Evaluation of Hydrophobic Polyurethane Foam as Sorbent Material for Oil Spill Recovery

In this work, hydrophobic polyurethane foam was prepared using hy-drosilicone oil-grafted polybutadiene as soft segment via foaming technology. It was found that the hydrophobic polyurethane foams exhibited good hydrophobic capability and were regenerated easily. Of great interest, the hydrophobic polyurethane foams expand in contact with the oils. This indicates that the process of sorption by the hydrophobic polyurethane foams involves both the filling of the pores with oils and the absorption of oils by the polymer regions (polyurethane elastomer skeleton), and the adsorption capacity of the hydrophobic polyurethane foams can be enhanced by the swelling of the polyurethane elastomer skeleton. We can use this finding to improve the adsorption capacity of the hydrophobic polyurethane foams without merely changing the porosity. The effect of the swelling property of the hydrophobic polyurethane foams on the sorption capacity was further investigated. The results suggest that the hydrophobic polyurethane foams are promising in the application of oil spill recovery.     

基于天然聚多糖的环境友好材料（II）-麻纤维和芦苇纤维多元醇的生物降解聚氨酯

以麻纤维和芦苇纤维制备的植物多元醇为原料,合成具有良好性能的生物降解 性硬质聚氨酯泡沫体,其密度40 kg/m~3左右,压缩强度150 kPa,弹性模量4 MPa 。而且多元醇中植物原料含量越大,其性能越好,这使植物原料的充分利用和材料 生产成本的降低成为可能。土壤掩埋实验表明,泡沫体有很好的土壤微生物降解性 。     

Ion-exchange foam chromatography: Part I. Preparation of rigid and flexible ion-exchange foams

In order to be able to apply the principles of foam chromatography to ion-exchange processes, preparative methods for open-cell ion-exchange foams, were investigated. Homogeneous ion-exchange foams were prepared by introducing ion-exchange groups on previously prepared phenol-formaldehyde, polyurethane and polyethylene foams. The maximum capacity of the produced sulfonated phenol-formaldehyde cation-exchange foams was 1.85 meq g^-1; that of the styrene-polyurethane interpolymer anion-exchange foams was 2.2 meq g^-1. Weak carboxylic ion-exchange foams were prepared by radiation grafting of polyurethane and polyethylene foams; the maximum capacity of these foams was 4.02 meq g^-1. Heterogeneous ion-exchange foams were prepared by foaming a fine powder of a commercially available cation exchanger with the precursors of open-cell polyether-type polyurethane foam. The capacity of such a foam containing 26% ion-exchange powder was 1.0 meq g^-1. The kinetics of the cation-exchange process on the heterogeneous foams was measured with ⁸⁵Sr.     

Epoxy modified polyurethane rigid foams

Rigid IPN foams were prepared by sequential polymerization of polyurethane and epoxy systems. Significantly higher compressive modulus and strength were observed with the IPN foams in comparison to the corresponding polyurethane rigid foams. The IPN foams show one glass transition temperature. The single T_g indicates the very small domain size in the PU-epoxy IPN's.     

An investigation of the influence of polymeric surfactants on the structure and properties of polyurethane foams

Features of fine-mesh structure polyurethane foams depending on the use of surfactants in the curing process were identified for the first time. It was revealed that a distinct change in the physical properties of polyurethane foams take place when adding the surfactants.     

The recovery of gold from thiourea solutions with open-cell polyurethane foams

The recovery of the gold-thiourea complex from aqueous solutions with TBP-loaded and unloaded polyurethane foams was investigated in batch experiments. The rates of adsorption of the gold complex on various types of loaded and unloaded foams were studied in detail and compared with the rate of adsorption on active carbon. Loaded and unloaded polyurethane foams of the polyether or polyester type behaved similarly to active carbon. The adsorption capacity of the foams was lower than that of active carbon but the use of foam simplifies the procedure by eliminating the filtration process which is necessary with carbon.     

New polyurethane foams modified with cellulose derivatives

New polyurethane foams were elaborated with different cellulose derivatives as raw material, by the one-shot process. The foams were submitted to soxhlet extraction in order to quantify the amount of cellulose derivative incorporated in the foam by chemical bonding. The foams were characterized by means of FTIR, solid state ¹³C NMR spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy and dynamic mechanical analysis (DMA). The FTIR- and solid state ¹³C NMR showed characteristic peaks for cellulose derivatives and polyurethane. DMA measurements indicated that storage modulus increased with increasing content of cellulose derivatives. The highest value was obtained for foams prepared with cellulose sulphate.     

WATER-BLOWN POLYURETHANE RIGID FOAMS MODIFIED BY CHEMICAL PLASTICATION

Water-blown polyurethane rigid foams are getting more and more attention, because the traditional blowing agent HCFC141b has already been abolished to prevent the ozone layer from destruction. However, the polyurethane rigid foams blown by water have serious defects, i.e. friability and resulting lower adhesion strength. Thus, the purpose of this study is to resolve the problems by chemical plastication. The maleate was added to polyol-premix containing water or to polyisocyanate,with both of which maleate does not react. To prove the reaction when polyol-premix and polyisocyanate were mixed, the model composite was synthesized and analyzed by IR, NMR and ESI (MS). Furthermore, a series of water-blown polyurethane rigid foams added different amount maleate were successfully prepared. By testing impact strength and adhesion strength of the foams, the actual effect of adding maleate was obtained.     

WATER-BLOWN POLYURETHANE RIGID FOAMS MODIFIED BY CHEMICAL PLASTICATION

1. INTRODUCTIONThese years, HCFC-141b may be the most used blowing agent for its useful properties. But, because of its high global warming effect leading to the destruction of the ozone layer, production of HCFC141b has been forbidden. However, there are…     

The 3D structure of real polymer foams

The intricate structure of polymeric foams may be examined using 3D imaging techniques such as MRI or X-ray tomography followed by image processing. Using a new 3D image processing technique, six images of polyurethane foams were analyzed to create computerized 3D models of the samples. Measurements on these models yielded distributions of many microstructural features, including strut length and window and cell shape distributions. Nearly 8000 struts, 4000 windows, and 376 cells were detected and measured in six polyurethane foam samples. When compared against previous theories and studies, these measurements showed that the structure of real polymeric foams differs significantly from both equilibrium models and aqueous foams. For example, previous studies of aqueous foams showed that about 70% of foam windows were pentagons. In the polymeric sample studied here, only 55% of windows were pentagonal.     

Preparation and characterization of rigid polyurethane–polyglycerol nanocomposite foams

This work reports on the preparation of polyurethane–polyisocyanurate (PUR–PIR) foams containing different polyglycerols and layered silicate nanoclays. The rigid polyurethane foams were obtained in a laboratory scale, in a single step method, from a two-component system with a NCO to OH groups ratio equal to two. The reaction mixture consisted of the proper amounts of a commercial oligoetherpolyol, polyglycerol, catalysts, water, nanofiller, and polymeric diphenylmethane diisocyanate. The obtained foams containing 6% of one of three types of montmorillonite (MMT) (Cloisite 30B, Laponite RD, Bentonite) were characterized in terms of their structure, density, brittleness, compressive strength and thermal stability. The nanocomposite foams showed a higher number of cells with a smaller cell size in the presence of MMT, while the foams modified with nanofiller Cloisite 30B presented the best compressive strength and the best fire resistance.     

Effects of biopitch on the properties of flexible polyurethane foams

Biopitches are industrial residues obtained by the distillation of the tar recovered during Eucalyptus charcoal production and can be used as a renewable polyol source. Flexible polyurethane foams were prepared with different proportions of biopitch and HTPB (hydroxyl-terminated polybutadiene) and using polymeric MDI (4,4′ diphenyl methane diisocyanate), N,N dimethylcyclohexylamine as a catalyst and water as a blowing agent. Elemental analysis, thermal analysis (TG/DSC), Fourier Transform Infrared Spectroscopy (FTIR), scanning electronic microscopy (SEM), and density results were used aiming to discuss the contribution of biopitch to foams properties. The higher the biopitch content, the higher the thermal stability and the lower the density of the flexible foams (air atmosphere), behaviors similar to those of lignin-based polyurethanes. Biopitch enhanced the oxygen content of the polyurethane foams synthesized, and their reaction with HTPB resulted in stable foams.     

Thermal characteristics of polyurethane foams incorporated with phase change materials

Thermal energy storage plays an important role in heat management because of the demand for developed energy conservation, and has applications in diverse areas, from building heating/cooling systems which enable solar energy incorporation into the structure, to textiles and clothings providing an enhanced thermal comfort. In this study, we aimed to improve thermal characteristics of polyurethane rigid foams that have been widely used for thermal insulation as the ultimate energy savers due to their ability to form sandwich structures with various facer materials. Through a laboratory-scale work, two paraffin waxes acting as phase change materials, namely n-hexadecane and n-octadecane, each of which is capable of managing large heat storage/release, were directly incorporated into the polyurethane foams at different ratios. Polymerization modified by means of n-alkane addition could be achieved without any adverse effect. In order to determine both structural and thermal characteristics, seven types of foams produced were examined by FT-IR, SEM, DSC analyses, calorimeter bomb and mechanical tests. Results show that polyurethane foams can be designed as thermal insulators equipped with an improved buffering function against temperature changes.     

Local analysis by infrared microscopy across membranes of a flexible polyurethane foam

Summary To contribute to the understanding of cell stability and cell opening in polyurethane foam, model foams with large cells were prepared and localised analysis was carried out across single membranes by means of IR-microscopy to measure membrane thickness, polyurethane and polyurea content.     

聚氨酯/环氧树脂互穿网络聚合物的性能研究

互穿聚合物网络（Interpenetrating polymer net-work,简称IPN）广泛应用的为聚氨酯基的互穿网络聚合物。其合成多集中在弹性体方面。本文用同步法合成的聚氨酯／环氧树脂互穿网络硬质泡沫塑料材料（简称PU／ERIPNF）,机械性能较好,并研究了其动态力学性能及形态变化。     

Atmospheric Pressure Liquefaction of Dried Distillers Grains (DDG) and Making Polyurethane Foams from Liquefied DDG

In this study, dried distillers grains (DDG) was liquefied in acidic conditions at atmospheric pressure, and polyurethane foams were subsequently prepared from the liquefied DDG. Liquefaction was examined over a range of conditions including liquefaction time of 1–3 h, temperature of 150–170 °C, sulfuric acid (as catalyst) concentration of 1.0–3.0 wt%, and liquefaction solvent (ethylene carbonate) to DDG ratio of 3:1–5:1. The bio-polyols in the liquefied DDG were rich in hydroxyl groups, which can react with methylene diphenyl diisocyanate (MDI) to form cross-linked polyurethane networks. The biodegradability of the prepared polyurethane foams was also evaluated. This study strives to broaden the application of DDG as a feedstock for bio-polyurethane preparation.     

Polyurethane‐graphene nanocomposite foams with enhanced thermal insulating properties

The improvement of thermal insulating performance of polyurethane rigid foams is a crucial task for their use. In this work, the effect of graphene on these properties has been studied by preparing and testing unfilled, 0.3 and 0.5 wt% graphene‐filled polyurethane foams. It was found that graphene is able, at very low content (0.3 wt%), to reduce the radiative contribution of the initial thermal conductivity by both decreasing the cell size and increasing the extinction coefficient. Due to the low graphene contents considered, no concerns about the solid‐phase contribution of thermal conductivity arise. Polyurethane–graphene nanocomposite foams showed also slower aging rate with respect to unfilled foams. Copyright © 2015 John Wiley & Sons, Ltd.     

Recovery of polyols from flexible polyurethane foam by “split-phase” glycolysis: Glycol influence

Scrap of flexible polyurethane foams from slabstock manufacturing comprises about 10% of the total production, leading to not only an environmental problem but also an economic one. The general purpose of polyurethane chemical recycling is to recover a valuable constituent, the polyol. Among the processes suitable, glycolysis, and specially glycolysis in two phases seems to be the method that allows better quality products. In this study glycolysis of flexible polyurethane foams in “split phase” was conducted with different glycols, in order to study their activity and select a system to obtain the highest quality recovered polyol. Reaction kinetics and the products obtained were investigated. Times required to reach complete conversion, chemical properties of the polyol phase and its purity depended on the glycol employed. Diethylene glycol proved to be the most suitable glycol to obtain a high purity in the polyol phase.     

A 1H magnetic resonance imaging study of porosity in polyurethane foams

¹H magnetic resonance imaging (MRI) is used to study the distribution of water in polyurethane foams. Flexible open-celled foams are easily distinguished from the closed-cell foams as the latter does not absorb any detectable amounts of water. Flexible foams degassed in vacuo revealed no structural detail due to the resolution limitation of approximately 100 μm. Incompletely degassed foams revealed considerable areas of trapped gas which were recorded as a function of distance beneath the water. Samples injected with water indicated that a tortuous flow pathway is taken due to the presence of cell windows. Samples with lower porosity had a higher resistance to flow.     

Influence of iron content on thermal stability of magnetic polyurethane foams

Magnetorheological (MR) materials are a group of smart materials which have the controllable magnetic properties with an external magnetic field. Magnetic foams, a specific type of MR solids, were synthesized from flexible polyurethane (PU) foams and carbonyl iron particles. Effects of the carbonyl iron particles on the thermal stability of the magnetic foams have been studied. Thermogravimetric analysis (TGA) was applied to characterize the thermal degradation process of the magnetic foams and then the apparent activation energy of degradation was calculated by using Ozawa's method [Ozawa T. A new method of analyzing thermogravimetric data. Bulletin of the Chemical Society of Japan 1965; 38: 1881-1886.]. The carbonyl iron particles were found to improve the thermal stability of magnetic foams in nitrogen by showing higher 10 wt% loss temperature, slower weight loss rate and higher apparent activation energy than pure PU foams. But the magnetic foams were observed to have slightly worse thermal stability in air than pure PU foams at the earlier degradation stage. At the later degradation stage, the magnetic foams exhibited the higher activation energy than pure PU foams in air.