Polyurethane Foam Composites Research Articles

Effect of small amount of functionalized multi-walled carbon nanotubes on the properties of rigid polyisocyanurate and polyurethane foam composites

Using small amounts of multi-walled carbon nanotubes (MWCNTs) functionalized with carboxyl groups, methyldiethanolamine and triethanolamine (from 0.005 to 0.1%), a series of rigid composite polyurethane-polyisocyanurate (PIR) and polyurethane (PUR) foams was obtained. The influence of these additives on the morphology of the cellular structure of the synthesized foams, as well as the change in their physical-mechanical and thermophysical characteristics, was analyzed. The effect of additions of functionalized MWCNTs on the change in compressive strength, Young’s modulus, thermal conductivity index, and mass loss during combustion of the synthesized foams has been studied. Based on the results obtained, the introduction of small amounts (up to 0.05%) of functionalized nanotubes in the foam composition improves the characteristics described above. The greatest effect was achieved using 0.05% carboxylated MWCNTs functionalized with triethanolamine.

Facile fabrication of stacked rGO/MoS2 reinforced polyurethane composite foam for effective electromagnetic interference shielding

Facile fabrication of stacked rGO/MoS2 reinforced polyurethane composite foam for effective electromagnetic interference shielding

Effect of Different Methods to Synthesize Polyol-Grafted-Cellulose Nanocrystals as Inter-Active Filler in Bio-Based Polyurethane Foams.

Currently, the scientific community has spent a lot of effort in developing "green" and environmentally friendly processes and products, due the contemporary problems connected to pollution and climate change. Cellulose nanocrystals (CNCs) are at the forefront of current research due to their multifunctional characteristics of biocompatibility, high mechanical properties, specific surface area, tunable surface chemistry and renewability. However, despite these many advantages, their inherent hydrophilicity poses a substantial challenge for the application of CNCs as a reinforcing filler in polymers, as it complicates their dispersion in hydrophobic polymeric matrices, such as polyurethane foams, often resulting in aggregate structures that compromise their properties. The manipulation and fine-tuning of the interfacial properties of CNCs is a crucial step to exploit their full potential in the development of new materials. In this respect, starting from an aqueous dispersion of CNCs, two different strategies were used to properly functionalize fillers: (i) freeze drying, solubilization in DMA/LiCl media and subsequent grafting with bio-based polyols; (ii) solvent exchange and subsequent grafting with bio-based polyols. The influence of the two functionalization methods on the chemical and thermal properties of CNCs was examined. In both cases, the role of the two bio-based polyols on filler functionalization was elucidated. Afterwards, the functionalized CNCs were used at 5 wt% to produce bio-based composite polyurethane foams and their effect on the morphological, thermal and mechanical properties was examined. It was found that CNCs modified through freeze drying, solubilization and bio-polyols grafting exhibited remarkably higher thermal stability (i.e., degradation stages > 100 °C) with respect to the unmodified freeze dried-CNCs. In addition, the use of the two grafting bio-polyols influenced the functionalization process, corresponding to different amount of grafted-silane-polyol and leading to different chemico-physical characteristics of the obtained CNCs. This was translated to higher thermal stability as well as improved functional and mechanical performances of the produced bio-based composite PUR foams with respect of the unmodified CNCs-composite ones (the best case attained compressive strength values three times more). Solvent exchange route slightly improved the thermal stability of the obtained CNCs; however; the so-obtained CNCs could not be properly dispersed within the polyurethane matrix, due to filler aggregation.

Multi-functional flame retardant coatings comprising chitosan/ gelatin and sodium phytate for rigid polyurethane foams

In this work, a renewable multi-functional composite was fabricated from the combination of chitosan, gelatin and sodium phytate by a simple and eco-friendly process. The obtained products were analyzed by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and X-ray photoelectron spectrometry. The above composites were then added onto the surface of rigid polyurethane foams by a rolling procedure. The flame performance test conducted by cone calorimeter demonstrated that the surface coating could effectively reduce the value of peak heat release rate and total heat release to 115.0 kW/m2 and 3.5 MJ/m2 from 247.2 kW/m2 and 6.8 MJ/m2 of the rigid polyurethane foams, respectively. Except for foams, the coating composite also exhibited high flame-retardant efficiency in wood, plastic and fiber. Through mechanism analysis (morphology observation by scanning electron microscopy, structural analysis by X-ray photoelectron spectrometry, Fourier transform infrared spectra and pyrolysis-gas chromatography/mass spectrometry), it was suggested that the coating composite mainly took effect in condensed phase by the formation of physical barriers. Moreover, the newly prepared polyurethane foam composites also exhibited superior organic dye adsorption properties. This work provides an efficient, simple and eco-friendly route for large-scale production of multi-functional renewable materials that can be used in the fields of fire safety and environmental conservation.

Quantitative Analysis of Mechanical Strength of Three-Phase Rigid Polyurethane Foam Composites Immersed with Water

The mechanical properties of rigid polyurethane foam (PUF) will be significantly affected because of the existence of water when applied in dam repair and road maintenance. The related studies generally consider the effects of water and matrix on the mechanical properties of rigid PUF. However, PUF is a three-phase composite consisting of water, air, and matrix in practical engineering. Its mechanical properties are subject to the combined effects of these three composites at the same time. In this case, an improved three-phase viscoelastic model was proposed to quantify the effects of water, air, and matrix on the compressive mechanical behavior of rigid polyurethane foam immersed in water (WRPF). Based on the improved viscoelastic model and piecewise method, a compressive strength prediction model of WRPF was developed to describe the change of WRPF’s compressive strength during the full-service life. Then uniaxial compression tests and electron microscope tests were conducted to verify the rationality of the model. Results show that water and air have reinforcing effects on the compressive property of WRPF in the short-term, unsaturated absorption stage. In contrast, water has weakening effects on its compressive property in the long-term, saturated stage. Finally, at different stages of water absorption, a semitheoretical and empirical formula was developed from the prediction model and the experimental data from compressive tests.

Inorganic/organic phosphorus‐based flame retardants synergistic flame retardant rigid polyurethane foam

AbstractThe flame‐retardant rigid polyurethane foam (RPUF) composites are fabricated by ammonium polyphosphate (APP) with pentaerythritol phosphate (PEPA), phenoxycycloposphazene (PCP), and aluminum diethylphosphinate (ADP), respectively, which are labeled as RPUF‐1, RPUF‐2, and RPUF‐3. The influence of flame retardants on the apparent density and compressive strength of RPUF is studied. The results reveal that flame retardants not only improve the apparent density, but also improve the compressive strength of RPUF composites. The limiting oxygen index (LOI) results reveal that these inorganic/organic phosphorus‐based flame retardants improve the LOI significantly, especially for RPUF‐2 and RPUF‐3 systems. The cone calorimeter test results suggest that the peak of heat release of RPUF‐1, RPUF‐2, and RPUF‐3 systems decrease by 38%, 41%, and 52% likened to that of pure RPUF. And APP and ADP system performs best in declining the heat release. And APP and PEPA systems perform best in decreasing the smoke release. The flame retardancy mechanism of RPUF composites is analyzed in details.

Combing High-Modulus Fibers with a Novel Foaming Structure Applied to Protective Sandwich-Structured Composites: Manufacturing Techniques and Property Evaluations.

This study proposes the composites with a sandwich structure that is primarily made by the multi-step foaming process. The staple material is polyurethane (PU) foam that is combined with carbon fibers, followed by a Kevlar woven fabric. The composites are evaluated in terms of puncture resistance, buffer absorption, and electromagnetic wave shielding effectiveness (EMSE). The manufacturing process provides the composites with a stabilized structure efficiently. Serving the interlayer, a Kevlar woven fabric are sealed between a top and a bottom layer consisting of both PU foam and an aluminum film in order, thereby forming five-layered composites. Namely, the upper and lower surfaces of the five-layered sandwiches are aluminum films which is laminated on a purpose for the EMSE reinforcement. The test results indicate that the PU foam composites are well bonded and thus acquire multiple functions from the constituent materials, including buffer absorption, puncture resistance, and EMSE. There is much prospect that the PU foam composites can be used as a protective material in diverse fields owing to a flexible range of functions.

The thermal and combustion properties of soybean oil phosphate-based polyurethane foam composites containing polyol of etidronic acid

In this work, a phosphorus-containing soybean oil-based polyol (PSOP) was successfully synthesized from epoxidized soybean oil by a ring-opening reaction with dibutyl phosphate. A phosphorous polyol (HEDP-PO) was synthesized by polymerization between 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) and propylene oxide (PO). The two new polyols were used together in the formation of flame-retardant polyurethane foams (FRPUF), which depicted good thermal stability and flame retardancy performance. The addition of PSOP/HEDP-PO polyols resulted in a reduction of cell size and an increasement of cell numbers of PUF composites, whose apparent density was observed to increase. Besides, the LOI value of PUF-80 could reach 23.7% and satisfy the V-0 rating in the vertical burning test. The cone calorimeter test showed a reduction in the heat release rate from 395 kW/m2 to 251 kW/m2 and the total heat release from 24.9 MJ/m2 to 18.0 MJ/m2. Polyurethane foam exhibited good flame retardancy because PSOP/HEDP-PO played a great free radical quenching effect in the gas phase by releasing the PO* and PO2* free radicals. Meanwhile, a more dense and complete carbon layer was formed to cut off the transfer of heat and oxygen between the matrix and the ambient.

Influence of Flash Graphene on the acoustic, thermal, and mechanical performance of flexible polyurethane foam

In this study, flexible polyurethane foam (PUF) composites were prepared using three types of Flash Graphene (FG) produced from different feedstock material. The acoustic, thermal, and mechanical properties of foam composites containing 0.025 wt% FG were characterized. It was shown that PUF-1 and PUF-3 had higher sound absorption in the frequency range of 500–2000 Hz compared to neat PUF (baseline). PUF-3 experienced a 47% reduction in thermal expansion coefficient relative to the baseline. The tensile strength and compressive modulus of all composites increased by 16–26% and 33–37% respectively. Compression force deflection and tear strength did not change relative to the baseline. This may be explained by the relatively low flake diameter and aspect ratio of each FG which led to agglomeration and impacted load transfer between the filler and matrix. Overall, the addition of 0.025 wt% FG1 and FG3 improved acoustic, thermal, and tensile properties of PUF without diminishing compression force deflection and tear resistance. PUF reinforced with FG had similar or enhanced properties compared to PUF containing commercially available, exfoliated graphene nanoplatelets (GNP). This supports the use of FG as a relatively sustainable, low-cost alternative to exfoliated GNP or chemical vapor deposition (CVD)-grown graphene in porous polymer composites.

Conversion of Recycled Palm Oil and Water Hyacinth Fiber into Polyurethane Composite Foam - Noise Reduction Media in Oxygen Concentrator Machine

Conversion of Recycled Palm Oil and Water Hyacinth Fiber into Polyurethane Composite Foam - Noise Reduction Media in Oxygen Concentrator Machine

Optimization and modeling of the sound absorption behavior of polyurethane composite foams reinforced with kenaf fiber

In this study, hybrid composites made of polyurethane (PU) matrix and natural kenaf fiber filler were designed and fabricated. The Response Surface Methodology (RSM) optimization approach coupled with a Central Composite Design (CCD) was used to design the experiments and optimize the parameters affecting the acoustic performance of the samples in the low and mid-frequency ranges. The acoustic performance of the samples was investigated using the impedance tube method. Additionally, the acoustic performance was predicted using a developed Quadratic model as well as the Delany-Bazley (DB) and Johnson-Champoux-Allard (JCA) models. The results showed that the acoustic absorption of neat PU foam is remarkably improved at all frequencies with the addition of kenaf fibers as the filler. It was found that the acoustic performance of the composite samples is optimal when the added amount of kenaf fibers to the polymer matrix and fiber length are 1.2 wt% and 8 mm, respectively. The sound absorption average (SAA) of the optimized composite and neat PU foam was calculated as 0.65 and 0.48, respectively i.e., an increase of 35.4 %. The Quadratic model showed very high accuracy for the prediction of the SAA of the optimized sample. The JCA model provided higher accuracy for the prediction of the frequency-dependent sound absorption coefficient of the composites as compared with the DB model.

Mechanical and acoustic properties of alkali treated agricultural waste reinforced sustainable polyurethane composites

In this research, polyurethane (PU) foam composites were prepared by using various agricultural waste (rice husk, corn silk, artichoke stem) particles. In order to enhance the compatibility and adhesion between the waste particle and PU matrix, alkali treatment was employed. The alkali treated particles were chemically and morphologically characterized by Fourier transform infrared (FTIR) spectroscopy, cellulose determination instrument, and scanning electron microscopy (SEM), respectively. The effects of the alkali treatment on the structural, morphological, mechanical, and acoustic properties of the overall PU foam composites were all examined. Due to the differences in chemical compositions of the agricultural wastes, the alkali treatment affected the acoustic and mechanical properties of the PU foam composites in varying ratios. The PU foam composite reinforced with alkali treated artichoke stem waste particles showed the highest tensile strength value of 265 kPa, whereas the highest sound absorption value of 40.5% as an enhancement on the acoustic properties compared to the blank PU foam composite was recorded in corn silk waste particle loaded sample.

Highly Stretchable Composite Foams via Sustainable Utilization of Waste Tire Rubbers for Temperature-Dependent Electromagnetic Wave Absorption.

Recently, the sustainable utilization of waste resources has become a low-cost and effective strategy to design high-performance functional materials to solve the increasingly serious environmental pollution problem. Herein, the flexible and highly stretchable polyurethane (PU) composite foams assisted by one-dimensional carbon nanotubes (CNTs) and zero-dimensional Fe3O4 were fabricated using waste tire rubbers (WTRs) as reinforcements during a simple self-foaming process. The collaborative introduction of conductive CNTs, magnetic Fe3O4, and WTRs with three-dimensional cross-linked structures enabled the construction of an efficient electronic transmission path and heterointerfaces inside the composite foam. The resulting composite foam possessed a desired minimum reflection loss (RLmin) of −47.43 dB, and also exhibited superior mechanical properties with a tensile strength of >3 MPa and multiple tensile deformation recovery abilities. In addition, increasing the temperature could significantly improve the electromagnetic wave absorption performance of the composite foam. This comprehensive composite foam derived from WTRs has shown a promising development potential for using waste materials to relieve electromagnetic pollution.

A study to determine electromagnetic interference‐shielding effectiveness on bio‐based polyurethane foam reinforced with PVDF/MgO/Ni for emerging applications

AbstractThe main objective of this study is to prepare nanoparticles‐induced bio‐based polyurethane foam to shield electromagnetic interference (EMI) radiation in the 8–12 GHz frequency range and compare the experimental result with optimization and simulation. Polyvinylidene fluoride (PVDF), magnesium oxide (MgO), and Nickel (Ni) nanoparticles were induced into bio‐based PU (polyurethane) foam through absorption and hydrothermal reduction technique, which includes mechanical stirring, compressing, heating and evaporating. The design of experiment (DOE) methodology was used to find nanoparticle weight percentage (wt%). EMI shielding effectiveness of the bio‐based PU foam composite was measured using Vector Network Analyzer (N5230A PNA‐L). The weight percentages of the optimized sample were predicted using the response surface methodology (RSM), in which the central composite design (CCD) employed the weight percentages of the three nanoparticles as input and the results of the electromagnetic interference shielding effectiveness (EMI SE) experiment as the response output. The result from CCD showed that 3 wt% of PVDF, 10 wt% of MgO, and 1 wt% of Ni gave a maximum EMI SE of 27.78 dB. Then a confirmation sample was created for the same, and EMI SE was estimated empirically. The results obtained for the confirmation sample are 27.56 dB. Then, a scanning electron microscope image was taken for the confirmation sample to analyze nanoparticle‐induced bio‐based PU foam's structural properties. The SEM image with dxf format is imported into the radio frequency (RF) module to calculate the EMI SE through COMSOL Multiphysics. The simulated EMI SE for the confirmation sample was 25.1 dB.

Soft Magneto‐Responsive Shape Memory Foam Composite Actuators

Front Cover: A novel conceptual material and design of magneto-responsive shape-memory polyurethane (SMP) foam composites with excellent stability and reversibility is introduced by Mohammadreza Lalegani Dezaki and Mahdi Bodaghi in article 2200490. They are lightweight, stable, shape-recoverable, soft, and programmable and are expected to be game changer in the soft robotics field.

Impact of Sunflower Press Cake and Its Modification with Liquid Glass on Polyurethane Foam Composites: Thermal Stability, Ignitability, and Fire Resistance.

Polyurethane (PUR) foams are some of the most promising thermal insulating materials because of their high flammability, but further applications are limited. Therefore, the development of flame-retardant materials with sufficient strength characteristics, water resistance, and low thermal insulating properties is of great importance to the modern building industry. This study evaluates the possibility of a vacuum-based liquid glass (LG) infusion into bio-based fillers, in this case, sunflower press cake (SFP) particles, to improve the mechanical performance, water absorption, thermal insulation, ignitability, thermal stability, and flame retardancy of the resulting polyurethane (PUR) foam composites. The main findings show that LG slightly improves the thermal stability and highly contributes to the ignitability and flame retardancy of the resulting products. Most importantly, from 10 wt.% to 30 wt.%, the SFP/LG filler reduces the thermal conductivity and water absorption values by up to 20% and 50%, respectively, and increases the compressive strength by up to 110%. The results obtained indicate that the proposed SFP/LG filler-modified PUR foam composites are suitable for applications as thermal insulation materials in building structures.

Rigid Polyurethane Biofoams Filled with Chemically Compatible Fruit Peels.

Banana and bergamot peels are underutilized byproducts of the essential oil and juice-processing industry. This study was designed for the development of rigid polyurethane foam (RPUF) composites using polysaccharide-rich fruit peels as fillers. These fillers were characterized for chemical properties using wet analyses. Additionally, the influences of the filler type and filler content on morphological, thermal, mechanical, hygroscopic, and colorimetric properties of the RPUF were investigated. The main results indicated that, in a comparison with the neat RPUF, the insertion of up to 15% of fillers yielded similar water uptake, apparent density, compressive strength, and color properties, as well as increases up to 115% in thermal stability and up to 80% in cell size.

SARS-CoV-2 removal with a polyurethane foam composite.

The pandemic of COVID-19 (SARS-CoV-2 disease) has been causing unprecedented health and economic impacts, alerting the world to the importance of basic sanitation and existing social inequalities. The risk of the spread and appearance of new diseases highlights the need for the removal of these pathogens through efficient techniques and materials. This study aimed to develop a polyurethane (PU) biofoam filled with dregs waste (leftover from the pulp and paper industry) for removal SARS-CoV-2 from the water. The biofoam was prepared by the free expansion method with the incorporation of 5wt% of dregs as a filler. For the removal assays, the all materials and its isolated phases were incubated for 24 h with an inactivated SARS-CoV-2 viral suspension. Then, the RNA was extracted and the viral load was quantified using the quantitative reverse transcription (RT-qPCR) technique. The biofoam (polyurethane/dregs) reached a great removal percentage of 91.55%, whereas the isolated dregs waste was 99.03%, commercial activated carbon was 99.64%, commercial activated carbon/polyurethane was 99.30%, and neat PU foam reached was 99.96% for this same property and without statistical difference. Those new materials endowed with low cost and high removal efficiency of SARS-CoV-2 as alternatives to conventional adsorbents.Graphical abstract

Acoustic Properties of Rigid Polyurethane Foam Mixed with Pet Bottle Wastes

Rigid closed-cell polyurethane foam is renowned for its outstanding sound absorption properties and its application as sound insulation panels. Studies show that mixing of rigid polyurethane foam with non-reactive filler materials during fabrication improves the sound absorption properties of the composite material. In this composite, foam was fabricated from polyol and isocyanate monomers with shredded pet bottle waste as a filler component. The percentages of pet wastes mixed with the polyurethane foam composites were varied by 0%, 10%, 15%, 20% and 25% of total weight. The measurement of sound absorption coefficient has been done using impedance tube technique. The results showed that the rigid polyurethane foam with 0% pet waste has poor acoustic absorption. Also, sound absorption coefficient results showed that a sample with higher amount of upto 20%pet bottle waste had better sound absorption even at higher frequencies. From this research it is clear that mixing of pet waste as a filler material upto 20% is ideal for fabricating sound absorption panels with better sound absorption average.

Coal fly ash reinforcement for the property enhancement of crude glycerol-based polyurethane foam composites

Coal fly ash reinforcement for the property enhancement of crude glycerol-based polyurethane foam composites