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Hemp (Cannabis sativa) stalk fibres from industry residues were incorporated into polybutylene adipate terephthalate, a synthetic biodegradable polyester, to produce films and paper coatings. The lignocellulosic components and the chemical composition of the fibres were analysed, and the results highlight the bioactivity due to cannabinoids, alkanoids, and lignin, among others, making the fibres attractive for active food packaging. The incorporation, without chemical modification, of 2% (w/w) hemp in the PBAT matrix increased the water vapour permeability of PBAT to around 22%. The impact on mechanical properties was determined, and the results show that the PBAT/hemp film is less stretchable but stronger than the pure PBAT film. The incorporation of hemp enhanced significantly the compostability of PBAT. The PBAT/hemp films and paper coatings composted two times faster than those using pure PBAT.

Summary Active packaging refers to a set of systems usually aiming to protect and extend the shelf life of food. The incorporation of metal (e.g. zinc, silver, copper, and gold) and metal oxide (e.g. zinc oxide, titanium dioxide, and magnesium oxide) nanoparticles into petroleum-based and bio-based polymers has progressively increased for active packaging purposes. These nanoparticles provide to the packaging functional characteristics such as antimicrobial capacity, oxygen scavenging, and photocatalytic activity, as well as better mechanical performance and enhancement of barrier properties. Therefore, the present chapter overviews the incorporation of metal and metal oxide nanoparticles into different materials for the development of active packaging systems with multiple functionalities. The types of metal nanoparticles applied to package materials, the main production methods, and the incorporation of them into the packaging are addressed. Additionally, the main features and limitations related to the effect of metal-based nanoparticles on the packaging properties, as well as the possible particle migration to the food and environment when discarded, are discussed., info:eu-repo/semantics/publishedVersion

A new phosphonic acid, (2-oxo-2-(thiophen-2-yl)ethyl) phosphonic acid (OTEPA), was synthesized and its molecular and crystal structures investigated using several experimental techniques complemented by different types of calculations. The experimental techniques used include infrared and Raman spectroscopies and single crystal X-ray crystallography. Calculations were performed at both molecular mechanics and DFT(B3LYP)/6–311++G(d,p) levels of approximation, for the isolated molecule. The conformational space of OTEPA was investigated and the most stable conformers characterized both structurally and spectroscopically. It was found that in the lower energy conformers of OTEPA an intramolecular H-bond exists between one of the OH groups of the phosphonic acid fragment and the carbonyl oxygen atom. The two lowest energy conformers have the sulphur atom of the thiophene ring eclipsed with the carbonyl oxygen atom, allowing for the establishment of an O⋯S stabilizing contact, similar to the N⋯S type contact found previously in other molecular systems. Noteworthy, in the crystalline phase the OTEPA molecules do not assume one of the most stable conformations for the isolated molecule, but exist in a conformation similar to that of high-energy conformers, which have predicted energies relative to the conformational ground state higher than 13 kJ mol−1. The infrared spectra of the monomeric molecules of the compound isolated in a low temperature solid argon matrix and of the crystal of the neat compound were also investigated and assigned, together with the Raman spectrum of the crystalline compound.

A new mixed-valence ironIII-zincII diphosphate, Zn2+Fe3+2(P2O7)2, has been prepared by a dry way and characterized structurally by several techniques. Analysis of the powder diffraction pattern of the synthesized diphosphate showed that it is isostructural with the ironIII-ironII diphosphate, Fe2+Fe3+2(P2O7)2, crystallizing in an orthorhombic symmetry in the Pnma space group. Other physical properties were characterized using Mossbauer spectroscopy and Vibrating Sample Magnetometer measurements, which showed that this new phosphate with Fe3+ ions in VI coordination has a paramagnetic behavior at room temperature. Infrared and Raman spectroscopies were also used in this study to help characterizing structurally the new synthesized material.

Structural studies of Zn2+Fe $_{2}^{3+}$ (P2O7)2 and Cu0.5Zn0.5Fe2(P2O7)2 were made using powder X-ray diffraction and refined by Rietveld method. Both phosphates crystallize in an orthorhombic structure with Pnma space group. Magnetometry measurements showed that below TN = 5.6 (1), Zn2+Fe $_{2}^{3+}$ (P2O7)2 becomes antiferromagnetic and the TN = 14 K is attributed to Cu0.5Zn0.5Fe2(P2O7)2. Mossbauer studies at room temperature and low temperature were performed in both samples.

A new valence-mixed iron(III)-zinc(II)-copper(II) pyrophosphate, Cu2+0.5 Zn2+0.5 Fe3+2 (P2O74−)2, has been synthesized by a dry-way method and structurally characterized by several techniques. The powder diffraction pattern of the new material shows that the pyrophosphate is isostructural with the iron(III)-iron(II) pyrophosphate Fe2+Fe3+2 (P2O74−)2, crystallizing in an orthorhombic arrangement in the Pnma space group. Cu2+Fe3+2 (P2O74−)2 was formed as a secondary phase, as determined both by X-ray diffraction and Mossbauer spectroscopy. Mossbauer spectroscopy and magnetometry measurements showed that Cu0.5Zn0.5Fe2(P2O7)2 is paramagnetic at room temperature and the iron ions are in octahedral coordination. Neel temperature is about 3 K. Infrared and Raman spectroscopies were also used in this study to characterize the new pyrophosphate.