Electrospun Multilayered Films Based on Poly(3-hydroxybutyrate-co-3-hydroxyvalerate), Copolyamide 1010/1014, and Electrosprayed Nanostructured Silica

Abstract

In this research, bio-based electrospun multilayered films for food packaging applications with good barrier properties and close to superhydrophobic behavior were developed. For this purpose, two different biopolymers, a low-melting point and fully bio-based synthetic aliphatic copolyamide 1010/1014 (PA1010/1014) and the microbially synthesized poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and food-contact-complying organomodified silica (SiO2) nanostructured microparticles, were processed by electrospinning. The production of the multilayer structure was finally obtained by means of a thermal post-treatment, with the aim to laminate all of the components by virtue of the so-called interfiber coalescence process. The so developed fully electrospun films were characterized according to their morphology, their permeance to water vapor and oxygen, the mechanical properties, and their water contact angle properties. Interestingly, the annealed electrospun copolyamide did not show the expected improved barrier behavior as a monolayer. However, when it was built into a multilayer form, the whole assembly exhibited a good barrier, an improved mechanical performance compared to pure PHBV, an apparent water contact angle of ca. 146°, and a sliding angle of 8°. Consequently, these new biopolymer-based multilayer films could be a bio-based alternative to be potentially considered in more environmentally friendly food packaging strategies.

Development of Polyhydroxybutyrate-Based Packaging Films and Methods to Their Ultrasonic Welding

“…Lattice parameters of the fitted phase were calculated using Rietveld refinement in the TOPAS 6 program, based on Williamson-Hall theory [22,23]. Rietveld refinement allows for the calculation of crystallite size and lattice strain of the crystalline part of PHB [24,25], while the crystallinity of the polymer was calculated using a peak decomposition method [26]. For the structural analysis, the unit cell parameter a is related to the short polymer axis, and c corresponds to the long axis of the molecule, while b is related to the inter-chain interactions.…”

“…where ∆H m is the experimental melting enthalpy value of the sample (J/g) obtained in the second heating DSC cycle, ∆H 0m is the melting enthalpy of 100% perfectly crystalline form of PHB (146 J/g) [24,27,28], and w PHB is the weight fraction of PHB in the plasticized sample. Thermomechanical studies of polymer systems were performed using thermomechanical analyzer Discovery 450 TMA (TA Instruments, Waters Co., USA) with the penetration method in the mode of uniaxial constant load (σ = 0.5 MPa) using the UIP-70M unit.…”