Effect of mixing pressure in a high-pressure machine on morphological and physical properties of flexible polyurethane foams

The feasibility of using mineral nano- and micro-fillers as replacement of copolymer polyols in flexible foams was examined. Nano-fillers were nano-clays, a natural montmorillonite (Cloisite Na+) and montmorillonite modified with an organic quaternary ammonium salt (Cloisite 10A), and nano-silica dispersed in methylethylketone. Micro-fillers were micronized clay and silica. Flexible foams were prepared from the ethylene oxide caped polyether triol and toluene diisocyanate with water as the chemical blowing agent. All foams had good morphology except those with nano-clay. The open cell content was above 95%, but air flow was very low in all samples. Micro-fillers did not significantly change cell structure and morphology of hard domains. They moderately increased density, hardness, compression strength, and compression set and decreased elongation at break. The other properties were not affected. Cloisite Na+ (non-treated montmorillonite) and nano-silica with a hydrophilic surface increased hardness, compression strength, and rebound resilience of the foams, whereas Nano-clay 10A (surface-treated montmorillonite) decreased the modulus, hardness, and compression strength. Tensile and tear strengths decreased with the addition of nano-clay fillers, but increased with nano-silica.

This study investigates the effects of variable pressure conditions (550 and 1013 mbar) on the physico‐mechanical and structural properties of flexible polyurethane foam, incorporating different compositions of calcium carbonate (CaCO3) filler. The objective is to achieve sustained mechanical and structural properties of flexible polyurethane foam while reducing costs through variable pressure foaming technology. With CaCO3filler concentrations ranging from 20 to 100 parts per hundred (pphp) of polyol, it was found that foam produced at low pressure (550 mbar) demonstrated improved resilience and durability, particularly with CaCO3compositions up to 100 pphp. Conversely, foam produced at standard atmospheric pressure (1013 mbar) using compositions up to 100 pphp did not exhibit significant enhancements in physico‐mechanical properties. The study employs various characterization techniques, including mechanical testing, scanning electron microscopy, differential scanning calorimetry, thermal gravimetric analysis, and Fourier transform infrared spectroscopic analysis, to assess the flexible polyurethane foam. It provides a detailed examination of the effects of variable pressure on cellular structure, cell size, filler distributions, mechanical properties, and thermal stability of flexible polyurethane foam using CaCO3filler.

ABSTRACTFlexible polyurethane foams (FPURFs) with varied concentration of water from 3.2 to 4.2% and rapeseed oil based polyol (ROP) in the range of 13–22% in polyol premix were obtained. Effects of changes in polyurethane (PUR) formulation on the foaming process and mechanical properties of FPURFs were analyzed. It was found that the change of water content in PUR formulation influences its foaming process. Higher water content in the PUR formulation increases the growth velocity and the temperature of reaction mixture. In the case of foams modified with ROP, an opposite effect can be observed, where higher content of that component resulted in overall downturn of the foaming process and decreases of registered temperature inside the foams core. An addition of ROP beneficially influences on foams cellular structure favoring creation of finer cells. Such modification of PUR formulation with ROP increased apparent density, reduced hardness, and resilience of flexible foams. What is more the support factor of FPURFs with ROP was higher in comparison to the reference foam. Along with higher water content in the PUR formulation, apparent density and hardness has decreased and foams ability to absorb energy has been increased. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42372.

Polyurethane foams have a wide variety of commercial applications in daily life due to their unique advantages. Traditionally, polyurethane foams are made from petroleum-based polyols and isocyanates. Due to the shortage of fossil resources, renewable biobased materials are studied as alternatives to petroleum. In this project, castor oil was chosen as a renewable biobased polyol in order to replace the nonrenewable petroleum-based polyols. Water-blown rigid foams were made from polyols with different levels of castor oil replacement. For foams without castor oil and with 25% castor oil replacement, the effects of water added content were studied. Another group of foams made from a castor oil/ glycerol mixture were also prepared to investigate the effects of hydroxyl number. With the help of glycerol, rigid polyurethane foams with 80%-95% castor oil replacement were successfully prepared and showed competitive physical properties. Water-blown flexible foams were made from polyols using different levels of castor oil replacement. At the same time, the influence of cross-linker contents and isocyanate index on flexible foam was studied. Considering the low reaction rate of castor oil during the synthesis of polyurethane, a specific heated mold method was applied. Density, compression force deflection (CFD), 50% constant deflection compression (CDC), tear resistance (TR) and resilience were tested to identify the physical properties of flexible polyurethane foams. Results show that castor oil replacement often leads to a high cross-linking density. With 0.5% necessary cross-linker and low isocyanate index, flexible polyurethane foams with 100% castor oil replacement showed a good recovery property and proved to be a suitable alternative to nonrenewable petroleum-based polyols.

In this paper, the analysis of the foaming process of flexible polyurethane modified with the addition of silica nanoparticles is presented. Flexible polyurethane foams (FPURF) were obtained using petrochemical components and a rapeseed-oil-based polyol (used in an amount of 20 wt %). Nanosilica was added to the polyurethane system in the amount of 0.5, 1.0 and 1.5 php (parts per hundred polyols). The characteristic parameters of the foaming process, such as the growth velocity of foamed materials, the core temperature and dielectric polarization, were measured using a Foamat device. It was observed that polyurethane-forming reactions slowed down as an effect of the increase of nanosilica content in the polyurethane composition. Consequently, the temperature in the core of the reaction mixture containing 1.5 php nanosilica was lower by approx. 35 °C compared to the reference material. Moreover, the influence of the method of homogenization of the nanofiller with polyols on the selected properties of prepared foams was analyzed. The following properties of flexible polyurethane foams were determined: apparent density, resilience, compressive strength, hardness, hysteresis and support factor. The introduction of nanosilica filler to the polyurethane formulation caused an increase in the apparent density from 24.6 kg/m3 for the reference foam to 28.5 kg/m3 for the foam containing 1.5 php of nanosilica. However, this nanofiller did not significantly affect the cell structure of foamed materials. The foams obtained with the nanosilica additive of 1.0 php had the most preferred properties, such as a slightly higher value of resilience, lower hardness and higher support factor than the reference foam without nanosilica.

Green Velvet Material (PLON), which is prepared from polyester slices, has been called a green material based on its ester composition, its ability to be degraded, and the possibility of recovering the value of used material by reprocessing. PLON is expected to be used as a material for the padding layer of upholstered furniture. This paper presented a comparative study of traditional flexible polyurethane foam and Green Velvet Material as the upholstered furniture’s padding layer. The compression mechanical properties of Green Velvet Material and flexible polyurethane foam, such as indentation force deflection, support performance, compression set, and resilience property, were analyzed. The results showed that Green Velvet Material had lower surface hardness and higher comfort compared to flexible polyurethane foam. In terms of resilience, both high-density and low-density Green Velvet Material performed better than the foam control group, but Green Velvet Material had a poorer ability to regain its shape after prolonged pressure. The 30 kg/m3 density Green Velvet Material was the closest to the compression and resilience properties of flexible polyurethane foam. The conclusions provide theoretical data for the effective and reasonable application of Green Velvet Material in upholstered furniture.

Flexible polyurethane foams filled with a fixed amount of carbon-based nanofillers, in particular multiwall nanotubes and graphenes, have been studied to clarify the influence of the morphology and functional groups on the physical properties of these polymeric foams. The effect of the carbon nanoparticles on the microphase separation has been analyzed by FT-IR spectroscopy revealing a decrease in the degree of phase separation of the segments. Variations of the glass transition temperature and an improved thermal stability were observed due to the presence of the nanoparticles. The EMI shielding effectiveness of flexible PU foams has also been enhanced, in particular for FGS nanocomposite foams.

Bio-polyols based on rapeseed oil were used to produce flexible polyurethane foams (FPURF). The bio-polyols were obtained on a laboratory and industrial scale with the two-step method involving epoxidation of double bonds in rapeseed oil and opening of oxirane rings with different alcohols, such as isopropanol (iP) and diethylene glycol (DEG). The impact of bio-polyols production scale on selected physical and mechanical properties of FPURF was analyzed. The applied bio-polyols differed slightly by hydroxyl number, functionality, and water content. It was found that the scale of bio-polyol production has no significant impact on FPURF properties such as apparent density, hardness, hysteresis, support factor, and resilience. However, it was observed, that the addition of the bio-polyol to polyurethane (PUR) formulation had the impact on the FPURF properties as compared to the reference foams that were not modified with the bio-polyols. Moreover, a continuous method was used to prepare FPURF samples modified with different rapeseed oil-based polyols. For this purpose mixing-dosing device with conveyor line was used to synthesize the foams. It was found that the replacement of petrochemical polyols with the bio-polyols resulted in lower reactivity of the modified for- mulations and the amount of catalysts had to be increased. Furthermore, the foams hysteresis, support factor, and hardness were higher, especially for foams modified with the bio-polyol that contained DEG in its structure. Moreover, the fatigue tests were performed and the results showed a beneficial effect of the bio-based polyols on the functional properties, a.o. support factor of flexible foams.

Flame retardancy and thermal decomposition of flexible polyurethane foams: Structural influence of organophosphorus compounds

Molded polyurethane foams for car seats are based on petrochemical polyols of molecular weight 4000-6000 and copolymer polyols containing micron size polymeric particles. Copolymer polyols (CPP) typically constitute 30% of the mixture with the base polyol. They help cell opening, increase load bearing and tear strength of the foams, but they are relatively expensive. Hyperbranched polyols of petrochemical origin were used in molded foams.[1] They are solid in the pure form and due to high crosslinking density could be incorporated at low concentration in conjunction with copolymer polyols. Instead, we have made hyperbranched polyols which could be a total replacement for CPP in molded foams. Six hyperbranched polyols with primary and secondary hydroxyl groups and different hydroxyl numbers were prepared from soybean oil and tested in flexible foams. Novel polyols were liquid even at very high molecular weights and could completely replace copolymer polyols. Functionality of these polyols increased linearly with molecular weight to very high values, resulting eventually in their high crosslinking power. The effects of the type of hydroxyl groups (primary vs. secondary), hydroxyl number (from 85 to 135 mg KOH/g), and concentration (7.5-30%) in the mixture with the base polyol on foam properties were analyzed. It was found that hyperbranched polyols could replace copolymer polyols completely but their effect on cell morphology and mechanical properties varied with the type of polyol and concentration.

Flexible polyurethane (PU) foams with different loading mass fraction (0%–2.0%) of fumed silica were synthesized by free-rising foaming method. The addition of 1.4% fumed silica makes the cells diffuse more uniform in the PU foam and the temperature of degradation occurring with a maximum weight loss rate is about 7 °C higher than that of pure PU foam. Most significantly, the sound absorption peaks of the filled PU foams shift to the low frequency region (from 997 Hz to 711 Hz) with increasing fumed silica content (0%–2.0%). The average sound absorption coefficients of filled PU foams increase except the content of 0.35% fumed silica. The experimental results show that flexible PU foams filled with fumed silica have excellent sound absorption characteristics in low-frequency regions.

The focus of this paper was to explore the acoustic properties of flexible polyurethane (FPU) foam modified by palm‐oil‐based polyol (POP). The presence of POP showed a marked influence on the microstructure and mechanical properties of FPU foam. A smaller mean pore diameter can be observed at lower POP content. Indeed, the introduction of POP caused a higher closed pore ratio and an increased air‐flow resistivity, which consequently improved the sound absorption coefficient and transmission loss. In particular, the acoustic performance of the all bio‐based FPU foam was enhanced at low frequency, and the density was lower than that of the reference foam. Additionally, the addition of POP also improved the compressive strength. Conversely, the tensile strength of FPU foam declined with increasing POP content. From this study, the outstanding acoustic ability of bio‐based FPU foam has been proved, with additional advantages of lower density and higher compressive strength. © 2019 Society of Chemical Industry

Flexible polyurethane (PU) foams were obtained from a two‐component system via the one‐step method. The foams were modified with thermally reduced graphene oxide added in the amount equal to 0.25, 0.5, and 0.75 wt%. The morphology, static and dynamic properties, and thermal stability of modified foams were determined. The application of carbon filler resulted in the visible increase in the cell size, apparent density, and rigidity of the modified systems, as confirmed by the measurements of glass transition temperature. Glass transition temperature increased with increasing content of nanofiller. In addition, thermally reduced graphene oxide had an effect on the thermal stability of the obtained foam systems. The addition of 0.5 wt% of nanofiller resulted in an increase in T5 by 16°C compared with the reference foam. This study also demonstrated that after exceeding a specific content of thermally reduced graphene oxide, that is, 0.5%, the physicochemical properties of the obtained systems start to deteriorate. The research results showed that thermally reduced graphene oxide can be successfully used as a modifier of mechanical and thermal properties in flexible PU foams. POLYM. COMPOS., 38:2248–2253, 2017. © 2015 Society of Plastics Engineers

Influence of Recycled Polyurethane Polyol on the Properties of Flexible Polyurethane Foams

Effects of biopitch on the properties of flexible polyurethane foams