Synthesis Of Rigid Polyurethane Foams Research Articles

Влияние фосфорсодержащих антипиренов на показатели пожарной опасности газонаполненных полимеров на основе реакционноспособных олигомеров

Introduc tion. The reduction of flammability of gas-filled polymers prone to carbonization is based on the use of phosphorus- and boron-containing compounds that reduce the formation of combustible volatile pyrolysis products and increase the yield of coke residue. This reduces the rate of heat release, heat and mass transfer between the material and the flame. In the scientific literature the data about the influence of phosphorus-containing flame retardants on thermal stability, combustibility and smokeability of foams are given, but there are no data about the influence of phosphorus concentration on fire danger indicators of foams. The aim of this paper is the development of effective methods of production of casting foams based on reactive oligomers with low fire hazard and high-performance. Objectives: to reveal the influence of phosphorus concentration on the technological and physical-mechanical characteristics, thermal resistance and fire hazard indices of foams and to develop fire-proof thermal insulation materials possessing high performance. Methods. Physical-mechanical properties and fire hazard indices of gas-filled polymers were determined according to current GOST. Thermal properties and composition of combustion products of foams have been studied with thermoanalytical complex DuPONT-9900 and chromatography-mass spectrometry. Results and discussion. The concentration of phosphorus in the synthesis of rigid polyurethane foams with reduced flammability and high performance should exceed 2.1 % wt. The low-combustible urea foams have been obtained at a phosphorus concentration of 0.2–0.3 % wt. For the production of non-flammable, low-­flammable resin foams, the phosphorus concentration is 0.6–0.7 % wt. At the same time, organophosphorus flame retardants containing reactive groups are highly effective. Conclusion s. As a result of experimental studies the influence of phosphorus concentration and content of organophosphorus-containing flame retardants on physical-mechanical properties, thermal stability and fire hazard of foams based on reactive oligomers was revealed, the pouring foams with lowered fire hazard and high performance were developed.

Preparation of rigid polyurethane foam from lignopolyol obtained through mild oxypropylation.

Lignin, one of the main components of lignocellulose, can be used as an alternative to chemical polyols in the production of polyurethane because of its abundant phenolic and alcohol hydroxyls. Traditionally, lignin is directly applied in the preparation of polyurethane; however, modified lignin has been proved to be superior, especially that obtained by the oxypropylation reaction. Therefore, lignopolyol obtained by mild and efficient oxypropylation was utilized in the production of rigid polyurethane foam in this study. Specifically, the effects of the content of lignopolyol on the chemical structure, morphological structure, mechanical properties and thermal stability of the lignin-based rigid polyurethane foam were investigated. It was found that the compressive strength of the rigid polyurethane foam was significantly improved with the addition of lignopolyol compared with that of the pure polyurethane foam, which was attributed to the fact that oxypropylation made lignin into highly branched and functionalized polyols by transforming all phenolic hydroxyls into aliphatic hydroxyls. Moreover, when the molal weight of lignopolyol accounted for 40% of the added polyols, the generated foam showed optimal uniformity and regularity, and the compressive strength reached 0.18 MPa, meeting the requirements of industrial application, below which, the amount of undesired reactions is bound to increase. As a consequence, the added amount of lignopolyol was increased as much as possible on the basis of guaranteeing the desired properties, which was more conducive to realizing the green degradation and economic synthesis of rigid polyurethane foam.

Bio-Based Rigid Polyurethane Foams Modified with Phosphorus Flame Retardants.

Rigid polyurethane foams (RPURF) containing a bio-polyol from rapeseed oil and different phosphorus-based flame retardants were obtained. Triethyl phosphate (TEP), dimethyl propane phosphonate (DMPP) and cyclic phosphonates Addforce CT 901 (20 parts per hundred polyol by weight) were used in the synthesis of RPURF. The influence of used flame retardants on foaming process, cell structure, and physical–mechanical properties as well as flammability of RPURF were examined. The addition of flame retardants influenced the parameters of the cellular structure and decreased compressive strength. All obtained foam materials had a low thermal conductivity coefficient, which allows them to be used as thermal insulation. The research results of bio-based RPURF were compared with foams obtained without bio-polyol. All modified materials had an oxygen index above 21 vol%; therefore, they can be classified as self-extinguishing materials. The analysis of parameters obtained after the cone calorimeter test showed that the modified RPURF have a lower tendency to fire development compared to the reference foams, which was particularly noticeable for the materials with the addition of DMPP.

Glycolysis of Polyurethanes Composites Containing Nanosilica.

Rigid polyurethane (RPU) foams have been successfully glycolyzed by using diethylene glycol (DEG) and crude glycerol (CG) as transesterification agents. However, DEG did not allow to achieve a split-phase process, obtaining a product with low polyol purity (61.7 wt %). On contrary, CG allowed to achieve a split-phase glycolysis improving the recovered polyol purity (76.5%). This is an important novelty since, up to now, RPUs were glycolyzed in single-phase processes giving products of low polyol concentration, which reduced the further applications. Moreover, the nanosilica used as filler of the glycolyzed foams was recovered completely pure. The recovered polyol successfully replaced up to 60% of the raw polyol in the synthesis of RPU foams and including the recovered nanosilica in the same concentration than in glycolyzed foam. Thus, the feasibility of the chemical recycling of this type of polyurethane composites has been demonstrated. Additionally, PU foams were synthesized employing fresh nanosilica to evaluate whether the recovered nanosilica has any influence on the RPU foam properties. These foams were characterized structurally, mechanically and thermally with the aim of proving that they met the specifications of commercial foams. Finally, the feasibility of recovering the of CG by vacuum distillation has been demonstrated.

Recovery of Residues from Olive Industry: Characterization of Simple and Acetylated Lignin

Lignin is a renewable material obtained in large quantities as a by-product of the olive industry. In this context, this study aims to examine lignin as macro-monomers in the synthesis of rigid polyurethane foam after chemical modification. Indeed, the lignin extracted from the olive residue is used by chemical treatment according to the organosolv process. Comparison by characterization of the single isolated lignin and the acetylated lignin according to the physicochemical analysisTGA, DSC, FTIR, C-13 NMR, 1-H NMR, and molar mass distribution (sec) shows its value as biomass capable of being transformed into polyol afterchemical modification. acetylation increases the weight and the number of molar masses by 25-50% was also determined. Acetylation has a greater effect on the short chains which are probably richer in free phenolic groups. Mass distribution analyzes reveal a relatively high molar mass in organosolv lignin moreover, polydispersity values are very high (20 >> 1). The characterization of spent olive cake reflects the interest of using this biomass as a source of renewable energy for the production of industrial polymers.

Application of Walnut Shells-Derived Biopolyol in the Synthesis of Rigid Polyurethane Foams.

This study aimed to examine rigid polyurethane (PUR) foam properties that were synthesized from walnut shells (WS)-based polyol. The Fourier Transform Infrared Spectroscopy (FTIR) results revealed that the liquefaction of walnut shells was successfully performed. The three types of polyurethane (PUR) foams were synthesized by replacement of 10, 20, and 30 wt% of a petrochemical polyol with WS-based polyol. The impact of WS-based polyol on the cellular morphology, mechanical, thermal, and insulating characteristics of PUR foams was examined. The produced PUR foams had apparent densities from 37 to 39 kg m−3, depending on the weight ratio of WS-based polyol. PUR foams that were obtained from WS-based polyol exhibited improved mechanical characteristics when compared with PUR foams that were derived from the petrochemical polyol. PUR foams produced from WS-based polyol showed compressive strength from 255 to 310 kPa, flexural strength from 420 to 458 kPa, and impact strength from 340 to 368 kPa. The foams that were produced from WS-based polyol exhibited less uniform cell structure than foams derived from the petrochemical polyol. The thermal conductivity of the PUR foams ranged between 0.026 and 0.032 W m−1K−1, depending on the concentration of WS-based polyol. The addition of WS-based polyol had no significant influence on the thermal degradation characteristics of PUR foams. The maximum temperature of thermal decomposition was observed for PUR foams with the highest loading of WS-based polyol.

Curcumin as a natural compound in the synthesis of rigid polyurethane foams with enhanced mechanical, antibacterial and anti-ageing properties

Abstract This paper presents the effect of natural compound (E,E)-1,7-bis(4-Hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione (curcumin) on the antibacterial, anti-aging, mechanical and morphological properties of polyurethane (PU) rigid foams. Concentrations of 1 wt%, 2 wt% and 5 wt% of antibacterial compound was used, and the infection reduction capacity was evaluated for different types of bacteria (Escherichia coli (G-) and Staphylococcus aureus (G+). In order to determine all assumed properties the synthesized PU foams were characterized by analytical (Fourier Transform Infrared Spectroscopy, FTR), morphological (Scanning Electron Microscopy, SEM), bactericidal effects (Disc Diffusion Method), thermal characteristic (Thermogravimetric Analysis, TGA), mechanical techniques (three-point bending test and compressive test) and physical properties (apparent density, dimensional stability, contact angle, water uptake, color characteristics). Compared to the reference foam, compositions modified with 1 and 2 wt% of the curcumin showed greater compressive strength (increase of 10 and 7%, respectively), higher flexural strength (increase of 17 and 7%, respectively), less water uptake (decrease by 12 and 10%, respectively), as well as, better thermal properties. On the other hand, it has been shown, that in all cases, curcumin can be used as a natural anti-ageing additive for polymers. The addition of curcumin in the amount of 1, 2 and 5 wt% considerably improved the stabilization of the polymer. Moreover, based on the microbiological results, it has been shown that the addition of 5 wt% of the extract is suitable for the manufacturing of PU foams with enhanced antibacterial properties.

Attempts to Upcycle PET Wastes into Bio-based Long-lasting Insulating Materials

Following the green chemistry principles, three series of polyols with tailored chemical structures were obtained from PET wastes degradation via glycolysis and/or aminolysis and subsequent esterification-transesterification and/or amidation reactions, using an organic catalyst. As cleaving agents there were used various mixtures of renewable or potentially renewable reagents, selected from those that can be obtained from biomass by already applied or investigated and eventually patented biochemical and/or chemical processes. The polyols were characterized by physical-chemical methods, 1H-NMR, 13C-NMR and FT-IR Spectroscopy, and tested in the synthesis of rigid polyurethane foams, showing appropriate properties for spray foams formation and leading to materials with properties similar to conventional spray foams.

Liquefaction of Peanut Shells with Cation Exchange Resin and Sulfuric Acid as Dual Catalyst for the Subsequent Synthesis of Rigid Polyurethane Foam

The conversion of lignocellulosic biomass from renewable raw materials to high value-added fine chemicals expanded their application in biodegradable polymers materials synthesis, such as polyurethanes and phenolic resin, etc. In this work, the strong-acid cation exchange resin and sulfuric acid as the dual catalyst offered an effective way to catalyze the liquefaction reaction of the peanut shells. The properties of liquefied products were characterized by means of hydroxyl value, viscosity and solubility tests, while the properties of peanut shells and liquefaction residue were analyzed by means of ATR-FTIR, TG and SEM techniques. The results indicated that the liquefied products could be completely dissolved in deionized water, methanol and polyethylene glycol, respectively, and they could be a preferable substitution of petrochemical polyols as soft segments to synthesize the rigid polyurethane foams. Moreover, the cellulose and hemicellulose in the peanut shells were easily decomposed into smaller molecules via the breakage of the C–O bond besides five-membered and hexatomic ring, while the lignin could be degraded via the breakage of the C–O chemical bonds of β-O-4, 4-O-5 and dibenzodioxocin units. The fabricated rigid polyurethane (RPU) foam, containing higher percentage of open pores with uniform size, can be potentially utilized for flower mud and sound-absorbing materials.

Effects of hydrotalcite on rigid polyurethane foam composites containing a fire retarding agent: compressive stress, combustion resistance, sound absorption, and electromagnetic shielding effectiveness.

Polyether polyol, isocyanate, and a flame retardant (10 wt%), hydrotalcite (0, 1, 3, 5, 7, and 9 wt%) are used to form a rigid PU foam, while a nylon nonwoven fabric (400 g m−2) and a polyester aluminum foil are combined to serve as the panel. The rigid PU foam and the panel are then combined to form the rigid foam composites. The cell structure, compressive stress, combustion resistance, thermal stability, sound absorption, and electromagnetic shielding effectiveness of the rigid foam composites are evaluated, examining the effects of using hydrotalcite. When the hydrotalcite is 5 wt%, the rigid foam composites have an optimal density of 0.168 g cm−3, an average cell size of 0.2858 mm, a maximum compressive stress of 479.95 kpa, an optimal LOI of 29, an optimal EMSE of 45 dB, and the maximum thermal stability and sound absorption.

The Study on Application of Biopolyols Obtained by Cellulose Biomass Liquefaction Performed with Crude Glycerol for the Synthesis of Rigid Polyurethane Foams

In this work rigid polyurethane foams (PUR) were obtained by replacement of 0–70 wt% of petrochemical polyol with bio-polyol obtained via cellulose liquefaction in presence of crude glycerol. The foams with different content of a bio-polyol were prepared by single step method for NCO/OH ratio equals 1.5. The prepared materials were analyzed in terms of their morphology, chemical structure, thermal stability and basic physical and mechanical properties. The effects of photo-oxidative and thermo-oxidative aging on chemical structure, apparent density and mechanical properties of the biomass based rigid polyurethane foams were investigated and discussed.

Synthesis of rigid polyurethane foams from phosphorylated biopolyols.

Renewable resources are playing a key role on the synthesis of biodegradable polyols. Moreover, the incorporation of covalently linked additives is increasing in importance in the polyurethane (PU) market. In this work, previously epoxidized grape seed oil and methyl oleate were transformed into phosphorylated biopolyols through an acid-catalyzed ring-opening hydrolysis in the presence of H3PO4. The formation of phosphate polyesters was confirmed by FT-IR and 31P-NMR. However, the synthesis of a high-quality PU rigid foam was not possible using exclusively these polyols attending to their low hydroxyl value. In that way, different rigid PU foams were prepared from the phosphorylated biopolyols and the commercial polyol Alcupol R4520. It was observed that phosphorylated biopolyols can be incorporated up to a 57wt.% in the PU synthesis without significant structural changes with respect to the commercial foam. Finally, thermogravimetric and EDAX analyses revealed an improvement of thermal stability by the formation of a protective phosphorocarbonaceous char layer.

Polyurethane/ground tire rubber composite foams based on polyglycerol: Processing, mechanical and thermal properties

During the synthesis of rigid polyurethane foams, petrochemical polyol was substituted with polyglycerol, the product of thermo-catalytic polycondensation of waste glycerol, resulting from biodiesel production. Two types of ground tire rubbers, untreated and thermo-mechanically reclaimed, were used to obtain “green” polyurethane-polyglycerol composite foams. Samples were prepared by a single-step method for the ratio of NCO/OH groups equal to 2. Foams containing different types of fillers showed noticeably various appearances, which suggested significant differences in the matrix–filler interactions between materials modified with untreated and reclaimed ground tire rubber. Addition of rubber particles shortened the processing time by more than 20 s and reduced the temperature during synthesis. Incorporation of ground tire rubber increased the size of the cells in comparison to unmodified foam. Modifications of rigid polyurethane foams resulted in the increase of apparent density and compressive strength even by 40% compared to neat foam. Enhancement was stronger for samples containing thermo-mechanically reclaimed ground tire rubber as a result of better developed surface of filler particles and their interfacial interactions with polyurethane matrix. Prepared polyurethane foams filled with untreated rubber particles also showed slightly enhanced thermal stability compared to neat foam.

Synthesis of rigid polyurethane foams with castor oil-based flame retardant polyols

A new method of introducing castor oil based flame-retardant polyols (COFPL) into polyurethane foams was explored in this paper. Castor oil was alcoholyzed with glycerol. And epoxidation of glycerolysis castor oil was carried out by formic acid and hydrogen peroxide (H2O2). The flame-retardant polyols were gotten though ring-opening reaction with diethyl phosphate. A novel castor oil-based polyurethane foam has been prepared by a one-shot process with and without COFPL. The structure of COFPL was characterized by FT-IR and 1HNMR and the two studies exhibited characteristic peaks for COFPL. The thermal degradation and fire behaviour of polyurethane foams were investigated by limiting oxygen index (LOI), cone calorimetry test and thermogravimetry analysis. It has been shown that although the content of P element is only about 3%, the fire retardant incorporated in the castor oil molecule chain increased thermal stability and LOI value of polyurethane foam can reach to 24.3% without any other flame retardant. The compression strength of polyurethane foam was also improved with the increase of flame-retardant polyols. Morphology of polyurethane foams was examined by scanning electron microscope (SEM) and found to be displayed the regular size and high percentage of close area of the cell. Therefore, rigid foams from castor oil-based flame retardant polyols appear suitable for a wide range of applications.

Novel Synthesis, Characterization of N1,N1,N4,N4-tetrakis (2-hydroxyethyl) terephthalamide (THETA) and Terephthalic Acid (TPA) by Depolymerization of PET Bottle Waste Using Diethanolamine

Chemical depolymerization of poly(ethylene terephthalate) (PET) waste is a possible remedy to huge amount of solid waste generation as it results in degradation products that possess a potential of recyclability. PET bottle waste was depolymerized by aminolysis using diethanolamine. Novel synthesis of N1, N1,N4,N4-tetrakis (2-hydroxyethyl) terephthalamide (THETA) with 73-76% yield and terephthalic acid (TPA) with 78-82% yield was achieved. The purified products were analyzed by FTIR, melting point, DSC, DTG and 1H-NMR. THETA has various applications in the synthesis of rigid polyurethane foam, unsaturated polyester resins and also as a cross linking agent/ hardener for epoxy resins.

Synthesis of Rigid Polyurethane Foams from Recycled Poly(ethylene Terephthalate) Waste

Glycolysis of poly(ethylene terephthalate), PET, waste using trimethylol propane (TMP) or pentaerytheritol (PEr) was used to produce suitable hydroxyoligomers for polyurethane foams. The glycolysis was carried out in the presence of manganese acetate as a catalyst, under high and normal pressure atmosphere in xylene and m-cresol at 220 °C. The prepared oligomers were reacted with 2,4- 2,6- toluene diisocyanate to produce different types of polyurethane foams. The compressive and flexural strengths, open and closed cell%, oxygen index% and curing times were determined and the results were correlated to the chemical structure of the produced oligomers.

Synthesis of phosphorylated esters and oligoesters, prepared from unsaturated acids and glycols, and their use as flame retardants for rigid polyurethane foams

Unsaturated esters and oligoesters of itaconic and methacrylic acid have been synthesized through transesterification of dimethyl itaconate and methyl methacrylate with ethylene glycol and diethylene glycol. Dialkyl phosphites and bis(ω-hydroxyethoxyethyl)phosphite have been added to the double bonds of the products by the Pudovik reaction. Some of the phosphorylated products have been employed as viscosity reducing additives to polyesteralcohols, which were used in the synthesis of rigid polyurethane foams. The presence of phosphorus in the additives accounts for the observed increase in the fire resistance of the prepared polymers.

Synthesis of rigid polyurethane foams from oligoester alcohols based on the residues from the distillation of crude dimethyl terephthalate and recrystallization of the dimethyl terephthalate/dimethyl isophthalate fraction

AbstractOligoester alcohols are synthesized from the resudes from the distillation of crude dimethyl terephthalate and recrystallization of the fraction dimethyl terephthalate/dimethyl isophthalate, diols, triols, tetrols, and tall oil. The polyol component containing various oligoester alcohols is suitable for preparing rigid polyurethane foams with good thermal stability and improved resistance to combustion.

Synthesis of rigid polyurethane foams from oligoester alcohols obtained from dimethyl terephthalate production wastes

AbstractA study was conducted to synthesize oligoester alcohols from dimethyl terephthalate production wastes via transesterification with diethylene glycol and trimethylol propane. The oligoester alcohols obtained are suitable for preparing rigid polyurethane foams. The oligoester alcohols from trimethylol propane possess good physical and mechanical properties. The oxygen indices indicate that the polyurethane foams exhibit improved resistance to combustion due to the increased content of aromatic nuclei in the oligoester alcohols.