Synthesis and characterization of rigid polyurethane foams from algae oil using biobased chain extenders

Sustainable microalgal biomass as a potential functional food and its applications in food industry: a comprehensive review

Microalgae (MA) are the most abundant seaweeds with high nutritional properties. They are accepted as potential biocatalysts for the bioremediation of wastewater. They are widely used in food, feed, and biofuel industries and can potentially be food for future generations. MA-based purification of wastewater technology could be a universal alternative solution for the recovery of resources from wastewater for low-cost biomass feedstock for industry. They provide a wide range of functional components, viz. omega-3 fatty acids, along with a plenteous number of pigments such as ß-carotene, astaxanthin, lutein, phycocyanin, and chlorophyll, which are used extensively as food additives and nutraceuticals. Further, proteins, lipids, vitamins, and carbohydrates are described as nutritional characteristics in MA. They are investigated as single-cell protein, thickening/stabilizing agents, and pigment sources in the food industry. The review emphasizes the production and extraction of nutritional and functional components of algal biomass and the role of microalgal polysaccharides in digestion and nutritional absorption in the gastrointestinal tract. Further, the use of MA in the food industry was also investigated along with their potential therapeutic applications.

Polyurethane Foam Incorporated with Nanosized Copper-Based Metal-Organic Framework: Its Antibacterial Properties and Biocompatibility

Polyurethane foams (PUFs) have attracted attention as biomaterials because of their low adhesion to the wound area and suitability as biodegradable or bioactive materials. The composition of the building blocks for PUFs can be controlled with additives, which provide excellent anti-drug resistance and biocompatibility. Herein, nanosized Cu-BTC (copper(II)-benzene-1,3,5-tricarboxylate) was incorporated into a PUF via the crosslinking reaction of castor oil and chitosan with toluene-2,4-diisocyanate, to enhance therapeutic efficiency through the modification of the surface of PUF. The physical and thermal properties of the nanosized Cu-BTC-incorporated PUF (PUF@Cu-BTC), e.g., swelling ratio, phase transition, thermal gravity loss, and cell morphology, were compared with those of the control PUF. The bactericidal activities of PUF@Cu-BTC and control PUF were evaluated against Pseudomonas aeruginosa, Klebsiella pneumoniae, and methicillin-resistant Staphylococcus aureus. PUF@Cu-BTC exhibited selective and significant antibacterial activity toward the tested bacteria and lower cytotoxicity for mouse embryonic fibroblasts compared with the control PUF at a dose of 2 mg mL-1. The Cu(II) ions release test showed that PUF@Cu-BTC was stable in phosphate buffered saline (PBS) for 24 h. The selective bactericidal activity and low cytotoxicity of PUF@Cu-BTC ensure it is a candidate for therapeutic applications for the drug delivery, treatment of skin disease, and wound healing.

Synthesis and Characterization of Polyurethanes from Residual Palm Oil with High Poly-Unsaturated Fatty Acid Oils as Additive

In the effort to produce renewable and biodegradable polymers, more studies are being undertaken to explore environmentally friendly sources to replace petroleum-based sources. The oil palm industry is not only the biggest vegetable-oil producer from crops but also one the biggest producers of residual oil that cannot be used for edible purposes due to its low quality. In this paper the development of biopolymers from residual palm oil, residual palm oil with 10% jatropha oil, and residual palm oil with 10% algae oil as additives were explored. Polyols from the different oils were prepared by epoxydation with peroxyacetic acid and alcoholysis under the same conditions and further reacted with poly isocyanate to form polyurethanes. Epoxidized oils, polyols and polyurethanes were analyzed by different techniques such as TGA, DSC, DMA, FTIR and H-NMR. Overall, although the IV of algae oil is slightly higher than that of jatropha oil, the usage of algae oil as additive into the residual palm oil was shown to significantly increase the hard segments and thermal stability of the bio polyurethane compared to the polymer with jatropha oil. Furthermore, when algae oil was mixed with the residual palm oil, it was possible to identify phosphate groups in the polyol which might enhance the fire-retardant properties of the final biopolymer.

Renewable Polyurethanes from Sustainable Biological Precursors

Due to the depletion of fossil fuels, higher oil prices, and greenhouse gas emissions, the scientific community has been conducting an ongoing search for viable renewable alternatives to petroleum-based products, with the anticipation of increased adaptation in the coming years. New academic and industrial developments have encouraged the utilization of renewable resources for the development of ecofriendly and sustainable materials, and here, we focus on those advances that impact polyurethane (PU) materials. Vegetable oils, algae oils, and polysaccharides are included among the major renewable resources that have supported the development of sustainable PU precursors to date. Renewable feedstocks such as algae have the benefit of requiring only sunshine, carbon dioxide, and trace minerals to generate a sustainable biomass source, offering an improved carbon footprint to lessen environmental impacts. Incorporation of renewable content into commercially viable polymer materials, particularly PUs, has increasing and realistic potential. Biobased polyols can currently be purchased, and the potential to expand into new monomers offers exciting possibilities for new product development. This Review highlights the latest developments in PU chemistry from renewable raw materials, as well as the various biological precursors being employed in the synthesis of thermoset and thermoplastic PUs. We also provide an overview of literature reports that focus on biobased polyols and isocyanates, the two major precursors to PUs.

Oxazolidone formation: myth or fact? The case of biobased polyurethane foams from different epoxidized triglycerides

Study of the oxazolidone formation by reaction between disubstituted epoxide and isocyanate in polyurethane foams and model.

Microstructure-Property Relationship of Polyurethane Foams Modified with Baltic Sea Biomass: Microcomputed Tomography vs. Scanning Electron Microscopy

In this paper, novel rigid polyurethane foams modified with Baltic Sea biomass were compared with traditional petro-based polyurethane foam as reference sample. A special attention was focused on complex studies of microstructure, which was visualized and measured in 3D with high-resolution microcomputed tomography (microCT) and, as commonly applied for this purpose, scanning electron microscopy (SEM). The impact of pore volume, area, shape and orientation on appearance density and thermal insulation properties of polyurethane foams was determined. The results presented in the paper confirm that microcomputed tomography is a useful tool for relatively quick estimation of polyurethane foams’ microstructure, what is crucial especially in the case of thermal insulation materials.

Polyurethane film prepared from ball-milled algal polyol particle and activated carbon filler for NH3-N removal

This research offers a novel approach of free chemical preparation to obtain algae-based biopolyol through a ball milling method. The algae-based polyurethane (AlgPU) film was obtained from a casting solution made of ball-milled algal polyol particle and methylene diphenyl diisocyanate (MDI). The characteristics of the material had been investigated using Fourier Transform Infrared, Scanning Electron Microscopy – Electron Dispersive Spectroscopy, Differential Scanning Calorimetry, and Tensile Strength Analysis. The surface area was determined by Brunauer–Emmett–Teller (BET) isotherm, meanwhile the total pore volume was by Barrett-Joyner-Halenda (BJH) isotherm, based on the adsorption-desorption of N₂. The addition of activated carbon contributed in the increase of functional group and surface area, which were important for the NH₃–N removal. As a result, the adsorption capacity increased greatly after the addition of activated carbon (from 187.84 to 393.43 μg/g). The results also suggested AlgPU as a good matrix for immobilizing activated carbon filler. The adsorption shows a better fit with Langmuir isotherm model, with R² = 0.97487 and root-mean-square error (RMSE) = 33.91952, compared to Freundlich isotherm model (R² = 0.96477 and RMSE = 44.05388). This means the NH₃–N adsorption followed the assumption of homogenous and monolayer adsorption, in which the maximum adsorption was found to be 797.95 μg/g. This research suggests the potential of newly developed material for NH₃–N removal.

Study on the Structure-Property Dependences of Rigid PUR-PIR Foams Obtained from Marine Biomass-Based Biopolyol

The paper describes the preparation and characterization of rigid polyurethane-polyisocyanurate (PUR-PIR) foams obtained with biopolyol synthesized in the process of liquefaction of biomass from the Baltic Sea. The obtained foams differed in the content of biopolyol in polyol mixture (0–30 wt%) and the isocyanate index (I_ISO = 200, 250, and 300). The prepared foams were characterized in terms of processing parameters (processing times, synthesis temperature), physical (sol fraction content, apparent density) and chemical structure (Fourier transform infrared spectroscopy), microstructure (computer microtomography), as well as mechanical (compressive strength, dynamic mechanical analysis), and thermal properties (thermogravimetric analysis, thermal conductivity coefficient). The influence of biopolyol and I_ISO content on the above properties was determined. The addition of up to 30 wt% of biopolyol increased the reactivity of the polyol mixture, and the obtained foams showed enhanced mechanical, thermal, and insulating properties compared to foams prepared solely with petrochemical polyol. The addition of up to 30 wt% of biopolyol did not significantly affect the chemical structure and average cell size. With the increase in I_ISO, a slight decrease in processing times and mechanical properties was observed. As expected, foams with higher I_ISO exhibited a higher relative concentration of polyisocyanurate groups in their chemical structure, which was confirmed using principal component analysis (PCA).

Preparation and Characterization of Rigid Polyurethane Foams with Different Loadings of Lignin-Derived Polycarboxylic Acids

Lignin was modified by oxidation to prepare lignin-derived polycarboxylic acids (LPCAs). LPCAs can be introduced into rigid polyurethane foams (RPUFs) via 1,4-dioxane. The expansion ratio and compressive strength of RPUFs were observed. When the loading of LPCAs was 0.67 wt% (based on polyol), the compressive strength of RPUF was the highest and was about 59.2% higher than that of the blank RPUF. The reinforcing mechanism of LPCAs was supposed that the interactions between LPCAs and RPUFs increased the strength of the cell walls. When the loading of LPCAs was less than 0.33 wt%, the expansion ratio of RPUFs increased slightly. The water resistance of RPUFs was not affected by LPCAs, suggesting that RPUFs with LPCAs could be used in a humid environment. Besides, the application of the oxidative modification products of lignin was broadened.

Chemical Recycling of Used Printed Circuit Board Scraps: Recovery and Utilization of Organic Products

The disposal of end-of-life printed circuit boards (PCBs) comprising cross-linked brominated epoxy resins, glass fiber, and metals has attracted considerable attention from the environmental aspect. In this study, valuable resources, especially organic material, were recovered by the effective chemical recycling of PCBs. Pulverized PCB was depolymerized by glycolysis using polyethylene glycol (PEG 200) with a molecular weight of 200 g/mol under basic conditions. The cross-linked epoxy resins were effectively decomposed into a low-molecular species by glycolysis with PEG 200, followed by the effective separation of the metals and glass fibers from organic materials. The organic material was modified into recycled polyol with an appropriate viscosity and a hydroxyl value for rigid polyurethane foams (RPUFs) by the Mannich reaction and the addition polymerization of propylene oxide. RPUFs prepared using the recycled polyol exhibited superior thermal and mechanical properties as well as thermal insulation properties compared to conventional RPUFs, indicating that the recycled polyol obtained from the used PCBs can be valuable as RPUF raw materials for heat insulation.

Polyurethane Foams: Past, Present, and Future

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.

Renewable polyols for advanced polyurethane foams from diverse biomass resources

This review highlights recent advances in the synthesis of renewable polyols, used for making polyurethane foams, from biomass.