approached the performance of Nafion™ for an IEC of 2 meq/g. POLYM. ENG. SCI., 45:1081–1091, 2005. © 2005 Society of Plastics Engineers

The phase behavior and crystallization of poly(ether ketone ketone)/polyimide blends was investigated by differential scanning calorimetry and dynamic mechanical analysis, and chemical interactions in the blends were probed by Fourier-transform infrared spectroscopy. Amorphous blends were miscible over the entire range of composition, although mixing was most favorable at higher thermoplastic polyimide concentrations. Blending suppressed crystallization, especially of the minor component, but crystallization of both components, however, did occur in most of the blends. While blends quenched from the melt exhibited only a single amorphous phase, melt crystallized blends appeared to possess two amorphous phases with different compositions. Shifts in the vibration frequencies of the carbonyl and imide bonds were inconsistent with the development of strong, specific intermolecular interactions, but may be explained by a disruption of the packing of the two homopolymers by nature of the mixing. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1227–1235, 2004

The addition of a thermotropic liquid crystalline, wholly aromatic copolyester, TLCP, improved the melt processability of poly(ether ketone ketone), PEKK. The tensile strength and modulus of the blends also improved with increasing TLCP, but the elongation at break decreased significantly. The blends were phase-sepa- rated, but the polymers were partially miscible as evident from shifts of the glass transition temperature (Tg) of each component towards that of the other component in the blend. Similarly, the melting points (Tm) of both components were depressed by blending. When the crystallization temperature was above Tm of the TLCP, the PEKK crystallization rate in the blend was slower than for the pure material, while crystallization was faster when the temperature was below Tm of the TLCP. Polym. Eng. Sci. 44:541-547, 2004. © 2004 Society of Plastics Engineers.

The effect of physical aging above Tg on ionic aggregation in the zinc salt of sulfonated poly(ethylene-co-propylene-co-ethylidene norbornene) ionomer was investigated by differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS), and dynamic mechanical thermal analysis (DMTA). The time-dependent development of a high temperature DSC endotherm and a high temperature tan δ relaxation were attributed to the dynamics of microphase separation of ionic aggregates. That conclusion was confirmed by the concurrent growth of a SAXS peak corresponding to the ionic microphase. The aging process at 25 °C occurred over a period of about 1 month, even though the ionomer was ca. 70 °C above Tg, where segmental mobility of the polymer is expected to be high. The kinetics of aging were dependent on temperature; a maximum in the rate of ionic aggregate formation occurred between 10 and 45 °C.

Thermal properties of blends of poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) and poly(styrene-co-acrylonitrile) (SAN) prepared by solution casting were investigated by differential scanning calorimetry. In the study of PHBV-SAN blends by differential scanning calorimetry, glass transition temperature and melting point of PHBV in the PHBV-SAN blends were almost unchanged compared with those of the pure PHBV. This result indicates that the blends of PHBV and SAN are immiscible. However, crystallization temperature of the PHBV in the blends decreased approximately 9–15°. From the results of the Avrami analysis of PHBV in the PHBV-SAN blends, crystallization rate constant of PHBV in the PHBV-SAN blends decreased compared with that of the pure PHBV. From the above results, it is suggested that the nucleation of PHBV in the blends is suppressed by the addition of SAN. From the measured crystallization half time and degree of supercooling, interfacial free energy for the formation of heterogeneous nuclei of PHBV in the PHBV-SAN blends was calculated and found to be 2360 (mN/m)3 for the pure PHBV and 2920–3120 (mN/m)3 for the blends. The values of interfacial free energy indicate that heterogeneity of PHBV in the PHBV-SAN blends is deactivated by the SAN. This result is consistent with the results of crystallization temperature and crystallization rate constant of PHBV in the PHBV-SAN blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 673–679, 2000

The thermal properties of blends of polycarbonate (PC) and poly(e-caprolactone) (PCL) were investigated by differential scanning calorimetry (DSC). From the thermal analysis of PC-PCL blends, a single glass-transition temperature (Tg) was observed for all the blend compositions. These results indicate that there is miscibility between the two components. From the modified Lu and Weiss equation, the polymer–polymer interaction parameter (χ12) of the PC-PCL blends was calculated and found to range from −0.012 to −0.040 with the compositions. The χ12 values calculated from the Tg method decreased with the increase of PC weight fraction. By taking PC-PCL blend as a model system, the values of χ12 were compared with two different methods, the Tg method and melting point depression method. The two methods are in reasonably good agreement for the χ12 values of the PC-PCL blends. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2072–2076, 2000

Binary blends of the sulfonated poly(ether ether ketone) (SPEEK)–poly(ether imide) (PEI) and SPEEK–polycarbonate (PC), and ternary blends of the SPEEK–PEI–PC, were investigated by differential scanning calorimetry. SPEEK was obtained by sulfonation of poly(ether ether ketone) using 95% sulfuric acid. From the thermal analysis of the SPEEK–PEI blends, single glass transition temperature (Tg) was observed at all the blend composition. For the SPEEK–PC blends, double Tgs were observed. From the results of thermal analysis, it is suggested that the SPEEK–PEI blends are miscible and the SPEEK–PC blends are immiscible. Polymer–polymer interaction parameter (χ12) of the SPEEK–PEI blends was calculated from the modified Lu and Weiss equation, and found to range from −0.011 to −0.825 with the blend composition. For the SPEEK–PC blends, the χ12 values were calculated from the modified Flory–Huggins equation, and found to range from 0.191 to 0.272 with the blend composition. For the SPEEK–PEI–PC ternary blends, phase separation regions that showed two Tgs were found to be consistent with the spinodal curves calculated from the χ12 values of the three binary blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2488–2494, 2000

Crystallization behavior and rheological properties of blends of bisphenol-A polycarbonate (PC) and polypropylene (PP) prepared by screw extrusion have been investigated by differential scanning calorimetry (DSC), polarized-light microscopy, scanning electron microscopy, and a Rheometrics Mechanical Spectrometer. In the study of thermal analysis of PC-PP blends by DSC, double crystallization peaks were observed in the PC-rich compositions. In the study of spherulite of 7/3 PC-PP blend, large droplets (>25 μm) of PP were crystallized between 115°C and 105°C, and then small droplets (

The thermal properties of blends of poly(ether ether ketone) (PEEK) and poly(ether imide) (PEI) prepared by screw extrusion were investigated by differential scanning calorimetry. From the thermal analysis of amorphous PEEK–PEI blends which were obtained by quenching in liquid nitrogen, a single glass transition temperature (Tg) and negative excess heat capacities of mixing were observed with the blend composition. These results indicate that there is a favorable interaction between the PEEK and PEI in the blends and that there is miscibility between the two components. From the Lu and Weiss equation and a modified equation from this work, the polymer–polymer interaction parameter (χ12) of the amorphous PEEK–PEI blends was calculated and found to range from −0.058 to −0.196 for the extruded blends with the compositions. The χ12 values calculated from this work appear to be lower than the χ12 values calculated from the Lu and Weiss equation. The χ12 values calculated from the Tg method both ways decreased with increase of the PEI weight fraction. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 733–739, 1999

Blends of a thermotropic liquid crystalline polymer (LCP) with poly(ether imide) (PEI), poly(ether ether ketone) (PEEK), polysulfone (PSF) and polyarylsulfone (PAS) prepared by screw extrusion have been investigated by differential scanning calorimeter and dynamic mechanical thermal analysis. From the measured glass transition temperature (Tg) and specific heat increment (ΔCp) at the Tg, it appears that the LCP dissolves more in the PEI- and PEEK-rich phases than does the PEI and PEEK in the LCP-rich phase. From the DSC study of PSF-LCP and PAS-LCP blends, the Tg(PSF) and Tg(PAS) of each blends are almost constant with blend composition. Therefore, it is concluded that PSF and PAS are immiscible with LCP. The polymer-polymer interaction parameter (χ12) and the degree of disorder (y/x1) of LCP have been investigated using the Flory lattice theory in which the anisotropy of LCP is considered. The χ12 values have been calculated from the Tg data and found to be 0.181 ± 0.004 at 593 K for the PEI-LCP blends and 0.069 ± 0.006 at 623 K for the PEEK-LCP blends. Using the previously presented method, the χ12 and y/x1 in partially miscible systems have been determined.

Transesterification reactions between polyarylate (PAr) and a copolyester (PETG) have been investigated by proton nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), and differential scanning calorimetry. Blends of PAr and PETG were prepared by melt mixing and solution-casting with weight fractions of PAr in the blends varying from 0.90 to 0.10. The PETG is a copolyester containing ethylene-1,4-cyclohexylene dimethylene terephthalate. From the thermal analysis of the PAr/PETG melt blends, a single glass transition temperature is observed, which indicates a miscibility between the PAr and PETG. The benzene insoluble fraction of the PAr/PETG (50/50) melt blends and solution-cast blends were characterized using NMR and FTIR. The results of NMR and FTIR support the conclusion that transesterification reactions between the PAr and PETG occurred under the melt blending conditions applied.

Blends of poly(ether imide) (PEI) and bisphenol-A polycarbonate (PC) have been investigated by differential scanning calorimetry, dynamic mechanical thermal analyzer, scanning electron microscopy, and transmission electron microscopy. Three different molecular weights of polycarbonate have been used in the PEI-PC blends. Blends were prepared by screw extrusion and solution casting with weight fractions of PEI in the blends varying from 0.90 to 0.10. From the measured glass transition temperature (T g ), the maximum decrease of T g (PEI) is observed for 0.9 weight fraction PEI in the PEI-PC blends. In the study of the morphology, the size of minor component domains (about 0.1 to 0.3 μm) in the 90/10 PEI-PC blend is small compared to the size of minor component domains (about 0.2 to 2.0 μm) in the 10/90 PEI-PC blend. This morphological behavior is attributed mainly to the difference of viscosity ratio between the dispersed phase and continuous phase. No considerable differences in the thermal behavior and morphologies have been observed among the blends of PEI and PC having different molecular weights.