Effect of Chain Dynamics, Crystallinity, and Free Volume on the Barrier Properties of Poly(ethylene terephthalate) Biaxially Oriented Films

Abstract

The primary focus of this work was to evaluate the relationship between free volume distribution, chain motion, crystallinity, and the gas properties of PET upon strain-induced crystallization (SIC) at different stretch ratios. The formation of a three-phase structure containing rigid amorphous phase, mobile amorphous phase, and crystalline phase upon SIC was confirmed by differential scanning calorimetry and positron annihilation lifetime spectroscopy (PALS). Dynamic mechanical analysis and PALS indicated that there was a significant reduction in the fractional free volume upon orientation at an extension ratio of 3 × 3. Sub-T g relaxation studies indicated that the activation energy of mechanical relaxation decreased with increasing the stretch ratio. Gas transport studies revealed that the reduction in permeability coefficient was mainly due to reduction in diffusivity. Permeation studies using gas molecules with different sizes revealed that strain-induced crystallization affects the free volume distribution as well as reducing the average fractional free volume.

Combined effect of small molecule antiplasticizers and strain induced crystallization on properties of polyethylene terephthalate

“…However, there is a need to further enhance the gas transport properties of PET to increase the product shelf life and broaden the usage of PET for high barrier packaging applications. In our previous studies, the effects of strain‐induced crystallization (SIC) and inclusion of small molecule antiplasticizers on the microstructure and barrier properties of PET were independently examined.…”

“…As reported in our previous work, upon SIC, PET exhibited a three‐phase morphology including mobile amorphous phase, rigid amorphous phase, and crystalline phase . The sharp decrease in permeability observed at an extension ratio of 2.5 × 2.5 was attributed to the formation of impermeable crystalline phase that resulted in an increase in tortuous path for diffusion jumps.…”

“…Stretch blow molding is a common process of manufacturing bottles from PET preforms in which SIC occurs and leads to approximately twofold decrease in the permeability and improvement in barrier . This method is extensively used in the packaging industry to process polyesters with enhanced barrier and physical/mechanical properties at low cost without changing the clarity of the final product .…”

Waste to Energy from Flue Gas of Industrial Plants to Biodiesel: Effect of CO2 on Microalgae Growth

“…The biomass of microalgae can be used as the source of biofuel, biopolymers and nutraceutical products [8,9]. The recent researches for production of polymer can be employed for efficient conversion of algal organic acids to high quality products [10,11]. For biofuel production hydrodeoxygenation can efficiently convert biomass to bio-oil [12].…”

Chemical Information of Chitosan-Based Complex Extracted from Coincidence Doppler Broadening Spectra

“…In recent years, positron annihilation spectroscopy (PAS) considering its sensitivity and uniqueness at the atomic and molecular level has been attracting increasing attention in polymeric field [1][2][3]. Typically, free volume properties (e.g.…”