Preparation and characterization of water‐blown polyurethane foams from liquefied cornstalk polyol

Polyurethane foams were prepared from the liquefied cornstalk polyol, which was obtained by the liquefaction of cornstalk in the presence of polyhydric alcohols using sulfuric acid as catalyst. The advisable liquefaction reaction conditions were selected by investigating their influences on the properties of liquefied cornstalk polyol, taking account of the requirement for the preparation of appropriate polyurethane foams. The influences of the contents of catalysts, water, surfactant, and isocyanate on the properties of polyurethane foams were also discussed, and feasible formulations for preparing cornstalk‐based polyurethane foams were proposed. The results indicated that the foams prepared from such liquefied cornstalk polyol exhibited excellent mechanical properties and thermal properties, and could be used as heat‐insulating materials. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Flame retardant polyurethane foam prepared from compatible blends of soybean oil‐based polyol and phosphorus containing polyol

A phosphorus containing polyether polyol (THPO‐PO) was synthesized by polymerization between tris(hydroxymethyl) phosphine oxide (THPO) and propylene oxide (PO). A soybean oil‐based polyol(SBP) was synthesized from epoxidized soybean oil by ring‐opening reaction with lactic acid. The corresponding polyurethane foams (PUFs) were prepared by mixing SBP with THPO‐PO. The density of these foams decreased as the content of THPO‐PO increased. The yield strength of PUFs was observed to be decreased firstly and then increased with the addition of THPO‐PO. Microphotographs of PUFs were examined by scanning electron microscope which displayed the cells as spherical or polyhedral. The thermal degradation and fire behavior of PUFs were investigated by thermogravimetric analysis, limiting oxygen index (LOI), and UL‐94 test. Although the thermal stability of PUFs were decreased with increasing THPO‐PO percentage, the flame retardancy of PUFs were improved. The LOI value increased to 27.5 with 40% THPO‐PO. THPO‐PO in sequence worked in inhibiting flame and forming phosphorus‐rich char layer, thus endowing PUFs with the increased flame‐retardant performance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45779.     

Preparation and physico‐mechanical,thermal and acoustic properties of flexible polyurethane foams based on hydroxytelechelic natural rubber

Novel flexible polyurethane foams were successfully prepared from a renewable source, hydroxytelechelic natural rubber (HTNR) having different molecular weights (1000–3400 g mol^?1) and variation of epoxide contents (EHTNR, 0–35% epoxidation) by a one‐shot technique. The chemical and cell structures as well as physico‐mechanical, thermal, and acoustic properties were characterized and compared with commercial polyol analogs. The obtained HTNR based foams are open cell structures with cell dimensions between 0.38 and 0.47 mm. The HTNR1000 based foam exhibits better mechanical properties but lower elongation at break than those of commercial polyol analog. However, the HTNR3400 based foam shows the best elastic properties. In a series of EHTNR based foams, the tensile and compressive strengths show a tendency to increase with increasing epoxide content and amount of 1,4‐butanediol (BD). The HTNR based foams demonstrate better low temperature flexibility than that of the foam based on commercial polyol. Moreover, the HTNR based polyurethane foams was found to be an excellent absorber of acoustics. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Castor-oil derived nonhalogenated reactive flame-retardant-based polyurethane foams with significant reduced heat release rate

National Fire Protection Association encounters one structural fire every 66 s. Rigid polyurethane foam is one of the principal components used in constructional and household applications. In this work, a reactive flame retardant (FR) was synthesized using a facile one-step thiol–ene reaction by reacting mercaptenized castor oil (MCO) and diethyl allyl phosphonate (DEAP). The obtained MCO–DEAP polyol was used for the preparation of polyurethanes having different weight percentages of phosphorus (P). Addition of FR polyol showed no adverse effect on the cellular structure of the foams and maintained the compressive strength. All the foams showed closed cell content greater than 95%. Horizontal burning test (HBT) was performed before and after the migration test to understand the stability of the FR within the foams. Foams showed no relative weight loss before and after the migration test and maintained equivalent results for HBT. For 1.5 wt % P foams, low extinguishing time of 3 s and weight loss of 4% was observed. The cone calorimeter test showed a reduction in the peak heat release rate from 313 to 158 kW m⁻³, the total heat release from 18 to 8 MJ m⁻², and O₂ consumption from 12 to 6 g. Our results suggest that MCO–DEAP polyol could act as an essential FR for rigid PU foam ensuring fire safety. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47276.     

Flame-retardant thermoplastic polyurethane based on reactive phosphonate polyol

Propylene oxide (PO) was used to block polycarboxyethyl phenyl ethylene phosphinate (PCEPEP) synthesized by 2-carboxyethylphenylphosphinic acid (CEPPA) and ethylene glycol (EG) to obtain a reactive phosphonate polyol. The results of chemical titration analysis and Fourier transform infrared spectrum (FT-IR) showed that the end-capping effect was best when the molar ratio of PO to acidic functional groups in PCEPEP was 6:1. Moreover, the obtained phosphorus-containing polyol was used as a reactive monomer to be introduced into thermoplastic polyurethane (TPU) to prepare flame retardant TPU. Cone calorimetry results demonstrated that TPU containing 20 wt% phosphorus-containing polyol showed a reduction of 3.8%, 72.2%, and 39.3% in the peak heat release rate, total heat release and total smoke release, and an increment of 351.9% in mass retention. The addition of phosphonate polyol enhanced the char-forming performance of TPU, which effectively prevented the transfer of combustible gas and heat, and displayed a good flame retardant effect.     

Insulating rigid polyurethane foams from laurel tree pruning based polyol

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

Physical properties of water‐blown rigid polyurethane foams from vegetable oil‐based polyols

Fifty vegetable oil‐based polyols were characterized in terms of their hydroxyl number and their potential of replacing up to 50% of the petroleum‐based polyol in waterborne rigid polyurethane foam applications was evaluated. Polyurethane foams were prepared by reacting isocyanates with polyols containing 50% of vegetable oil‐based polyols and 50% of petroleum‐based polyol and their thermal conductivity, density, and compressive strength were determined. The vegetable oil‐based polyols included epoxidized soybean oil reacted with acetol, commercial soybean oil polyols (soyoils), polyols derived from epoxidized soybean oil and diglycerides, etc. Most of the foams made with polyols containing 50% of vegetable oil‐based polyols were inferior to foams made from 100% petroleum‐based polyol. However, foams made with polyols containing 50% hydroxy soybean oil, epoxidized soybean oil reacted with acetol, and oxidized epoxidized diglyceride of soybean oil not only had superior thermal conductivity, but also better density and compressive strength properties than had foams made from 100% petroleum polyol. Although the epoxidized soybean oil did not have any hydroxyl functional group to react with isocyanate, when used in 50 : 50 blend with the petroleum‐based polyol the resulting polyurethane foams had density versus compressive properties similar to polyurethane foams made from 100% petroleum‐based polyol. The density and compressive strength of foams were affected by the hydroxyl number of polyols, but the thermal conductivity of foams was not. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effect of different concentration of rapeseed‐oil‐based polyol and water on structure and mechanical properties of flexible polyurethane foams

Flexible 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 from alkaline lignin‐based polyether polyol

As a byproduct produced during biorefining, alkaline lignin (AL) possesses multiple benzene ring and phenol hydroxyl groups with high chemical reactivity, and is renewable and cheaper than petrochemical products. Here, AL was liquefied in polyethylene glycol‐400/glycerol and subsequently used to prepare polyurethane foams (PUFs). The results showed that the AL could be almost completely liquefied. The resulting lignin‐based polyether polyol (LPP) exhibited physicochemical properties similar to a commercial polyether polyol (PP). The PUFs made from LPP presented better thermal stability and higher compressive strength than those PUFs obtained from commercial PP, suggesting this could be a viable commercial application for AL. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43261.     

Thermal degradation and combustion behavior of intumescent flame‐retardant polypropylene with novel phosphorus‐based flame retardants

The objective of this study was to develop an environmentally friendly fire‐retardant polypropylene (PP) with significantly improved fire‐retardancy performance with a novel flame‐retardant (FR) system. The system was composed of ammonium polyphosphate (APP), melamine (MEL), and novel phosphorus‐based FRs. Because of the synergistic FR effects among the three FRs, the FR PP composites achieved a V‐0 classification, and the limiting oxygen index reached as high as 36.5%. In the cone calorimeter test, both the peak heat‐release rate (pHRR) and total heat release (THR) of the FR PP composites were remarkably reduced by the incorporation of the novel FR system. The FR mechanism of the MEL–APP–FR–PP composites was investigated through thermogravimetric analysis and char residue characterization, and the results reveal that the addition of MEL–APP–FRs promoted the formation of stable intumescent char layers. This led to the reduction of pHRR and THR and resulted in the improvement of the fire retardancy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45962.     

The effect of different palm oil‐based bio‐polyols on foaming process and selected properties of porous polyurethanes

Rigid polyurethane foams were successfully prepared by blending up to 70 wt% of two different palm oil‐based bio‐polyols with a petrochemical polyether polyol. The bio‐polyols were synthesized by epoxidation–oxirane ring‐opening process using water (PP102) and diethylene glycol (PP147), respectively. Due to the high viscosity of both bio‐polyols the reactive mixture was heated to start the foaming reaction at about 50 °C. Under these conditions, the gelling reactions speed up as the amount of PP147 increases but slow down to a great extent when PP102 is used. The thermal conductivity of modified foams is higher and the closed cell content lower compared to reference ones, even when the bio‐foams present a lower apparent density. However, all foams exhibit reduced water absorption, excellent dimensional stability and better thermal stability at temperatures up to 400 °C than the control foam. Conversely, their mechanical and dynamic mechanical properties become poorer as the PP147 concentration increases and even more so if PP102 is used instead. PP147 foams containing up to 50% bio‐polyol could be used as a green replacement of petroleum‐based ones in applications where excellent behaviour in compression (the most affected properties) is not fundamental, with the additional advantages of reduced density and increased content of bio‐derived components. © 2017 Society of Chemical Industry     

Nanoclay filled soy‐based polyurethane foam

Polyurethane foam was fabricated from polymeric diphenylmethane diisocyanate (pMDI) and soy‐based polyol. Nanoclay Cloisite 30B was incorporated into the foam systems to improve their thermal stabilities and mechanical properties. Neat polyurethane was used as a control. Soy‐based polyurethane foams with 0.5–3 parts per hundred of polyols by weight (php) of nanoclay were prepared. The distribution of nanoclay in the composites was analyzed by X‐ray diffraction (XRD), and the morphology of the composites was analyzed through scanning electron microscopy (SEM). The thermal properties were evaluated through dynamic mechanical thermal analysis (DMTA). Compression and three‐point bending tests were conducted on the composites. The densities of nanoclay soy‐based polyurethane foams were higher than that of the neat soy‐based polyurethane foam. At a loading of 0.5 php nanoclay, the compressive, flexural strength, and modulus of the soy‐based polyurethane foam were increased by 98%, 26%, 22%, and 65%, respectively, as compared to those of the neat soy‐based polyurethane foam. The storage modulus of the soy‐based polyurethane foam was improved by the incorporation of nanoclay. The glass transition temperature of the foam was increased as the nanoclay loading was increased. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Reinforcement of soy polyol‐based rigid polyurethane foams by cellulose microfibers and nanoclays

Water‐blown rigid polyurethane foams from soy‐based polyol were prepared and their structure–property correlations investigated. Cellulose microfibers and nanoclays were added to the formulations to investigate their effect on morphology, mechanical, and thermal properties of polyurethane foams. Physical properties of foams, including density and compressive strength, were determined. The cellular morphologies of foams were analyzed by SEM and X‐ray micro‐CT and revealed that incorporation of microfibers and nanoclays into foam altered the cellular structure of the foams. Average cell size decreased, cell size distribution narrowed and number fractions of small cells increased with the incorporation of microfibers and nanoclays into the foam, thereby altering the foam mechanical properties. The morphology and properties of nanoclay reinforced polyurethane foams were also found to be dependent on the functional groups of the organic modifiers. Results showed that the compressive strengths of rigid foams were increased by addition of cellulose microfibers or nanoclays into the foams. Thermogravimetric analysis (TGA) was used to characterize the thermal decomposition properties of the foams. The thermal decomposition behavior of all soy‐based polyurethane foams was a three‐step process and while the addition of cellulose microfibers delayed the onset of degradation, incorporation of nanoclays seemed to have no significant influence on the thermal degradation properties of the foams as compared to the foams without reinforcements. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and application of phosphorous‐containing bio‐polyols in polyurethane foams

A bio‐polyol phosphonate acting as the polyol component in the preparation of polyurethane foam was synthesized from the liquefaction product of bagasse by the halogenation of the liquefaction product followed by the Michaelis–Arbuzov rearrangement. The FT‐IR spectra showed that phosphorus‐containing groups were introduced into the polyol chain. The data of the viscosity and the hydroxyl number suggested that the bio‐polyol phosphonate would be a good polyol component in the preparation of polyurethane foam. The limiting oxygen index of polyurethane foam containing bio‐polyol phosphonate varied in the range of 24–28, while that of polyurethane foam without bio‐polyol phosphonate was 23, demonstrating that the introduction of the phosphorus‐containing group into the polymer helped to improve the flame retardancy. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40422.     

Phosphorus‐containing silica gel‐coated ammonium polyphosphate: Preparation,characterization, and its effect on the flame retardancy of rigid polyurethane foam

A phosphorus‐containing silica gel was synthesized via a reaction between phenyl dichlorophosphate, poly(ether polyol), and γ‐aminopropyltriethoxysilane. Ammonium polyphosphate (APP) was modified by the synthesized phosphorus‐containing silica gel (MAPP) and then incorporated into the rigid polyurethane foam (PU). Results showed that APP had a smaller particle size, lower initial decomposition temperature, better heat resistance at high temperature, and better compatibility with PU matrix after the modification. The cone calorimeter test results showed that the incorporation of MAPP obviously reduced the values including peak of heat release rate, total heat release, average effective heat of combustion, and total smoke release, and increased the char yield of PU composite comparing with APP. The improved flame retardancy of PU/MAPP composite was attributed to the quenching effect of PO· and PO₂· free radicals released by MAPP in the early stage and the improved thermal stability of phosphorus‐ and silicon‐containing char layer formed in the later stage. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46334.     

Polyurethane–cement‐based foams: Characterization and potential uses

The production of a new lightweight composite material based on polyurethane and Portland cement was investigated. The composite was obtained by the mixture of polyurethane foam precursors with different amounts of cement and water. To allow cement hydration, samples were aged in water and characterized through scanning electron microscopy, X‐ray diffraction, differential scanning calorimetry, and compressive testing. We studied the cement hydration reactions and the effect of the organic phase on hydration by determining the amount of chemically bonded water by calcination. The results showed that the amount of water affected the morphology and porosity of the foams and thereby affected the cement hydration reaction. Furthermore, the mechanical properties of the hybrid composite varied in a wide range, depending on the cement and water contents and on whether the hydrated cement particles behaved as fillers or were allowed to interact to form stronger inorganic networks within the polymeric matrix forming the bubble walls. The polyurethane–cement composite foams showed an increase in the stiffness and the yield strength. In addition, the ductile behavior of the polymeric foams was preserved, even at high filler loadings, due to the chemical compatibility between the hydroxyl groups of the polyol and the cement. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and flammability testing of epoxy functionalized phosphorous‐based flame retardants

Several potential new phosphorus‐containing flame retardant molecules were evaluated for heat release reduction potential by incorporation of the molecules into a polyurethane, generated from methylene diphenyl diisocyanate and 1,3‐propane diol. The heat release reduction potential of these substances was evaluated using the pyrolysis combustion flow calorimeter (PCFC). The polyurethanes were prepared in the presence of the potential flame retardants via solvent mixing and copolymerization methods to qualitatively evaluate their potential reactivity into the polyurethane prior to heat release testing. The functionality of the flame retardants was epoxide based that would potentially react with the diol during polyurethane synthesis. Flammability testing via PCFC showed that the heat release reduction potential of each of the flame retardants was structure dependent, with phosphates tending to show more effectiveness than phosphonates in this study, and alkyl functionalized phosphorus groups (phosphate or phosphonate) being more effective at heat release reduction than cyclic functionalized groups. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42296.     

Development of water‐blown bio‐based thermoplastic polyurethane foams using bio‐derived chain extender

Water‐blown bio‐based thermoplastic polyurethane (TPU) formulations were developed to fulfill the requirements of the reactive rotational molding/foaming process. They were prepared using synthetic and bio‐based chain extenders. Foams were prepared by stirring polyether polyol (macrodiol), chain extender (diol), surfactant (silicone oil), chemical blowing agent (distilled water), catalyst, and diisocyanate. The concentration of chain extender, blowing agent, and surfactant were varied and their effects on foaming kinetics, physical, mechanical, and morphological properties of foams were investigated. Density, compressive strength, and modulus of foams decrease with increasing blowing agent concentration and increase with increasing chain extender concentration, but are not significantly affected by changes in surfactant concentration. The foam glass‐transition temperatures increase with increasing blowing agent and chain extender concentrations. The foam cell size slightly increases with increasing blowing agent content and decreases upon surfactant addition (without any dependence on concentration), whereas chain extender concentration has no effect on cell size. Bio‐based 1,3‐propanediol can be used successfully for the preparation TPU foams without sacrificing any properties. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Characterization of flexible polyurethane foams based on soybean‐based polyols

Two series of flexible polyurethane foams were fabricated by substituting conventional petroleum‐based polyols with increasing amounts of soy‐based polyols (SBP) having different hydroxyl numbers. The mechanical properties of the foams were characterized by stress–strain analysis in the compression mode and DMA in tension mode, the cellular morphology was analyzed by SEM and the microphase‐separation of the foams was noted by SAXS. Our results showed that the cellular morphology and mechanical properties of the flexible foams were affected significantly by the foam fabrication method and SBP hydroxyl numbers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Rigid polyurethane foams made from high viscosity soy‐polyols

This study investigated the physical properties of water‐blown rigid polyurethane (PU) foams made from VORANOL®490 (petroleum‐based polyether polyol) mixed with 0–50% high viscosity (13,000–31,000 cP at 22°C) soy‐polyols. The density of these foams decreased as the soy‐polyol percentage increased. The compressive strength decreased, decreased and then increased, or remained unchanged and then increased with increasing soy‐polyol percentage depending on the viscosity of the soy‐polyol. Foams made from high viscosity (21,000–31,000 cP) soy‐polyols exhibited similar or superior density‐compressive strength properties to the control foam made from 100% VORNAOL® 490. The thermal conductivity of foams containing soy‐polyols was slightly higher than the control foam. The maximal foaming temperatures of foams slightly decreased with increasing soy‐polyol percentage. Micrographs of foams showed that they had many cells in the shape of sphere or polyhedra. With increasing soy‐polyol percentage, the cell size decreased, and the cell number increased. Based on the analysis of isocyanate content and compressive strength of foams, it was concluded that rigid PU foams could be made by replacing 50% petroleum‐based polyol with a high viscosity soy‐polyol resulting in a 30% reduction in the isocyanate content. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013