Thermoplastic Films Based on Polyelectrolyte Complexes of Arabino Glucurono‐Xylan and Polyethylenimine

Abstract

This work investigates film formation using polyelectrolyte complexes (PECs) of xylan and polyethylenimine (PEI). Different xylan/PEI mass ratios (from 50/50 to 90/10) and pH values (5.0 and 7.0) are analyzed and both parameters have an effect on complex size and film properties. Furthermore, the mass ratio corresponding to the neutralization charge depends on pH. When xylan/PEI mass ratios are near the neutralization charge ratio, a coacervation process is observed. In this case, separation between the coacervate and the supernatant dilute phase is possible. In the supernatant, both concentrations, xylan and PEI, depend on pH. The complex suspensions are used to obtain films by PECs casting/evaporation process. For films obtained from the whole suspension, by increasing the xylan content the stress at break is improved (up to 23 MPa for 85/15, at pH 7.0) and the strain at break is decreased (to 2.5%). When only coacervate is used to prepare films, the tensile strength is higher, reaching a value of 37 MPa for 85/15 mass ratio. Dynamic mechanical thermal analysis shows that the glass transition temperature (Tg) of the films is affected by composition. The thermoplastic behavior of a 50/50 xylan/PEI film is confirmed using a hot‐compression molding.

Polyester-Based Polyelectrolyte Complexes: Combining Thermo- and Saloplastic Properties

“…However, PECs tend to become brittle and unprocessable under poorly hydrated or dry conditions due to their strong ionic cross-links. ,, The processing of PECs remains challenging without plasticization, primarily because of thermally induced degradation before reaching a glass transition temperature. This limits their applicability in the field of engineering materials. , Additionally, common synthetic PEs consist of fossil-based vinyl building blocks consisting of a C–C backbone and lack the implementation of sustainable and renewable resources. − As of now, the design of PECs that combine thermoplastic and saloplastic properties under dry conditions, while overcoming their inherent brittleness, has not been addressed. One of the key parameters to achieve this would involve decreasing the charge density by balancing the charges in the polymeric backbone and touching upon the interface between saloplastic and thermoplastic properties.…”

Enhancing Hydrophobicity and Oxygen Barrier of Xylan/PVOH Composite Film by 1,2,3,4-Butane Tetracarboxylic Acid Crosslinking

“…However, the application of xylan in food packaging is limited because of its short molecular chain, low molecular weight, poor film-forming ability and strong hydrophilicity. Recently, many attempts have been made to solve these defects, including blending xylan with other polymers [13,14], adding plasticizers [15,16] and the chemical modification of xylan [17,18], so as to improve the properties of xylan film. Creating composites of xylan and polymers is an effective method to improve the film-forming properties.…”