The interchange reaction between poly(ethylene terephthalate) and poly(m‐xylylene adipamide)

Abstract

The interchange reaction in blends of poly (ethylene terephthalate) (PET) and poly(m-xylylene adipamide) (MXD6) has been characterized in terms of changes observed in spectra obtained with a 600-MHz 1 H-NMR. The selective degradation of PET components in the blends was carried out in the NMR tubes prior to evaluation. Results indicate that there is no chemical reaction between the PET and MXD6 in the absence of sodium p-toluenesulfonate catalyst. The presence of the catalyst activates the interchange reaction between these two resins. A mathematical method was applied to calculate the degree of randomness of PET-MXD6 copolymer. In addition, the reaction degree was found to be affected by exposure temperature, time, shear rate, and catalyst concentration.

When medical evidence alone is simply not enough

“…Moreover, the authors did not report any measure of properties as a function of reaction conditions, which correlate with the average molar masses of the melt‐mixed PET/MXD6 investigated. In accordance with our previous studies on the PET/Ny6 melt‐mixed blends,5 we believe, contrary to the Xie et al,30 that p ‐TSONa and p ‐TSOH 5 are reagents and not catalysts and that exchange reactions between PET and MXD6 occur via the attack of reactive carboxylic acid end groups on ester and amide inner groups. Carboxylic acid end groups can be produced in situ by the reaction of p ‐TSONa with PET homopolymer, which has been confirmed by the preliminary studies performed in the present work.…”

“…In this work, we extend our mechanicistic studies on the PET/MXD6 melt‐mixed blends. These blends have attracted scientific,30–35 technical,37 and commercial interest, in particular, in the area of food packaging because of their potential for combining the low O 2 and CO 2 permeability of the MXD6 (and order of magnitude higher than that of PET38–39) with the good toughness, clarity, and economics of PET. However, PET and MXD6 give incompatible blends with low optical clarity and an undesirable yellow color when processed in the molten state 40.…”

“…The goal of the studies on the PET/MXD6 blends is to achieve the improved gas barrier, while maintaining good optical clarity, inducing the interchange reaction between PET and MXD6 to produce in situ their copolymers and, thus to overcome their incompatibility. Xie et al reported that the interchange reaction in PET/MXD6 blends (90/10 w/w) in the molten state (290–310 °C) occurs only in the presence of sodium p ‐toluenesulfonate ( p ‐TSONa) 30. They have characterized the melt‐mixed blends by 1 H NMR in deuterated sulfuric acid (D 2 SO 4 ) to degrade selectively the PET components of reacted blends, and applying a mathematical model have calculated the degree of randomness of PET‐MXD6 copolymer.…”

In situ ester–amide exchange reaction between polyamide 6 and ethylene‐vinyl acetate rubber during melt blending

“…For ester–amide reactions, such as those between PET/PA or PBS/PA, the copolymer formed at interfaces was commonly hard to be isolated owing to their low quantity. Here, the exchange reaction extent increased (Table ) with the addition of DBTO and increasing reaction time; therefore, the formed graft copolymer was extracted successfully, and the content of EVM‐ g ‐PA6 (Fraction III) was increased from 2.0 to 6.8% with increasing reaction time from 10 to 60 min for PA6/EVM/DBTO (60/40/1) blend (Supporting Information Table S2).…”

“…In this article, the exchange reaction between PA6 and EVM at elevated temperatures was investigated in detail. Dibutyltin oxide (DBTO) is used as the catalyst as it is more effective and mild in facilitating ester–amide exchange reactions when compared with TsOH, terephthalic acid, and sodium p ‐toluenesulfonate . The effects of DBTO content, PA6/EVM ratio, and rotor rotation rate on the exchange reaction were studied.…”