No abstract

A tercet molecular nanocomposite is a ternary miscible polymer system in which a miscible blend of two flexible polymers is molecularly reinforced at nanometre level by a rigid-rod macromolecule and the tercet molecular nanocomposite demonstrates properties better than those of the constituent flexible polymers and their blend. A tercet molecular nanocomposite of a blend of flexible polyamide-6 (PA6) and polyamide-6,6 (PA6,6) molecularly reinforced at the nanometre level by a rigid-rod poly-p-phenylene-terephthalamide (PPTA) has been processed by coagulating a sulfuric acid solution of the components in water. This study reports miscibility, structure and properties of PPTA/[PA6/PA6,6] tercet molecular nanocomposites. Miscibility has been established by recording single intermediate glass transition temperatures by differential scanning calorimetry. Homogeneous morphology and dispersion of PPTA in [PA-6/PA-6,6] below 5 nanometre level has been established by scanning electron microscopy. Intermolecular interactions dispersing PPTA in [PA-6/PA-6,6] below the 5 nm level by imparting miscible homogeneous morphology and have been identified by Fourier transform infra red (FTIR) spectroscopy. Improved tensile mechanical properties of the tercet molecular nanocomposite, compared to those of the constituent flexible polymer blend, have been established by universal testing machine.

Liquid chromatography at critical conditions (LCCC) of poly(propylene) (PP) holds unique potential to further augment the understanding of molecular heterogeneities present in PP. The critical conditions for isotactic poly(propylene) (iPP) and syndiotactic poly(propylene) (sPP) have been identifi ed using porous graphitic carbon as stationary phase and combinations of adsorption and desorption promoting solvents. It is found that 1,2,4-trichlorobenzene is a stronger desorption promoting eluent compared to 1,2-dichlorobenzene, while 2-octanol shows a weaker adsorption promoting effect compared to 2-ethyl-1-hexanol for all stereo-isomeric forms of PP. The fraction of desorption promoting solvent needs to reach critical conditions decreased in a linear manner with the temperature. High temperature 2D liquid chromatography with infrared detection provides quantitative information about the fractions of the constituents (iPP and ethylene-propylene copolymer) of a model high impact PP sample at LCCC of iPP.