Investigation of Microphase Separation and Thermal Properties of Noncrystalline Ethylene Ionomers. 2. IR, DSC, and Dielectric Characterization

Abstract

The microphase structure of noncrystalline poly(ethylene-co-13.3 mol % methacrylic acid) (E-0.133MAA) ionomers was investigated by using infrared (IR) spectroscopic, X-ray scattering, differential scanning calorimetric (DSC), and dielectric measurements. The noncrystallinity was confirmed by small-angle X-ray scattering (SAXS) and DSC studies, which has enabled a quantitative analysis of the SAXS ionic peak associated with ionic aggregates without being perturbed by the polyethylene lamellae peak. In 60% neutralized Na ionomer, it was revealed that almost 100% of MAA side groups including unneutralized COOH are incorporated into the ionic aggregates with an average ionic core radius (R 1) of ∼6 Å. The dielectric relaxation studies showed that the ionic aggregates form a microphase-separated ionic cluster. Analysis of dielectric strengths indicated the most (∼90%) of the COONa groups are present in the ionic cluster. On the other hand, in the 60% neutralized Zn ionomer, both SAXS and dielectric studies indicated that the ionic aggregates with R 1 ∼ 4 Å are almost isolated and dispersed in the matrix; the formation of ionic cluster was not recognized. Similarly to partly crystalline E-MAA ionomers, all noncrystalline E-0.133MAA ionomers exhibited an endothermic peak at 320−330 K (labeled T i) on the first heating, depending on the aging time at room temperature. Several factors that would be critical for the DSC T i peak were discussed. It was concluded that the DSC T i peak is certainly associated with changes of the state of ionic aggregate region.

Thermal, dynamic mechanical, and creep behavior of carbon nanotube reinforced ASA/Na‐ionomer blend

“…It maintained the same time span for aging each specimen. This process removes any moisture effect and the room temperature aging effects, which can affect the DSC thermogram . All the DSC analysis were executed in Q10 (TA Instruments, USA) differential scanning calorimeter.…”

Study of Dynamic Rheological, Dynamic Mechanical and Creep Properties of Acrylonitrile Styrene Acrylate (ASA)/Zn+2poly(ethylene-co-methacrylic acid) Ionomer Blend

“…Prior to experiment, 2 to 5 mg sample taken in DSC aluminum pan was first melted at 250 C under N 2 atmosphere and kept in vacuum desiccators for 21 days before the measurements in order to remove all the previous thermal history and to maintain the same length of room temperature aging time. These pretreatments nullified the effect of moisture and room temperature aging of all the samples in the DSC thermograms (44)(45)(46). The degree of crystallinity (X c ), due to the presence of polyethylene crystallite region of ionomer, was also calculated assuming the heat of fusion of polyethylene crystallites is 290.4 J/g (47).…”

Influence of the acid content of (acrylate processing aid)‐based lanthanum(III)‐neutralized ionomer on the thermal degradation and fusion behavior of rigid poly(vinyl chloride)

“…The as‐prepared ACR‐0.25‐0.37 shows two endothermic peaks at 140 and 225°C. These peaks are assigned to the relaxation of the chains restricted in the ionic aggregates . All of these transition peaks are absent from an immediate second heating scan following the first run (blue dashed curves).…”

“…The curves recorded during the second heating scan exhibit only a single glass transition at around 125, 157, and 187°C for ACR‐0.25‐0.37, ACR‐1.80‐0.28, and ACR‐2.90‐0.23, respectively, thereby indicating that the restriction due to multiplets and clusters is eliminated by heat treatment up to 250°C. This observation is ascribed to the migration of ion groups as Fickian diffusion in the form of ion pairs − between multiplets; i.e., “ion hopping” occurred at elevated temperatures . The “ion hopping” makes the rigid ionic aggregate regions soften and break down .…”

“…This observation is ascribed to the migration of ion groups as Fickian diffusion in the form of ion pairs − between multiplets; i.e., “ion hopping” occurred at elevated temperatures . The “ion hopping” makes the rigid ionic aggregate regions soften and break down . The ionic aggregate structure could hardly reform immediately after cooling, so that the endothermic peaks involving the multiplet relaxation could not be observed in an immediate second scan .…”