Crystallization, properties, and crystal and nanoscale morphology of PET-clay nanocomposites

Abstract

The crystallization process and crystal morphology of poly(ethylene terephathalate) (PET)–clay nanoscale composites prepared by intercalation, followed by in‐situ polymerization, have been investigated by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM), dynamic scanning calorimetry (DSC), and X‐ray techniques, together with mechanical methods. Results of the nonisothermal crystallization dynamics show that the nanocomposites of PET (Nano‐PET) have 3 times greater crystallization rate than that of pure PET. The thermal properties of Nano‐PET showed heat distortion temperature (HDT) 20–50°C higher than the pure PET, while with a clay content of 5%, the modulus of Nano‐PET is as much as 3 times that of pure PET. Statistical results of particle distribution show that the average nanoscale size ranges from 10 to 100 nm. The particles are homogenously distributed with their size percentages in normal distribution. The agglomerated particles are 4% or so with some particles size in the micrometer scale. The morphology of exfoliated clay particles are in a diordered state, in which the morphology of the PET spherulitics are not easy to detect in most of microdomains compared with the pure PET. The molecular chains intercalated in the interlamellae of clay are confined to some extent, which will explain the narrow distribution of the Nano‐PET molecular weight. The stripe‐belt morphology of the intercalated clay show that polymer PET molecular chains are intercalated into the enlarged interlamellar space. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1139–1146, 1999

Preparation of polymer–clay nanocomposites and their properties

“…However, characterization of the resulting composite was not reported. 130 In this report, the authors claim that water serves as a dispersing aid for the intercalation of monomers into the galleries of the organoclay.…”

Oscillation Process of Bubble in Polymers

“…1) and disaggregated nano-granules scale around the bubble is about 10 −8 m (see Figs. [2][3][4]. When the processing of ISBS was appraised from the theory, the estimating results were: if we consider the bubble inflating process as an isothermal process and the bubble expanded very fast (about 10 −6 s), we can calculate that work done by the bubble on the polymer melt was about 5.8 × 10 −9 J; the resultant force was about 9.43 × 10 −8 N which acted on the nanoscale secondary granule in the polymer, and the corresponding value obtained using the Hamaker equation was 4.1 × 10 −10 N. Thus it can be seen that the dispersive force of bubble inflation on the agglomerated particles was two orders of magnitude larger than that obtained using the Hamaker equation, and is sufficient to bring about dispersion of the nanogranules.…”

“…This method is only suitable for dispersion of materials having a layered structure (such as montmorillonite or hydrotalcite), and is ineffective in dispersing non-layered materials (such as CaCO 3 or ZnO). [1][2][3] In Situ Bubble Stretching Method (ISBS Method) for dispersion of nanogranules in a polymer melt is based on that bubble inflation in the foaming process is so fast that the polymer melt around the bubble is stretched in all directions with very high speed, and because bubbles are formed around the nano-granules, the stretching forces will also be experienced by the agglomerated nano-granules. Therefore agglomerated nano-granules may be separated with the help of melt stretching induced by inflation of the bubbles.…”

Crystallization, dispersion behavior and the induced properties through forming a controllable network in the crosslinked polyester‐SiO2 nanocomposites

“…2 Generally, incorporation of nanophase, such as SiO 2 nanoparticles or layered silicates, into PET improved its thermal, mechanical, and crystallization behaviors. [3][4][5][6][7][8][9][10] The nanoparticles could restrain the spheru-lite growth. 9,10 However, their agglomeration and unstable dispersion patterns usually affected the nanocomposite material processing behavior, gas permeability, and surface performance.…”

“…[5][6][7][8] In the previously established dispersion methods, the intercalation of the layered silicates and particle surface treating were popular. In the intercalation polymerization process, [5][6][7][8][9][10][11][12][13] the nanoparticles in situ formed and dispersed well in the polymer matrix to obviously improve the crystallization behavior. [11][12][13] When the nanoparticles dispersed in PET, they acted as the heterogeneous nucleation centers to accelerate the crystallization process.…”