Layer Of Polyurethane Foam Research Articles

Fire resistance of gypsum drywall partitions with polyurethane foam filling

AbstractGypsum drywall systems have gained their popularity, among other reasons, due to the excellent fire‐resistant properties. The use of different variants of the structures filled with insulating material (most often mineral wool) makes it possible to shape the parameters of fire resistance according to the requirements. The use of polyurethane foam for filling spaces inside drywall systems has become increasingly popular. This is especially applicable to the performance of thermal insulation of wooden roof slopes. The advantages of polyurethane foams over mineral wool include good adhesion to the substrate, lower specific weight, lower thermal conductivity and shorter time to make a tight filling layer. Its undoubted disadvantage is lower fire resistance. The paper presents a research on the fire resistance of gypsum drywall systems with self‐extinguishing polyurethane foam filling. The fire resistance time of the structures was measured in accordance with EN1363‐1 using a standard temperature‐time curve. The tests simulated a fire on the outside of a service shaft with a layer of polyurethane foam on its interior side, and a fire in an attic room with self‐extinguishing polyurethane foam thermal insulation between wooden rafters, and an interior enclosure made of two layers of gypsum board on a steel frame. The tests made it possible to determine the times of meeting the fire resistance criteria of partitions with polyurethane filling.

Force attenuation properties of shear-thickening polymer (STP)-based hip protector in simulated sideways fall

Shear-thickening polymer (STP) has a unique property of increasing its viscosity with an increase in shear strain to attenuate the application of force, implying that it can be used as a material for hip protectors. This study introduces a new hip protector composed of STP and compares its force attenuation capacity to that of other commercial hip protectors in simulated sideways falls. The performance of the STP-based hip protector was analyzed against eight commercial hip protectors (Pelican, Posey, SafeHip, Hornsby, FallSafe, HipSaver, Impact Wear (Hard), Impact Wear (Soft)). The simulated sideways fall conditions were created by a drop weight impact testing system using an anatomical hip model. The machine was dropped from a 20 or 30 cm height resulting in impact energy of 25.1 J (low) or 44.1 J (moderate), respectively. At low impact energy, the commercial hip protectors showed an attenuation range from 21.6 % to 53.3 %, and the STP-based hip pad was able to attenuate the force by 42.7 %. At moderate impact energy, the commercial hip protectors showed an attenuation range from 23 % to 54.3 %, and the STP-based hip pad was able to attenuate the force by 32.6 %. The low coefficient of variance showed a high precision in the execution of the experiments. Although the STP-based hip protector was thinner than the average of commercial soft shell pads and retained comfortable fit, it showed comparable force attenuation capacity to the commercial ones for the low impact energy test. This study highlights that STP, in combination with a polyurethane foam layer, provides the best features in energy-absorption and shunting, showing that it can be used in hip protectors to gain a competitive advantage over others.

Impacts of PU Foam Stand-Off Layer on the Vibration Damping Performance of Stand-Off Free Layer Damping Cantilever Beams

Stand-off free layer damping is a vibration reduction method based on the traditional free layer damping. In this paper, a stand-off free layer damping cantilever beam is prepared with the steel plate as the base layer, rigid polyurethane (PU) foam as the stand-off layer, and rubber as the damping layer, and the motion equation of the cantilever beam is derived. The dynamic mechanical properties of damping rubber and PU foam are tested and analyzed. Through hammering tests, we have studied the effect of the density and thickness of the PU foam layer on the amplitude-frequency curves, modal frequencies, and loss factors of the cantilever beams. The results show that the rubber damping material is a major font of energy dissipation of the cantilever beam, and PU foam acts mainly to expand the deformation of the damping layer and plays a role in energy consumption. By increasing the density and thickness of PU foam within a certain range, the vibration peaks of the first five modes of the cantilever beam decreases gradually, the loss factors rise, and the damping performance is improved. Meanwhile, increased density and thickness enhances the overall stiffness of the beam, making the modal frequencies get higher.

The Effect of Shoulder Pad Design on Head Impact Severity during Checking.

Shoulder-to-head contact is the most common cause of concussions in ice hockey, accounting for 42% of cases in the National Hockey League. The goal of this project was to determine how shoulder pad stiffness, modified by adding foam padding over the shoulder cap of existing shoulder pads, affected head impact severity when participants delivered checks to an instrumented dummy. Fifteen participants administered "the hardest shoulder checks they were comfortable delivering" to the head of a dummy equipped with triaxial accelerometers and gyros mounted in its helmet. Trials were conducted with participants wearing two common types of shoulder pads, with and without a 2-cm-thick layer of polyurethane foam over the shoulder pad cap. When participants delivered checks with foam-modified pads versus unmodified pads, there was a decrease of 25.0% in the average peak linear head acceleration (28.73g vs 38.31g, mean difference = 9.58g, 95% confidence interval = 6.35-12.81, P < 0.0001) and a decrease of 12.4% in the average value of peak rotational head velocity (838.0°·s vs 956.7°·s, mean difference = 118.65°·s, 95% confidence interval = 55.37-181.94, P = 0.001). The protective benefit of the foam layer did not depend on the type of shoulder pad or the checking scenario. The integration of foam padding on top of the plastic caps of shoulder pads reduced impact severity to the head and warrants further examination as a method for contributing to the prevention of brain injuries in ice hockey.

Impact properties of flexible composites made of nylon/high-resilience non-woven fabric with an inter/intra-ply hybrid structure

This study examines how inter/intra-ply hybrid structures influence the impact load of sandwich-structured flexible composites determined by static or low-velocity impact tests. The flexible composites are composed of nylon/high-resilient non-woven polyester fabrics as the surface sheet and polyurethane foam as the core layer. The polyurethane foam layer has a specified thickness and density, while the surface layers comprise various fiber blending ratios, different blending methods, different lamination procedures and lamination orders. The test results show that the flexible composites have an optimal impact absorption of 1901 N for a static impact when the nylon/high-resilient polyester non-woven fabrics are composed of an inter-ply hybrid structure. In contrast, they have an optimal impact absorption of 8255 N for a low-velocity impact when the nylon/high-resilience polyester non-woven fabrics are composed of an intra-ply hybrid structure.

Calculating sound insulation of a sandwich structure on the basis of the «inverse matrix» method

Multilayered structures are widely used in housing construction, shipbuilding, aviation and space-rocket engineering. In designing such structures it is necessary to estimate their sound insulation capacity for the forecasting of levels of noise taking place in this or that premise or compartment. The paper presents a methodology of calculating sound insulation of a multilayered structure developed on the basis of solving wave equations in each of the layers taking into account the incident angle of sound waves and losses in layers; introduction of boundary conditions establishing equality on the borders of media of normal oscillatory speeds and acoustic pressure; drawing up a system of algebraic complex equations and a matrix equation corresponding to them; drawing up an inverse matrix of factors at functions of acoustic pressure. Examples of calculating factors of sound insulation for multilayered structures with various parameters are presented (superficial weights, thickness of layers, various incident angles). A graphic comparison of the results of calculations using the methods of inverse matrix and the impedance method as well as a graphic comparison of results of flight-design measurements (FDM) of the sound insulation of a regular head part, consisting of layers of coal tape, fiber glass fabrics, aluminum honeycombs and a layer of polyurethane foam are given. The results of calculation using the inverse matrix method are given and the advantage of the method is emphasized.

Use of Indigenously Made Negative-Pressure Wound Therapy System for Patients with Diabetic Foot

Negative-pressure wound therapy (NPWT) is a well-known treatment modality for chronic, difficult, nonhealing wounds. Unfortunately, many commercially available negative-pressure therapy systems for wounds are expensive, require hospitalization, and may not be available throughout the world. The authors have designed a less expensive and effective NPWT system from components readily available in the hospital. The system is assembled from ethylene oxide sterilized polyurethane foam, transparent adhesive dressing, and a simple negative suction drain system, which is being routinely used in surgical cases. The multiple holes suction tube is inserted between 2 layers of polyurethane foam and is put on the wound, which is sealed by adhesive dressing. The negative pressure is created using a closed wound suction set. The dressing is changed every third day or as needed. The authors have used this system in 11 patients with diabetic foot. The mean time for preparation of wound for surgery with this system was 7 days (5-9 days). The raw areas were either secondarily closed or were covered with split-thickness skin graft. The mean hospital stay for debridement and definitive surgical procedure was 11 days (8-15 days). In the authors' experience, the NPWT system developed from off-the-shelf components reduces the length of hospital stays and therefore cost, without any compromise on quality. It leads to a quicker wound closure and reduces the need for multiple surgeries or flaps. This modification presents a simple, cheap, and effective alternative to commercially available NPWT machines.

Field Evaluation of Solid Sorbents for Ambient Air Sampling of Pesticides

Seven solid sorbents including Amberlite® XAD-2 and XAD-4, Tenax-TA®, Anasorb-747, Chromosorb 102, 108, and 750 were evaluated for the collection of the gas phase fraction of pesticides under field conditions at an agricultural site, Bratt's Lake, SK, located in the Canadian prairies. The polyurethane foam (PUF)/sorbent cartridge consists of two PUF layers which sandwich the solid sorbent and each layer was analyzed separately to determine which portion of the PUF/solid sorbent retained the pesticides and the extent of breakthrough. The pesticides that had high detection frequency throughout the study and ambient air concentrations well above MDL were triallate, trifluralin, ethalfluralin, and chlorpyrifos. All sorbents had improved collection efficiency as compared to a standard 7.6 cm PUF and the improvement varied with each pesticide. The most effective sorbents for trapping gas phase fraction of pesticides were XAD-2, XAD-4, Tenax-TA, and Chromosorb 108. The only sorbent not recommended for use is Chromosorb 750. For selected sampling periods when ambient concentrations were above detection limits a number of other organochlorine and organophosphorus pesticides also showed more efficient collection with PUF/solid sorbent cartridges as compared to PUF cartridge. Shorter sample collection periods of 4-days improved detection frequency of pesticides.

Limiting resistance of an HMX-based explosive under shock-wave loading

The action of shock-wave loading on specimens of an OTK-90 explosive composition is studied. The limiting levels of loading that correspond to the initial stage of explosive conversion of the specimens impacted by steel plates of different thickness are determined. The limiting resistance of the specimens subjected to the gliding detonation of a TP-83 plastic explosive through a polyurethane-foam layer and also to the gliding and normal detonations of a NIL-1 low-density explosive is examined. It is shown that the boundaries of the transition from the purely mechanical failure of OTK-90 to a mechanochemical reaction that were obtained by different methods of shock-wave loading agree well.

A COMPACT HIGH-FLOWRATE RESPIRABLE DUST SAMPLER: THE CPM3

The technical characteristics of the portable self-energized respirable dust sampler CPM3 are described. This instrument was originally developed in France in the 1970s by the Centre d'Etudes et Recherches de Charbonnages de France (CERCHAR) for use in coal mines; it is now also widely used elsewhere for industrial hygiene measurements. A high-speed rotating cup containing two layers of polyurethane foam provides the suction of the ambient aerosol at a high flowrate, 50 l. min −1 , and at the same time acts like a filter and traps the respirable particles that penetrate the cyclone-type preselector. The sampling characteristics (in calm air conditions only) were studied using two polydisperse test aerosols: coal and aluminium oxide (Aloxite 50). The particle collection efficiency of the instrument is shown to be very close to the conventional selectivity for the alveolar fraction as defined by ISO. The experimental results are compared with those obtained in similar conditions for two reference instruments: the U.S. 10-mm Dorr-Oliver cyclone at 1.7 l. min −1 and the British MRE Type 113A Gravimetric Sampler (Casella Ltd, London) at 2.5 l. min −1 .

Stored blood microfiltration. Evaluation of micro-aggregate filter composed of polyurethane foam and nylon wool.

Aggregates of amorphous material which develop during storage of banked blood have been implicated as a cause of pulmonary micro-embolism in man following massive transfusion. Such pulmonary micro-embolism may be a causal factor in the development of post traumatic pulmonary insufficiency. At present several microaggregate filters for use in massive transfusion are commercially available, and on of these is the Fenwal filter. It is composed of a screen filter which removes microclots of 250 microns and higher, a layer of polyurethane foam and a layer of nylon wool. The resistance of this device is very acceptable and the filter may be used for several blood units, but its efficiency seems less than that of Dacron wool filter.

Banked Blood Microfiltration I. MICROFILTER COMPOSED OF FIVE POLYURETHANE FOAM LAYERS WITH GRADED PORE SIZE

Aggregates of amorphous material which develop with storage of banked blood may be a source of pulmonary microembolism in patients having massive transfusions. In order to remove such debris, blood microfilters have been developed and are in routine clinical use. This paper describes the evaluation of one such filter, the Bentley PF 127 model B, which is composed of five layers of polyurethane foam. The time of filtration as a function of the pressure applied, the number of particles removed, the observed changes in blood cells, and the results of scanning electron microscopy of the filter after filtration of human banked blood, are reported.

Elasticity and strength of polyurethane foams with cylindrical cavities

The strength and elasticity of layers of polyurethane foam with cylindrical cavities have been investigated on the interval of variation of the specific weight of the foam from ρ0 = 0.2 to ρ0 = 0.7 gf/cm3. A correlation has been established between the proportionality limit in compression along the channel axes and the modulus of elasticity of a cylindrical tube of foam with a radially restrained outer surface taken as a model of a layer with cylindrical cavities. The experimental results are compared with the theory of elastic compression of tubes with free and restrained ends.