Preparation Of Polyurethane Foams Research Articles

Bio-Based Polyurethane Composites from Macauba Kernel Oil: Part 1, Matrix Synthesis from Glycerol-Based Polyol

Polyurethanes are the result of a reaction between an isocyanate and a polyol. The large variety of possible reagents creates many possible polyurethanes to be made, such as soft foams, rigid foams, coatings, and adhesives. This polymer is one of the most produced and consumed polymers in the world with an ever-increasing demand. Despite its usual petrochemical nature, research on bio-based polyurethanes flourishes due to the ease in creating bio-based polyols. This work covers the synthesis of a novel macauba kernel oil polyol by the epoxidation of the oil, followed by a ring-opening reaction of the epoxide with glycerol, used for the preparation of polyurethane foams using different NCO/OH ratios. The FTIR and H1 results confirm the formation of the epoxide and polyol, and the polymers in all NCO/OH ratios were confirmed by FTIR, showing great similarities between the samples, especially PU 1.0 and PU 1.2. Despite the TGs showing close behaviors for the three samples, their DTGs showed great difference between the samples, with PU 1.0 presenting a regular PU DTG profile with three degradation peaks while the other two sample presented five degradation peaks, indicating a higher crosslinking density in them.

Phenolic Foam Preparation Using Hydrofluoroolefin Blowing Agents and the Toughening Effect of Polyethylene Glycol.

In this work, a new class of fourth-generation, zero ozone depletion potential, hydrofluoroolefin-based blowing agents were used to prepare phenolic foam. While hydrofluoroolefin blowing agents have been used previously to prepare polyurethane foams, few studies have been reported on their use in phenolic foams. We introduce an effective method for foam preparation using two low-boiling blowing agents, cis-1,1,1,4,4,4-hexafluoro-2-butene and trans-1,1,1,4,4,4-hexafluoro-2-butene, and their combinations with hexane. Traditionally, phenolic foams have been prepared using chlorofluorocarbons and hydrochlorofluorocarbons, which can have harmful effects on the environment due to their high ozone depletion potential or global warming potential. Conductor-like screening model for real solvents (COSMO-RS) modeling studies were performed to understand the effects of different blowing agent combinations on their boiling points. A series of phenolic foams were prepared by varying the concentration of the hydrofluoroolefin and the hydrofluoroolefin-hexane blowing agent combinations. The concentrations of the surfactant, Agnique CSO 30, and the toughening agent, polyethylene glycol, were also varied to yield a formulation with the optimal properties. The foams formulated with the hydrofluoroolefin-hexane mixture displayed a higher compressive strength and a lower thermal conductivity than those prepared with either hydrofluoroolefin or hexane alone. The cell microstructure of all the foams was examined using scanning electron microscopy. By introducing flexible chains into the resin matrix, PEG facilitates proper distribution of hydrofluoroolefin-hexane blowing agents and other reagents and thereby increases the mechanical strength of the foam.

One‐Step Solvent‐Free Synthesis of Dimer Diamine‐Based Autocatalytic Polyol for the Preparation of Polyurethane Foams

AbstractHerein, this work reports the facile synthesis of a dimer diamine‐based autocatalytic polyol (ACP) and its use in polyurethane foam preparation. The ACP, namely TETRAOL is synthesized in one step, without using solvent, and with 100% atom economy. Additionally, a phosphorous‐modified polyol is synthesized by using 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) and castor oil. In this study, all of the polyol components of the foams are of vegetable oil origin, and amine or tin‐based auxiliary catalysts are not used. The structures of the synthesized autocatalytic polyol as well as other bio‐polyols are characterized by Fourier‐transform infrared (FTIR) and Nuclear magnetic resonance (NMR) spectroscopies. The densities, rise and gel time values, and thermal and mechanical properties of the foams are determined and compared to foams prepared by using a petroleum‐based commercial ACP. The bio‐based TETRAOL‐containing foams display comparable densities and improve thermal properties but longer rise and gel time values concerning the foam prepared by using the commercial ACP.

Upcycling of waste epoxy thermosets to robust polyurethane foams via an in situ degradation-foaming process

High-efficiency and energy-saving conversion of epoxy thermosets into "three-high" (high value, high quality and high performance) products is highly desired from the viewpoints of both environmental protection and resource utilization. Here, we demonstrate a new strategy for mild degradation of epoxy thermosets and in situ preparation of polyurethane foam from degradation solutions. The degradation solution contains the unreacted solvent polyethylene glycol and polyol degradation products after alcoholysis, both of which can react with isocyanate to produce polyurethane. The use of an insoluble catalyst makes it possible to achieve in-situ foaming of the degradation solution, which realizes the direct and full utilization of degradation products. Owing to the rigid epoxy skeleton of the degradation products, the obtained rigid polyurethane foam exhibited high mechanical properties (∼170kPa), good thermal insulation performance (33–35 mW•m−1•K−1), low water absorption (3–5%), regular pore structure and good thermal stability, thus can be a good candidate for building insulation materials.

Effect of bio-based polyols and chain extender on the microphase separation structure, mechanical properties and morphology of rigid polyurethane foams

The preparation of polyurethane foams from bio-based polyols was a preferable alternative to save fossil resources, and the investigation of the microphase separation structure of foams can effectively guide their application. In this work, rigid polyurethane (PU) foams from three bio-based polyols and different content of chain extender of 1,4-butanediol were prepared. Microphase separation behavior and thermodynamic properties of the foams were analyzed by ATR-FTIR, SEM, TG, DSC and DMA. The hydrogen bond content increases and the microphase separation tendency is suppressed with the addition of bio-based polyols. The TG analysis reveals that the thermal loss of bio-based foams is earlier than that of petroleum-based foams at the initial stage. The hydrogen bond content of bio-based rigid PU foam derived from corn stalks increases by 6.03 % relative to petroleum-based foam, and the compression strength reaches 160.18 KPa. Furthermore, with the addition of 1,4-butanediol (5 wt%), the compression strength of bio-based rigid PU foam derived from corn stalks rises to 325.05 KPa, while the proportion of ordered hydrogen bonds is considerably higher than that of the original foam, demonstrating the increase in the degree of microphase separation.

Successive organic solvent fractionation and homogenization of technical lignin for polyurethane foam with high mechanical performance

This work demonstrates an organic solvent fractionation method for lignin homogenization, which can effectively reduce the lignin heterogeneity and use each lignin fraction to prepare polyurethane foams (PUFs) with excellent mechanical properties. Such fractions were fully characterized by GPC, NMR (31P, 2D-HSQC), FTIR, and TG to obtain a detailed description of the structures and properties. The properties of PUFs from each lignin fraction showed higher compatibility than that from unfractionated industrial lignin, as studied by morphology and DSC analysis. The improvement of compatibility between the fractionated lignin fractions and polyethylene glycol can effectively enhance the mechanical properties of the prepared PUFs. The hysteresis loss (43.10%–51.85%) and resilience (95.81%–98.81%) of the fractionated lignin polyurethane foams (LPUFs) were better than that from the unfractionated LPUFs (hysteresis loss 41.64%, resilience 94.67%) at the lignin content of 5%. Subsequently, the strong relationships between lignin structures and PUF properties were demonstrated in detail. The suggested approach provides greater possibilities to prepare LPUFs with tunable properties based on real industrial lignin fractions, rather than modified lignin.

Chemical and structural characterization of hardwood and softwood LignoForce™ lignins

Knowledge about lignin structure after isolation is paramount for demonstrating its potential for industrial applications. This paper presents for the first time the detailed characterization of LignoForce™ hardwood (LFHL) and softwood (LFSL) kraft lignins that were obtained from industrially realistic lignin production facilities. The moisture content was circa 8 % for both LFHL and LFSL, and their total carbon contents were 62.8 and 64.4 %, respectively. Both samples had low ash and carbohydrate contents and total lignin contents higher than 97 %. The macromolecular properties and functional groups of lignin were characterized by nuclear magnetic resonance, analytical pyrolysis (Py-GC–MS), thermal analysis, mass spectrometry, and size exclusion chromatography. LFHL presented lower aliphatic and phenolic OH groups, higher methoxyl content (S/G ratio of 1.97), lower weight-average apparent molecular mass (Mw) and degree of condensation, higher solubility in organic solvents, and lower thermal stability compared to LFSL. C1-Guaiacol and C1-syringol predominated in the Py-GC–MS analyses of LFSL and LFHL, respectively, whose β-O-4′ contents were 5.8 and 6.2 per 100 aromatic units. The high total OH groups of both lignins suggests their suitability for replacing petroleum-based polyols in the preparation of polyurethane foams. LFHL would be preferable in this application due to its higher solubility in the reaction medium. Also, the lower Mw and glass transition temperature of LFHL would facilitate its blending with polymers in thermoplastic applications. LFSL would be a suitable replacement of phenol in phenol-formaldehyde resins, and its higher Mw and improved thermal stability are expected to be useful for making carbon fibers.

The Influence of Microstructure on Sound Absorption of Polyurethane Foams through Numerical Simulation

Front Cover: The structure of isocyanate contains unsaturated bonds and has high activity. It easily reacts with some organic or inorganic substances with active groups. In the preparation of polyurethane foam, a porous polyurethane foam can be generated by reacting isocyanate radicals with the hydroxyl compound in the plant-based polyol. This is reported by Shuming Chen and co-workers, in article number 2000075.

Preparation of polyurethane foam fine polishing wheel for stainless steel surface

AbstractComparing with dry polishing, the wet‐polishing of the stainless steel surface can significantly reduce dust, noise and other pollution, and improve the polished quality. Thus, it is important to develop new polishing tools. In this work, the effects of the foaming agent and diluents on the mechanical properties of the polyurethane foam (PUF) system were investigated, and then the effect of the filler of graphite on the structure and mechanical properties of PUF was studied. Furthermore, the PUF fine polishing wheel with aluminum oxide was prepared. Results show that the bi‐component diluents combined cyclohexane and dimethylformamide significantly affects the porosity and hardness of the PUF matrix. The filler of graphite can decrease the mechanical properties of the polyurethane matrix and increase the porosity of PUF, consequently, improve the self‐sharpening of the PUF polishing wheel. The PUF fine polishing wheel with aluminum oxide shows fine polishing performance.

Influence of carbon nanotubes on the properties of biopolyol based polyurethane foams

Biopolyols were obtained from liquefaction of sugarcane bagasse and rice husk. Acid and hydroxyl numbers were determined for estimating the polyol value of the liquid products. These prepared biopolyols were mixed with the commercial polyol for the preparation of polyurethane foam (PU). To study the effects of biopolyol on properties of PU foam, various ratios of biopolyol to commercial polyol were used. It was observed that the density and foaming time of the PU foam increases with the increase in biopolyol content. The calculated Isocyanate index showed that sugarcane bagasse polyol can be used to make flexible foam and that rice husk can be used to make rigid foam. Foaming times and full rise times increased with increase in the biopolyol content. The Fourier-transform infrared spectroscopy (FTIR) spectra of prepared foams showed the characteristic peaks related to PU foam. The morphological studies were carried out using scanning electron microscopy (SEM). Thermal conductivity tests proved that the synthesized PU foams can be used as insulating materials. Further, PU foams were also prepared with the incorporation of carbon nanotubes (CNTs) in the polyol. The densities, thermal conductivities and SEM analysis of PU foams with and without carbon nanotubes were compared.

Insulating rigid polyurethane foams from laurel tree pruning based polyol

AbstractThe present work deals with the production of a natural polyol from laurel tree pruning waste, aiming the preparation of polyurethane foams. The obtained bio‐polyol was characterized and applied into foams studying the influence of the isocyanate used and the addition of the physical blowing agent. The incorporation of the polyol allowed 40% polyol substitution for those foams in which TDI was used, and up to 60% using MDI. Apparent density, cell morphology, mechanical, and thermal properties were evaluated. Mechanical and thermal properties of the foams improve to a greater amount of polyol in the matrix. Specifically, the best thermal and mechanical properties (274.99 and 7275.91 kPa for compressive strength and Young Modulus, respectively) were obtained with 50% polyol substitution (0.63 RNCO/OH). Foams showed small, well‐defined cell morphology. Laurel derived polyol can be used for the preparation of foams using MDI, since the mechanical, and thermal properties are promising for obtaining insulation materials in the construction industry.

Effects of Modified Used Cooking Oil on Structure and Properties of Closed-Cell Polyurethane foams

The aim of this work is to evaluate the influence of bio-polyol synthesized from used cooking oil on selected properties of rigid polyurethane foams. Application of bio-polyol allows utilization of used cooking oil in the preparation of polyurethane foams according to circular economy. In our work, bio-polyurethane foams were obtained by replacing 20, 60 and 100% of petrochemical polyol with bio-polyol from waste oil. It was observed that the introduction of the bio-polyol caused an increase in the reactivity of the polyurethane system during the foaming process, which was also confirmed by dielectric polarization changes. A complete replacement of petrochemical polyol with the bio-polyol caused cell opening in the foams. A replacement of 20 wt% of petrochemical polyol with the bio-polyol allowed preparation of polyurethane foams with improved thermal insulating properties. The introduction of 20% of the bio-polyol resulted in an increase of the compressive strength in a parallel direction compared to the reference material. The dimensional stability of bio-foams was very high since none of the dimensions differed by more than 0.5% upon treatment with an elevated temperature (70 °C).

Polyurethane Foams and Bio-Polyols from Liquefied Cotton Stalk Agricultural Waste

Cotton is planted on a large scale in China, especially in the Xinjiang Region. A large amount of agricultural waste from cotton plants is produced annually, and currently poses a disposal problem. In this study the product after liquefaction of cotton stalk powder was mixed with diphenylmethane diisocyanate to prepare polyurethane foams. The effects of the liquefaction conditions on the properties of the polyols and polyurethane foams produced using cotton stalk were investigated. The optimal processing conditions for the liquefied product, considering the quality of the polyurethane foams, were studied as a function of the residue fraction. Bio-polyols with promising material properties were produced using liquefaction conditions of 150 °C, reaction time of 90 min, catalyst content of 3 wt.%, and 20 w/w% cotton stalk loading. We investigated the optimal processing conditions for producing bio-foam materials with mechanical properties comparable to those of petroleum-based foam materials. This study demonstrated the potential of cotton stalk agricultural waste for use as a feedstock for producing polyols via liquefaction. It was shown that polyethylene glycol 400 (PEG400) and glycerin can be used as alternative solvents for liquefaction of lignocellulosic biomass, such as cotton stalk, to produce bio-polyol and polyurethane foams.

Borohydride-modified polyurethane foam: a new form of a widely known reducing agent in synthesis of metal nanoparticles for sensing applications

Currently a lot of synthetic routs have been proposed for preparation of various metal nanoparticles for sensing applications. A majority of them are based on the borohydride approach. We have found that some polymers (e.g. polyurethane) can be a promising support for immobilization of borohydride. The present work describes a method for preparation of polyurethane foam modified with borohydride as a new form of the widely known reducing agent and its possibilities for synthesis of metal nanoparticles. This new reagent is quite stable when stored at low temperature and is convenient for use in the synthesis of nanoparticles since it ensures precise dosing of a reductant. Metal nanoparticles could be synthesized both in solution and on polymer surface by varying reagents concentrations during the modified polyurethane foam preparation. It was illustrated that nanoparticles prepared using the borohydride-modified polymer have a narrower size distribution that probably should be ascribed to the stabilizing effect of the polymeric matrix. Optical properties of polyurethane foam-based nanocomposites with metal nanoparticles open a possibility of their using for sensing substances that affect formation of nanoparticles or their distribution between the polymer and the solution.

Influence of modifying coatings on dielectric permittivity of ceramic materials with composite coatings

The results of research of features of modification of aluminosilicate ceramics by suspension of fluoroplastic, aluminophosphate binder (AFS), non-aqueous compositions of polyurethane components, are presented. Samples of aluminosilicate ceramics for research were obtained by technological methods, including batch preparation operations, sample pressing, pre-annealing and sintering at a temperature of 1200–1350 °C. Polydisperse powders of aluminosilicates obtained by grinding waste of porcelain production (porcelain ware, GOST 28390-89); low-melting clay raw materials were selected as initial components. Modification of surface of aluminosilicate materials was carried out by impregnation of aqueous compositions based on a suspension of fluoroplastic and aluminophosphate binder (AFS), non-aqueous compositions of polyurethane components used in the preparation of polyurethane foam and 5 % solution of polyethylene hydrosiloxane in toluene with the formation of composite coatings on the surface of ceramic materials. It is shown that the application of organic film coatings (based on polyurethane, aluminophosphate binder and a suspension of fluoroplastic-4D, polyethylene hydrosiloxane) leads to formation of a multilayer dielectric material in which there are interface surfaces separating areas with different dielectric properties. In the presence of an external electric field, conditions are created for migration polarization between the crystalline phase of the substrate and the amorphous phase of the coating, due to the redistribution of free charges in the volume of the composite. Moreover, the chemical interaction of AFS with ceramics leads to the smoothing of the surface relief of the aluminosilicate base and the overgrowth of deep pores. Composite “aluminosilicate – AFS-fluoroplastic coating” differs from other materials, primarily in that aluminophosphate binder coating chemically reacts with the ceramic base. The impurity ions introduced during coating application, its composite structure, as well as the heterogeneity of the interface determine the pronounced frequency dependence ε and tgδ, as well as large dielectric losses of the composite in comparison with the original aluminosilicate material.

Polyurethane foam modified with borohydride: preparation and possibilities of using for synthesis of gold nanoparticles and their nanocomposites

The present work describes preparation of polyurethane foam modified with borohydride. Adsorption of borohydride from alkaline solutions in presence of a cationic surfactant is discussed. The polyurethane foam modified with borohydride possesses reductive ability with respect to Au(III). Possibilities of the new material for synthesis of gold nanoparticles are described. This solid reducting agent is convenient for use in the synthesis of nanoparticles, since it ensures precise dosing of a reductant while desorbed from polymer. Gold nanoparticles can be synthesized both in solution and on the polymer surface by varying reagents concentrations during the preparation of modified polyurethane foam.

Reactivity of Isocyanate-Functionalized Lignins: A Key Factor for the Preparation of Lignin-Based Polyurethanes.

Using isocyanate-functionalized Kraft lignin as a reactive macromonomer for the preparation of polyurethane foams by a prepolymer technique is a well-known strategy to incorporate the biomacromolecule into a higher value polymer material. However, as of today the mechanical properties of the resulting materials are still insufficient for a number of possible applications. One reason for this limitation is that the reaction pathway and the morphological arrangement of such foams is of uttermost complexity and depends on a large number of influencing material-intrinsic factors. One important parameter is the reactivity of the functionalized lignin, which has a great impact on the interphase reaction kinetics and thus, on the geometry and mechanical properties of the resulting polyurethane foams. The reactivity is implied, amongst others, by the electron affinity of the isocyanate moiety. Herein, we investigate the reactivity of Kraft lignin modified with different commercially used isocyanates in the reaction with conventional polyols. Therefore, differently reactive prepolymers were synthesized, characterized and polyurethane foams were prepared thereof by using these compounds and the foam formation kinetics, morphological as well as mechanical properties were investigated. Finally, the results were supported by quantum mechanical calculations of the electron affinities of representative model compounds for the lignin-based prepolymers. This work gives rise to a better understanding of the effect of the reactivity and isocyanate structure linked to Kraft lignin on the polyurethane formation and enables rational choice of the isocyanate for pre-functionalization of lignin to prepare materials with better mechanical performance.

Preparation of biomass carbon/polyurethane foams for selective oil/water absorption

Although the preparation of polyurethane foam (PUF) composites for oil absorption have attracted increasing research attention, the preparation process of PUF composites are still a thorny problem due to the nonrenewable raw materials. Proposed herein is an environmentally friendly method to prepare the biomass carbon/PUF composites. In this proposal, the biomass carbon with superhydrophobicity was prepared by using the cellulose of bamboo as precursors. Then, the biomass carbon/PUF composites were synthesized using one step foaming technology using the biomass carbon as modifier. This facile synthesis technique has the advantages of scalable fabrication of porous PUF composite for versatile water–oil separation. The PUF composites are mainly composed of hollow microspheres with holes on their surfaces. The PUF composite show very high efficiency in oil separation and quickly absorb edible oil from the glass surface and heavy oils under water. The resulting PUF composites exhibited high oil absorption capacities in the range from 8.59 to 37.10 times of their own weight for various organic solvents. Importantly, recovery oils absorption for PUF composites was obtained for 5 consecutive cycles without a significant decrease in the oil absorption properties. This study suggests potential environmental advantage in using biomass materials in improving the oil absorption properties of oil-absorbing resin for recovering oils from oily wastewater.

Properties of a novel inherently flame‐retardant rigid polyurethane foam composite bearing imide and oxazolidinone

ABSTRACTA novel inherently flame‐retardant rigid polyurethane (PU) foam with imide and oxazolidinone was prepared by using 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (PTDA) and 9,10‐dihydro‐9‐oxa‐(10‐glycidoxypropylene)‐10‐phosphap‐henanthrene‐10‐oxide (e‐DOPO) as reactive flame retardants. The physical and mechanical properties of the prepared PU foams were investigated. The compressive strength was improved to 0.22 MPa, the thermal conductivity decreased, and the density hardly changed. Thermogravimetric (TG) analysis and TG analysis coupled with Fourier transform infrared spectroscopy indicated that the PTDA and e‐DOPO showed a small improvement in thermal properties. The fire behaviors were evaluated based on the limited oxygen index (LOI), cone‐calorimetry experiment, and smoke‐density test. The LOI of the PU foam with PTDA and e‐DOPO reached 22.4%. The peak of heat release rate and total heat release decreased to 227.50 kW m−2 and 11.27 MJ m−2 from 281.28 kW m−2 and 14.05 MJ m−2, respectively. The morphologies of the PU foam and residues after the cone‐calorimetry test were characterized by scanning electron microscopy. X‐ray photoelectron spectroscopy analysis indicated that PTDA and e‐DOPO lead to an increase in graphite in the residue and the formation of a better barrier to prevent burning by the condensed‐phase mechanism. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47943.

Polyurethane foams from chlorinated and non‐chlorinated metathesis modified canola oil polyols

ABSTRACTThe product of 1‐butene metathesis of canola triacylglycerol (CMTAG), with shortened structures, terminal double bonds (50% of the total), and oligomers (40% dimer and trimer, and 10% higher oligomers) was used to synthesize novel polyols and polyurethane foams. A non‐chlorinated (Pol‐1) and a chlorinated polyol (Pol‐2) having OH value (170 and 190 mg KOH/g, respectively) were synthesized from CMTAG by epoxidation followed by hydroxylation, and epoxidation followed by hydrogenation, respectively. Both polyols remained liquid below ambient temperature and demonstrated physical characteristics such as viscosity which allowed for the facile preparation of polyurethane foams. The foam obtained with Pol‐1 was relatively soft (∼0.32 MPa at 10% strain) and very flexible (recovery ∼90%); whereas, the foam obtained with Pol‐2 was semi‐rigid (∼1.1 MPa at 10% strain and recovery of 64%). The higher strength and rigidity of Pol‐2 foam compared to Pol‐1 foam is chiefly attributable to the effect of the bulky chlorines on the crosslink density. Importantly, this work highlights that one can improve and control jointly the mechanical properties and deformation recovery ability of bio‐based foams by combining primary functional groups, oligomers, and high molar volume molecules in the polyols. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46616.