Polyether Foam Research Articles

Chemical degradation of polyurethanes2. Degradation of flexible polyether foam by dimethyl phosphonate

Flexible polyether polyurethane foam based on toluene diisocyanate and polyether polyol has been liquefied by dimethyl phosphonate (CH 3O) 2P(O)H at 160°C. The degraded products have been studied by 1H, 13C and 31P NMR spectroscopy and shown to be phosphorus-containing oligomers.

Molecular Structure of the Hard Segments in Flexible Foams

The main basis of structure-property-relationships of polymeric materials is a good characterization of the structure under study. Such is the case for cross linked polyurethanes such as flexible foams. To overcome the problems of solubility of these materials, a selective degradation process was used, leaving the hard segments unaffected. These were then analyzed by MALDI-TOF (Matrix Assisted Laser Desorption-Ionization Time of Flight mass spectrometry). Using these techniques, the length distribution of the hard segments was examined. It was found that the length of the hard segments decreases much slower for polyester foams than for polyether foams. This fact was attributed to a lower solubility of the hard segments in polyethers, which leads to an earlier onset of phase separation. Thus, both mobility and reactivity of the segments in the segregated hard domains are reduced. This fact also explains why the length of the hard segments is only slightly dependent on the water content, or the index, at least in polyether foams. Chemical differences such as the incorporation of polymeric MDI or reactive catalysts could also be shown. Furthermore, this work shows for the first time that presence of cyclic hard segments could be established in a foam.

Modeling of iron adsorption on HTTA-loaded polyurethane foam using Freundlich, Langmuir and D-R isotherm expressions

The sorption of Fe(III) at low pH range from 1 to 4.5 on open cell polyether type HTTA-loaded polyurethane foam has been carried out using batch technique. The optimum shaking time for 2.5· 10−4M solution of Fe(III) was found to be 30 minutes. The concept of macropore and micropore nature of polyurethane foam sorbent offers unique advantages of adsorption. Freundlich and Langmuir adsorption isotherms are followed at low concentration range from 1·10−4 to 3·10−4M solution of Fe(III). The Freundlich constant (1/n=0.46±0.013 andK=9.16±1.39 mg·g−1) and Langmuir isotherm constants(M=21.78 mg·g−1 andb=88.41±9.731·g−1) were established. The sorption mean free energyE=12.22±0.09 kJ·mol−1 and loading capacityCm=145.21±6.1 mg·g−1 were evaluated using Dubinin-Radushkevich isotherm, which suggested that the adsorption mechanism was chemisorption.

Preconcentration and separation of acaricides by polyether based polyurethane foam

This paper reports the preconcentration of some dissolved organic phosphorous and chlorinated acaricides in water by porous polyether based polyurethane foam. Preliminary screening tests on the retention of the tested compounds, i.e., dicofol and bromopropylate, by polyether foams indicated that a very high percent removal of the tested species was obtained. The retention rate was found fast and reaches equilibrium in a few minutes. The various parameters, e.g., pH, extraction media, shaking time, salt effect, temperature and sample volumes affecting the preconcentration of the tested species by the unloaded foam, trioctylamine and trimethylphosphate treated foam have been optimized via batch modes of separation. The unloaded foams were employed in column modes for the retention and recovery of the tested species. The sorption efficiency and recovery of the compounds by the unloaded foams column were found to be up to 97.5%. The height equivalent to a theoretical plate (HETP) obtained by the unloaded foam was found to be in the range 1.1-1.3 ± 0.2 mm. The sorption mechanism of the tested compounds by the foams was discussed.

Reconstituted Versus Virgin Open Cell Foams in Floating Floors

Sound reducing flooring systems using flexible polymer foams as a decoupling resilient layer are increasingly being used in both new build and refurbishment. Such foams have been investigated and results suggest that reconstituted polyether foam from waste products may offer some advantages over the low density open cell l.d.o.c.) foams currently used in some systems. It has been shown that reconstituted open cell (o.c.) foams have an almost linear compressive stress-strain relationship up to about 40% strain without the marked yield point observed with virgin o.c. foams. Stress strain characteristics for reconstituted o.c. and virgin l.d.o.c. foams compared in this study indicate that, for stresses below the yield point for the virgin foam, greater strain is observed in reconstituted foam. When tested according to BSEN 29052-1, systems comprising reconstituted foam exhibited lower natural frequencies than those with the lower density virgin foam.

Advanced Property Prediction Models for Flexible Slabstock Foam

The properties of all water blown conventional polyether polyurethane foams are controlled by formulation and processing conditions, more so than individual component properties. If discussions are limited to only good quality, high air flow cushioning grades, either furniture or carpet pad, catalyst and surfactant effects are generally small. Therefore only the major effects of water, index and polymer solids need to be considered. (Throughout this discussion the term «polymer solids» is used interchangeably with «parts of polymer polyol» even though these two items differ by a constant factor.)

The separation of tellurium and selenium by polyurethane foam sorbents

Tellurium and selenium can be sorbed from hydrochloric acid and hydrobromic acid solution by both polyether and polyester-based polyurethane foam. Although some acid is needed, the substitution of sodium chloride or sodium bromide increases the extraction significantly. Tellurium is extracted rapidly with > 99% sorbed in 2 min from 1.0/5.0 M and 2.0/4.0 M hydrochloric acid/sodium bromide. Selenium can also be sorbed quantitatively but much more slowly so that a separation is possible based on the relative rates of extraction. The capacity of polyether foam is 3% by weight of tellurium.

The impact of a shock wave on porous compressible foams

A phenomenological study of the processes occurring when a shock wave interacts with porous polyester and polyether foams has been undertaken. Plane shock waves generated in a shock tube were reflected off a slab of foam mounted against the back wall of the tube. Tests were conducted with an initial shock wave Mach number of 1.4 and a 70 mm thick slab of foam. The reduction in reflected shock wave strength and substantial increase in the back wall pressure over that for rigid wall reflection, found by other workers, were confirmed. Piezoelectric pressure transducers were used to record the pressure before, alongside and behind the foam specimen. Schlieren photographs of the flow were made and showed some features not previously reported. In particular it is shown that there is a flow of gas across the face of the foam at some point of the process. Previous investigations of this interaction process have assumed that the face of the foam is a contact surface. Short duration photographs of the distortion of the foam were taken, enabling the wave propagation in the foam material itself to be studied. It is established that the front of this compaction wave in the foam material moves at considerably lower velocity (- 90 m/s) than the gas wave as detected by the pressure transducers (- 200 m/s). This result contrasts with the assumption made in previous work that the two-phase medium behaves essentially as a homogeneous substance. A simple physical model based on a zone of compacted material in the foam acting as a high-resistance flow barrier, is proposed to explain the observed phenomena.

The Effects of Formulation Variables on Foam Durability: Water Content, Polymer Solids, Index

The durability of polyether polyrethane foams, particularly high load bearing foams like carpet pad, is controlled by formulation and processing conditions. Processing conditions include those which impact foam breathability, structure and cell count. Within the framework of slabstock foam formulating, it is well knwon that durability is primarily affected by water content, polymer polyol content and isocyanante index (for index 100 and above). Trends are well known in the industry; increasing any one of the above three variables in a formulation decreases durability

Extraction of Alkali Metal Tetraphenylborates by Polyurethane Foam

Abstract The extraction of alkali metal tetraphenylborates by polyurethane foam was investigated. The extractability sequences are K+ ≈ Rb+ > Cs+ and K+ ≈ Rb+ ≈ Cs+ for polyether and polyester foams, respectively. The high extraction of K+ by polyether foam can be explained by the cation chelation mechanism.

Extraction mechanism of monovalent ion-pairs by polyurethane foams

The extractability sequence of K + ≈ Rb + > Cs + > Na + > Li + for the extraction with polyether foam suggests that the cation chelation mechanism might be operative. However, the same order was obtained for the extraction with 100% polypropylene oxide polyether foam which does not normally adopt a helical structure to form oxygen-rich cavities as easily or as effectively as polyethylene oxide to accommodate alkali metal ions. This result indicates that a hole-size/cation-diameter relationship may not be required for the high extraction of K +. The extraction of alkali metal DPAs and hydroxides from methanol demonstrates the importance of the solvent effect. It indicates that the water-structure enforced ion-pairing (WSEIP) is the driving force for extraction of the ion-pairs. The extraction mechanism for ionic species can be described as an ion-pair extraction process. The overall effect of ion-pair formation in water and interaction of the extracted ions with foam appears to determine the extractability of the ions of the extractable ion-pair.

Polyurethane foam extraction of platinum—tin halide complexes

The sorptive capacity of the polyether-based foam was determined to be between 0.85 and 0.92 moles/kg for the platinum—tin(II) chloride complex. At hydrochloric and hydrobromic acid concentrations up to 3.0 M, the platinum—tin(II) bromide complex had higher extraction efficiencies than the platinum—tin(II) chloride complex. Sorptions were optimized at 5.0 M hydrochloric acid and 3.0 M hydrobromic acid and distribution ratios as high as 2.0 × 10 5 1./kg were observed at high foam:platinum ratios. The percent of platinum extracted increased when the alkali metal cations are added in the order K + < Na + < Li + for polyether foam, and decreased in the order K + > Na + > Li + for polyester foam. Also, the sorption efficiencies increased as the proportion of poly(ethylene oxide) of the foam was increased. A Scatchard plot analysis shows that there is a 2:1 ratio of loosely bound platinum to tightly bound platinum with the polyether foam, however, the experimental results are consistent with a weak-base anion exchange mechanism as the prominent method of sorption. For polyester foam, results are consistent with a solvent-like ion-pair sorption mechanism.

Extraction of alkylammonium tetraphenylborates and dipicrylaminates by polyurethane foam

Alkylammonium ions are extractable by polyether- and polyester-type polyurethane foams from aqueous solution in the presence of bulky and hydrophobic anions such as tetraphenylborate (TPB -) and dipicrylaminate (DPA -). The selectivity for the alkylammonium ions is affected by a combination of effects including steric and inductive effects and hydrophobic interaction. The extractability sequences of NH 4 + > tert-butylammonium > isopropylammonium > ethylammonium > methylammonium for the extraction with polyether foam and tert-butylammonium ≈ isopropylammonium > NH 4 + > ethylammonium > methylammonium for the extraction with polyester foam suggest that there may be some steric hinderance effect for the extraction with polyether foam and the cation chelation mechanism may be predominant. However, these results can also be explained by the weaker hydrogen bonding with polyester foam which gives rise to increasing extraction of isopropylammonium and tert-butylammonium through hydrophobic interaction relative to NH 4 +. Therefore, there is no conclusive evidence for the cation chelation mechanism occurring for the extraction with polyether foam.

Extraction of aromatic acids and phenols by polyurethane foam

The extraction of several aromatic acids and phenols including salicylic acid, 8-hydroxyquinoline, 1-amino-2-naphthol-4-sulphonic acid and cinnamic acid in the presence of various protonated alkylamines, ammonia and alkali metal cations from aqueous solution by polyurethane foam has been investigated. These compounds are extracted only in the neutral form by a solvent extraction mechanism. The mechanism has been confirmed by the salting-out effect and pH studies. With the exception of 8-hydroxyquinoline, the compounds are more extractable by polyether foam than by polyester foam, suggesting that hydrogen bonding is stronger with the polyether foam.

Sorption of iron(III) and iron(II) from acidic chloride solutions by polyether and polyester type polyurethane foams

Iron(III) is sorbed by polyether type open-cell polyurethane foams from HCl solutions of 4 mol/l or higher. The capacity of the foams is around 50 mg·l−1. The iron (III) sorbed can be eluted from the foam with 0.01 mol/l HCl or distilled water. An optimization of the sorption conditions showed that the process can be used for analytical applications. The polyurethane foam sorbents examined did not sorb iron(II). The mechanism of sorption by polyether foams seems to follow a mechanism similar to that of the extraction of iron(III) by etheric solvents.

Environmental Considerations in the Production of Flexible Slabstock

Total gas loss by the production of flexible polyether foam may range between 4–20 weight percent; higher densities are mainly blown with carbon dioxide – the lower densities partially with CO2, partially with either fluorocarbon and/or methylene chloride. During blow-off approximately 30% of the total gas loss will escape spontaneously from the top surface, the other 70% being contained in the block will mainly diffuse via the vertical sides and the bottom of the block. The speed of diffusion depends upon a number of physical variables and was measured and determined respectively (a) from smaller lab tests, (b) a larger 2 × 2 × 1 metres box test and finally (c) from 20 metres long blocks (2 metres wide, 1 metre high) which were made on the pilot plant. During these trials the installation and application of adequate chlorofluoro-carbon (or CFC 11) and/or methylene chloride recycling systems was made. For the block test 2 × 2 × 1 metres a 5 kgs capacity adsorption unit was installed; diffusion rates and fan capacities were determined and with this information a pilot plant for 20 metres long block was designed and built by Laader Berg. The objectives for this newly developed foaming system were: 1. Producing emissions at environmentally acceptable limits with a controllable degree of adsorption and recovery which may vary from 0·99%. 2. Improved formulation accuracy achieved by application of the computer in combination with gas analysis equipment, resulting in a narrower spread of the properties. 3. Improved working atmosphere for the operators – TDI concentrations approaching to zero. 4. Remote controlled starts and stops using improved mechanical methods which can be controlled by microprocessors. The existing situation with this project is as follows: 1. The pilot machine can produce a wide range of foams. 2. A filter adsorption system was operational at the end of Feb. 1987. 3. Various tests were carried out through 1987. 4. Cost-price comparison calculations indicate positive feasibility.

Extraction of aromatic organic compounds by polyurethane foam

The mechanism of extraction of organic compounds by open-cell polyurethane foam has been investigated through a detailed study with simple aromatic compounds. Comparison with identical extractions into diethyl ether suggests that the basic extraction mechanism is an ether-like solvent extraction process. The addition of salt increases the extraction and changing the dielectric constant of the aqueous solution also affects the extraction. For organic compounds which have a group capable of hydrogen bonding, some additional factor appears to influence the extraction. This appears to be hydrogen bonding with the polyurethane foam; it is stronger with polyether foam and reduced by the presence of a strong intramolecular hydrogen-bonding group placed ortho to the hydrogen-bonding group. Thermodynamic studies support these conclusions.

Fire, Foams and Furniture

Placing the words Fire, Foams and Furniture together, may create a picture of rapidly burning high temperature fires with dense smoke. This is almost the traditional view of furniture containing polyurethane foams and while it is recognised that such furniture does exist, it must be emphasised that many items of furniture containing polyurethane foam have excellent fire behaviour. Foams used in furniture can be the flexible polyether foams used for upholstery but the latter could also comprise other materials, e.g. polyester fibre mats, waddings, rubber latex foam, etc. Foams may also be found as flexible fire barrier materials and also as rigid structural elements. The outer layer of upholstered furniture is almost invariably a fabric. Many fabrics exist; in conjunction with the sub-structure of the upholstery they determine the ignitability and initial burning characteristics of the furniture. By carefully selecting materials and considering the interactions of materials and design, it is possible to build furniture which will resist large ignition sources even when vandalised Such performance demands inevitably lead to compromises and limitations to the choice of fabrics or designs and to the comfort (e.g. soft or hard) of the furniture. They may also probably lead to increase in costs. Modern technology has produced materials which will, in selected designs, give extremely good fire behaviour. It is the responsibility of the specifiers and purchasers to decide the level of performance required in a particular end-use environment and thereby create a market for such products.

Mechanism of extraction of the palladium(ii) thiocyanate complex by polyether foam

The mechanism of sorption of the palladium(II) thiocyanate complex by polyether-type Polyurethane foam has been investigated. At low thiocyanate concentration, palladium is most likely extracted as Pd(SCN) 2. The results obtained in the presence of enough thiocyanate for formation of the Pd(SCN) 4 2− complex are in disagreement with several possible mechanisms for sorption of the anionic metal complex by the foam, such as adsorption, solvent extraction, ligand addition or exchange, and weak or strong base anion-exchange. The extraction of Pd(SCN) 4 2− at high pH increased in the order Li +< Na + < Cs +< Rb + < K +< NH 4 + which is in good relation with the “cation-chelation” mechanism. This mechanism was also found predominant in the extraction of Pd(SCN) 4 2− complex from hydrochloric acid solutions.

Studies on the extraction of phosphomolybdate by polyether foam

To establish the mechanism of heteropoly anion extraction, the sorption of phosphomolybdate by polyether-based polyurethane foam was investigated. The effect of several variables on the extraction was studied and the optimum conditions were ascertained. The results of this study indicate that the cation-chelation mechanism cannot account for the extraction of phosphomolybdate by polyether foam.