Supercritical CO2 foamed biodegradable polymer blends of polycaprolactone and Mater-Bi.

Supercritical CO2 foam processing of biopolymers represents a green processing route to environmentally friendly media and packaging foams. Mater-Bi, a multiconstituent biopolymer of polyester, starch and vegetable oils has shown much promise for biodegradation. The polymer, however, is not foamable with CO2 so blended with another polymer which is. Polycaprolactone is a biopolymer with potential of 4000% change in volume with CO2. Thus we investigate blends of Mater-Bi (MB) and polycaprolactone (PCL) foamed in supercritical CO2 using the batch process. Characterization of the foamed and unfoamed samples were done using X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Micrographs of the samples from the SEM revealed that the cell size of the foams reduced and increased with increase in MB concentration and increase in the foaming temperature respectively. Mechanical tests; tensile, compression, shear and impact were performed on the foamed samples. It was noted that between the 20-25% wt. MB, there was an improvement in the mechanical properties. This suggests that at these compositions, there is a high interaction between PCL and MB at the molecular level compared to other compositions. The results indicate that green processing of polymer blends is viable

Advanced material applications of starch and its derivatives

The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.eurpolymj.2018.09.039 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/Starch as a natural polymer has attracted significant interest and is currently used in numerous industrial applications. This is because of its renewability, biodegradability, abundance, and cohesive film-forming properties. Moreover, the hydroxyl (OH) groups associated with the anhydroglucose units provide it with several modification possibilities. These features have resulted in substantial interests for its use in several advanced functional material applications in addition to the typical consumer plastic applications. The goal of this review is to shed light on the recent advances achieved in the utilization of starch for advanced functional material applications and its derivatives. The review specifically focuses on applications ranging from electronics, drug delivery, pharmaceuticals, antimicrobial materials to structural materials.Department of Chemical Engineering and the Faculty of Engineering of the University of Waterlo

Using lignocellulosic fractions of coffee husk to improve properties of compatibilised starch-PLA blend films

[EN] The effectiveness of the incorporation of cellulosic reinforcing agents (cellulosic fibres: CF and cellulose nanocrystals: CNC) and antioxidant aqueous extract (AE) from coffee husk at improving the functional properties of compatibilised starch-PLA blend films was studied. Tensile and barrier properties, crystallization pattern and thermal behaviour were analysed in films containing 1 wt% of CF or CNC incorporated by two different methods or 5.8 wt% of antioxidant extract. The antioxidant properties of the films were also tested through their efficacy at preserving sunflower oil from oxidation. Of the cellulosic fractions, CNC directly blended with the starch phase were the most effective at reinforcing tensile properties of the material (148% and 45% increase in elastic modulus and tensile strength, respectively) and at reducing their water vapour and oxygen permeability (28% and 42% reduction, respectively). The AE did not improve the mechanical performance of the blend films, but conferred antioxidant capacity useful for food packaging applications.The authors thank the Ministerio de Economia y Competitividad (Spain) for the financial support provided through Project AGL2016-76699-R. The authors also wish to thank the Electron Microscopy Service of the UPV for their technical assistance.Collazo-Bigliardi, S.; Ortega-Toro, R.; Chiralt Boix, MA. (2019). Using lignocellulosic fractions of coffee husk to improve properties of compatibilised starch-PLA blend films. Food Packaging and Shelf Life. 22:1-10. https://doi.org/10.1016/j.fpsl.2019.100423S1102

Trends in Advanced Functional Material Applications of Nanocellulose

The need to transition to more sustainable and renewable technology has resulted in a focus on cellulose nanofibrils (CNFs) and nanocrystals (CNCs) as one of the materials of the future with potential for replacing currently used synthetic materials. Its abundance and bio-derived source make it attractive and sought after as well. CNFs and CNCs are naturally hydrophilic due to the abundance of -OH group on their surface which makes them an excellent recipient for applications in the medical industry. However, the hydrophilicity is a deterrent to many other industries, subsequently limiting their application scope. In either light, the increased rate of progress using CNCs in advanced materials applications are well underway and is becoming applicable on an industrial scale. Therefore, this review explores the current modification platforms and processes of nanocellulose directly as functional materials and as carriers/substrates of other functional materials for advanced materials applications. Niche functional attributes such as superhydrophobicity, barrier, electrical, and antimicrobial properties are reviewed due to the focus and significance of such attributes in industrial applications

Multi-Fold Enhancement in Compressive Properties of Polystyrene Foam Using Pre-delaminated Stearate Functionalized Layer Double Hydroxides

Developing an environmentally benign styrene foam is a critical environmental need. Supercritical CO2 use in foams has proven to be a valuable path. Adding fillers to increase bubble nucleation has been pursued concurrently. A prominent filler used is high surface area fillers, such as smectic clays. However, all studies to date show a limit of 152% in compressive moduli and 260% in the compressive stress. The values, even with such gains, limit structural application. A seminal work in 1987 by Suh and Cotton proved that carbonyl linkages in calcium carbonates and CO2 interact and impact nucleation efficiency and performance in supercritical CO2 foams. In this paper, a high surface area clay (layer double hydroxides) which begins in an exfoliated state, then functionalized with a long chain alkyl carboxylate (stearic acid) is synthesized. The result is a remarkable multi-fold improvement to the compressive properties in comparison to polystyrene (PS); a 268% and 512% increase in compressive modulus and strength, respectively. Using a pre-delaminated approach, the higher surface area was achieved in the clays. The presence of the stearate improved the interactions between the clay galleries and PS through hydrophobic-hydrophobic interactions. The glass transition temperature of the nanocomposites was observed to shift to higher values after foaming. The results point to a new path to increase performance using a pre-delaminated clay with functional groups for environmentally benign foams

Mechanical, Chemical, and Physical Properties of Wood and Perennial Grass Biochars for Possible Composite Application

Miscanthus, switchgrass, and softwood chip biochars, produced by slow pyrolysis, were characterized to evaluate their properties in light of potential alternative and novel applications. This work investigated specific physical and chemical properties of biochars that have not been previously reported. Atomic force microscopy (AFM), moisture absorption, and electrical and thermal analysis were conducted to demonstrate the mechanical, physical, and chemical properties of biochars. In addition, elemental analysis, specific surface area, Fourier transform infrared in the attenuated total reflectance (FTIR-ATR), and X-ray diffraction were performed. The state-of-art quantitative nano-mechanical measurement yielded a modulus of elasticity of approximately 10 GPa for the wood chip biochar, while the grass-based samples exhibited a comparatively lower modulus of approximately 5 GPa. In addition, the pore blocking phenomenon by water molecules was identified as a cause for atypical behavior of the biochars’ moisture absorptions, resulting in wood chip biochar having the lowest equilibrium moisture content of 6.2 wt.%. Results from electrical and thermal conductivity measurements demonstrated relatively lower values in comparison to carbonized biomass