Polymeric foams can be found virtually everywhere due to their advantageous properties compared with counterparts materials. Possibly the most important class of polymeric foams are polyurethane foams (PUFs), as their low density and thermal conductivity combined with their interesting mechanical properties make them excellent thermal and sound insulators, as well as structural and comfort materials. Despite the broad range of applications, the production of PUFs is still highly petroleum-dependent, so this industry must adapt to ever more strict regulations and rigorous consumers. In that sense, the well-established raw materials and process technologies can face a turning point in the near future, due to the need of using renewable raw materials and new process technologies, such as three-dimensional (3D) printing. In this work, the fundamental aspects of the production of PUFs are reviewed, the new challenges that the PUFs industry are expected to confront regarding process methodologies in the near future are outlined, and some alternatives are also presented. Then, the strategies for the improvement of PUFs sustainability, including recycling, and the enhancement of their properties are discussed.

https://www.mdpi.com/1996-1944/11/10/1841/pdf/1

Polyurethane Foams: Past, Present, and Future

Edible films and coatings: a review.

Edible films and coatings are produced from edible biopolymers and food-grade additives. Film-forming biopolymers can be proteins, polysaccharides (carbohydrates and gums), lipids, or a mixture of these Gennadios et al., 1997 (see Figure 9.1). Plasticizers and other additives are combined with the film-forming biopolymers to modify the physical properties or other functionality of the edible films. Biopolymers have multiple film-forming mechanisms, including intermolecular forces such as covalent bonds (e.g., disulfide bonds and crosslinking) and electrostatic, hydrophobic, or ionic interactions. For the resulting films or coatings to be edible, the film-forming mechanism involved in fabrication should be an appropriate food process—namely, pH modification, salt addition, heating, enzymatic modification, drying, use of food-grade solvents, or reactions with other food-grade chemicals. The control of fabrication process conditions is very important because the changes in treatment conditions can alter kinetics and reaction mechanisms (Guilbert et al., 1996, 1997).

Chapter 9 – Edible Films and Coatings: A Review

Polyurethanes (PUs), produced from the condensation polymerizations between polyols and isocyanates, are one of the most versatile polymer families. Currently, both polyols and isocyanates are largely petroleum derived. Recently, there have been extensive research interests in developing bio-based polyols and PUs from renewable resources. As the world's most abundant renewable biomass, lignocellulosic biomass is rich in hydroxyl groups and has potential as a feedstock to produce bio-based polyols and PUs. Lignocellulosic biomass can be converted to liquid polyols for PU applications through acid- or base-catalyzed atmospheric liquefaction processes using polyhydric alcohols as liquefaction solvents. Biomass liquefaction-derived polyols can be used to prepare various PU products, such as foams, films and adhesives. The properties of biomass liquefaction-derived polyols and PUs depend on various factors, such as feedstock characteristics, liquefaction conditions, and PU formulations.

Polyols and polyurethanes from the liquefaction of lignocellulosic biomass.

Preparation and characterization of rigid polyurethane foam prepared from sugar-cane bagasse polyol

Sugar-cane bagasse was liquefied in ethylene glycol/phthalic anhydride mixture catalyzed by sulphuric acid at temperatures 160-220°C, liquefaction times 60-240 minutes, and ethylene glycol amounts 5-20 ml for each three grams of sugar-cane bagasse. The residue obtained was characterized by FT-IR, X-ray diffraction, and scanning electron microscope. The percentages of residue, average molecular weight, hydroxyl and acid numbers were determined as an estimate of polyol value of the liquid products. Optimal conditions for liquefaction were established: reaction temperature 160°C, reaction time 180 minutes, and ethylene glycol amount 20 ml/three grams sugar-cane bagasse.

Optimization and characterization of sugar-cane bagasse liquefaction process

HEREIN, we demonstrate a promising route to prepare an eco-friendly particleboards (Pb) bonded with novel itaconic polyamidoamine epichlorohydrin/soy protein adhesive (IA-PEA/SP). The as prepared materials, IA-PEA and (IA-PEA/SP), characterized with 1H-NMR spectroscopy, viscosity, solid content, shear bonding strength, and water resistance. The physico-mechanical tests of IA-PEA/SP bonded- plywood (0.5/5 weight ratio) attained an enhanced dry and wet shear bonding strength of 5.94 ±0.36 MPa and 1.220.02± MPa compared with an alkali-denatured SP adhesive control. The water resistance tests, proved the sustainability of the prepared composite. Moduli of rupture and elasticity of Pb were 7.07 ± 0.12 MPa and of 0.21± 0.005 GPa. A two-fold internal bonding strength (IB) was obtained at IA-PAE/SP adhesive (40%) compared to the control. The water absorption and the thickness swelling improve by ~ 40% and 33%. TGA and Ʃ Ea calculations showed proper thermal properties. The proposed IA-PAE/SP adhesive paves the way for using green wood adhesives.

https://ejchem.journals.ekb.eg/article_43931_26aed728f4c83b589ab1245ef387a3d9.pdf

Eco-friendly lignocellulosic particleboards bonded with free-formaldehyde itaconic polyamidoamine epichlorohydrin/soy protein adhesive

Edible filmswere prepared frommaleic anhydridemodified alkaline hydrolyzed chicken feather protein, poly vinyl alcohol and starch. The effect of glycerol and 1,2- propandiol as plasticizers on protein based film was investigated. Intermolecular interaction between film components was investigated using FTIR. Morphology using scanning electron microscopy (SEM) reflects films of good appearances. Thermal analysis (TGA) of edible films indicates that glycerol ÂÂ plasticized-PVA/starch/modified protein filmismore thermaly stable than 1,2-propanediol-plasticized PVA/ starch/modified protein. Glycerol has significant effect on % elongation and oxygen permeability (OP) more than 1,2- propanediol. Edible films containing proteins have good tensile strengths. The lowest OP was obtained from protein based film without plasticizer, which can make these films suitable as sachets or pouches for dry foods, thus reducing the need for plastic materials Antimicrobial activity of selected edible films was studied.

Preparation and characterization of PVA/starch blend composite film based on modified chicken feather protein and effect of plasticizer type on its properties

Maha Sultan

Papers

Preparation and characterization of rigid polyurethane foam prepared from sugar-cane bagasse polyol

Optimization and characterization of sugar-cane bagasse liquefaction process

Eco-friendly lignocellulosic particleboards bonded with free-formaldehyde itaconic polyamidoamine epichlorohydrin/soy protein adhesive

Preparation and characterization of PVA/starch blend composite film based on modified chicken feather protein and effect of plasticizer type on its properties

Fabrication and evaluation of antimicrobial cellulose/Arabic gum hydrogels as potential drug delivery vehicle.