Highly functional lactic acid ring‐opened soybean polyols applied to rigid polyurethane foams

Development of lactic acid based chain extender and soybean oil-derived polyurethanes for ecofriendly sustained drug delivery systems

In the present study, a range of sustainable, biocompatible and biodegradable polyurethanes (PU-1 to PU-4) were synthesized using different combinations of biobased polyol (obtained through the epoxidation of soybean oil, followed by ring opening with ethanol) and polyethylene glycol (PEG) and isophorone diisocyanate. The sustainable chain extender used in this study was synthesized by the esterification of lactic acid with ethylene glycol (EG). The synthesized PU samples were characterized through scanning electron microscopy (SEM), Fourier transformed infrared (FTIR) and nuclear magnetic resonance (1H NMR and 13C NMR) spectroscopy. Wetting ability and thermal degradation analysis (TGA) of the samples were also studied. Subsequently, these PUs were examined as potential drug delivery systems using Gabapentin as a model drug, which was loaded in the polymer matrix using the solvent evaporation method. The drug release studies were carried out in 0.06 N HCl as a release medium according to the method outlined in the United States Pharmacopeia. The maximum drug release was observed for sample PU-P1, which was found to be 53.0 % after 6 h. Moreover, a comparison of different PU samples revealed a trend wherein the values of drug release were decreased with an increase in the PEG content.

A Review of Rigid Polymeric Cellular Foams and Their Greener Tannin-Based Alternatives

This review focuses on the description of the main processes and materials used for the formulation of rigid polymer foams. Polyurethanes and their derivatives, as well as phenolic systems, are described, and their main components, foaming routes, end of life, and recycling are considered. Due to environmental concerns and the need to find bio-based alternatives for these products, special attention is given to a recent class of polymeric foams: tannin-based foams. In addition to their formulation and foaming procedures, their main structural, thermal, mechanical, and fire resistance properties are described in detail, with emphasis on their advanced applications and recycling routes. These systems have been shown to possess very interesting properties that allow them to be considered as potential substitutes for non-renewable rigid polymeric cellular foams.

Casein/Apricot Filler in the Production of Flame-Retardant Polyurethane Composites

Polyurethane (PUR) composites reinforced with 1, 2, and 5 wt.% of apricot filler modified with casein were synthesized in the following study. The impact of 1, 2, and 5 wt.% of casein/apricot filler on the cellular structure and physico-mechanical performances of reinforced PUR composites were determined. It was found that the incorporation of 1 and 2 wt.% of casein/apricot filler resulted in the production of PUR composites with improved selected physical, thermal, and mechanical properties, while the addition of 5 wt.% of casein/apricot filler led to some deterioration of their physico-mechanical performance. The best results were obtained for PUR composites reinforced with 2 wt.% of casein/apricot filler. Those composites were characterized by a uniform structure and a high content of closed cells. Compared with the reference foam, the incorporation of 2 wt.% of casein/apricot filler resulted in improvement in compressive strength, flexural strength, impact strength, and dynamic mechanical properties-such as glass transition temperature and storage modulus. Most importantly, PUR composites showed better fire resistance and thermal stability due to the good thermal performance of casein. The main aim of this article is to determine the influence of the natural combination of the apricot filler and casein on the mechanical properties and flammability of the obtained composites.

The Prospering of Macromolecular Materials Based on Plant Oils within the Blooming Field of Polymers from Renewable Resources

This paper provides an overview of the recent progress in research and development dealing with polymers derived from plant oils. It highlights the widening interest in novel approaches to the synthesis, characterization, and properties of these materials from renewable resources and emphasizes their growing impact on sustainable macromolecular science and technology. The monomers used include unmodified triglycerides, their fatty acids or the corresponding esters, and chemically modified triglycerides and fatty acid esters. Comonomers include styrene, divinylbenzene, acrylics, furan derivatives, epoxides, etc. The synthetic pathways adopted for the preparation of these materials are very varied, going from traditional free radical and cationic polymerizations to polycondensation reactions, as well as metatheses and Diels-Alder syntheses. In addition to this general appraisal, the specific topic of the use of tung oil as a source of original polymers, copolymers, and (nano)composites is discussed in greater detail in terms of mechanisms, structures, properties, and possible applications.

Polyurethane Hybrid Composites Reinforced with Lavender Residue Functionalized with Kaolinite and Hydroxyapatite

Polyurethane (PUR) composites were modified with 2 wt.% of lavender fillers functionalized with kaolinite (K) and hydroxyapatite (HA). The impact of lavender fillers on selected properties of PUR composites, such as rheological properties (dynamic viscosity, foaming behavior), mechanical properties (compressive strength, flexural strength, impact strength), insulation properties (thermal conductivity), thermal characteristic (temperature of thermal decomposition stages), flame retardancy (e.g., ignition time, limiting oxygen index, heat peak release) and performance properties (water uptake, contact angle) was investigated. Among all modified types of PUR composites, the greatest improvement was observed for PUR composites filled with lavender fillers functionalized with kaolinite and hydroxyapatite. For example, on the addition of functionalized lavender fillers, the compressive strength was enhanced by ~16-18%, flexural strength by ~9-12%, and impact strength by ~7%. Due to the functionalization of lavender filler with thermally stable flame retardant compounds, such modified PUR composites were characterized by higher temperatures of thermal decomposition. Most importantly, PUR composites filled with flame retardant compounds exhibited improved flame resistance characteristics-in both cases, the value of peak heat release was reduced by ~50%, while the value of total smoke release was reduced by ~30%.