Effect of the ionic aggregation on the crystallisation behavior of poly(ethylene) part of ionomer

Journal of Thermal Analysis and Calorimetry (Impact Factor: 2.21). 01/2003; 73(1):361-380. DOI: 10.1023/A:1025178818103

ABSTRACT The influence of ionic interaction on the melt-crystallization behavior of the ethylene ionomer was studied using modulated
DSC (MDSCTM), wide angle X-ray scattering (XRD) and hot stage microscopy. The kinetics of the crystallization process of the ionomer
was evaluated using isothermal differential scanning calorimetry (iso-DSC). Wide-angle X-ray scattering was used to examine
the d spacing of poly(ethylene) part. The crystallinity of the poly(ethylene) part of ionomer measured from XRD is found to
be 24%, which is comparable to that obtained from MDSCTM. Small-angle X-ray scattering (SAXS) results show that the clusters and multiplets exist in the ionomer, and the cluster
is about 127Ĺ. The kinetics of crystallization process obtained using Avrami equation shows that the crystallization process
is fundamentally similar to poly(ethylene) as it goes through nucleation and propagation stages of the crystals. However,
the morphology of the crystal appears to be different and influenced by clusters (platelike and/or needle-shaped) as evident
from Avrami constant. This is different from the poly(ethylene) (which is spherulitic in nature) due to polar cluster and
hydrophobic PE melt interaction.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Ionomer–silica hybrid materials were made from polyethylene-co-acrylic acid neutralized by a zinc salt (PI) and tetraethoxy silane (TEOS) via the sol–gel reaction. The effects of various experimental parameters such as solvents, H2O/Si ratio and the amount of TEOS in the ionomer solution on the hybrid structure and properties were examined. The spectroscopic results show that solvents do not affect the structure of the hybrids, but influence the thermal properties. The hybrids made using highly polar solvent exhibit better thermal stability and dynamic mechanical properties at high TEOS contents. The amount of water used for hydrolysis and subsequent condensation play a significant role in the network formation. The varying amount of TEOS in solutions gives rise to different silica content of the hybrid. Above 50 wt%, the sample becomes opaque due to silica aggregation. The high ratio of H2O/Si leads to phase separation during the reaction. Transparent hybrid materials can only be obtained when the ratio of H2O/Si is below 5.
    Polymer 05/2005; 46(12-46):4013-4022. DOI:10.1016/j.polymer.2005.03.053 · 3.77 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ethylene-co-methacrylic acid (EMAA) ionomers are incorporated into polyelectrolyte complexes and thin films fabricated with the layer-by-layer technique using mixed solvent systems of THF and water. EMAA ionomers have been reported to have self-healing properties. The thin films were optically clear and can be made as a coating or freestanding. Their composition was determined with elemental analysis. DSC showed these polymer blend materials to have suppressed polyethylene crystallinity compared to bulk EMAA and an increased amount of energy required to create the order-to-disorder transition of disrupting the associations between the ionic groups of the ionomer.
    ACS Macro Letters 12/2011; 1(1):209–212. DOI:10.1021/mz200119b · 5.24 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The structure, morphology, and properties of an ionomer, poly(ethylene-acrylic-acid) neutralized by zinc salts (PI) depend on the free carboxylic acid content. In this work, metal acetates (Na, Zn, and Al acetates) were used to control the neutralization levels. A wide range of techniques were used, such as spectroscopic Fourier transform infrared spectroscopy (FTIR), thermal [thermogravimetric analysis, modulated differential scanning calorimetry (MDSC), and dynamic mechanical analysis (DMA)], mechanical (tensile measurement), and small angle neutron scattering (SANS). The melt rheological properties of the samples were also examined. The results show that metal acetate neutralizes free acrylic acid in the ionomer, which has the primary role in controlling ionic association. The number of ionic groups in ionic domains and multiplets in the matrix is dependent on the neutralization level. Metal valence determines the ionic domain or multiplet structure (FTIR), further properties of PI. Dynamic mechanical properties, the ionic transition behaviour, and the mechanical properties are improved compared with PI using monovalent cation (Na+), but decreased using trivalent cation (Al3+) or shows less significant changes due to steric effects. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
    Journal of Applied Polymer Science 05/2012; 124(4). DOI:10.1002/app.35310 · 1.64 Impact Factor
Show more