Supercritical carbon dioxide (scCO₂) dispersion of poly(ethylene terephthalate)/clay nanocomposites: Structural, mechanical, thermal, and barrier properties

Abstract

Dispersed poly(ethylene terephthalate) (PET)/clay nanocomposites can lead to materials with superior barrier and mechanical properties. PET/clay nanocomposites were prepared by melting extrusion of PET with as-received or supercritical carbon dioxide (scCO 2 ) predispersed Cloisite V R 30B (30B). The predispersion of 30B was assessed by WAXD, SEM, and TGA, and results indicated that scCO 2 processing could predisperse 30B and the surface modification of the clay was preserved after processing. The structure of PET/30B nanocomposites was investigated by WAXD and TEM confirming that PET has penetrated into the clays intergalleries and the predispersed clays lead to improved interfacial interaction and homogenous clay dispersion. Both tensile strength and Young's modulus were improved by 12.1% and 24.9% respectively, as incorporating of 3 wt % of scCO 2 processed clay. Differential scanning calorimetry (DSC) results indicated that clay particles served as nucleation agent could increase the crystallinity whereas had no impact on melting process. In addition, with the addition of 1 wt % of predispersed clay, a significant reduction of oxygen permeation (33%) was achieved at 23 8C and the maximum reduction (44%) was achieved by adding 3 wt % processed clay. Moreover, we confirmed the effect of temperature on the permeation of PET/30B nanocomposites depended both on the Arrhenius behavior of the organic phases and tortuous path effects, where improved clay dispersion resulted in a higher effective activation energy. Moreover, the transparency of PET matrix was preserved for all nanocomposites.

The Effect of Processing and Clay Modifications on Properties of Pet/Nano Clay Nanocomposites

“…RESULTS AND DISCUSSION Figure 1 shows the XRD patterns for PET/clay nanocomposites prepared with 5 wt% ScCO2 and without scCO2. These patterns similar to the previous studies results of Fengyuan Yang [14] FIG1: NC's with 5wt% clay (A) 30B (B) 20A and (C) 10B WAXD patterns All NC showed properly-described both d001 and d002 diffraction peaks, no matter their surface chemistry or processing of scCO2, advising the existence of sure exceeding clay structures which are ordered in all NC. In addition, all of NC confirmed shifts of the d001 peaks to especially lower 2θ compared with corresponding pristine clays, advising that the polymer have been embedded into the galleries of clay.…”

“…Then resins of PET with diverse kinds of clay (scCO2 processed or as-received), modification (20A,30B and 10A) and fraction (1, 3 and five wt%) had been closed in a foil bag made of aluminium and blended mechanically by the usage of a "Thumler's tumbler" for 12h before extrusion. [14] PET/clay NC have been compounded with the aid of the use of a micro-compounder of laboratory scale ("Thermo Haake Minilab") with a recirculation channel which permits the processing of batches of usually 5-40 g, a barrel temperature of 265 o C and screws of twin counter-rotations at a velocity of 50rpm. At last, the strands which have been extruded cooled down to the temperature of the room and are made into pellets.…”

“…Thin (~0.2mm) samples of pure PET films and NC had been made via pellet melt pressing right into a cupper mold which is custom-made ("diameter=56mm") among foil sheets coated with Teflon. [14] II.…”

“…[9][10][11][12][13][14][15] B. Transmission Electron Microscopy (TEM) NC Thin sections (70-100nm) had been made the use of a "Leica Ultramicrotome with a diamond knife (knife angle =35 o )" and positioned on two hundred mesh grids made of copper protected with carbon.…”

Improvement in mechanical and structural properties of poly(ethylene terephthalate) nanohybrid

“…Young's modulus was improved up to 33% using 4 wt% 30B clay, whereas reduction in toughness was around 92%. Yang et al [17] reported supercritical carbon dioxide pre-dispersed Cloisite 30B melt extruded with PET matrix. The Young's modulus and tensile strength were improved by 12% and ~ 25%, respectively, whereas elongation at break was reduced by ~ 80%.…”