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     

Mechanical and thermal properties of phenolic/glass fiber foam modified with phosphorus‐containing polyurethane prepolymer

Phenolic foam exhibits outstanding flame, smoke and toxicity properties, good insulation properties and low production costs. However, the brittleness and pulverization of phenolic foam have severely limited its application in many fields. In this study, a novel phosphorus‐containing polyurethane prepolymer (DOPU) modifier was firstly synthesized, and then the foaming formula and processing of toughening phenolic foam modified with DOPU and glass fiber were explored. The structure and reactive behavior of prepolymer and phenolic resin were investigated using Fourier transform infrared spectroscopy. The effects of DOPU and glass fiber on the apparent density, compressive strength, bending strength and water absorption were investigated. The results suggested that the apparent density, compressive strength and bending strength of modified phenolic foam tended to increase irregularly with increasing content of DOPU. The addition of DOPU led to lower water absorption of glass fiber‐filled foam. Thermal stability and flame retardancy were examined using thermogravimetric analysis and limiting oxygen index (LOI) tests. It was found that foam with 3% DOPU and 0.5% glass fiber added exhibited good thermal stability and high char yields. The LOI value of modified phenolic foams decreased with increasing DOPU content, but it still remained at 41.0% even if the amount of modifier loaded was 10 wt%. © 2012 Society of Chemical Industry     

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     

Thermosetting foam with a high bio‐based content from acrylated epoxidized soybean oil and carbon dioxide

A resilient, thermosetting foam system with a bio‐based content of 96 wt % (resulting in 81% of C₁₄) was successfully developed. We implemented a pressurized carbon dioxide foaming process that produces polymeric foams from acrylated epoxidized soybean oil (AESO). A study of the cell dynamics of uncured CO₂/ AESO foams proved useful to optimize cure conditions. During collapse, the foam's bulk density increased linearly with time, and the cell size and cell density exhibited power‐law degradation rates. Also, low temperature foaming and cure (i.e. high viscosity) are desirable to minimize foam cell degradation. The AESO was cured with a free‐radical initiator (tert‐butyl peroxy‐2‐ethyl hexanoate, T_i ～ 60°C). Cobalt naphtenate was used as an accelerator to promote quick foam cure at lower temperature (40–50°C). The foam's density was controlled by the carbon dioxide pressure inside the reactor and by the vacuum applied during cure. The viscosity increased linearly during polymerization. The viscosity was proportional to the extent of reaction before gelation, and the cured foam's structure showed a dependence on the time of vacuum application. The average cell size increased and the cell density decreased with foam expansion at a low extent of cure; however, the foam expansion became limited and unhomogeneous with advanced reaction. When vacuum was applied at an intermediate viscosity, samples with densities ～ 0.25 g/cm³ were obtained with small (<1 mm) homogeneous cells. The mechanical properties were promising, with a compressive strength of ～ 1 MPa and a compressive modulus of ～ 20 MPa. The new foams are biocompatible. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Processing‐structure‐property relationship in rigid polyurethane foams

Rigid polyurethane (PU) foam is used as a thermal insulating and supporting material in domestic refrigerator/freezers and it is produced by reaction injection molding (RIM) process. There is a need to improve the thermal property of rigid PU foam but this is still a challenging problem. Accordingly, this work investigates the RIM process parameters to evaluate their effects on rigid PU foam's structure and hence property. It has been found that mold temperature is a key parameter whereas curing time has negligible effect on structure of PU foam. Cell size, strut thickness, and foam density have been found very critical in controlling the thermal and mechanical properties. Upper and lower values of 30 to 32 kg/m³ density are critical to observe contribution of radiation and solid conductivity separately. Finally, PU foam with 160 µm average cell size, 16 µm strut thickness, below 10% open cell content, and 30 to 32 kg/m³ density allow obtaining better thermal insulation without significant reducing in the compressive strength. The presented work provides a better understanding of processing‐structure‐property relationship to gain knowledge on producing high‐quality rigid PU foams with improved properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44870.     

Development of polylactide open‐cell foams with bimodal structure for high‐acoustic absorption

In this study, a highly porous and interconnected foam structure was fabricated using compression molding combined with particulate‐leaching technique. The foamed structures were fabricated with polylactide (PLA) and polyethylene glycol (PEG) with salt as the particulate. The pore size of the foam structure is controlled by the particulates size and higher interconnectivity is achieved by the co‐continuous blending morphology of the PLA matrix with the water‐soluble PEG. PLA is a fully bio‐based thermoplastic polymer and is derived from renewable resources, such as cornstarch or sugarcanes. PEG is also fully biodegradable polymer produced from ethylene. Fabricated foams were characterized for cellular, acoustic, and mechanical properties. The acoustic performance of the foams was studied by measuring the normal incident absorption coefficient in accordance with the ASTM E1050 standard. The results show open porosity as high as 88% was achieved and the effect of water‐soluble polymer on cellular properties and acoustic and mechanical performance of the foams was studied. As a result of the secondary porous structure formed into cell walls by water soluble polymer, the overall absorption of fabricated PLA foams was increased to above 90% while the average absorption of the foams remained unchanged. In addition, the resulting acoustic foams are benign and environmentally friendly. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39518.     

Production of a high‐functionality RBD palm kernel oil‐based polyester polyol

A diol‐based refined, bleached, and deodorized (RBD) palm kernel oil polyol was prepared. It was found that the polyurethane foam produced only gives a good compressive strength property at a 45 kg/m³ molded density. The combination of sorbitol into the polyol system resulted in a better dimensional stability and improved thermal conductivity as well as enhanced compressive strength. These were obtained by increasing the functionality of the polyol (functionality of 4.5) through introduction of a high molecular weight and branching polyhidric compound. Direct polycondensation and transesterification methods were used for the syntheses. The hydroxyl value, TLC, and FTIR were used to study the completion of the reaction. A comparative study of the mechanical properties and morphological behavior was carried out with a diol‐based polyol. From the water‐blown molded foam (zero ODP) with a density of about 44.2 kg/m³ and a closed‐cell content of 93%, a compressive strength of 222 kPa and a dimensional stability of 0.09, 0.10, and 0.12% at the length, width, and thickness of the foam, respectively, conditioned at ?15°C for 24 h, were obtained. The thermal conductivity improved to an initial value of 0.00198 W/mK, tested at 0°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 384–389, 2001     

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     

Comparative study of physical properties of water‐blown rigid polyurethane foams extended with commercial soy flours

The use of renewable resources (mainly carbohydrates) in rigid polyurethane foam has been known to offer several advantages, such as increased strength, improved flame resistance, and enhanced biodegradability. Less attention has been directed to inexpensive protein‐based materials, such as defatted soy flour. The objectives of this study were to develop water‐blown rigid polyurethane foams, containing defatted soy flour, that have acceptable or improved physical properties which also lower the cost of the foam formulation and to compare the properties of developed foams extended with three kinds of commercial soy flour. Water‐blown low‐density rigid polyurethane foams were prepared with poly(ether polyol)s, polymeric isocyanates, defatted soy flour, water, a catalyst mixture, and a surfactant. Soy flour and the initial water content were varied from 0 to 40% and from 4.5 to 5.5% of the poly(ether polyol) content, respectively. A standard laboratory mixing procedure was followed for making foams using a high‐speed industrial mixer. After mixing, the mixture was poured into boxes and allowed to rise at ambient conditions. Foams were removed from boxes after 1 h and cured at room temperature for 24 h before measurement of the thermal conductivity and for 1 week before other property tests. Foam properties were determined according to ASTM procedures. Measurement of the physical properties (compressive strength, modulus, thermal conductivity, and dimensional stability under thermal and humid aging) of these foams showed that the addition of 10–20% of three kinds of soy flour imparted water‐blown rigid polyurethane foams with similar or improved strength, modulus, insulation, and dimensional stability. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 10–19, 2001     

Halogen‐free flame‐retardant rigid polyurethane foams: Effect of alumina trihydrate and triphenylphosphate on the properties of polyurethane foams

Rigid polyurethane foam (PUF) filled with mixture of alumina trihydrate (ATH) and triphenyl phosphate (TPP) as fire retardant additive was prepared with water as a blowing agent. In this study, the ATH content was varied from 10 to 100 parts per hundred polyol by weight (php), and TPP was used at a higher loading of ATH (75 and 100 php) in a ratio of 1 : 5 to enhance the processing during PUF preparation. The effects of ATH on properties such as density, compressive strength, morphological, thermal conductivity, thermal stability, flame‐retardant (FR) behavior, and smoke characteristics were studied. The density and compressive strength of the ATH‐filled PUF decreased initially and then increased with further increase in ATH content. There was no significant change in the thermal stability with increasing ATH loading. We determined the FR properties of these foam samples by measuring the limiting oxygen index (LOI), smoke density, rate of burning, and char yield. The addition of ATH with TPP to PUF significantly decreased the flame‐spread rate and increased LOI. The addition of TPP resulted in easy processing and also improved FR characteristics of the foam. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Mechanical and acoustic performance of compression‐molded open‐cell polypropylene foams

Open‐cell materials are lightweight and multifunctional capable of absorbing acoustic energy and supporting mechanical load. The acoustic and mechanical performance of open‐cell materials can be optimized through processing. In this article, the relationships between processing parameters and acoustic and mechanical performance are shown for polypropylene (PP) foams. PP foam samples are fabricated using a combined compression molding and particulate leaching process. The results from a parametric study showed that both salt size and salt to polymer ratio affect the acoustic and mechanical performance of open‐cell PP foams. As salt size increases, cell size increased and cell density decreased. The salt to polymer ratio had opposite affect on cell density, and increasing the salt to polymer mass ratio increased the open‐cell content. The airflow resistivity decreased significantly by increasing the cell size, which means that foam samples with smaller cell size have better sound absorption. When foam samples were thin, smaller cell sizes produced better sound absorption; however, as thickness of the sample increases, medium cell size offered the best acoustic performance. The compressive strength of the foams was increased by increasing the relative density. Acoustic performance results from the parametric study were compared to the Johnson‐Allard model with good agreement. Finally, optimal cellular morphologies for acoustic absorption and mechanical performance were identified. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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     

Mechanical properties of a particle‐strengthened polyurethane foam

Quasi‐static compression tests have been performed on polyurethane foam specimens. The modulus of the foam exhibited a power‐law dependence with respect to density of the form: E* ∝ (ρ*)ⁿ, where n = 1.7. The modulus data are described well by a simple geometric model (based on the work of Gibson and Ashby) for a closed‐cell foam in which the stiffness of the foam is governed by the flexure of the cell struts and cell walls. The compressive strength of the foam is also found to follow a power‐law behavior with respect to foam density. In this instance, Euler buckling is used to explain the density dependence. The modulus of the foam was modified by addition of gas‐atomized, spherical, aluminum powder. Additions of 30 and 50 wt % Al measurably increased the foam modulus, but without a change in the density dependence. However, there was no observable increase in modulus with 5 and 10 wt % additions of the metal powder. Strength was also increased at high loading fractions of powder. The increase in modulus and strength could be predicted by combining the Gibson–Ashby model, referred to above, with a well‐known model describing the effect on modulus of a rigid dispersoid in a compliant matrix. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2724–2736, 1999     

Hyperbranched‐modified epoxy thermosets: Enhancement of thermomechanical and shape‐memory performances

In this study a complete characterization of the thermomechanical and shape‐memory properties of epoxy shape‐memory polymers modified with hyperbranched polymer and aliphatic diamine was performed. Focusing on the mechanical properties that are highly desirable for shape‐memory polymers, tensile behavior until break was analyzed at different temperatures and microhardness and impact strength were determined at room temperature. As regards shape memory performance, the materials were fully characterized at different programming temperatures to study how this influenced the recovery ratio, fixity ratio, shape‐recovery velocity, and switching temperature. Tensile testing revealed a peak in deformability and in the stored energy density at the onset of the glass transition temperature, demonstrating that this is the best programming temperature for obtaining the best shape‐memory performances. The Young's moduli revealed more rigid structures in formulations with higher hyperbranched polymer content, while microhardness showed higher values with increasing hyperbranched polymer content due to the increased crosslinking density. Impact strength was greatly improved as the aliphatic diamine content increases due to the energy dissipation capability of its flexible structure. As regards the shape‐memory properties, increasing the programming temperature has a minor effect on formulations with a lower hyperbranched polymer content and worsens these properties when the hyperbranched polymer content is increased. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44623.     

Highly flame‐retardant polyurethane foam based on reactive phosphorus polyol and limonene‐based polyol

Polyurethane foams are in general flammable and their flammability can be controlled by adding flame‐retardant (FR) materials. Reactive FR have the advantage of making strong bond within the polyurethane chains to provide excellent FR over time without compromising physico‐mechanical properties. Here, phenyl phosphonic acid and propylene oxide‐based reactive FR polyol was synthesized and used along with limonene based polyol for preparation of FR polyurethanes. All the obtained foams showed higher closed cell content (above 96%). By the addition of FR–polyol, the compressive strength of the foams showed 160% increment which could be due to reactive nature of FR–polyol. Moreover, 1.5 wt % of phosphorus (P) content reduced the self‐extinguishing time of the foam from 81 (28% weight loss) to 11.2 s (weight loss of 9.8%). Cone test showed 68.6% reduction in peak heat release rate along with 23.4% reduction in thermal heat release. The change in char structure of carbon after burning was analyzed using Raman spectra which, suggests increment in the graphitic phase of the carbon over increased concentration of phosphorus. It can be concluded from this study that phosphorous based polyol could be blended with bio‐based polyols to prepare highly FR and superior physico‐mechanical rigid polyurethane foams. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46224.     

泡沫掺量对发泡碱激发矿渣聚合物性能和孔隙特征的影响

以水玻璃激发矿渣为胶凝材料,采用压缩空气发泡方式制备了泡沫矿渣聚合物材料,通过Image-Pro plus(IPP)表征了不同泡沫掺量下泡沫矿渣聚合物的孔隙结构特征,并研究了泡沫掺量对泡沫矿渣矿物聚合物干密度、抗压强度和导热系数的影响.结果表明:当泡沫掺量为4.45%~10.70%(质量分数)时,随泡沫掺量增加,泡沫矿渣聚合物的孔隙率增加、平均孔径及孔圆度值增大,泡沫矿渣聚合物相应的干密度、抗压强度和导热系数均呈负指数关系降低且相关性强;当泡沫掺量为4.45%~12.00%(质量分数)时,所制备碱激发矿渣聚合物泡沫材料的干密度389~1325 kg/m3、抗压强度1.12~17.81 MPa、导热系数0.0813~0.2211 W/(m·K),其综合性能优于通用水泥泡沫混凝土制品.     

Development,characterization, and modeling of environmentally friendly open‐cell acoustic foams

This study shows the development of new polymeric open‐cell foams from polypropylene (PP) and polylactide (PLA) resins with a focus on sound absorption properties and modeling of these foams. The objective is to develop new environmentally friendly foams to replace the existing non‐recyclable Polyurethane foams are currently used for sound insulation in industry. Through this research, open‐cell foams of about 90% porosity were fabricated from PP and PLA. These resins were selected since PP is a recyclable thermoplastic polymer, and PLA is a bio‐based thermoplastic polymer made from renewable resources. Polyurethane (PU) foam which is currently used for sound absorption and noise control in industry was compared to the fabricated PP and PLA foams. As the first attempt to fabricate environmentally friendly acoustic foams, the resulting foam structures show improved properties as compared to the existing materials. The average absorption of PP and PLA foams fabricated is in the range of 0.42–0.55 which is comparable or even higher than the average absorption of PU foam. To better understand the effect of structural and material properties on sound absorption and further improve the acoustic performance of bio‐based foams, an analytical model based on Johnson–Champoux–Allard model was used to numerically simulate the acoustic performance of foams under study. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers     

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     

Physico‐Mechanical Properties,Odor and VOC Emission of Bio‐Flour‐Filled Poly(propylene) Bio‐Composites with Different Volcanic Pozzolan Contents

Summary: This study investigated the physico‐mechanical properties, odor and VOC emission of bio‐flour filled PP bio‐composites with different pozzolan contents. On increasing the pozzolan content, the tensile and flexural strengths of the bio‐composites were not significantly changed, whereas the impact strength and water absorption increased slightly and the odor intensity decreased due to the absorption of thermal degradation gases of PP and bio‐flour at the pore surface of the pozzolan. The VOC emission of the bio‐composites, analyzed by GC‐MSD, was mainly due to PP oxidation and the thermal degradation of bio‐flour during the extrusion process at high manufacturing temperatures. With increased pozzolan content, other organic compounds of the bio‐composites were not significantly changed, but the toluene emission of the bio‐composites was decreased. SEM and SEM/EDX mapping techniques were employed to investigate the porous form and the pozzolan distribution in the bio‐composites. From these results, we concluded that the addition of pozzolan in the bio‐composites was an effective method for reducing their odor and VOC emission without any reduction in mechanical properties.

SEM micrograph of pozzolan (10 000×).     

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