Industrial Polyurethane Research Articles

Effect of bio-polyol molecular weight on the structure and properties of polyurethane-polyisocyanurate (PUR-PIR) foams

The increasing interest in polyurethane materials has raised the question of the environmental impact of these materials. For this reason, the scientists aim to find an extremely difficult balance between new material technologies and sustainable development. This work attempts to validate the possibility of replacing petrochemical polyols with previously synthesized bio-polyols and their impact on the structure and properties of rigid polyurethane-polyisocyanurate (PUR-PIR). To date, biobased polyols were frequently used in the manufacturing of PU, but application of bio-polyols synthesized via solvothermal liquefaction using different chains of polyethylene glycol has not been comprehensively discussed. In this work, ten sets of rigid polyurethane foams were synthesized. The influence of bio-polyols addition on foam properties was investigated by mechanical testing, thermogravimetric analysis (TGA), and cone calorimetry. The structure was determined by scanning electron microscopy (SEM) and a gas pycnometer. The tests revealed a significant extension of foam growth time, which can be explained by possible steric hindrances and the presence of less reactive secondary hydroxyl groups. Moreover, an increase average size of pores and aspect ratio was noticed. This can be interpreted by the modification of the cell growth process by the introduction of a less reactive bio-polyol with different viscosity. The analysis of foams mechanical properties showed that the normalized compressive strength increased up to 40% due to incorporation of more cross-linked structures. The thermogravimetric analysis demonstrated that the addition of bio-based polyols increased temperature of 2% (T2%) and 5% (T5%) mass degradation. On the other hand, evaluation of flammability of manufactured foams showed increase of total heat release (HRR) and smoke release (TSR) what may be caused by reduction of char layer stability. These findings add substantially to our understanding of the incorporation of bio-polyols into industrial polyurethane systems and suggest the necessity of conducting further research on these materials.

Enhancing the formation of eco-friendly CO2 adsorbent through utilizing the RSM technique and implementation of PAN/PU electrospinning and radiation-grafted approaches

In this research, the original, efficient, novel NF-PAN/PU-GMA-EA nanocomposite was fabricated and used as an adsorbent to remove carbon dioxide from methane. For this purpose, two cheap polymers, including industrial polyacrylonitrile (PAN) and industrial polyurethane (PU) were used to prepare NF-PAN nanofibers under the electrospinning method. Then, the synthesis procedure was performed by grafting glycidyl methacrylate (GMA) onto NF-PAN nanofibers and ethanolamine (EA), diethylamine (DEA), and triethylamine (TEA) as the modified agents. In addition, the response surface methodology based on the central composite design experiments was developed to predict adsorption capacity. The aforementioned approach determined the impacts of GMA monomer (10–30%); gamma radiation at doses (10–50 kGy); and amine concentrations (40–100%). The results showed that ethanolamine was the best amine to modify the surface of NF-PAN/PU nanofibers. The highest adsorption was obtained equal to 2.95 mmol CO2/g adsorbents at a radiation dose of 28.03 kGy, 25.77% GMA and 66.45% EA. The results described that the variation from micro to nanoscale increases the adsorption capacity. Also, a significant increase in the adsorption capacity in the radiation-grafted adsorbent was observed equally to be 73.15% higher than the non-irradiated adsorbent. The adsorption capacity was decreased by about 9% after four adsorption and desorption cycles (regeneration at 80 °C and 15 min), indicating the proper performance of the novel eco-friendly synthesized adsorbents.

Bio-based non-isocyanate polyurethane(urea) waterborne dispersions for water resistant textile coatings

Currently, the resins used in industrial polyurethane coatings are made from petro-based polyols and isocyanate building blocks. In traditional coating formulations, polyurethane resins can be solubilized in solvents for their application on substrates, thus releasing possibly volatile organic compounds (VOCs) upon drying. To circumvent these issues, polyurethanes synthesized from non-isocyanate and bio-based building blocks are receiving more interest. However, only few references describe the development of waterborne non-isocyanate dispersions with a direct application.In this study, non-isocyanate polyurethane(urea)s of very high bio-based contents (>80 wt%) and having controlled amount of reactive hydroxyl ends were synthesized via transcarbamoylation. The obtained resins were used as cationic waterborne dispersions in a sustainable coating system. The influence of the functionality and hydrophobicity of the neutralization agent used to protonate the non-isocyanate polyurethane(urea) backbones, as well as the dicarbamate monomer structures were assessed. It was found that the combination of monofunctional and hydrophilic dl-lactic acid neutralization agent (for electrostatic repulsion) led to stable dispersions with better properties (particle size and zeta potential) than the commercial waterborne polyurethane dispersion reference. Those dispersions were cross-linked through their reactive hydroxyl end groups with tetramethylol acetylene diurea into freestanding films and adhesive layers for textile coatings. The freestanding films exhibited high cross-linking efficiency (gel content >90 %), low water uptake (down to 2 %) and high water and methyl ethyl ketone (MEK) resistance (≥200 rubs) as well as good mechanical properties (Young's modulus between 1.5 MPa and 3.1 MPa and elongation at break up to 300 %) to resist the deformation of the fabrics when applied on them. Finally, when used as an adhesive layer on textiles, good resistance to hydrolysis and heat aging were ensured by the coating system, thus potentially replacing isocyanate based adhesive layers.

Microstructure characterization and stochastic modeling of open‐cell foam based on μCT‐image analysis

AbstractFoam is a cellular material whose mechanical properties are strongly determined by its complex microstructure. To study the microstructure, at first a foam characterization based on CT image processing is required. Here we present an image segmentation procedure and determine the foam's characteristics using the lattice cell‐based concept of intrinsic volumes. Information like porosity, pore size distribution, and ligament shape are derived. These data are then employed as input for the generation of stochastic foam volume elements with the corresponding morphology. The introduced microstructural characterization and foam generation procedures are validated by an inverse analysis, that is, by a CT image analysis of the stochastic foam volume element. Additionally, an example investigation of industrial polyurethane foam proves the concepts.

Highly selective adsorbent by gamma radiation-induced grafting of glycidyl methacrylate on polyacrylonitrile/polyurethane nanofiber: Evaluation of CO2 capture

In this paper, a new adsorbent was investigated for carbon dioxide adsorption from a combination of two polymers, industrial polyacrylic nitrile (PAN) and industrial polyurethane (PU). PAN/PU nanofibers were prepared by electrospinning and successfully bonded to Glycidyl methacrylate (GMA). After, amination was performed with ethanolamine (EA) to make a functional group. Dynamic CO2 adsorption experiments were performed in a fixed-bed column with a mixture of two CO2/N2 gases at a concentration of 5% CO2 at atmospheric pressure and ambient temperature. The results showed the highest adsorption capacity of 2.98 mmol/g for amination with ethanolamine (168.63% degree of amination, 30 kGy radiation dose and 167.92% degree of grafting). Satisfactory results were obtained by predicting and fitting the breakthrough curves of CO2 adsorption of experimental data with Bohart-Adams, Thomas, Yoon Nelson and Yan models. Also, four adsorption–desorption cycles at low temperatures have confirmed the applicability of this adsorbent.

Osteoarticular vascular corrosion casting using industrial polyurethane for the 3D representation of the vascular tree on human knee

Vascular casting is a widely used method for the representation of body vascularization. Many different injection materials have been described throughout the time to enhance the arterial vascular supply within a specifically defined anatomical location. The use of industrial polyurethane has been recently evaluated and applied to animal and human anatomy. The aim of this study was to confirm the safe and reliable use of industrial polyurethane in knee specimen in order to obtain a three-dimensional vascular tree of the distal femur. 10 fresh-frozen knees (mid-thigh to mid tibia) were used to assess the vascularity around the femoral condyles. Industrial polyurethane foam (Soudal™ foam) was diluted with acetone in order to obtain a runny fluid, easy to inject. After injection, the knees were bathed in a 10% NaOH solution, heated at 30°. The corrosion process took from 20 to 24h and allowed all the soft tissue surrounding the knee to be subsided, leaving only the bone with polyurethane vascular architecture. After soft tissue corrosion, the vascular network around the knees was easily identified underlying the relation of the vessels to the bone. Even small arterioles (diameter<1mm) were distinguished with a good resistance to breakage. Corrosion casting remains an easy and reliable alternative to dissection for the understanding of tissue perfusion as the handling of the polyurethane is easy and has low costs. The described author’s method can be used osteo-articular specimen as well as in other organs. The protocol of injection and corrosion needs however to be adapted to the different specimen and anatomical location. Polyurethane associated to acetone can safely be used as injection material in order to demonstrate the vascularity of a specimen and remains easy to use.

Comparitive study on the flexural behaviour of glulam built-up beams based on ambient and standard fire tests

The experimental study presented in this paper proposes a type of glulam beam with a hollow cross-section that can further optimise solid glulam beams. The study investigated the structural behaviour of glulam built-up box-section beams under four-point flexural bending at both ambient and elevated temperatures. A total of eleven 3100-mm long simply supported beam assemblies were experimentally examined: seven beams were tested at ambient temperature; and four beams were subjected to CAN/ULC-S101 standard fire. Five of the seven beam assemblies tested at ambient temperature were fabricated using self-tapping screws, while the other two assemblies were built using industrial polyurethane adhesive. Each built-up beam assembly was made of four glulam panels, all of 44 mm thickness except the bottom flange panel which had 86 mm thickness. Through ambient testing, it was concluded that when the spacing of the screws connecting the top and bottom flange panels of the built-up section to its web panels was decreased from 800 to 200 mm, the flexural resistance of the beam assembly was increased by about 45%. Whereas further reduction of the spacing from 200 to 100 mm for the screws connecting the bottom flange panel to the web panels over a distance equals to one-third of the span length of the beam from both supports, where shear stresses are maximum, increased the flexural resistance of the beam additionally by 10%. However, the experimental results of the glued beam assemblies show significantly high flexural strength that was almost equal to the calculated strength of an equivalent hollow-section glulam beam. In a subsequent phase, only the strongest beam assemblies (two screwed and two glued) were tested under the effect of standard fire while subjected to monotonic loading that caused a bending moment that is equivalent to the beam full resistance moment calculated for ambient condition. Fire tests' results show that both screwed and glued glulam built-up box-section beams can sustain the applied design load under standard fire exposure for more than 30 min without any fire protection.

Functional Modification of Borassus flabellifer Sheath Fibres Using Isocyanate

An active hydroxyl content of Borassus flabellifer leaf sheath fibers are measured by the isocyanate back titration method, catalytically reacted with 1, 6 – hexamethylene diisocyanate biuret trimer and 2, 4-toluene diisocyanate-trimethylolpropane adduct, which is being used as cross-linkers in most of the automotive and industrial polyurethane coatings. The functional modifications of the fibers are confirmed by NCO titration method and Fourier-transform Infrared Spectroscopy (FTIR). The resultant biochemical fiber is analyzed for the thermal property, and surface topography measurement is done by Scanning Electron Microscope (SEM) and Thermogravimetric analysis (TGA), respectively. Moreover, 1, 6 – hexamethylene diisocyanate biuret trimer (HDT) treated BFSF having higher thermal stability due to higher urethane to urea content and intermolecular hydrogen bonding.

Biobased Polyurethane Foams Based on New Polyol Architectures from Microalgae Oil

Environmental concerns continuously drive research to find alternatives to fossil-based constituents in a greener way. Industrial polyurethane (PU) foams are usually obtained from the polyaddition ...

Functional Modification of Borassus flabellifer Sheath Fibres Using Isocyanate

An active hydroxyl content of Borassus flabellifer leaf sheath fibers are measured by the isocyanate back titration method, catalytically reacted with 1, 6 – hexamethylene diisocyanate biuret trimer and 2, 4-toluene diisocyanate-trimethylolpropane adduct which is being used as cross-linkers in most of the automotive and industrial polyurethane coatings. The functional modifications of the fibers are confirmed by NCO titration method and Fourier-transform Infrared Spectroscopy (FTIR). The resultant biochemical fiber is analyzed for the thermal property, and surface topography measurement is done by Scanning Electron Microscope (SEM) and Thermogravimetric analysis (TGA), respectively. Moreover, 1, 6 – hexamethylene diisocyanate biuret trimer (HDT) treated BFSF having higher thermal stability due to higher urethane to urea content and intermolecular hydrogen bonding.

Recovery of Flexible Polyurethane Foam Waste for Efficient Reuse in Industrial Formulations

Ester polyurethane (PU) foam waste was reacted at atmospheric pressure in an autoclave and using microwaves with diethylene glycol (DEG) at different PU/DEG ratios in the presence of diethanolamine as a catalyst to find the glycolysis conditions that allow for the improved recovery of the PU foam waste and enable the recycling of the whole glycolysis product in foam formulations suitable for industrial application. The recycled polyol was characterized by dynamic viscosity, hydroxyl number, water content, and density, while thermal stability was assessed using thermogravimetric analysis. In the PU foam formulation, 1% and 5% of the glycolyzed material was reused. The relationship between the reuse level of the recycled polyol and the physical properties of the foam was thoroughly investigated. It was observed that both hardness and air flow decreased with increasing recycled polyol content, particularly for the polyester type foam, while tensile strength and compression strength increased. Depending on the amount of recycled polyol and catalyst used, polyether-based foams could be obtained with a low air permeability, needed in special applications as sealed foams, or with higher air permeability desirable for comfort PU foams. The results open the way for further optimization studies of industrial polyurethane foam formulations using a glycolysis process without any separation stage.

Feasibility of polyamines and cyclic carbonate terminated prepolymers in polyurethane/polyhydroxyurethane synthesis

Polyurethanes are a well-established part of adhesive markets. However due to the toxicity of di-isocyanates used in the synthesis, finding an alternative route to synthetize polyurethanes is increasingly important. One strategy is to use cyclic carbonate terminated prepolymers with polyamines to yield polyhydroxyurethanes. This research highlights the possibility to use commercially available polyurethane prepolymers with different isocyanate chemistries for cyclic carbonate terminated prepolymer synthesis with the help of glycerol carbonate and a catalyst. These synthetized prepolymers were used in a screening study with different commercially available low toxic amines. It was observed that when secondary amines were used, the reaction advanced at room temperature with no further heating required. The development of lap shear strength over time on stainless steel, gel content, tensile strength and elongation were measured from room temperature cured polymers. The synthetized polyurethane/polyhydroxyurethane (PU/PHU) hybrid materials had high initial lap shear strength close to current industrial polyurethane adhesives. The strength development over time was negligible. Full conversions were seen within one month from the reaction. Tensile strength levels were slightly lower than typical industrial polyurethane adhesives. Even though the lap shear strength results and gel contents at room temperature were on a good level, curing at elevated temperature had a positive impact on them. The best performing combination was cyclic carbonate functionalised hexamethylene di-isocyanate prepolymer with multifunctional polyethyleneimine amine. In short, di-isocyanate free PU/PHU hybrid materials were successfully synthetized from commercial raw materials and their performance was comparable with current industrial polyurethane adhesives.

Evaluation of an Experimentally Designed Molecular Imprinted Polyurethane Foam Performance for Extraction of Alprazolam.

Industrial polyurethane rigid foam (PUF) was selected as a substrate for selective solid phase extraction of Alprazolam. Effective parameters for raising selectivity of the PUF were evaluated. Synthetic molecularly imprinted polyurethane foam (MIPUF) was tracked as selective adsorbent and its characteristic was pondered by analytical methods. Optimization was done by central composite design (CCD) to have high efficiency of the polymer adsorption. Two different extraction methods were compared in the selective adsorption processes using MIPUF and NIPUF, batch system and continuous (cartridge) system. Results of the adsorption of alprazolam on the MIPUF had 39% more recovery than NIPUF (reference polymer). Then, the proposed method suggests a selective extraction of mentioned analyte from urine and tablets as complex matrixes.

Investigation of Industrial Polyurethane Foams Modified with Antimicrobial Copper Nanoparticles.

Antimicrobial copper nanoparticles (CuNPs) were electrosynthetized and applied to the controlled impregnation of industrial polyurethane foams used as padding in the textile production or as filters for air conditioning systems. CuNP-modified materials were investigated and characterized morphologically and spectroscopically, by means of Transmission Electron Microscopy (TEM), and X-ray Photoelectron Spectroscopy (XPS). The release of copper ions in solution was studied by Electro-Thermal Atomic Absorption Spectroscopy (ETAAS). Finally, the antimicrobial activity of freshly prepared, as well as aged samples—stored for two months—was demonstrated towards different target microorganisms.

Consolidation of artificially degraded polyurethane ester foam with aminoalkylalkoxysilanes

Museum artifacts made of polyurethane ester foam are frequently affected by conservation issues mainly related to the loss of their mechanical properties. Modification of mechanical properties often leads to structure crumbling and in some cases to the loss of the entire artifact. A previous study evaluated the possibility to reinforce new flexible industrial polyurethane ester foam with aminoalkylalkoxysilane (AAAS) based treatments. In this paper AAAS are applied on artificially degraded polyurethane ester foam to investigate the possibility to reinforce already degraded objects. Two AAAS, the 3-Aminopropylmethyldiethoxysilane and the N-(2-Aminoethyl)-3-aminopropylmethyldimethoxysilane have been tested. AAAS solutions at different concentrations have been used to apply the monomers on the foam samples by immersion. Mechanical properties have been studied by Compression Force Deflection Test, which shows that after AAAS treatment the resistance of the foam to compression improves and the cell collapse is prevented. The color of the samples, before and after consolidation, has been monitored to assess the impact of the treatment on the visual aspect of the foam. AAAS distribution in the thickness of the samples has been investigated by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Silicon Magic angle spinning nuclear magnetic resonance (29Si MAS NMR) has been used to confirm AAAS polymerization and to evaluate its average polymer chain length. 29Si MAS NMR has also been used to investigate the behavior of AAAS polymers in time by analyzing four years old reinforced samples. The results highlighted the stability of the poly-AAAS chains after four years of natural aging.

Generalization of the memory integer model for the analysis of the quasi-static behaviour of polyurethane foams

Polyurethane foam is a cellular material characterized by an interesting mechanical spectrum of properties: low density, capacity to absorb the deformation energy and low stiffness. This spectrum of properties makes polyurethane foam commonly used in many thermal, acoustic and comfort applications. Several models, such as memory, hyper-elastic and pseudo-elastic models have been developed in the literature to describe the mechanical response of polyurethane foam under quasi-static and dynamic test conditions. The main disadvantage of these models is the dependence of their parameters against the test conditions (strain rate, maximum compression level, etc). This affects the general character of their representativeness to the quasi-static and dynamic behaviours of polyurethane foam. The main goal of this article is to implement reliable mechanical model which is able to provide the quasi-static response of the polyurethane foam under different strain rates and large compressive deformation. The dimensional parameters of our model can be expressed by the product of two independent parts; the first contain only the test conditions and the second define the dimensionless and invariant parameters that characterize the foam material. The developed model has been proposed after several experimental studies allowing the apprehension of the quasi-static behaviour (through unidirectional compression tests). The polyurethane foam, under large deformations, exhibits a nonlinear elastic behaviour and viscoelastic behaviour. To assess the ability of our model to be a general representation, three industrial polyurethane foams have been considered.

대용량 중력장 SPLITT Fractionation: 분획효율에 미치는 채널 두께와 유속의 영향

SPLITT fractionation (SF) allows continuous (and thus a preparative scale) separation of micron- sized particles into two size fractions ('fraction-a' and 'fraction-b'). SF is usually carried out in a thin rectangular channel with two inlets and two outlets, which is equipped with flow stream splitters at the inlet and the outlet of the channel, respectively. A new large scale splitter-less gravitational SF (GSF) system had been assembled, which was designed to eliminate the flow stream splitters and thus is operated by the full feed depletion (FFD) mode (FFD-GSF). In the FFD mode, there is only one inlet through which the sample is fed. There is no carrier liquid fed into the channel, and thus prevents the sample dilution. The effects of the sample-feeding flow rate, the channel thickness on the fractionation efficiency (FE, number % of particles that have the size predicted by theory) of FFD-GSF was investigated using industrial polyurethane (PU) latex beads. The carrier liquid was water containing 0.1% FL-70 (particle dispersing agent) and 0.02% sodium azide (used as bactericide). The sample loading rate was varied from about 4 to 7 L/hr with the sample concentration fixed at 0.01%. The GSF channel thickness was varied from 900 to 1300 µm. Particles exiting the GSF channel were collected and monitored by optical microscopy (OM). Sample recovery was monitored by collecting the fractionated particles on a 0.45 µm membrane filter. It was found that FE of fraction-a was increased as the channel thickness increases, and FE of fraction-b was increased as the flow rate was increased. In all cases, the sample recovery has higher than 95%. It seems the new splitter-less FFD GSF system could become a useful tool for large scale separations of various types of micron-sized particles. 요약 : SPLITT 분획법(Split-flow thin cell fractionation, SF)은 입자성 물질이나 거대분자를 크기에

Produção e caracterização de espumas cerâmicas obtidas a partir de lodo de anodização de alumínio

Ceramic foams were produced from a sludge generated in the aluminum anodizing process by using an industrial polyurethane foam (replication method) with open cell sizes of 10 ± 5 ppi (porosity = 97%) which were impregnated with suspensions containing 50-61 wt.% alumina, 1 wt.% citric acid, 6 wt.% bentonite and fired at 1600 oC for 2 h. The aluminum anodizing sludge shows a high alumina content (87.5 wt.%) and a low particle size (~1.7 mm) after calcination and milling. The obtained filters show porosity of approximately 70%, filtration capability (mass water flow) of 1.7 kg/s and mechanical strength under compression of 2.40 MPa.

Products of the reaction of petroleum residues with diisocyanates

Polyurethane derivatives of petroleum asphaltites that can be used as adhesive materials were obtained by reacting the products of condensation of resin-asphaltene components with formaldehyde-formalites and diisocyanates. In contrast to industrial polyurethane adhesives, they provide a stronger bond for metal surfaces (St3), are more resistant to variable temperatures from +60 to − 60°C, and to g radiation with a dose of up to 3.7 × 106 Gy.

Recycling of Industrial Polyurethane Residue and the Characterisation of its Properties

The globalisation process has forced manufacturers to produce higher quality products with less environmental hazard. The newly developed industrial products produce residues, which pose challenges for recycling. In this work, we present the mechanical recycling of the industrial polyurethane residues incorporated in different proportions with polyurethane resins. Effect of temperature in the process and proportion of residues were considered for the process development. The products obtained in different proportions (weight of new resin: weight of residue) 1:4, 1:8, 1:12.5, 1:20 have been characterised by mechanical properties, resistance to abrasion and hardness which are required for the possible applications of the developed product.