Polyurethane Foam Composites Research Articles

Bio‐based rigid polyurethane foam composites reinforced with flame retardants: From synthesis to performance evaluation

AbstractThe building and construction industry is under increasing pressure to make insulation materials greener, more sustainable, and less flammable. In this study, sugar beet pulp was liquified under the optimized liquefaction conditions and used as the source of bio‐polyol (SBpol) in the production of bio‐based rigid polyurethane foam (sPUF). In order to improve the flame retardancy, sPUF composites were prepared with the addition of flame retardants; expandable graphite (EG) and/or dimethyl methyl phosphonate (DMMP). The bio‐polyol was used at a fixed ratio of 50 php in sPUF composites whereas the total ratio of flame retardants was fixed at 20 php. The effects of the ratio of EG and/or DMMP on the morphological, physicomechanical, thermal, and flame retardant properties of sPUF composites were evaluated. Although the thermal conductivity values of flame retardant added sPUF composites were increased in comparison to the petroleum‐based foam, the compressive strength values were decreased as the amount of DMMP increased in the flame retardant formulation. Thermogravimetric analysis showed that the onset of decomposition of 20 php DMMP‐containing sPUF composite decreased to 168.3°C. Although the limiting oxygen index (LOI) value of the petroleum‐based PUF was as low as 19.7%, the LOI value of the sPUF/10E/10D foam increased to 24.9% (by about 26%). According to the cone calorimeter results, the peak heat release rate (pHRR) of sPUF was much higher than the petroleum‐based foam. The incorporation of both DMMP and EG could further improve the flame retardant properties. The pHRR value of sPUF/10E/10D was 28.1% lower than that of sPUF. The results have shown that flame retardancy of sPUF composites could be improved by the addition of EG which acts in the condensed phase and DMMP, which acts mainly in the gas phase during burning. Flame retardant incorporated sPUF composites are considered as promising materials for use in insulation applications.

Lightweight, superhydrophobic, lignin-based polyurethane foam composites for underwater pressure sensing

Underwater flexible sensors are important for the exploration of and detection in underwater environments.

Effectiveness of Fish Scale‐Derived Collagen as an Alternative Filler Material in the Fabrication of Polyurethane Foam Composites

Effectiveness of Fish Scale‐Derived Collagen as an Alternative Filler Material in the Fabrication of Polyurethane Foam Composites

Enhanced anti-impact resistance of polyurethane foam composites with multi-phase shear thickening fluids containing various carbon nanofillers

Polyurethane (PU) foams are commonly used as impact-absorbing materials in various applications. However, the anti-impact performance of PU foams can be improved by incorporating non-Newtonian based smart fluids in their strudture. This study enhanced a open-cell based PU foam with multi-phase shear thickening fluids (M-STFs) containing three types of carbon nanofillers (carbon nanotubes, carbon nanofibers, and their mixture). M-STFs were prepared by adding 0.5, 1.0, 1.5, and 2.0 wt% of carbon nanofillers to the STF (55 wt% SiO2) and subsequently impregnating them into the structure of PU foams. Various configurations of PU foam composites were designed and evaluated for their impact resistance performance using a low-velocity drop tower system. The rheological behavior of fabricated suspensions were characterized using a rotational two plate-based system. The chemical structure and morphology of M-STF-treated PU foams were characterized by FTIR spectroscopy and SEM, respectively. The peak deceleration values in terms of G were measured after subjecting the designed samples to impacts at three different heights of 0.1, 0.2, and 0.3 m. The results indicated that the addition of nanofillers enhaced the initial and peak viscosity of the STF, and carbon nanotube had the most significant effect. The PUF-STF/CNT(1.5) sample exhibited approximately 62.7% to 73.0% reduction at different heights in peak deceleration compared to the clean PU foam sample. Moreover, to investigate the impact of filler content, drop height, and type of fillers on the peak deceleration of M-STF-treated PU foams, a response surface methodology analysis was utilized and the model provided insight into the optimal conditions for minimizing peak deceleration. This study highlights the potential of using M-STFs to enhance the anti-impact performance of PU foams.

Efficient recycling pathway of bio-based composite polyurethane foams via sustainable diamine

Aminolysis is widely recognized as a valuable chemical route for depolymerizing polymeric materials containing ester, amide, or urethane functional groups, including polyurethane foams. Bio-based polyurethane foams, pristine and reinforced with 40 wt% of sustainable fillers, were depolymerized in the presence of bio-derived butane-1,4-diamine, BDA. A process comparison was made using fossil-derived ethane-1,2-diamine, EDA, by varying amine/polyurethane ratio (F/A, 1:1 and 1:0.6). The obtained depolymerized systems were analyzed by FTIR and NMR characterizations to understand the effect of both diamines on the degradation pathway. The use of bio-based BDA seemed to be more effective with respect to conventional EDA, owing to its stronger basicity (and thus higher nucleophilicity), corresponding to faster depolymerization rates. BDA-based depolymerized systems were then employed to prepare second-generation bio-based composite polyurethane foams by partial replacement of isocyanate components (20 wt%). The morphological, mechanical, and thermal conductivity properties of the second-generation polyurethane foams were evaluated. The best performances (σ10 %=71 ± 9 kPa, λ = 0.042 ± 0.015 W∙ m-1 ∙K-1) were attained by employing the lowest F/A ratio (1:0.6); this demonstrates their potential application in different sectors such as packaging or construction, fulfilling the paradigm of the circular economy.

Asymmetric Al/Bi2O3/WPU composite foam with low emissivity and thermal insulation performance for high-efficiency infrared stealth

High-efficiency infrared stealth materials with low emissivity and heat-insulating ability are indispensable in fundamental materials science and modern military, but it still remains a great challenge of realizing these two features integration in a composite material with all-in-one structure, and without interface compatibility and adhesive problems. Herein, a lightweight aluminum/bismuth oxide/waterborne polyurethane (Al/Bi2O3/WPU) composite foam with asymmetric structure was fabricated by a simple density-induced fillers separation associated freeze-drying process, in which the asymmetric structure was derived from the high-density Al/Bi2O3 sheets deposited at the bottom of composite by the gravity effect during the processing, acting as a low infrared emissivity layer, while the WPU foam formed on the top side as a thermal insulation layer. Through joining the two features in this all-in-one composite foam, it shows a relatively low surface infrared emissivity (0.68), low thermal conductivity (∼48.5 mW·m−1·K−1) and good infrared stealth ability to infrared thermal signal. And the temperature difference of about 48.5 °C can be generated with the hot target at 100 °C. Furthermore, benefiting from the interconnected porous framework, the composite also exhibits good mechanical and thermal stabilities, making it possible for application in various scenarios. This study provides a promising inspiration for designing and developing high-efficiency infrared stealth materials.

Novel expandable graphite/dimethyl methyl phosphonate/bio-based rigid polyurethane foam composites: flame retardancy and physicomechanical properties

Novel expandable graphite/dimethyl methyl phosphonate/bio-based rigid polyurethane foam composites: flame retardancy and physicomechanical properties

Poly(ionic liquid) Grafted MXene via Si-ATRP and its Polyurethane Composite Foam: Mechanical, Flame Retardant and Sensing Properties

Compared with other types of sensors, capacitive flexible pressure sensors (CFPS), with low sensitivity, are more susceptible to environmental changes. It is still a considerable challenge to achieve high sensitivity, excellent mechanical properties and long-time structural stability simultaneously. Targeting the aforementioned issues, herein, Ti3C2 (MXene) with high dielectric constant was firstly chemically modified with a poly(ionic liquid) (PIL) via surface-initiated ATRP, and then combined with a porous polyurethane foam (PUF) 3D network structure via a one-step blending foaming method. Thanks to the organic-inorganic hybrid network based on the PU/MXene porous structures and the uniformly distributed micro-capacitor structure provided by MXene@PIL, the mechanical properties, structural stability, flame retardancy and dielectric properties of the composite foam were all significantly enhanced. When the content of MXene@PIL was 10%, the sensitivity of CFPS based on this dielectric were 17.1, 5.2, and 2.5/KPa in the pressure ranges of 0-1 KPa, 1-12 KPa and 12-100 KPa, respectively. In addition, the sensor showed the response and recovery times of 88 and 82 ms under a low pressure of 355 Pa. The light, flexible sensor prepared in this work is expected to be used in wearable devices to monitor physiological signals, and it should also be a good candidate for the next generation of man-machine interface characterization devices.

Metal–Organic Frameworks Polyurethane Composite Foams for the Capture of Volatile Organic Compounds

Metal–Organic Frameworks Polyurethane Composite Foams for the Capture of Volatile Organic Compounds

Performance optimization of acrylonitrile butadiene styrene/thermoplastic polyurethane composite foams blown with carbon dioxide using Taguchi technique

AbstractIn this study, acrylonitrile butadiene styrene (ABS)/thermoplastic polyurethane (TPU) composite foam blown with CO2 was fabricated. Optimization was done by design of experiment (DOE) on the cellular structure using the Taguchi method. Foaming time (20, 40, and 80 s), saturation pressure (4, 5.5, and 7 MPa), and foaming temperature (80, 90, and 120°C) are the input parameters. The results obtained from the signal‐to‐noise (S/N) analysis showed that the most effective factor on the cell density (CD) was the saturation pressure and its influence rate was 48.05%, and also, the CD improved with the increase in the saturation pressure because the high saturation pressure leads to an enhancement in gas solubility and the rate of cell nucleation. Moreover, the foaming temperature and the foaming time had a noteworthy impact on the void fraction and the cell size (CS), and they should be controlled accurately. The impression rate of the foaming time on the CS was 50.86%, and also, with increase in the temperature and the time of foaming, the void fraction showed an increasing trend. The optimal values for the CD, the CS, and the void fraction were predicted to be 1.18 × 109 cells/cm3, 5.37 μm, and 0.5744%, respectively.

Acoustic characterization of natural areca catechu fiber‐reinforced flexible polyurethane foam composites

AbstractThe development of acoustic absorbers from natural resources is a novel approach in acoustics. In the current study, the effect of unprocessed raw areca fiber (AF) particle reinforcement on the sound absorption (SA) behavior of polyurethane (PU) foam composites is investigated. Influences of fiber weight percentage and graded distribution of fiber with varying fiber weight percentage on the SA coefficient (SAC) of the composite foams are examined through the impedance tube approach. Morphological studies are carried out with the help of FESEM images to investigate the acoustic energy dissipation mechanism of PU foam and its composites. It is found that the SA capability of the composite foam is enhanced by increased fiber weight percentage, graded distribution of fiber wt%, varying sample thickness, and air cavity length. In general, PU‐AF composite specimens show a peak SA value of 0.95 around 450 Hz, which is not the case for other natural fiber results available in the literature. Theoretical results predicted using the JCA (Johnson‐Champoux Allard) model agree with the experimental results.

Debonding imaging of the aluminium/rigid polyurethane foam composite plates using A0 mode Lamb waves

ABSTRACT Debonding regions can occur at the interface of aluminium/rigid polyurethane foam composite plates (ARCP) during manufacturing. To help improve the technological process of manufacture, it is essential to precisely locate these debonding regions. This paper proposed a method to image the debonding regions in the ARCP based on the A0 mode Lamb waves. To study the influence of overlap between the debonding region and the coil of the electromagnetic acoustic transducer (EMAT) on Lamb wave propagation, a three-dimensional finite element simulation model was developed. A positive linear relationship was obtained between the amplitude of the A0 mode and the overlap rate between the debonding region and the coil of the EMAT, which was verified through experiments. Based on such relationship, an imaging method was proposed. The imaging method consisted a horizontal scanning for the entire sample and vertical scanning for possible debonding regions determined from the horizontal scanning. The result of the imaging experiments can precisely reveal the size and position of the debonding regions, the maximum relative error of the centre position of the defect is 7.5% and the maximum relative deviation of the dimensions is 16.0%. This imaging method can serve as a reference for debonding imaging in composite plates.

Temperature-stimulated composite foams for reversibly switching microwave absorption towards electromagnetic interference shielding capability

Currently, electromagnetic interference (EMI) shielding and microwave absorption are two important means to alleviate the increasingly severe electromagnetic (EM) pollution. However, the application areas of EMI shielding and microwave absorption are quite different, so integrating these two capabilities in the same material is a great challenge. Herein, multiple-scale polyurethane (PU) composite foams (CFs) assisted by tadpole-like carbon nanotube (CNT)@Fe3O4 nanocomposites were designed by a facile solvothermal and self-foaming method. By adjusting the CNT@Fe3O4 loadings and ambient temperatures, the EM parameters and interface impedance matching of PU/CNT@Fe3O4 CFs could be optimized, thus realizing the coexistence of EMI shielding and microwave absorption inside one same material. The resulting CF exhibited an effective minimum reflection loss (RLmin) of −41.9 dB and EMI shielding effectiveness (SE) of ∼20 dB. Furthermore, the elevated temperatures within a range of −20-60 °C would stimulate the transformation of individual CF from microwave absorption towards EMI shielding capability and vice versa. This work will promote the development of intelligent EM compatible devices in the field of optional EM protection.

Lightweight, compressible, and stretchable composite foams for ultra-efficient and high-stable electromagnetic interference shielding materials

Lightweight, flexible, high-stable and ultra-efficient electromagnetic shielding materials are the extremely desired materials for electronic devices and products. In this paper, a lightweight, compressible, and stretchable ferric trichloride (FeCl3)/carbon nanotubes (CNTs)/polyvinyl pyrrolidone (PVP)/polyurethane (PU) composite foam with ultra-efficient electromagnetic interference shielding is fabricated by the chemical foaming method and subsequent ultrasound assisted loading of conductive layer onto PU skeleton. The as-prepared FeCl3/CNTs/PVP/PU composite foam with a density of 40 mg/cm3 possesses ultrahigh electromagnetic interference shielding properties at X-band (∼91.5 dB at 12.4 GHz) attributed to the unique porous structure to dissipate electromagnetic wave as well as the synergistic shielding effect of FeCl3 and CNTs. More importantly, the ultra-efficient electromagnetic shielding performance can still remain even after subjected to water-washing, long-term cyclic compression or high/low temperature treatment because the addition of PVP can greatly enhance the interaction between CNTs and PU skeleton. The current work proposes a simple and scalable method to fabricate ultra-efficient electromagnetic interference shielding materials for wearable and portable electronic devices.

Effect of milled fish scale powder reinforcement on physical properties of ether‐based polyurethane foam composite

AbstractThis study investigated the effects of reinforcing ether‐based flexible polyurethane foam (PUF) with milled fish scale powder (MFSP) on the physical properties of the resulting composite under different temperature conditions. The composites were prepared with varying MFSP concentrations (0%, 0.5 wt%, 1 wt%) with the PUF matrix and then subjected to the resulting mixture in a mold and cured in an oven at 70 degrees for 15 min. The physical properties of the composites, namely tensile strength, elongation at break, tear resistance, density, color, and cell structure were characterized under different temperature conditions. The results showed that at standard temperature (23°C), the addition of 0.5 wt% MFSP resulted in an 18.8% increase in tensile strength and a 15.7% increase in elongation at break. Tear resistance exhibited significant improvements under heat aging, with a 22% increase (0.5 wt% MFSP) and a remarkable 37% increase (1 wt% MFSP). The cell structure revealed closed cells after the addition of MFSP to the PUF matrix. The salient feature of the study suggests that the use of MFSP as a reinforcing agent for PUF‐based composites has the potential to improve their physical properties. This is critical in producing PUF at a reduced cost with less impact on the environment.

Study of Aerogel-Modified Recycled Polyurethane Nanocomposites.

In this study, a liquid regenerated polyether polyol was obtained after the degradation of waste PU foam by the two-component decrosslinker agents ethylene glycol and ethanolamine. The regenerated polyol-based polyurethane foam was modified by adding different ratios of SiO2 aerogel through the self-preparation of silica aerogel (SiO2 aerogel) to prepare aerogel/regenerated polyurethane foam nanocomposites of SiO2 aerogel-modified regenerated polyurethane composites. A series of analytical tests on self-prepared silica aerogel and aerogel-modified recycled polyurethane foam composites were performed. The analysis of the test results shows that the regenerated rigid PU foam obtained with SiO2 aerogel addition of 0.3% in the polyurethane degradation material has a small density, low thermal conductivity, and higher compressive strength; hence, the prepared silica aerogel-regenerated polyol-based polyurethane nanocomposite has good thermal insulation and strength support properties. The clean, low-carbon, and high-value utilization of recycled waste polyurethane was achieved.

Biomass-Based Shape-Stabilized Composite Phase-Change Materials with High Solar-Thermal Conversion Efficiency for Thermal Energy Storage.

To alleviate the increasing energy crisis and achieve energy saving and consumption reduction in building materials, preparing shape-stabilized phase-change materials using bio-porous carbon materials from renewable organic waste to building envelope materials is an effective strategy. In this work, pine cone porous biomass carbon (PCC) was prepared via a chemical activation method using renewable biomaterial pine cone as a precursor and potassium hydroxide (KOH) as an activator. Polyethylene glycol (PEG) and octadecane (OD) were loaded into PCC using the vacuum impregnation method to prepare polyethylene glycol/pine cone porous biomass carbon (PEG/PCC) and octadecane/pine cone porous biomass carbon (OD/PCC) shape-stabilized phase-change materials. PCCs with a high specific surface area and pore volume were obtained by adjusting the calcination temperature and amount of KOH, which was shown as a caterpillar-like and block morphology. The shape-stabilized PEG/PCC and OD/PCC composites showed high phase-change enthalpies of 144.3 J/g and 162.3 J/g, and the solar-thermal energy conversion efficiencies of the PEG/PCC and OD/PCC reached 79.9% and 84.8%, respectively. The effects of the contents of PEG/PCC and OD/PCC on the temperature-controlling capability of rigid polyurethane foam composites were further investigated. The results showed that the temperature-regulating and temperature-controlling capabilities of the energy-storing rigid polyurethane foam composites were gradually enhanced with an increase in the phase-change material content, and there was a significant thermostatic plateau in energy absorption at 25 °C and energy release at 10 °C, which decreased the energy consumption.

Pretreated cellulose fiber for enhancing fire resistance of flexible polyurethane foam composites with reinforced properties

To promote environmentally sustainable behavior, it is meaningful to develop a simple preparation method of polyurethane foam (PUF) with excellent performance and degradability. Herein, PUF composites were economically and conveniently synthesized by mixed foaming of polyurethane prepolymer and cellulose nanocrystals (CNCs). After the hydrolysis of dissolving pulp fibers with formic acid (FA), hydrophobic ester groups were introduced in CNCs, thereby increasing the surface hydrophobicity of PUF composites. CNCs acted as a reinforcement agent capable can replace 10% up to 60% prepolymer for foaming, the modified PUF exhibiting gradient morphology structure and enhanced specific mechanical and thermal properties. When the CNCs replacement ratio was 50%, the maximum compressive stress was 1103.19 kPa, which is 21-fold that of the original foam. Remarkably, the addition of CNCs enhanced thermal insulation performance of the prepared foam, which of thermal conductivity decreased from 0.0780 W/mK to 0.0549 W/mK. The upgraded polyurethane foam composites promise to open exciting new windows on producing fire resistance PUF with enhanced performance.

Acoustic performance of flexible polyurethane composite foams filled with melamine particles

Acoustic performance of flexible polyurethane composite foams filled with melamine particles

Study on the Flame Retardancy of Rigid Polyurethane Foam with Phytic Acid-Functionalized Graphene Oxide.

A rigid polyurethane foam (RPUF) composite was prepared by compounding phytic acid (PA)-functionalized Graphite oxide (PA-GO) with flame-retardant poly (Ammonium phosphate) (APP) and expandable graphite (EG). The effects of PA-GO on the thermal, flame-retardant, and mechanical properties of RPUF were studied using a thermogravimetric analyzer, a limiting oxygen index (LOI) tester, a UL-94 vertical combustion tester, a cone calorimeter, scanning electron microscopy, and a universal tensile testing machine. The results indicated that there was a significant synergistic flame-retardant effect between PA-GO and the intumescent flame retardants (IFR) in the RPUF matrix. Compared with RPUF-1, the addition of 0.3 wt% PA-GO could increase LOI from 25.7% to 26.5%, increase UL-94 rating from V-2 to V-0, and reduce the peak heat release rate (PHRR) and total heat release rate (THR) by 28.5% and 22.2%, respectively. Moreover, the amount of residual char increased from 22.2 wt% to 24.6 wt%, and the char layer was continuous and dense, with almost no holes. Meanwhile, the loss of mechanical properties was apparently lightened.