Polyurethane Foam Sheets Research Articles

Sound absorption and thermal insulation materials from waste palm oil for housing application: Green polyurethane/water hyacinth fiber sheet composite

This research presents an eco-friendly method for producing polyurethane foam (PUF) and water hyacinth fiber (WHF) sheets. The objectives were to engineer wall materials with sound-absorption and thermal insulation capabilities while also improving the mechanical properties of pure PUF. Waste palm oil (WPO) was successfully utilized as a polyol substrate, playing a substantially role in PUF generation, acting as a PU binder, and serving as a PU adhesive. The productions of PUF (NCO index of 100) combined with WHF sheets (WHF/PU binder ratio of 60/40) using four distinct fabrication methods (sheet-foam-sheet (SFS), foam-sheet-foam (FSF), foam-foam-foam (FFF), and sheet-sheet-sheet (SSS)) were investigated with a fabrication thickness of 150 mm. The findings indicate that the SFS configuration demonstrates remarkable sound absorption properties, with an average sound absorption (SAA) of 0.59, noise reduction coefficient (NRC) of 0.39, and the highest sound absorption coefficient (SAC) of 0.93 at 1900 Hz, alongside a thermal conductivity of 0.0301 W/mK. Importantly, all four methodologies produce SAC values greater than 0.4, outperforming commercial counterparts while demonstrating low thermal conductivity indicative of effective thermal insulation. The result noted that WHF sheet exhibited self-extinguishing properties, making them suitable for use in construction materials. As a result, SFS emerges as the best method for constructing superior sound absorption and thermal insulation materials. This study emphasizes the potential of waste derived WPO and WHF as advantageous eco-friendly substrates for industrial wall and housing materials.

Structural response of steel sandwich panels with PUR foam core subjected to edgewise compression: Experimental, numerical, and analytical considerations

With the objective of leading to innovative lightweight structural components in the construction sector using sandwich panels with polyurethane foam and steel face sheets, different studies were conducted on such structures, including experimental, numerical, and analytical campaigns. The experimental campaign includes the mechanical characterisation of the constituent materials and the edgewise compressive test of small-scale sandwich panels. The test protocols are detailed, and their influence on the results is assessed. Through the use of digital image correlation recordings, deformation patterns and failure mechanisms in the constituent materials and the composite structure are identified. Material constitutive models are calibrated based on the experimentally obtained results. The accuracy of such models is first evaluated against the stress–strain curves recorded during the experiments. In the second stage, the response of the sandwich panels subjected to edgewise compressive loading is simulated. A parametric analysis on the sensitivity of the numerical models to the initial geometrical imperfections is shown to be fundamental to capturing the behaviour of the sandwich panels. Furthermore, the experimental and numerical results are compared to analytical solutions of the problem of the edgewise compression of sandwich panels. Finally, a thorough discussion of the obtained experimental, numerical and analytical results is presented, along with comparisons to results available in the literature.

Mechanochemistry recycling of polyurethane foam using urethane exchange reaction

Although the recycling and reuse of polyurethane foam (PUF) is a promising route to deal with this type of waste commodity polymer, highly efficient and green processing protocols are a great challenge due to their stable crosslink structure. In this study, a strategy of urethane exchange reactions was proposed to transform commercial rigid PUF into PUF sheets. The process was composed of the pulverization of the foam, the pretreatment method and the hot pressing. The effects of the pretreatment method on the structure and properties of the recycled commercial PUF were studied. The results show that the ball milling pretreatment method can effectively pulverize the commercial PUF into powder of 74.5 µm and a specific surface area as high as 2991.0 m2/kg, which can promote the urethane exchange reaction in close contact with the catalyst. The recycle method of ball milling pretreatment makes the crosslink density and tensile strength of the PUF sheets reach 2236.8 mol/m3 and 32.6 MPa, which means an increase of 9.9 times and 3.3 times, respectively, compared to the method of other pretreatment. Moreover, PUF sheets can still maintain 71.5% of the tensile strength after two cycles of recycling, indicating the potential of this recycling method for PUF. This simple and efficient method enhances the sustainability of rigid PUF utilization and shows the enormous potential for value-added recycling of thermosets.

Unique biofilm structure and mass transfer mechanisms in the foam aerated biofilm reactor (FABR)

ABSTRACT The foam-aerated biofilm reactor (FABR) is a novel biofilm process that can simultaneously remove carbon and nitrogen from wastewater. A porous polyurethane foam sheet forms an interface between wastewater and aerated water, making it a counter-diffusional biofilm process similar to the membrane-aerated biofilm reactor (MABR). However, it is not clear how biofilm develops the foam interior, and how this impacts mass transfer and performance. This research explored biofilm development within the foam sheet and determined whether advective transport within the sheet played a significant role. Foam sheets with 2-, 4.5- and 9-mm thicknesses were explored. Oxygen, nitrate, nitrite and ammonia profiles in the sheet were measured using microsensors, and biofilm imaging studies were carried out using optical coherence tomography (OCT). On the foam’s aerated side, a dense nitrifying biofilm formed. Beyond the aerobic zone, much less biomass was observed, with a high porosity foam-biofilm layer. The higher effective diffusivity within the foam for the 4- and 9-mm sheets suggested advective transport within the foam channel structures. Using an effective diffusivity factor in conventional 1-D biofilm models reproduced the measured substrate concentration profiles within the foam. Four different practical conditions were modelled. The maximum TN removal efficiency was about 70% and a nitrogen removal flux of 1.25 gN.m−2.d−1. We conclude that mass transfer resistance occurred primarily in the dense, nitrifying layer near the aerated side. The rest of the foam sheet was porous, allowing the advective mass transfer.

Comparative In Vitro Evaluation of the Primary Stability in D3 Synthetic Bone of Two Different Shapes and Pitches of the Implant Threads

Background: Implant primary stability can be affected by several factors related to implant macrogeometry, local anatomy, and surgical techniques. The aim of this research was to study primary stability on polyurethane foam sheets of wide-threaded implant design compared to narrow-threaded implants. Materials and methods: Two different implant designs were positioned on D3 density polyurethane blocks in a standardized environment: the wide-threaded implant and the narrow-threaded implant, for a total of 160 specimens. Moreover, for each group, two different sizes were considered: 3.8 mm × 12 mm and 4.8 mm × 12 mm. The insertion torque (IT) values, the removal strength (RT), and the Periotest analyses were evaluated. Results: A significantly higher IT and RT was reported for wide-threaded implants and two-stage implants (p < 0.01), compared to the narrow-threaded implants. The diameters seemed to provide a significant effect on the primary stability for both implants’ geometry (p < 0.01). A higher mean of the one-stage implant was evident in the Periotest measurements (p < 0.01). Conclusions: Both of the implants showed sufficient stability in polyurethane artificial simulation, while the wide-threaded implant design showed a higher primary stability on alveolar cancellous synthetic bone in vitro. Additionally, the prosthetic joint connection seemed to have a determinant effect on Periotest analysis, and the one-stage implants seemed to provide a high stability of the fixture when positioned in the osteotomy, which could be important for the immediate loading protocol.

Compression Molding of Thermoplastic Polyurethane Foam Sheets with Beads Expanded by Supercritical CO2 Foaming.

Expanded thermoplastic polyurethane (ETPU) beads were prepared by a supercritical CO2 foaming process and compression molded to manufacture foam sheets. The effect of the cell structure of the foamed beads on the properties of the foam sheets was studied. Higher foaming pressure resulted in a greater number of cells and thus, smaller cell size, while increasing the foaming temperature at a fixed pressure lowered the viscosity to result in fewer cells and a larger cell size, increasing the expansion ratio of the ETPU. Although the processing window in which the cell structure of the ETPU beads can be maintained was very limited compared to that of steam chest molding, compression molding of ETPU beads to produce foam sheets was possible by controlling the compression pressure and temperature to obtain sintering of the bead surfaces. Properties of the foam sheets are influenced by the expansion ratio of the beads and the increase in the expansion ratio increased the foam resilience, decreased the hardness, and increased the tensile strength and elongation at break.

Acoustical absorptive properties of meltblown nonwovens for textile machinery

Noise pollution is one of the harmful physical sources in the textile industry, which is among those industries that are faced with noise exposure problems. The results of environmental sound measurements at modern textile mills have shown that the sound pressure level varied from 95 to 130 dB, where the highest sound pressure level was at weaving machines. Textile insulation materials can be fitted in order to decrease sound pollution at a low cost. The objective of this work is to design a sound absorber that can be fixed to the body of the machines, at the point of the noise generation, to reduce noise pollution. Poly(lactic acid) (PLA), which is an environmentally friendly material, was used to produce different samples of meltblown nonwoven absorbers to be used for damping the noise of textile machinery. PLA meltblown nonwoven fabric with the areal density of 16.7 g/m2, average fiber diameter of 1.1 µm, mean pore diameter of 9.8 µm and thickness of 0.27 mm exhibited significant sound absorption. The sample with the smallest average fiber diameter among those investigated had the highest damping effect: 23.95, 41.29 and 29.32 dBA at frequencies of 400, 1000 and 1500 Hz, respectively. Our goal is to have a practical tool that accurately evaluates the absorber sound damping under the actual running conditions of the textile machinery. The design of the absorber from one layer of the PLA meltblown nonwoven over a rigid polyurethane foam sheet had an excellent sound absorption property.

An in vitro evaluation on polyurethane foam sheets of the insertion torque, removal torque values, and resonance frequency analysis (RFA) of a self-tapping threads and round apex implant

The dental implant primary stability and micromovement absence represent critical factor for dental implant osseointegration. The aim of the present in vitro investigation was to simulate the bone response on different polyurethane densities the effect of self-tapping threads and round apex implant geometry. A total of 40 implants were positioned in D1, D2, D3 and D4 polyurethane block densities following a calibrated drilling protocol. The Insertion, removal Torque and resonance frequency analysis (RFA) means were calculated. All experimental conditions showed insertion torque values >30 Ncm. A significant higher insertion torque, removal and RFA was present in D1 polyurethane. Similar evidences were evidenced for D3 and D4. The effectiveness of the present study suggested a valuable clinical advantage for self-tapping threads and round apex implant using, such as in case of reduced bone density in the posterior maxilla

Microcellular thermoplastic polyurethanes and their flexible properties prepared by mold foaming process with supercritical CO2

A mold foaming process for preparing thermoplastic polyurethane foam sheets was proposed and realized in pilot scale hot-press machine based on the mechanism of solid-state polymer foaming. Thermop...

An In Vitro Evaluation, on Polyurethane Foam Sheets, of the Insertion Torque (IT) Values, Pull-Out Torque Values, and Resonance Frequency Analysis (RFA) of NanoShort Dental Implants.

Objectives: The aim of this study was to investigate, in polyurethane foam sheets, the primary implant stability of a NanoShort implant compared to a self-condenser implant and to a standard, conventional implant. Materials and Methods: Three implant designs were evaluated in the present in vitro investigation: The Test implant (NanoShort), the Control A implant (self-condenser), and the Control B implant (standard design). The study was conducted by comparing the insertion torque values, the pull-out strength values, and the resonance frequency analysis (RFA) values of the Test and Control A and B implants inserted in polyurethane foam models of different thicknesses and densities. The foam densities were 10, 20, and 30 pounds per cubic foot (pcf). Three thicknesses of polyurethane foams (1, 2, 3 mm) were evaluated for a total of 640 experimental sites. Results: The Pearson correlation showed a moderate/strong correlation between all study groups (r > 0.3) for insertion torque and pull-out strength levels. Increased stability of the Test implants was obtained in 3 mm polyurethane sheets. The 2.5 and 3.5 mm Test implants presented good stability in 3 mm polyurethane sheets of 20–30 pcf densities. The Control implants showed better results compared to the Test implants in 1, 2, and 3 mm polyurethane sheets with densities of 10, 20, and 30 pcf. Conclusions: The NanoShort dental implant evaluated in this in vitro study showed a high level of stability in some experimental conditions, and could represent a useful tool, especially in the posterior mandible, as an alternative to vertical augmentation procedures.

Modeling of Flexible Polyurethane Foam Shrinkage for Bra Cup Moulding Process Control.

Nowadays, moulding technology has become a remarkable manufacturing process in the intimate apparel industry. Polyurethane (PU) foam sheets are used to mould three-dimensional (3D) seamless bra cups of various softness and shapes, which eliminate bulky seams and reduce production costs. However, it has been challenging to accurately and effectively control the moulding process and bra cup thickness. In this study, the theoretical mechanism of heat transfer and the thermal conductivity of PU foams are first examined. Experimental studies are carried out to investigate the changes in foam materials at various moulding conditions (viz., temperatures, and lengths of dwell time) in terms of surface morphology and thickness by using electron and optical microscopy. Based on the theoretical and experimental investigations of the thermal conductivity of the foam materials, empirical equations of shrinkage ratio and thermal conduction of foam materials were established. A regression model to predict flexible PU foam shrinkage during the bra cup moulding process was formulated by using the Levenberg-Marquardt method of nonlinear least squares algorithm and verified for accuracy. This study therefore provides an effective approach that optimizes control of the bra cup moulding process and assures the ultimate quality and thickness of moulded foam cups.

Crystallization of inorganic salt hydrates in polymeric foam for thermal energy storage application

Inorganic salt hydrates as phase change material (PCM) offers high energy storage density, low heat of combustion and relatively high thermal conductivity than organic PCMs at a reasonable cost. Moreover, these are nonflammable and also available in the large temperature range for the thermal energy storage (TES) application. However, phase segregation, supercooling and incongruent melting are the main disadvantages which confine them for TES application. In this present study, open cell polyurethane foam (PU foam) as a heterogeneous surface was introduced to mitigate the problem of phase segregation during its repeated thermal cycles. Composite (PU-PCM) having a combination of porous polyurethane foam sheet and saturated inorganic salt solution, by soaking different saturated salt solutions within pores, was prepared. Solution crystallization process was carried out to develop inorganic salt hydrate crystals within the pores from their aqueous solutions. For thermal insulation application, a model experimental setup was constructed and performance of PU-PCM composite sheet compared with the performance of dry PU foam. Various melting and freezing cycles of salt hydrates inside the porous structure were analyzed and the results are discussed.

BENDING AFTER IMPACTKOMPOSIT SANDWICH BERPENGUAT SERAT BAMBU-FIBERGLASS DENGAN COREPOLYURETHANE RIGID FOAM

Impact of the composite sandwich made of materials that become defect, how defects after impact in material need to be examined .Is that defected composites and wich still has the strength toremain in use?, then the bending after impact strength testing must be done to answer these questions.Composite sandwich with bamboo fiber-fiber glass reinforcement and with a core of 25mm rigid polyurethane foam sheet was produced. Composite sandwich made with two composite sandwich laminate as skinflanking the core. Laminated composite sandwich in this study varied number of layers of reinforcing fibers and type of fiber. Specimens subjected to drop weight impact with varying energy then defect researched and bending after impact strengthtested. Defects formed on the composite experiencing a drop weight impact loads are: delamination, basin and through hole. The more layers of reinforcing fibers in the composite skin causing moreshallowbasinformed by theresidualimpact. The greater the impact energy causes greater depth of residual basin. Composite sandwich still has the bending strength after impact. Residual bending strength decreases with increasing impact energy imposed on the composite.

Effect of packaging materials on quality losses in fresh fig (Ficus carica L.) fruits during transportation

The protection of the fig fruit quality in the chains from harvesting to marketing is very important. Vibration often causes some damages to perishable fruits in transportation and reduces their quality. The fruit injury due to vibration is related to the transportation characteristics of vehicles, packaging boxes and the conditions of the roads. The objective of this study was to investigate the effectiveness of packaging materials to reduce the quality loss of fresh fig during transportation. The experiments were carried out with five packaging materials and three transportation distances. The results showed that the CFB box with news paper lining was not proper for transporting of the fresh fig fruits in all transportation distance. The mass loss and total soluble solids of fresh fig fruits packed in CFB box with paper lining was more than CFB box with polyurethane foam sheet and polyethylene foam sheet. Also the decay loss of fresh fig fruits was more in CFB box with paper lining. Fruits packed in CFB box with polyurethane foam sheet were more firm and extended shelf-life than other packaging material.

Cyclic and Static Tests to Evaluate the Seismic Strength of Walls and Connections of Prefab Lightweight Panels for Housing Construction Projects

AbstractApproximately 75% of deaths attributed to earthquakes in Latin America are caused by the collapse of heavy buildings. Hence, it is necessary to study new technological alternatives for structural systems to be used in 1-story housing units that are able to withstand seismic forces. Such structural systems must also be otherwise durable in nature as well as lightweight and moderately priced. The prefabricated system presented in this paper is made of self-supported panels (polyurethane foam and steel decking sheets—materials traditionally used for nonstructural elements), and it is currently being considered as part of a structural system for use in 1-story houses. During the last 10 years, several laboratory tests have been done to the panels to assess their materials and connections. According to the results, the panels display excellent promise, mainly from their demonstrated characteristics of low weight, high relative stiffness, and good performance of connections. These results further sugges...

Biodegradation of gas-phase styrene in a high-performance biotrickling filter using porous polyurethane foam as a packing medium

A biotrickling filter (BTF) packed with porous polyurethane (PU) foam sheets was developed and operated for removal of gas-phase styrene. The specific surface area and void fraction of the PU foam sheet were determined to be 497 m2/m3 and 0.92, respectively, by using mathematical modeling and experimental measurement. The effects of gas flow direction (co-current and counter-current), styrene loading rate and empty bed residence time on the efficiency of the BTF were analyzed. The BTF achieved a high elimination capacity of 4.0 ∼ 5.0 kg styrene/m3 day due to the high specific surface area of the PU foam. The BTF could be operated repeatedly when excessively-grown biomass was periodically removed, using circulating NaOH solution for 2 h every four days.

Study of thermal–mechanical properties of polyurethane foam and the three-dimensional shape of molded bra cups

Molded bras nowadays are dominating the overall bra market place, while the bra cups are mostly made of polyurethane foam sheets. The smooth and seamless inner surface of a molded bra cup gives three-dimensional nice fit to the wearer and provides unlimited designs for different softness and thickness. However, it has been a difficult question to determine the optimum molding conditions for various types of foam and there was no reliable method to measure the cup shape conformity. In this study, the properties of five polyurethane foams were investigated by thermal–mechanical analysis (TMA) and their 3D shapes formed in various molding conditions were measured by a Steinbichler Comet scanner and a new parameterization-based remesh algorithm method. The results revealed that the optimal temperature and dwell time for molding bra cups were greatly affected by the thermal–mechanical properties of polyurethane foams. The softening temperature and deformation properties of the foams tested by TMA can facilitate the determination of optimal molding temperature for the desirable cup shape and thickness. This study provides an effective and quantitative approach to eliminate the time-consuming “trial-and-error” in the molding tests traditionally being used in the industry.

Bioprocess for Solubilization of Rock Phosphate on Starch Based Medium by Paecilomyces marquandii Immobilized on Polyurethane Foam

Paecilomyces marquandii, a phosphate-solubilizing, starch-utilizing filamentous fungus, was immobilized on polyurethane foam (PUF). The immobilized fungus was applied in a repeated batch (six batches) fermentation process to solubilize Hirapur rock phosphate. The fungus was immobilized on PUF cubes and was used for phosphate solubilization in shake flask repeated batch cultivations. The fungus was also immobilized on PUF sheet and utilized in an airlift bioreactor in a repeated batch process. Maximum soluble phosphate (370 microg/ml) was recorded after third batch with 8 g rock phosphate/l. After 12 days of fermentation, a total production of 1,643 microg phosphate/ml was achieved.

A Pilot-Scale Rotating Drum Biotrickling Filter for Removing Gaseous Styrene

A new type of biofilter, the rotating drum biotrickling filter (RDBF) system, was developed and operated to remove styrene from waste gas stream. Porous polyurethane foam sheets were used as a packing material for the RDBF and a pure culture of the Gram-positive bacterium Brevibacillus sp. SP1 was as an inoculum. The reactor showed a short start-up period of 18 days. Once uniform biofilms were developed on the packing, a high and stable removal of styrene over 95 % was observed at an incoming concentration of 200 ppmv and a retention time of 0.5 min. The maximum elimination capacity was estimated to be 125 g/m3/hr. The outstanding performance was attributed to an efficient gas-liquid mass transfer and proper supply of nutrient solution to the packing during the rotation of the drum. However, this performance of the RDBF was not maintained longer than 7 days because of the clogging of the open pores in the polyurethane foam due to an excessive growth of the biofilms. This result indicates that the RDBF has great potential as a gas purification system if a proper method to control the biofilm growth is developed.

Polyurethane foam sheets for relieving pressure from diabetic neuropathic plantar ulcers: a pilot study

INTRODUCTION: Lesions of the diabetic neuropathic foot are mainly caused by pressure in anatomically altered areas. This leads to hyperkeratosis, skin disruption and finally to ulcerations that can progress to underlying bone. Therapy for plantar neuropathic ulcerations in diabetic patients involves relieving pressure from ulcerated areas to allow re-epithelialization. Traditional methods, such as casts, orthoses and special shoes, are not well tolerated by patients. OBJECTIVE: To test whether polyurethane foam sheets, regularly used for dressing neuropathic ulcers of the diabetic foot, may also play a role in pressure relieving, we conducted a pilot study in a group of neuropathic diabetic outpatients. METHODS: Ten diabetic patients with non-complicated neuropathic plantar ulcerations were consecutively selected among the attenders of our diabetic foot clinic. The patients underwent careful debridement of the ulcerated area and elimination of perilesional hyperkeratosis. The ulcers were then covered with semipermeable film to allow measurements to be made. An evaluation of static and dynamic plantar pressure was then performed with F-SCAN, specialized software that analyses data collected from two 960-LED insoles (one for each foot). Static plantar pressures were acquired after patients had stood still on both feet for 15 s, while dynamic pressures were measured after walking for 2 min. The same evaluations were performed after positioning over and around the ulcers a double layer of polyurethane foam sheeting (Allevyn Adhesive) tailored to adapt to the conformation of the foot. The following parameters were then evaluated: peak pressure (PP: kPa); areas of peak pressure (APP:cm 2 ); time of application of peak pressure (TPP:s). RESULTS: The PP was significantly lower after application of the polyurethane sheeting (P<0.01), while the APP significantly increased (P<0.001). No significant differences were observed for TPP. Differences in PP (Delta PP) and in APP (Delta APP) were then calculated: Delta PP significantly inversely correlated with Delta APP, both in static and in dynamic conditions (P<0.001). CONCLUSION: Polyurethane foam sheets proved to be effective in reducing plantar pressures in neuropathic feet, probably because of an increased area of pressure distribution. Further studies are necessary to verify whether the use of this material could actually reduce the healing time of neuropathic ulcers in diabetic patients. (J Dermatol Treat (2000) 11:39–42)