Microbeam X-ray and Scanning Electron Microscopic Analyses on Sector-Banded Spherulites of Poly(p-dioxanone) Justified with Pixelated Iridescence.

Poly(p-dioxanone) (PPDO) is crystallized with amorphous poly(p-vinyl phenol) (PVPh) and tannic acid (TA) as co-diluents to regulate and induce dendritic-ringed PPDO spherulites, with spoke- or sector-bands, aiming for convenience of analyses on interior lamellar assembly. Morphologies and interior lamellar arrangement leading to the peculiar rings on individual dendrites are evaluated by using polarized-light microscopy (PLM) and scanning electron microscope (SEM). Combinatory microbeam small-/wide-angle X-ray scattering (SAXS/WAXS) analyses further confirm the unique assembly patterns in periodic cycles.

Microbeam X-ray Reanalysis on Periodically Assembled Poly(β-Hydroxybutyric acid-Co-β-hydroxyvaleric acid) Tailored with Diluents.

Self-assembly of 3D interiors and iridescence properties of poly(β-hydroxybutyric acid-co-β-hydroxyvaleric acid) (PHBV) periodic crystals are examined using microcopy techniques and microbeam X-ray diffraction. Morphology of PHBV can be tailored by crystallizing in presence of poly(vinyl acetate) (PVAc) or poly(trimethylene adipate) (PTA) for displaying desired periodicity patterns. The regular alternate-layered lamellae of banded PHBV crystal aggregates, resembling the structures the natural mineral moonstone or nacre, are examined to elaborate the origin of light interference and formation mechanisms of periodic lamellar aggregation of PHBV spherulites.

From Nano-Crystals to Periodically Aggregated Assembly in Arylate Polyesters-Continuous Helicoid or Discrete Cross-Hatch Grating?

This work used several model arylate polymers with the number of methylene segment n = 3, 9, 10, and 12, which all crystallized to display similar types of periodically banded spherulites at various T and kinetic factors. Universal mechanisms of nano- to microscale crystal-by-crystal self-assembly to final periodic aggregates showing alternate birefringence rings were probed via 3D dissection. The fractured interiors of the birefringent-banded poly(decamethylene terephthalate) (PDT) spherulites at T = 90 °C revealed multi-shell spheroid bands composed of perpendicularly intersecting lamellae bundles, where each shell (measuring 4 μm) was composed of the interior tangential and radial lamellae, as revealed in the SEM results, and its shell thickness was equal to the optical inter-band spacing (4 μm).

Chemical Interaction-Induced Evolution of Phase Compatibilization in Blends of Poly(hydroxy ether of bisphenol-A)/Poly(1,4-butylene terephthalate).

An immiscible blend of poly(hydroxy ether of bisphenol-A) (phenoxy) and poly(1,4-butylene terephthalate) (PBT) with phase separation was observed in as-blended samples. The compatibilization of phenoxy/PBT blends can be promoted through chemical exchange reactions of phenoxy with PBT upon annealing. The annealed phenoxy/PBT blends had a homogeneous phase with a single that could be enhanced by annealing at 260 °C.

Synthesis and Properties of Carbon Nanotube-Grafted Silica Nanoarchitecture-Reinforced Poly(Lactic Acid).

A novel nanoarchitecture-reinforced poly(lactic acid) (PLA) nanocomposite was prepared using multi-walled carbon nanotube (MWCNT)-grafted silica nanohybrids as reinforcements. MWCNT-grafted silica nanohybrids were synthesized by the generation of silica nanoparticles on the MWCNT surface through the sol-gel technique. This synthetic method involves organo-modified MWCNTs that are dispersed in tetrahydrofuran, which incorporates tetraethoxysilane that undergoes an ultrasonic sol-gel process.

Enhancing the Compatibility of Poly (1,4-butylene adipate) and Phenoxy Resin in Blends.

This work concerns the enhancement in the compatibility of blends of poly (1,4-butylene adipate) (PBA) with poly (hydroxy ether of bisphenol-A) (phenoxy) via alcoholytic exchange. Results on the thermal behavior and morphology show that the blended PBA/phenoxy system exhibits a homogeneous phase and a composition-dependent glass transition temperature (T). The interaction parameter () of PBA/phenoxy blends was calculated using the melting point depression method and was found to be -0.

Characterization and Curing Kinetics of Epoxy/Silica Nano-Hybrids.

The sol-gel technique was used to prepare epoxy/silica nano-hybrids. The thermal characteristics, curing kinetics and structure of epoxy/silica nano-hybrids were studied using differential scanning calorimetry (DSC), Si nuclear magnetic resonance (NMR) and transmission electron microscopy (TEM). To improve the compatibility between the organic and inorganic phases, a coupling agent was used to modify the diglycidyl ether of bisphenol A (DGEBA) epoxy.

Perpendicularly oriented lamellae in poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) blended with an amorphous polymer: ultra-thin to thick films.

The oppositely oriented lamellae in ridge and valley bands of ring-banded spherulites in biodegradable poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (PHBV) interacting with amorphous poly(vinyl acetate) (PVAc) were examined using polarized-light optical, scanning electron, and atomic-force microscopy techniques (POM, SEM, AFM). Solvent-etching and fracturing were utilized for probing the interior morphology of the large-size ring-banded spherulites in PHBV/PVAc (70/30) blend [T(c) = 110 °C] films or thick bulk of various thicknesses. SEM analysis revealed that dual ridges of two opposite-oriented lamellae correspond to two-color bands (yellow and blue) of successive rings in POM micrographs.

Developing the dielectric mechanisms of polyetherimide/multiwalled carbon nanotube/(Ba0.8Sr0.2)(Ti0.9Zr0.1)O3 composites.

Various amounts of multiwalled carbon nanotubes [MWNTs] were embedded into polyetherimide [PEI] to form PEI/MWNT composites, and their dielectric properties were measured at 1 MHz. The Lichtenecker mixing rule was used to find a reasonable dielectric constant for the MWNTs used in this study. The dielectric constants of the developed composites were significantly increased, and the loss tangents were significantly decreased as 2.