Phosphonium‐based layered silicate—Poly(ethylene terephthalate) nanocomposites: Stability, thermal and mechanical properties

Abstract

PET-clay nanocomposites were prepared using alkyl quaternary ammonium and phosphonium modified clays by melt-mixing at 280 C using a micro twin screw extruder. The latter clays were prepared by synthesizing phosphonium surfactants using a simple onestep method followed by a cation exchange reaction. The onset temperature of decomposition (T onset ) for phosphonium clays (>300 C) was found to be significantly higher than that of ammonium clays (around 240 C). The clay modified with a lower concentration (0.8 meq) of phosphonium surfactant showed a higher T onset as compared to the clay modified with a higher concentration (1.5 meq) of surfactants. Nanocomposites prepared with octadecyltriphenyl phosphonium (C18P) modified clay showed a higher extent of polymer intercalation as compared with benzyltriphenylphosphonium (BTP) and dodecyltriphenylphosphonium (C12P) modified clays. The nanocomposites prepared with ammonium clays showed a significant decrease in the molecular weight of PET during processing due to thermal degradation of ammonium surfactants. This resulted in a substantial decrease in the mechanical properties. The molecular weight of PET was not considerably reduced during processing upon addition of phosphonium clay. The nanocomposites prepared using phosphonium clays showed an improvement in thermal properties as compared with ammonium clay-based nanocomposites. T onset increased significantly in the phosphonium clay-based nanocomposites and was higher for nanocomposites which contained clay modified with lower amount of surfactant. The tensile strength decreased slightly; however, the modulus showed a significant improvement upon addition of phosphonium clays, as compared with PET. Elongation at break decreased sharply with clay.

Preparation of PET/clay nanocomposites via in situ polymerization in the presence of monomer‐activated organoclay

“…The M n is decreased approximately 48% and 51% by inclusion of 1 wt% Cloisite 30B and RM-Cloisite 30B in the PET matrix, respectively. This observation is opposite to the findings whereby the more OMMT that is introduced into the IIPC process, the greater the increase in molecular weight of the PET nanocomposite [17,18]. The findings in the current work verify that the addition of nanoclay particles probably causes some steric hindrance for the in situ interlayer polymerization and as a result shorter polymer chains with lower molecular weights are formed.…”

“…As can be noticed, with increasing either the Cloisite 30B or the RM-Cloisite 30B content in the PET matrix, the position of the exothermic peaks is gradually shifted, whereas the peaks become moderately narrower and sharper. The DT c values of PETCNs are in the range of [14][15][16][17][18] C, which are narrower than that for pure PET (about 26 C), indicating that the added nanoclay particles act as effective heterogeneous nucleating agents that significantly enhance the crystalline structures as their loading is increased. It is also suggested that nanoclay itself can help the PET molecules stack on each other in order to grow into crystallites, thus leading to the higher crystallization rate [24].…”

Dispersion of Organically Modified Layered Silicates in Melt Blended Poly(Lactic Acid) Composites: Effects of Cation Head Groups and Oxygenated Alkyl Chains

“…Since PLA is a fairly polar polymer, the increased hydrophobicity and strong π -π interactions between neighboring phenyl groups likely decreased the ability for PLA to enter the galleries. Similar behavior has been observed in poly(ethylene-co-terephthalate) composites containing alkyltriphenylphosphonium exchanged clays (23). Fluorescence measurements were used to assess the applicability of NB exfoliation monitoring in PLA.…”

Novel preparation method for improving the dispersion of ionic liquid‐modified montmorillonite in poly(ethylene terephthalate)

“…In order to investigate the hydrophobicity of the samples, the experiment was performed on samples as received (not dried). Evaporation of free water (an indication of hydrophobicity) in clay results in an initial mass loss below 200 C; while, evaporation of structural water under dehydroxylation causes a mass loss between 570 and 700 C in the unmodified clay [20,28,29]. There was no other significant mass loss for unmodified clay up to 570 C. In the case of 30B organoclays, however, the major mass loss occurred in the temperature range of 240-420 C. Quaternary ammonium ions presented in 30B clays started to degrade at the onset of decomposition temperature (T 0 ) of 240 C. This temperature is below the PET processing temperature of 300 C. Significant increases in T 0 were observed for clays modified with C1C4-Im and 3C6C14-Ph to give values of 375 C and 490 C, respectively.…”