In the field of biodegradable polymers such as poly(Lactic Acid) (PLA), it is quite well known that their kinetics of hydrolysis strongly depend on the pH of the hydrolyzing medium. The idea explored during this study focused on PLA, is the addition of additives that are able to control the pH of water when it diffuses inside the polymer. For instance, acids (i.e. succinic acid, also used as food additive) are bio- and eco- friendly additives that are able to play this role. In order to control the release of these molecules and their dispersion inside the polymer, their intercalation in biocompatible nanofillers like layered double hydroxides (LDH) is here considered. The additives have been dispersed in the polymer by melt compounding, commonly used in the plastic industry. Several composites of PLA (4032D) and LDH intercalated with organic acids (succinic, fumaric, and ascorbic acid) have been obtained by an extrusion process. From all extruded materials, PLA films obtained by compression molding were then subjected to hydrolysis tests. The results showed that the mentioned molecules, dispersed in the polymer, are able to control the rate of hydrolysis, and experimental results show an increase of degradation time for samples containing LDH-organic acid (in particular with LDH-succinic acid), making such hybrid additives an appropriate and efficient solution for PLA.

This article presents the effect analysis of the printing time sequences on the mechanical properties in correlation with the crystallization kinetics and rheological behavior. For this purpose, two printing order of 3D printed samples (printed simultaneously or in sequence) were chosen. In addition, two different infill patterns (line and gyroid) and building directions (horizontal and vertical) have been used. Concerning the polymer filaments, two commercial polylactic acid (PLA 3D870 and PLA 3D850) having different crystallization kinetics were used. The effect of the printing time delay between each layer on the temperature profile and the crystallization evolution was studied using a finite element analysis method simulation. The simulation results show a greater thermal excursion for longer delay times between the layers and with a crystallization degree evolution characterized by a step pattern. Moreover, a major density of crystals appears in the center of the final part. A new approach was adapted to measure the volumetric contraction of the material as a function of the temperature; it was performed with a gap test using a rotational rheometer under static conditions (without external deformation). The normal force measured from the test has shown a faster and higher increase of the contraction for the material with faster crystallization kinetics and with a higher degree of crystallinity. The results concerning the tensile properties show better rigidity for the samples printed in sequence due to the minor time of delay between the deposited layers. The mesostructure of the printed parts was analyzed with an X-ray tomography and a scanning electron microscope. The highest difference is presented from the PLA 3D870 characterized by the highest rate of crystallization resulting in more microvoids compared with the PLA 3D850, due to the less welding cohesion between the layers.

Poly(butylene succinate-co-butylene adipate) (PBSA)-based materials are receiving growing attention in the packaging industry for their promising biodegradability. However, poor gas barrier properties and low durability of biodegradable polymers, such as PBSA, have limited their wide-spread use in food packaging applications. Here we report a scalable solution to improve gas barrier properties and stabilize PBSA against photo-aging, with minimal modifications to the biodegradable polymer backbone by using a commercially available and biocompatible layered double hydroxide (LDH) filler. We investigate and compare the mechanical, gas barrier, and photoaging properties of PBSA and PBSA-LDH nanocomposite films produced on a pilot scale. An increase in rigidity in the nanocomposite was observed upon addition of LDH fillers to neat PBSA, which direct the application of neat PBSA and PBSA-LDH nanocomposite to different food packaging applications. The addition of LDH fillers into neat PBSA improves the oxygen and water vapour barriers for the PBSA based nanocomposites, which increases the attractiveness of PBSA material in food packaging applications. Through changes in the viscoelastic behaviour, we observe an improved photo-durability of photoaged PBSA-LDH nanocomposites compared to neat PBSA. It is clear from our studies that the presence of LDH enhances the lifetime durability and modulates the photodegradation rate of the elaborated biocomposites.

Fused deposition modelling is a rapidly growing additive manufacturing technology due to its ability to build functional parts with complex geometries. The mechanical properties of a built part depend on several process parameters. The effect of wood content on the properties of 3D printed parts has been studied. Four types of filaments using poly(butylene succinate-co-adipate) (PBSA) with different reinforcement levels of Typha stem powder 0%, 5%, 10%, and 15% by weight were used for 3D printing. The density of the filaments and parts printed in this study increased with the Typha stem powder content. The thermal stability, mechanical performance, and viscoelastic properties of the different biocomposite filaments and 3D printed objects were analysed. The results show an increase in the crystallisation kinetics and a slight decrease in the thermal stability of the biomaterials. Compared to virgin PBSA FDM filaments, the PBSA biocomposite filament filled with Typha stem powder showed an increase in the tensile strength of the parts and specimens from 2.5 MPa to 8 MPa and in the modulus of elasticity from 160 MPa to 375 MPa, respectively, with additions of 5%, 10%, and 15% by mass. The addition of Typha stem fibres generated an increase in the elastic behaviour and relaxation time of the biomaterial structure, visualised by increases in the values of the viscosity components. The surface morphology reveals a decrease in the porosity of the printed samples.

Extrusion and hot compressing molding processes were used to create bio-polyethylene (BioPE) composites reinforced with argan byproducts (shell, pulp, and argan cake) as bio-fillers. The thermal stability of the composites wass analyzed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Dynamical mechanical analysis and rheological testing were used to investigate their mechanical properties. The morphological results showed a good adhesion between the argan and BioPE matrix. More efficient mechanical properties have been distinguished in the case of argan byproduct-based composite. A higher Young’s modulus was noted for all the biocomposites compared to pure BioPE. Thermal analysis revealed that the addition of bio-filler to polymer reduced decomposition temperatures. This study provides an ecological alternative for upgrading the valorization of abundant and underutilized Moroccan biomass. Furthermore, the possibility of using argan byproducts in composite manufacturing will help open up new markets for what is currently considered waste.

A new eco-composite polymer for material extrusion fabrication based on fine fraction pozzolan waste was developed. In addition, the composite materials obtained were used to produce a self-watering pot with complex geometry and a permeable porous part to regulate the passage of water from the storage area to the roots of the plant. Moreover, the system was devised with a cover characterized by a UV-B barrier film. The results have shown the possibility of the 3D printing of complex geometric parts as microporous structures or thin films using a composite based on poly lactic acid (PLA) and pozzolan. The pozzolan has an effect of reinforcement for the composite and at the same time improves the cohesion between the layers of the part during printing.