Carbon Black and Multi Wall Carbon Nanotubes Loaded Polyurethane Foam Composite Flexible Thermal Radiator

Carbon black (CB) or multi walled carbon nanotubes (MWCNT) loaded polyurethane conductive foams are used as heaters, electrodes, radar absorbers and shielding. This paper discusses the performance of an innovative flexible thermal radiator (FTR) constructed with CB filled or MWCNT filled conductive foam and powering electrode structure constructed with textiles manufacturing process (knitting, weaving or nonwoven). Silver (Ag) yarns are used for the powering electrodes construction. This paper discusses the construction, electro-thermal analysis, performance and applications of FTR. Also this paper compare the thermal and electrical characteristics of CB filled and MWCNT filled FTRs. The electro-thermal model is simulated by using finite element methods.

Experimental investigation on weak shock wave mitigation characteristics of flexible polyurethane foam and polyurea

In recent years,explosion shock wave has been considered as a signature injury of the current military conflicts.Although strong shock wave is lethal to the human body,weak shock wave can cause many more lasting consequences.To investigate the protection ability and characteristics of flexible materials and structures under weak shock wave loading,the blast wave produced by TNT explosive is loaded on the polyurethane foam with the density of 200.0 kg/m3(F-200)and 400.0 kg/m3(F-400),polyurea with the density of 1100.0 kg/m^(3)(P-1100)and structures composed of the two materials,which are intended for individual protection.Experimental results indicate that the shock wave is attenuated to weak pressure disturbance after interacting with the flexible materials which are not damaged.The shock wave protective capability of single-layer materials is dependent on their thickness,density and microscopic characteristics.The overpressure,maximum pressure rise rate and impulse of transmitted wave decrease exponentially with increase in sample thickness.For the same thickness,F-400 provides better protective capability than F-200 while P-1100 shows the best protective capability among the three materials.In this study,as the materials are not destroyed,F-200 with a thickness more than10.0 mm,F-400 with a thickness more than 4.0 mm,and P-1100 with a thickness more than 1.0 mm can attenuate the overpressure amplitude more than 90.0%.Further,multi-layer flexible composites are designed.Different layer layouts of designed structures and layer thickness of the single-layer materials can affect the protective performance.Within the research range,the structure in which polyurea is placed on the impact side shows the optimal shock wave protective performance,and the thicknesses of polyurea and polyurethane foam are 1.0 mm and 4.0 mm respectively.The overpressure attenuation rate reached maximum value of 93.3%and impulse attenuation capacity of this structure are better than those of single-layer polyurea and polyurethane foam with higher areal density.

The role of polyurethane foam compressible layer in the mechanical behaviour of multi-layer yielding supports for deep soft rock tunnels

The polyurethane foam(PU)compressible layer is a viable solution to the problem of damage to the secondary lining in squeezing tunnels.Nevertheless,the mechanical behaviour of the multi-layer yielding supports has not been thoroughly investigated.To fill this gap,large-scale model tests were conducted in this study.The synergistic load-bearing mechanics were analyzed using the convergenceconfinement method.Two types of multi-layer yielding supports with different thicknesses(2.5 cm,3.75 cm and 5 cm)of PU compressible layers were investigated respectively.Digital image correlation(DIC)analysis and acoustic emission(AE)techniques were used for detecting the deformation fields and damage evolution of the multi-layer yielding supports in real-time.Results indicated that the loaddisplacement relationship of the multi-layer yielding supports could be divided into the crack initiation,crack propagation,strain-hardening,and failure stages.Compared with those of the stiff support,the toughness,deformability and ultimate load of the yielding supports were increased by an average of 225%,61%and 32%,respectively.Additionally,the PU compressible layer is positioned between two primary linings to allow the yielding support to have greater mechanical properties.The analysis of the synergistic bearing effect suggested that the thickness of PU compressible layer and its location significantly affect the mechanical properties of the yielding supports.The use of yielding supports with a compressible layer positioned between the primary and secondary linings is recommended to mitigate the effects of high geo-stress in squeezing tunnels.

Propagation Properties of Shock Waves in Polyurethane Foam based on Atomistic Simulations

Porous materials are widely used in the field of protection because of their excellent energy absorption characteristics.In this work,a series of polyurethane microscopic models are established and the effect of porosity on the shock waves is studied with classical molecular dynamics simulations.Firstly,shock Hugoniot relations for different porosities are obtained,which compare well with the experimental data.The pores collapse and form local stress wave,which results in the complex multi-wave structure of the shock wave.The microstructure analysis shows that the local stress increases and the local velocity decreases gradually during the process of pore collapse to complete compaction.Finally,it leads to stress relaxation and velocity homogenization.The shock stress peaks can be fitted with two exponential functions,and the amplitude of attenuation coefficient decreases with the increase of density.Besides,the pore collapse under shock or non-shock are discussed by the entropy increase rate of the system.The energy is dissipated mainly through the multiple interactions of the waves under shock.The energy is dissipated mainly by the friction between atoms under non-shock.

Bio-Based Rigid Polyurethane Foams for Cryogenic Insulation

Cryogenic insulation material rigid polyurethane(PU)foams were developed using bio-based and recycled feedstock.Polyols obtained from tall oil fatty acids produced as a side stream of wood biomass pulping and recycled polyethylene terephthalate were used to develop rigid PU foam formulations.The 4th generation physical blowing agents with low global warming potential and low ozone depletion potential were used to develop rigid PU foam cryogenic insulation with excellent mechanical and thermal properties.Obtained rigid PU foams had a thermal conductivity coefficient as low as 0.0171 W/m·K and an apparent density of 37-40 kg/m^(3).The developed rigid PU foams had anisotropic compression strength properties,which were higher parallel to the foaming direction.Moreover,the compression strength was also influenced by the type of applied bio-based polyol.The bio-based polyols with higher OH group functionality delivered higher crosslinking density of polymer matrix;thus,the mechanical properties were also higher.The mechanical strength of the foams increased when materials were tested at liquid nitrogen temperature due to the stiffening of the polymer matrix.The thermal properties of the developed materials were determined using differential scanning calorimetry,dynamic mechanical analysis,and thermogravimetric analysis methods.Lastly,the developed rigid PU foams had good adhesion to the aluminium substrate before and after applying cyroshock and an excellent safety coefficient of 4-5.Rigid PU foams developed using Solstice LBA delivered adhesion strength of~0.5 MPa and may be considered for application as cryogenic insulation in the aerospace industry.

Development of polyurethane foam dressing containing silver and asiaticoside for healing of dermal wound

Polyurethane foam dressings for dermal wounds were formulated with natural polyols in order to improve the foam characteristics and the release of 2 active agents,silver and asiaticoside(AS)as an antimicrobial agent and an herbal wound healing agent,respectively.The foam was instantly formed by interaction of polyols and diisocyanate.Hydroxypropyl methylcellulose,chitosan and sodium alginate were individually mixed with themain polyols,polypropylene glycol,in the formulation while the active componentswere impregnated into the obtained foam dressing sheets.Although the type and amount of the natural polyols slightly affected the pore size,water sorption-desorption profile and compression strength of the obtained foam sheets,a prominent effect was found in the release of both active components.Among natural polyols formulations,foam sheets with alginate showed the highest silver and AS release.Non-cytotoxicity of these foam sheets to human fibroblast cells was confirmed.Antimicrobial testing on four bacteria strains showed that 1mg/cm^2 silver in formulations with 6%of natural polyols and without natural polyols had sufficient content of the silver release with comparable inhibition zone and significantly larger zone than other formulations.In pig study,the foam dressing with 6%alginate,1mg/cm^2 silver and 5%AS could improve wound healing in both the percentage of the wound closure and histological parameters of the dermal wound without any dermatologic reactions.In conclusion,this innovative foam dressing had potential to be a good candidate for wound treatment.

The Influence of Polyurethane Foam on the Insulation Characteristics of Mortar Pastes

Rigid polyurethane foam is found virtually everywhere in our modern world and is used in sound and thermal insulation applications such as refrigerators, insulated buildings, thermosets. Organometallic compounds are used as polyurethane catalysts since they are very highly selective towards the isocyanate-polyol reaction. Also, amine catalysts are used to balance both the gelling reaction and the gas-forming or foaming reaction responsible for foam formation. In this work, the effect of a tin octoate catalyst on the mechanical properties and morphology of polyurethane foam were investigated. Also, the thermal conductivity and sound absorption coefficient for polyurethane foam mortar formulations were measured. The morphological properties of polyurethane foam were investigated using scanning electron microscope to determine the influence of varying the concentration of tin octoate. It was clear from the results that polyurethane foam has good thermal and sound insulation capabilities.

Optimum Calcium Carbonate Filler Concentration for Flexible Polyurethane Foam Composite

The production cost of flexible polyurethane foam is significantly dependent on the cost of polyol, which constitute the largest percentage of materials used in foam production with the characteracterics to induce superior mechanical properties. Suitable fillers that are relatively cheap can be introduced in the foam matrix as replacement for polyol. However, certain compositions of filler have deleterious effect on some relevant mechanical properties of the foam. This paper investigates the effect of CaCO3 filler in flexible polyurethane foam matrix for the dual purposes of achieving sustained mechanical properties and reduction in production cost. The optimum CaCO3 composition was found to be 20 wt % representing a concomitant 18.54% reduction in cost of production.

Numerical study of forward smoldering combustionof polyurethane foam

A two-dimensional and two-phase numerical model is presented for the smolder propagation in a horizontal polyurethane foam. The chemical processes considered include endothermic pyrolysis and exotherrnic oxidation degradation of polyurethane foam and exothermic oxidation of char. The governing equations are discretized in space using the finite element method and solved by the software package FEMLAB. Predicted profiles of solid temperature as well as evolutions of solid compositions （including foam, char and ash） are presented at an airflow velocity of 0. 28 cm/s. The computed average smoldering velocity is 0. 021 4 cm/s, and the average maximum temperature is 644. 67 K. Based on the evolutions of solid compositions, the packed bed can be obviously divided into four zones： unreacted zone, fuel pyrolysis and oxidation zone, char oxidation zone and fuel burned-out zone. Simultaneously, the effects of inlet air velocity and fuel properties （including thermal conductivity, specific heat, density and pore diameter） are studied on the smoldering propagation. The results show that the smoldering velocity and temperature have a roughly linear increase with increasing inlet air velocity; the fuel density is the most important factor in determining smoldering propagation; radiation has a non-negligible role on the smoldering velocity for larger pore diameters of porous material. The computational results are compared with the experimental data and a general agreement is reached.

Optimizing the Properties of Polyether Based Polyurethane Foam

Effect of different chemicals and additives used in producing polyester foam was investigated. Reference samples were produced from polyol, toluene di isocyanate (TDI), amine stannous octoate distil water, and silicone oil using laboratory mix formulation based on 500 g polyether based polyol. Other samples were produced by consecutively varying the content of all the additives with the exception of polyol. Standard sample dimensions for density test, indentation test, compression set test, tensile strength and elongation tests were produced from the samples. The various tests were carried out on the samples using the ASTM-D3574 standards. It was observed that the degree of indentation affects the value of indentation hardness and increasing the percentage content of TDI results in acceptable compression set value for the polyester samples. It was concluded that Holding all other parameters constant, reducing the water content and increasing the TDI content will yield polyester foam of optimum properties.

Properties of Water Blown Rigid Polyurethane Foams with Different Funetionality

Water blown rigid polyurethane foams with different functionality were prepared. The physical properties of rigid foams were measured with rotational viscometer （NDJ-1 ）, universal testing machine （Instron3365）, scanning electron microscope （SEM） and differential scanning calorimeter （DSC）. The results show that the viscosity of polyether polyol increases exponentially from 62 mPa s to 6 000 mPa s with the increase of functionality from 2 to 5.6, respectively. The overall density of foam increases slightly from 31.7 kg/m^3 to 37.4 kg/m^3 with increasing functionality while core density exhibited little difference. Compressive strength of foam shows the similar behavior with density except for 2-functional sample. At the same time, dimensional stability becomes better with increasing functionality except for 5.6-functional foam that has worse stability than 4.8-functional foam. From the SEM results, the functionality is not an important factor in determining distribution of cell size of foam. According to the results of thermal analysis, the glass transition temperature （T） shifts to a higher temperature from 128.9 ℃ to 166.3 ℃ for the 2 to 5.6 functional foam, respectively.

Performance characterization, of rigid polyurethane foam with refined alkali lignin and modified alkali lignin

The two kinds of rigid polyurethane （PU） foams were prepared with respectively adding the refined alkali lignin and alkali lignin modified by 3-chloro-1,2-epoxypropane to be instead of 15% of the polyether glycol in weight. The indexes of mechanical performance, apparent density, thermal stability and aging resistance were separately tested for the prepared PU foams. The results show that the mechanical property, thermal insulation and thermal stability for PU foam with modified alkali lignin are excellent among two kinds of PU foams and control samples. The additions of the refined alkali lignin and modified alkali lignin to PU foam have little effect on the natural aging or heat aging resistance except for decreasing hot alkali resistance apparently. Additionally, the thermal conductivity of modified alkali lignin PU foam is lowest among two kinds of PU foams and control samples. The alkali lignin PU foam modified by 3-chloro-1,2-epoxypropane could be applied in the heat preservation field.

Physico-mechanical characterization of polyurethane foam dressings containing natural polyols

Advanced wound dressings are replaced traditional dressings in order to provide appropriate environment for healing and also to promote cell migration[1].The key characteristics of wound dressings are non-toxic,highly absorbed,air permeable,biocompatible and have good mechanical properties[2].Due to providing moist environment and also protecting maceration at the wound edge area,foam dressings are used in various clinical applications[3].They are mostly prepared from polyurethane between polyols and isocyanate polymerization.

Electroless copper plating on microcellular polyurethane foam

In order to obtain substrates with good conductive foam for high porosity foam metal materials used in the metal electrodes,the technique of electroless copper plating on the microcellular polyurethane foam with pore size of 0.3 mm was investigated.The main factors affecting the deposition rate such as the solution composition,temperature,pH value and adding ultrasonic were explored.The results show that the optimum process conditions are CuSO4 16 g/L,HCHO 5 mL/L,NaKC4H4O6 30 g/L,Na2EDTA 20 g/L,K4Fe(CN)6 25 mg/L,pH value of 12.5-13.0 and temperature of 40-50℃.Under these technical conditions, the process has excellent bath stability.Adding ultrasonic on the process can elevate the deposition rate of copper by 20%-30%.The foam metal material with a porosity of 92.2%and a three-dimensional network structure,was fabricated by electro-deposition after the electroless copper plating.

STUDIES ON POLYURETHANE FOAM POLISHING TOOL

This paper deals with Polyurethane Foam Polishing Tool (PFPT), which has three dimensional softness and are adapted to polishing sophisticated curved surfaces. The manufacturing technology, the equilibrium theory of matter and energy have been discussed and the PFPT is produced successfully at our laboratory. After investigating their properties, the effective factors to the behavior of the PFPT are studied. The microcosmic construction of the PFPT have been observed by sweep electron microscope(SEM) and the polishing mechanism studied. A great deal of experiments have been carried out to optimize the manufacturing parameters.

Bio-Based Trivalent Phytate:A Novel Strategy for Enhancing Fire Performance of Rigid Polyurethane Foam Composites

Biomass phytic acid has potential flame retardant value as the main form of phosphorus in plant seeds.In this study,phytate-based flame retardants aluminum phytate(PA-Al)and iron phytate(PA-Fe)were synthesized and characterized.Subsequently,they were introduced into rigid polyurethane foam(RPUF)as flame retardants by one-step water-blown method.The results indicated that RPUF/PA-Fe30 exhibited the highest char residue of 22.1 wt%,significantly higher than 12.4 wt%of RPUF.Cone calorimetry analysis showed that the total heat release(THR)of RPUF/PA-Al30 decreased by 17.0%and total smoke release(TSR)decreased by 22.0%compared with pure RPUF,which were the lowest,demonstrating a low fire risk and good smoke suppression.Thermogravimetric analysis-Fourier transform infrared spectrometer(TG-FTIR)implied the release intensity of flammable gases(hydrocarbons,esters)and toxic gases(isocyanate,CO,aromatic compounds,HCN)of composites was significantly reduced after the addition of PA-Fe.The analysis of char residue indicated that the RPUF composites formed a dense char layer with a high degree of graphitization after the addition of PA-Al/PA-Fe,endowing RPUF composites with excellent mass&heat transmission inhibition effect and fire resistance in the combustion process.

Thermal Decomposition and Kinetics of Rigid Polyurethane Foams Derived from Sugarcane Bagasse

Rigid polyurethane foams were fabricated with five kinds of liquefied sugarcane bagasse polyols （LBP）. The foams derived from sugarcane bagasse were investigated by thermogravimetric analysis （TGA）, and the thermal degradation data were analyzed using the Coast-Redfern method and Ozawa method to obtain the reaction order and activation energy. The results indicate that the sugarcane bagasse-foams exhibit an excellent heat-resistant property, whereas their pyrolysis procedures are quite complicated. The reaction as first order only takes place from 250 to 400 ℃, and the pyrolysis activation energies vary from 20 to 140 kJ/mol during the whole pyrolysis process.

Hydrolysable Chestnut Tannin Extract Chemical Complexity in Its Reactions for Non-Isocyanate Polyurethanes(NIPU)Foams

Non-isocyanate polyurethane(NIPU)foams from a commercial hydrolysable tannin extract,chestnut wood tannin extract,have been prepared to determine what chemical species and products are taking part in the reactions involved.This method is based on two main steps:the reaction with dimethyl carbonate and the formation of urethane bonds by further reaction of the carbonated tannin with a diamine-like hexamethylene diamine.The hydroxyl groups on the tannin polyphenols and on the carbohydrates intimately linked with it and part of a hydrolysable tannin are the groups involved in these reactions.The carbohydrate skeleton of the hydrolysable tannin is also able to participate through its hydroxyl groups to the same two reactions rendering the whole molecular complex able to react to form NIPUs.The analysis by Matrix-Assisted Laser Desorption Ionization(MALDI-TOF)mass spectrometry and 13C Nuclear Magnetic Resonance(13C NMR)to further investigate the reaction mechanisms involved revealed the unsuspected complexity of chestnut hydrolysable tannin,with different fragments reacting in different manners forming a hardened network of considerable complexity.As the morphology and performance of these types of foams changes slightly with the change in the amount of glutaraldehyde and hexamine hardeners,the best performing foam formulation previously determined was scanned by SEM and analysed chemically for the structures formed.

Trifuntional Oligoetherols and Polyurethane Foams with Carbazole Ring

The method of synthesis of trifuntional oligoetherols with carbazole ring from 9-(2,3-epoxypropyl)carbazole and die- thanolamine and oxiranes like ethylene and propylene oxide was presented. Structure and some physicochemical prope- rties of the products were described. The oligoetherols were demonstrated as good substrates for synthesis of polyure- thane foams of enhanced thermal resistance. It has been found that the obtained foams are rigid at room temperature and their apparent density was 34 kg/m3- 44 kg/m3. The water uptake was low, maximum to 10.5 mass%. Dynamic thermal analysis of this foams showed that 5% mass loss starts at 200?C - 220?C, while temperature of 50% mass loss was 340?C - 370?C. Concomitantly the increase of compression strength was observed.

耐高温起泡剂膦甲基酚醛树脂PMP的合成及性能

由苯酚、甲醛、PCl3合成了水溶性固体膦甲基酚醛树脂(PMP),其HLB值为20 7。简介了合成方法,考察了PMP作为起泡剂的配方性能。PMP溶液室温发泡体积Vf随浓度增大(5～20g/L)而略有增大,泡沫半衰期t1/2在浓度12 5g/L时最长,为20 2min,此时Vf=520mL(/100mL溶液)。在该浓度PMP溶液中分别加入CMC、硅酸钠、三乙醇胺、膨润土使Vf值略降,t1/2值在适宜加量范围大幅延长,加量分别为1 0、2 0、12 5、40g/L时有最大值370 0、85 2、180 2、174 2min;这4个复配PMP/添加剂溶液在温度升高时(30～90℃)Vf值增大但t1/2值大幅缩短。12 5g/LPMP溶液在150～200℃滚动16h后室温下Vf值不变,t1/2值随滚动温度升高而降低,200℃时为11 3min;12 5/2 0/10/40g/LPMP/硅酸钠/三乙醇胺/膨润土溶液在200℃滚动16h后,室温下Vf值为470mL,t1/2值高达50h。PMP为耐高温性能良好的起泡剂,可与硅酸钠、三乙醇胺、膨润土复配使用。图2表4参10。