Polyurethane Sheets Research Articles

Electrospun polyurethane membrane with Ag/ZnO microparticles as an antibacterial surface on polyurethane sheets

ABSTRACTA method of antibacterial modification of the polyurethane (PU) surface is presented in this article. An electrospun PU membrane with an incorporated antibacterial agent was applied as a coating of the PU sheets. As an antibacterial agent, a hybrid bimetallic filler was used; it combined the antibacterial effects of silver and zinc oxide. With an electrospun submicrometer‐fiber membrane, the filler was uniformly and thinly applied on the PU surface by compression molding. The antibacterial activities of three filler concentrations were tested, and they demonstrated an effective antibacterial action against Staphylococcus aureus and Escherichia coli. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43020.

SYNTHESIS AND CHARACTERIZATION OF NATURAL FIBRE REINFORCED POLYURETHANE COMPOSITES BASED ON CARDANOL

In recent studies importance has been given to the use of natural products from renewable resources due to the decrease in the supply and price escalations of petroleum raw materials. Cardanol based resole type phenolic resin has been synthesized by condensing cardanol with furfural in a particular mole ratio using dicarboxylic acid catalyst such as phthalic acid. Polyurethane sheets were prepared by treating cardanol furfural resin with 4,41 – methylene bis(cyclohexyl isocyanate) and the catalyst dibutyltin dilaurate. Natural fibres are prospective reinforcing materials and their use until now has been more traditional than technical. Among the various fibres sisal is of particular interest in that its composites have high impact strength besides having moderate tensile and flexural properties compared to other fibres. Fibre reinforced polyurethane composites have been prepared by treating sisal fibre (10%) into polyurethane. The physico chemical, spectral and thermal properties of polyurethane and fibre reinforced polyurethane composites have been studied.

Experimental study on warm roll bonding of metal/polymer/metal multilayer composites

The manufacturing of metal/polymer sandwich composites via roll bonding can offer great advantages over other techniques such as overmolding and injection molding, because those techniques are more complex and costly. Roll bonding of multilayer composites, however, is challenging due to significant differences in the mechanical properties and adhesion characteristics of polymeric and metallic materials. In this study, warm roll bonding (WRB) has been applied to fabricate a sandwich composite consisting of commercially pure aluminum (AL1100) and polyurethane (PU) sheets. The effects of WRB process parameters, which include surface roughness, preheat temperature, rolling speed, and total thickness reduction, on the adhesion strength have been investigated using the peel test. Mechanical interlocking was the primary adhesion mechanism in direct bonding of AL1100 and PU by rolling. An optimal surface roughness value was observed at 5.63μm where the failure mode transitioned from adhesive to cohesive as the surface roughness increased. An optimum temperature and rolling speed were identified to be 200.2°C and 29.7rpm, respectively. The study showed a promising potential for applying WRB to mass produce metal/polymer hybrid composite panels.

Thermal Conductivity of Polyurethane Sheets Containing Alumina Nanofibers

Thermal Conductivity of Polyurethane Sheets Containing Alumina Nanofibers

The Design of Online Measurement System for Polyurethane Sheet

The polyurethane sheet is an important part of automotive interior trim. For a long time, the measurement and recording are both accomplished by hand. It has problems such as low measuring precision, low working efficiency. Accordance with the existed problem of polyurethane sheet measurement, we developed an online measurement for polyurethane sheet and code-spurting system. The system measures the thickness through two channels using laser displacement sensors. PLC collects data and controls the alarm device. Weighing is completed by belt scale and weighing instrument PT650D. Host computer software communicates with slave computer through serial interface. It not only makes data processing and storage function true, but also can make database operations such as data query, statistics and so on. In order to be convenient for quality tracing, the system sets and prints a number for each block. It also can print irregular information such as thickness and weight.

An elastomeric transparent composite electrode based on copper nanowires and polyurethane

An elastomeric transparent composite electrode has been fabricated comprising a percolation network of copper nanowires (CuNWs) embedded in the surface layer of an elastomeric polyurethane (PU) matrix. The composite electrode was fabricated by first forming a highly conductive CuNW network on glass, then overcoating with a layer of a liquid polyurethane precursor which was subsequently polymerized, and finally peeling off the resulting PU sheet. The composite retained the elastomeric stretchability of the polymer matrix. Pre-treatment of the CuNW network with 6-aminohexanoic acid enhanced the bonding between nanowires and PU matrix, and significantly improved the reversibility of the surface conductance of the composite electrode during repeated stretching at room temperature. The composite electrodes exhibited a low sheet resistance of <102 Ω sq−1 at tensile strains up to 60%. High stretchability was obtained in a wide range of strain rates over 200 cycles of stretching. Morphological development during the stretching–releasing processes was consistent with the important role of the bonding between the nanowires and the PU matrix in the stretchability of the composite electrode.

Fabrication and evaluation of physical properties and cytotoxicity of zein-based polyurethanes

Polyurethane prepolymer (PUP) was first synthesized from polycaprolactone diol and isophorone diisocyanate; and then a series of zein-based polyurethane (ZEPU) sheets was fabricated from PUP and zein (ZE) using a hot press and moulding process without addition of other additives. Effects of ZE content (WZE) on the structure and properties of the resultant ZEPU sheets were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, dynamic mechanical analysis, tensile testing, and dissolubility testing in alcohol. The results indicated that cross-linking and grafting reactions occurred between ZE and PUP to form new polyurethane showing a higher thermal stability, flexibility, and alcohol-resistance than the neat ZE sheets. For example, the elongation at break of ZEPU with 50% WZE was 211.2%, which was 47 times higher than that of neat ZE sheet. ZE molecules acted as both cross-linkers and polymer fillers in ZEPU sheets. The cytotoxicity and cytocompatibility of ZEPU sheets were evaluated by cell culture in vitro. The ZEPU sheets showed non- or low-cytotoxicity, and L929 cells grew and expanded well on the surfaces of the sheets with WZE over 50%. Undoubtedly, the fabrication of ZE-based polyurethanes without toxic additives such as catalysts, cross-linkers and chain extenders improved the physical properties and cytocompatibility of zein, thus widening the possible range of applications for zein-based biomaterials.

Cilostazol, a selective Type III phosphodiesterase inhibitor: prevention of cervical myelopathy in a rat chronic compression model

Regional blood flow is decreased in experimental models of chronic spinal cord compression, and the alteration presumably contributes to the development of myelopathy. Cilostazol (Otsuka Pharmaceuticals Co.), a selective Type III phosphodiesterase inhibitor, has been shown to be neuroprotective in cerebral hypoperfusion animal models and clinically effective in preventing the recurrence of cerebral infarction. To investigate the neuroprotective effect of cilostazol on cervical spondylotic myelopathy, the preventive effect against progressive motor dysfunction and the loss of anterior horn motor neurons were assessed using a chronic cord compression model in rats. To produce chronic cervical cord compression in male Wistar rats, thin polyurethane sheets (3 × 5 × 0.7 mm) that gradually expand over 48-72 hours by absorbing water were implanted under the C5-6 laminae. In sham operations, the sheets were momentarily placed and then immediately removed. This model has been shown to reproduce characteristic features of clinical cervical myelopathy, with progressive motor disturbances after a latency period and insidious neuronal loss preceding the onset of symptoms. In the treatment group, cilostazol (30 mg/kg/day) was orally administered to the rats once a day, starting the day after surgery and continuing through the entire observation period of 25 weeks. In the control group, vehicle solution was administered under the same protocol. Changes in motor function were monitored by measuring bilateral forepaw grip strength and the duration of forced running on a treadmill. Twenty-five weeks after surgery, cervical spinal cords were examined histopathologically. Cilostazol preserved both forepaw grip strength and forced running capability. The drug also preserved anterior horn motor neurons in the C5-6 spinal cord segment, which diminished in number in the untreated chronic compression group. The drug decreased the number of TUNEL-positive apoptotic cells. These results indicate that cilostazol is neuroprotective in the chronically compressed cervical cord and is potentially useful in the treatment of cervical spondylotic myelopathy.

Evaluation of two different reinforcing materials used with silicone auricular prostheses

ObjectiveClinical and laboratory evaluation of the effect of addition of polyurethane sheets or polypropylene fibers as reinforcing materials to silicone that was used in auricular prostheses. Materials and methodsFifteen patients with a history of acquired auricular defects were divided into three equal groups. Group I patients received silicone prostheses (control group), Group II patients received silicone prostheses lined with polyurethane sheets, and Group III patients received silicone prostheses reinforced with polypropylene fibers. The final prostheses were made from medical grade silicone rubber (RTV, MDX4-4210). The basic principles for construction of successful auricular prosthesis were followed. ResultsClinical evaluation of this study revealed an acceptable and well tolerated use of modified silicone ear prostheses either silicone lined with polyurethane sheets or silicone reinforced with polypropylene fibers. ConclusionNone of the tested prostheses showed any clinically detrimental effects on the underlying tissues. Reinforcing silicone with polyurethane sheets and polypropylene fibers improved the tear strength, tensile strength and modulus of elasticity thus providing better marginal integrity and durability of prostheses. Addition for modifying the silicone as a famous maxillofacial prosthetic material seems to be an active area for further researches.

On factors influencing the absorption capacity of surgical sponges.

Cotton balls and surgical gauzes (CSG) have been routinely used for mopping fluids and blood in surgeries. Polyurethane sheets (PUS) are increasingly used instead of CSG. The factors influencing the absorption of fluids by CSG and PUS have not been studied in detail. There are a variety of factors that could be modified by the manufacturer while a limited number of them could be manipulated by the operator. Mathematical models and equations have been employed in this study. The impact of absorbency was performed by modulating various factors. A variety of factors such as thickness, density of the web, radius of fiber, temperature, surface tension and viscosity of fluid, all influenced the absorption rate and capacity to varying degrees. The optimal variation by which the PUS can be effectively used is discussed. The suggested mathematical model will help the operator to choose the appropriate type of PUS based on the individual's needs. In an area of rapidly developing technology and change in biomaterials, where the choice of such materials are overwhelming, hopefully this basic knowledge will help the clinician to make a more educated and rational decision.

Polyols and Polyurethanes from Crude Algal Oil

AbstractThe composition of crude algal oil was analyzed and determined by several methods. Oil was converted to polyols by ozonolysis, epoxidation, and hydroformylation. Ozonolysis gave a polyol with lighter color but a low OH number and was unsuitable for polyurethane applications. Epoxidation also improved the color and gave a polyol with an OH number around 150 mg KOH/g, which with diphenylmethane diisocyanate gave a homogeneous, rubbery, transparent sheet. Desirable rigid foams were prepared with the addition of water to the formulation. Hydroformylation was carried out successfully giving an OH number of about 150 mg KOH/g, but the polyol was black. Casting the polyurethane sheet was difficult due to the very high reactivity of the polyol. Polyurethane foam of lower quality than from epoxidation polyol was obtained. More work on optimization of the foaming system would improve the foam. Crude algal oil is a viable starting material for the production of polyols. Better results would be obtained from refined algal oils.

Development of a large-area planar surface-wave plasma source with a cavity launcher driven by a 915 MHz UHF wave

A large-area planar surface-wave plasma (SWP) source driven by a 915 MHz ultrahigh frequency (UHF) wave was developed. To avoid using large, thick dielectric plates as vacuum windows, we propose a cavity launcher consisting of a cylindrical cavity with several small quartz discs at the bottom. Three types of launchers with quartz discs located at different positions were tested to compare their plasma production efficiencies and spatial distributions of electron density. With the optimum launcher, large-area plasma discharges with a radial uniformity within ±10% were obtained in a radius of about 25–30 cm in Ar gas at 8 Pa for incident power in the range 0.5–2.5 kW. The maximum electron density and temperature were approximately (0.95–1.1) × 1011 cm−3 and 1.9–2.0 eV, respectively, as measured by a Langmuir probe located 24 cm below the bottom of the cavity launcher. Using an Ar/NH3 SWP with the optimum launcher, we demonstrated large-area amino-group surface modification of polyurethane sheets. Experimental results indicated that a uniform amino-group modification was achieved over a radius of approximately 40 cm, which is slightly larger than the radial uniformity of the electron density distribution.

Surface modified and medicated polyurethane materials capable of controlling microorganisms causing foot skin infection in athletes

Foot odor and foot infection are major problems of athletes and persons with hyperhidrosis. Many shoes especially sports shoes have removable cushion insoles/foot beds for foot comfort. Polyurethane (PU) foam and elastomer have been used as cushion insole in shoes. In the present work, new insole materials based on porous viscoelastic PU sheets having hydrophilic property and antimicrobial drug coating to control foot infection and odor were developed. Bacteria and fungus that are causing infection and bad odor of the foot of athletes were isolated by microbial cell culturing of foot sweat. The surface of porous viscoelastic PU sheets was modified using hydrophilic polymers and coated with antimicrobial agent, silver sulfadiazine (SS). The surface modified PU sheets were characterized using ATR-FTIR, TGA, DSC, SEM, contact angle measurement and water absorption study. Results had shown that modified PU sheets have hydrophilicity greater than that of original PU sheet. FTIR spectra and SEM pictures confirmed modification of PU surface with hydrophilic polymers and coating with SS. Minimum inhibitory concentration studies indicated that SS has activity on all isolated bacteria of athletic foot sweat. The maximum inhibition was found for Pseudomonas (20mm) followed by Micrococci (17mm), Diphtheroids (16mm) and Staphylococci (12mm). During perspiration of foot the hydrophilic polymers on PU surface will swell and release SS. Future work will confirm the application of these materials as inserts in athletic shoes.

활성 슬러지조 폭기를 위한 에너지 절감형 판형 멤브레인 산기장치의 개발

In an effort to commercialization of energy saving aeration apparatus, panel-type aeration membranes were prepared from polyurethane sheet of J company in Korea having tensile strength higher than with thickness of 0.5mm. Micropores of 100 m size were made by poring technique utilizing needles. From lab-tests in 450 L water tank at temperature of , the performance of aeration panels at 40 L/min aeration rate showed 5 mg/L DO in less than 3 minutes approaching saturation point of 8 mg/L within 8 minutes. The results show very high efficiency with (), Standard oxygen transfer efficiency (SOTE 54.7%) and Standard aeration efficienct (SAE 7.88 kg/kwh). Other pilot scale test in a water tank with water temperature () and aeration rate (30 L/min) showed DO exceeding 5 mg/L within 8 minutes along with (), SOTE (42.1%) and SAE (6.41 kg/kwh). These efficiencies represent 2~2.5 times higher than conventional aeration devices. Especially, the achievement of higher Oxygen Transfer Rate indicate higher commercial viability. Conventional aeration devices when applied to clean water and wastewater frequently cause problems due to differences in actual Oxygen Transfer Rate. Our actual tests with animal farm wastewater resulted very high efficiencies with Oxygen transfer efficiency ( 22.1%) and (39.6%).

Engineered channels enhance cellular density in perfused scaffolds

Scaffold-based tissue engineering provides cells with an engineered matrix to enhance and direct cell attachment, proliferation and differentiation. One critical limitation to current tissue engineering approaches is the inability to create densely populated constructs thicker than a few 100 μm. We hypothesized that development of porous, channeled scaffolds would increase cell density and uniformity of their spatial distribution through scaffold channel perfusion. Patterned polyurethane sheets were fabricated using a sprayed phase separation technique and laminated together to form 1.5 mm thick channeled scaffolds. Hydraulic permeability testing confirmed the presence of functional channels throughout the multilaminate construct. A continuous flow bioreactor was used to perfuse the construct with medium during the culture period. Cross-sectional cell densities and spatial uniformities were measured in channeled and nonchanneled scaffolds under different seeding and culture conditions. Channeled scaffolds were found to have higher densities of human mesenchymal stem cells than nonchanneled samples. Perfused scaffolds had more uniform spatial distribution of cells within the scaffold compared to statically cultured scaffolds. In conclusion, we have shown the channeled scaffolds to be a promising approach toward creating thick tissue-engineered constructs.

Limaprost Alfadex, a Prostaglandin E1 Derivative, Prevents Deterioration of Forced Exercise Capability in Rats with Chronic Compression of the Spinal Cord

Basic animal research. Cervical spondylotic myelopathy is a common condition among elderly and often treated by surgery. To explore possibility of pharmacologic treatment, limaprost alfadex, a prostaglandin E1 derivative with vasodilatory and antiplatelet action, was tried in a rat chronic spinal cord compression model. Limaprost increased the blood flow of cauda equina and improved motor functions in animal models of lumbar stenosis. The drug is clinically used to treat neurogenic intermittent claudication. : Forty-two rats were allocated to four groups: (A) sham operation without permanent cord compression, given 5 mL/kg of distilled water twice a day (n = 6); (B) sham operation, receiving 300 μg/kg limaprost twice a day (n = 6); (C) cord compression, receiving the vehicle (n = 15); and (D) cord compression receiving the drug (n = 15). A thin polyurethane sheet that expands by absorbing water was implanted under the C5-C6 laminae to produce cord compression. For sham operation, the sheet was immediately removed. Exercise tests were repeated on a rotating treadmill until 26 weeks after surgery, and then the animals were killed and the spinal cord harvested for motor neurons counts. RESULTS.: Treadmill endurance (seconds, mean ± standard error of mean) 2 weeks after surgery was 497.7 ± 2.3, 434.5 ± 65.5, 423.1 ± 33.0, and 480.5 ± 19.5 in groups A, B, C, and D, respectively. At 26th week, the duration was 497.7 ± 2.3, 421.2 ± 78.8, 21.3 ± 11.7, and 441.3 ± 40.4 (P < 0.0001 for the decrease in C group, multivariate analysis of variance with correction for multiple measures.) The motor neuron counts were 38.3 ± 3.6, 38.2 ± 2.6, 32.6 ± 1.9, and 36.2 ± 2.3 in groups A, B, C, and D (P = 0.34), respectively. Limaprost alfadex prevented decline of forced locomotion capability in rats with chronic compression of the cervical cord.

Polyurethane sheet: A potential substitute of surgical cotton gauze

Polyurethane sheet is a pure white, soft, and flexible synthetic sponge with a mechanical strength and abrasion resistance equivalent or even superior to other sponge materials. Our study indicates that the blood absorption power of the polyurethane sheet is equivalent to that of the cotton gauze even after repeated use, and it has the potential to decrease the total amount of sponge usage. Further, accurately identifying the bleeding point might be easier with the polyurethane sheet.

Polyurethanes from benzene polyols synthesized from vegetable oils: Dependence of physical properties on structure

AbstractAsymmetric and symmetric aromatic triol isomers were synthesized from erucic acid. The pure asymmetric and symmetric triols were crosslinked with MDI into their corresponding polyurethane sheets. The physico‐chemical properties of these polyurethanes were studied by Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetric analysis coupled with Fourier transform infrared (TGA‐FTIR) spectroscopy, and tensile analysis. The A‐PU and S‐PU demonstrated differences in their glass transition temperatures (Tg) and crosslinking densities. The difference inTgof these polyurethanes could be explained by the differences in crosslinking densities, which could be related to the increase in steric hindrance, to the crosslinking MDI molecules, between adjacent hydroxyl groups of the asymmetric triol monomers. Overall, it was found that both polyurethanes had similar mechanical and thermal properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

폴리우레탄 평판 음향 원도우 제조와 수중에서 기계적 및 음향적 특성 연구

Polyurethane (PU) sheets were fabricated by the reaction of polypropylene glycol (PPG) and liquid diphenyl methane diisocyanate (L-MDI) with various trimethylol propane (TMP) contents. The value was varied from 34.8 to 49.9 according to the TMP content. As the content of TMP was increased from 4 to 12 wt%, the modulus of the PU sheet was increased from 322 MPa to 423 MPa, its tensile strength was increased from 10.6 MPa to 14.8 MPa, and its elongation was decreased from 62.8% to 49%. In case of acoustic properties, the sound speed of PU sheet was increased while its attenuation coefficient was decreased as the content of TMP was increased. The fabricated PU sheet was stable in water bath for 4 weeks.

Oleic Acid-based Polyurethane and its Biocomposites with Oil Palm Trunk Fiber Dust

The main objectives of the present research are (i) to obtain a monoglyceride from oleic acid through a direct esterification process, (ii) utilization of the obtained monoglycerides to prepare polyurethane (PU) sheet, and (iii) the preparation of a series of biocomposites using prepared PU and different amounts of oil palm trunk (OPT) fiber dust. The tensile strength of OPT fiber dust incorporated PU biocomposites is found to be increased with the increase in the OPT fiber dust content up to 20% in the composites. The tensile strengths of PU and its biocomposites with 20% OPT fiber dust were 0.6 and 2.15 MPa, respectively. The thermal properties of PU and its biocomposites having varied amounts of OPT fiber dust of 0—40% have been investigated using dynamic mechanical analyzer (DMA) and thermogravimetric analyzer (TGA). TGA studies revealed that PU and its biocomposites have undergone two- and three-step degradation, respectively. From DMA studies, a shift in the tan δ value was noticed for the biocomposites containing 30 and 40% OPT fiber dust. The morphology of the tensile fractured composite specimens was analyzed using scanning electron microscope.