Preparation of poly(ethylene terephthalate)/organoclay nanocomposites using a polyester ionomer as a compatibilizer

Abstract

In this work, poly(ethylene terephthalate)/organically modified montmorillonite (PET/o‐MMT) nanocomposites were prepared via direct melt compounding in a twin‐screw extruder. The main objective was to study the effects of using a polyester ionomer (PETi) as a compatibilizer to promote the intercalation and/or exfoliation of the o‐MMT in the PET. The o‐MMT content was 0, 1, 3, or 5 wt % and the PETi/o‐MMT mass ratio was 0/1, 1/1, or 3/1. The PETi was efficient to promote the intercalation/exfoliation of the o‐MMT in the PET matrix, as revealed by wide angle X‐ray scattering and transmission electron microscopy. Rheological characterization showed that the PET/o‐MMT nanocomposites exhibited a higher complex viscosity at low frequencies than PET, which is characteristic of materials presenting yield strength. Moreover, the higher the content and/or the degree of intercalation/exfoliation of the o‐MMT, the more the nanocomposite behaved like a solid because of a percolated structure formed by the o‐MMT layers, and the more the storage and loss modulus, G′ and G″, became independent of the frequency at low frequencies. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3084–3091, 2007

Effect of an Organo-Modified Montmorillonite on the Barrier Properties of PET Nanocomposites Using a Polyester Ionomer as a Compatibilizing Agent

“…Moreover, the o-MMT particles were better dispersed in nanocomposites containing PETi. Overall, they were smaller and randomly distributed in the PET matrix 21 . The TEM micrographs indicated the formation of intercalated structure for all nanocomposites.…”

“…The screw speed and feed rate were 100 rpm and 3 kg/h, respectively. The screw profile used was described in a previous paper 21 . Prior to compounding, the PET and PETi were dried for 24 hours at 100 and 60ºC, respectively.…”

“…A complete study of morphology of PET/organoclay nanocomposites using a polyester ionomer as a compatibilizing agent was developed in a previous work 21 . Figure 2 shows the DSC thermograms curves for the neat PET and PET/o-Mt nanocomposites containing 5wt% of the o-Mt.…”

“…Optimal mixing conditions and adequate surface treatment of silicates should be applied to prepare exfoliated nanocomposites [12][13][14][15][16] . The use of polymers containing polar functional groups and/or ionomers as compatibilizers also promotes the dispersion of silicates and may lead to intercalated and/or exfoliated nanocomposites [17][18][19][20][21] . The gas permeation in a homogeneous polymer matrix is governed by a mechanism of diffusion and solubility.…”

“…This is consistent with the literature 3,10,34 . The presence of the polyester ionomer compatibilizer amplifies this effect due to better o-Mt intercalation and/or exfoliation, as demonstrated by WAXS, TEM and rheological analyses 21 . This effect, in addition to the increase of PET crystallinity (impermeable phase) induced by organoclay, resulted in a decrease in the apparent diffusion coefficient (Table 3) and led to a decrease in permeability (Figure 3).…”