Development of eco-friendly polyurethane foams based on Lesquerella fendleri (A. Grey) oil-based polyol

Alternative Methods for Biodiesel Cetane Number Valuation: A Technical Note

Biodiesel is an environmentally beneficial and clean energy source that may replace fossil fuels, which are detrimental to the environment and cannot be replenished. Therefore, the physicochemical parameters of biodiesel must be determined in order to verify its quality. The cetane number is a crucial dimensionless fuel property that gauges the fuel ignition quality in power diesel engines. A higher cetane number results in a shorter ignition delay time, and vice versa. Biodiesel's cetane number may fluctuate due to a variety of fatty acid compositions, including variations in carbon chain length and the degree of unsaturation. The cetane number generally increases with increasing saturation and chain length, while it decreases as chain length is reduced and degrees of unsaturation and branching increase. This is the main reason for why alkanes possess a higher cetane number than alkenes and aromatics. The standard protocols for evaluating the cetane number of biodiesel are ASTM D613 and ISO 5165 test techniques using a monocylindrical cetane engine. However, adhering to these conventional procedures is quite challenging and time-consuming, and the cetane number test result may also be affected by the presence of certain gases and fumes. As a result, many researchers are bothered with cetane number valuation, and occasionally they skip it due to a lack of other options. Consequently, the aim of this paper is to present a set of more straightforward and relevant alternative techniques that can be applied to predict the cetane number of biodiesel when engine-based measurement is not practical. The three techniques with their designed pictographic outlooks conferred in this article include color indicator titration, aniline point, and fatty acid composition-based methods. The reported values of these procedures meet the minimum cut point of the biodiesel cetane number required by ASTM D6751 (≥47) and exhibit minimal variation from the typical standard methods. Nevertheless, the above-mentioned techniques are not applicable to other alternative biofuels except biodiesel products because they have a direct implication on the characteristics of the fatty acid profiles of different oil precursors, such as carbon chain length, degree of saturation or unsaturation, and aromaticity, which make up monoalkyl esters.

Recent Developments in Synthesis, Properties, Applications and Recycling of Bio-Based Elastomers

In 2021, global plastics production was 390.7 Mt; in 2022, it was 400.3 Mt, showing an increase of 2.4%, and this rising tendency will increase yearly. Of this data, less than 2% correspond to bio-based plastics. Currently, polymers, including elastomers, are non-recyclable and come from non-renewable sources. Additionally, most elastomers are thermosets, making them complex to recycle and reuse. It takes hundreds to thousands of years to decompose or biodegrade, contributing to plastic waste accumulation, nano and microplastic formation, and environmental pollution. Due to this, the synthesis of elastomers from natural and renewable resources has attracted the attention of researchers and industries. In this review paper, new methods and strategies are proposed for the preparation of bio-based elastomers. The main goals are the advances and improvements in the synthesis, properties, and applications of bio-based elastomers from natural and industrial rubbers, polyurethanes, polyesters, and polyethers, and an approach to their circular economy and sustainability. Olefin metathesis is proposed as a novel and sustainable method for the synthesis of bio-based elastomers, which allows for the depolymerization or degradation of rubbers with the use of essential oils, terpenes, fatty acids, and fatty alcohols from natural resources such as chain transfer agents (CTA) or donors of the terminal groups in the main chain, which allow for control of the molecular weights and functional groups, obtaining new compounds, oligomers, and bio-based elastomers with an added value for the application of new polymers and materials. This tendency contributes to the development of bio-based elastomers that can reduce carbon emissions, avoid cross-contamination from fossil fuels, and obtain a greener material with biodegradable and/or compostable behavior.

Waterborne Polyurethane/Acrylic Adhesive Blends from Physaria fendleri Oil for Food Packaging Applications

Environmental concerns and the diminishing acceptability of using petrochemical polymers require innovative synthetic approaches to materials for essential polymeric technologies such as adhesives. Biobased plant oils have been suggested as replacements for petrochemical monomers in polyurethane formulations. A variety of seed oil extracts from plants contain naturally occurring functional groups such as hydroxyl and glycidyl ether, which can be utilized in polyurethane synthesis. Most studies of bioderived polyurethane adhesives occur in solventborne systems and with chemically modified oils. However, rising concerns and manufacturing limitations of volatile organic compounds in solventborne systems warrant investigation into more sustainable and alternatives that are easier to handle. In this work, we synthesized waterborne polyurethanes comprised of oil derived from Physaria fendleri seed (naturally occurring hydroxyl functionality), hexamethylene diisocyanate, toluene diisocyanate, and dimethyl propionic acid. Acrylate copolymers were synthesized via emulsion polymerization comprised of different butyl and methylmethacrylate monomer ratios. These polymers were formulated into waterborne polyurethane/acrylic adhesive blends. The resulting formulations possess a commercially comparable peel strength of >6 N and are suggested for use in resealable food packaging applications. This study demonstrates the utility of oil derived from Physaria fendleri seeds in waterborne adhesive applications, adding value with bioderived materials and increasing sustainability of polyurethane adhesives.

Synthesis, Characterization and Properties of Soybean Oil-Based Polyurethane

At present, the consumption of polyurethane is huge in various industries. As a result, it has become a research hotspot to use environmentally friendly and renewable bio-based raw materials (instead of petroleum-based raw materials) to prepare polyurethane. In this paper, epoxy soybean oil (ESO) was used as raw material, and polyethylene glycol (PEG-600) was used for ring opening. Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (¹H NMR) analysis proved that soybean oil-based polyester polyols was prepared. Soybean oil-based polyurethane (SPU) was synthesized by the reaction of the soybean oil-based polyol with isophorone diisocyanate (IPDI), so as to save energy and protect the environment. The properties of SPU films were adjusted by changing the R value (the molar ration of -NCO/-OH) and the film forming temperature. The chemical structure and properties of the SPU were characterized by FTIR, ¹H NMR, gel permeation chromatography (GPC), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results show that the mechanical strength, water contact angle, microphase separation degree, barrier property, and thermal stability of SPU films gradually increase, while the transparency, oxygen permeability coefficient and moisture permeability coefficient of SPU films gradually decrease with the increase of R value and film forming temperature.

Use of Novel Non-Toxic Bismuth Catalyst for the Preparation of Flexible Polyurethane Foam

Foam products are one of the largest markets for polyurethane (PU) and are heavily used in many sectors. However, current PU formulations use highly toxic and environmentally unfriendly production processes. Meanwhile, the increasing environmental concerns and regulations are intensifying the research into green and non-toxic products. In this study, we synthesized flexible polyurethane foam (PUF) using different weight percentages (0.025%, 0.05% and 0.1%) of a non-toxic bismuth catalyst. The bismuth-catalyzed foams presented a well evolved cellular structure with an open cell morphology. The properties of the bismuth-catalyzed flexible PUF, such as the mechanical, morphological, kinetic and thermal behaviors, were optimized and compared with a conventional tin-catalyzed PUF. The bismuth-catalyst revealed a higher isocyanate conversion efficiency than the stannous octoate catalyst. When comparing samples with similar densities, the bismuth-catalyzed foams present better mechanical behavior than the tin-catalyzed sample with similar thermal stability. The high solubility of bismuth triflate in water, together with its high Lewis acidity, have been shown to benefit the production of PU foams.