Semi-rigid Polyurethane Foams Research Articles

Preventing the Collapse Behavior of Polyurethane Foams with the Addition of Cellulose Nanofiber.

Polyurethane foam manufacturing depends on its materials and processes. A polyol that contains primary alcohol is very reactive with isocyanate. Sometimes, this may cause unexpected problems. In this study, a semi-rigid polyurethane foam was fabricated; however, its collapse occurred. The cellulose nanofiber was fabricated to solve this problem, and a weight ratio of 0.25, 0.5, 1, and 3% (based on total parts per weight of polyols) of the nanofiber was added to the polyurethane foams. The effect of the cellulose nanofiber on the polyurethane foams' rheological, chemical, morphological, thermal, and anti-collapse performances was analyzed. The rheological analysis showed that 3 wt% of the cellulose nanofiber was unsuitable because of the aggregation of the filler. It was observed that the addition of the cellulose nanofiber showed the improved hydrogen bonding of the urethane linkage, even if it was not chemically reacted with the isocyanate groups. Moreover, due to the nucleating effect of the cellulose nanofiber, the average cell area of the produced foams decreased according to the amount of the cellulose nanofiber present, and the average cell area especially was reduced about five times when it contained 1 wt% more of the cellulose nanofiber than the neat foam. Although the thermal stability declined slightly, the glass transition temperature shifted from 25.8 °C to 37.6, 38.2, and 40.1 °C by when the cellulose nanofiber increased. Furthermore, the shrinkage ratio after 14 days from the foaming (%shrinkage) of the polyurethane foams decreased 15.4 times for the 1 wt% cellulose nanofiber polyurethane composite.

ТЕХНОЛОГИЯ УДАЛЕНИЯ НЕФТЯНЫХ РАЗЛИВОВ С ПОМОЩЬЮ СОРБЦИОННОГО МАТЕРИАЛА НА ОСНОВЕ ХИТОЗАНА И ПЕНОПОЛИУРЕТАНА

Chitin-containing materials were most widely used in wastewater treatment. In production processes accompanied by the release of proteins, chitosan is used as a flocculant in the treatment of contaminated wastewater. Using chitosan, metals are extracted from mining waste. The introduction of chitosan into the soil leads to the removal of scattered heavy metals and radionuclides from the natural cycle.There are a number of patents in the field of water treatment using chitosan. However, there is much less work on the use of chitin and chitosan as a sorbent for oil and oil products. Alaa Eldin Muhammad Younes et al used chitin and chitosan to remove Tengiz oil spills from the water surface. At the same time, oil with chitin formed clots, which eventually (~ 2 hours) precipitated. On the contrary, chitosan forms floating clots, which contributes to their extraction. The authors on the model systems determined the flow rates for the collection and removal of oil film from the surface of 1 m2. This is 0.16 kg of chitin or chitosan with an amount of 10% of the sorbent based on the weight of the oil film. It has been suggested that extractable products can be used in asphalt concrete pavements. A high degree of water purification (up to 99.8%), and almost complete purification of waters containing oil emulsions makes it possible to recommend it as a highly effective flocculant with its content of 0.0028. It is characteristic that chitosan works better with a high oil content in water. However, efficient recovery of chitosan with absorbed oil remains an unresolved issue. In this case, oil flows from the sorbent, leading to secondary pollution. The invention proposes a method of oil and petroleum product spill response and purification at water bodies, as well as reduction of environmental pollution by waste water of industrial enterprises with the help of highly efficient, economically justified sorption material based on chitosan and semi-rigid polyurethane foam and a technological process of its production. Sorption material using crushed chitosan soluble in acid in amount of 30% of total weight and elastic polyurethane foam PPUel-30-HC has optimal absorption capacity of ~ 14.0 g/g at weight ratio of sorption material components A: B: chitosan = 1: 0.6: 0.48. The environmental friendliness of the developed sorption material is confirmed by the possibility of its repeated use up to 19 times after squeezing the absorbed product without significant changes in oil capacity. Disclosed is a technological scheme for producing a developed sorbent named Grinsorb X and a method for eliminating oil spills using it.

Composites of Semi-Rigid Polyurethane Foams with Keratin Fibers Derived from Poultry Feathers and Flame Retardant Additives.

Semi-rigid composites of polyurethane foams (SRPUF) modified with the addition of keratin flour from poultry feathers and flame retardant additives were manufactured. Ten percent by mass of keratin fibers was added to the foams as well as halogen-free flame retardant additives such as Fyrol PNX, expandable graphite, metal oxides, in amounts such that their total mass did not exceed 15%. Thermal and mechanical properties were tested. Water absorption, dimensional stability, apparent density and flammability of produced foams were determined. It was found that the use of keratin fibers and flame retardant additives changes the foam synthesis process, changes their structure and properties as well as their combustion process. The addition of the filler made of keratin fibers significantly limits the amount of smoke generated during foam burning. The most favorable reduction of heat and smoke release rate was observed for foams with the addition of 10% keratin fibers and 10% expandable graphite. Systems of reducing combustibility of polyurethane foams using keratin fillers are a new solution on a global scale.

Studies on Modelling of Mechanical Properties of Polyester-based Semi-rigid Polyurethane Foams

This paper describes the mechanical behaviour of castor oil based semi rigid polyurethane foams with relative density below 0.05moulded by varying isocyanate index (Isocyanate equivalent/hydroxyl equivalent) from 1:1 to 1:2. Mechanical properties of polyurethane foam mainly compressive strength is measured experimentally and the values were compared using three widely referred theoretical models namely: (i) the Empirical model (ii) Gibson and Ashby approach widely used for foam description and (iii) modified Gent Thomas model. Empirical model suggested that the synthesised polyurethane foam is closed-cell foams, which have cell walls that undergo stretching and struts that undergo bending. Experiment values showed variation from Gibson and Ashby model and Gent Thomas model, since both these models are based on the deformation of a simple cubic or rectangular structure, which is not representative of a real foam structure.

Synergistic Flame Retardant Effects of Expandable Graphite and Ammonium Polyphosphate in Water-Blow Polyurethane Foam

In this research, expandable graphite (EG) and ammonium polyphosphate (APP) were incorporated into water-blow semirigid polyurethane foam (SPUF) as flame retardants. The synergistic flame retardant effects of EG with APP in SPUF had been studied by thermogravimetric analysis (TGA), limiting oxygen index (LOI), horizontal burning test, polarizing microscope, and scanning electron microscopy (SEM). The results indicated that APP and EG used together in SPUF could effectively improve the flame retardancy of SPUF. When the EG to APP ratio reached 2 : 1 under the total content of flame retardants was kept constant as 20%, the LOI value was increased by about 51% compared to pure SPUF, 2.9% to SPUF/EG and 16.3% to SPUF/APP. Besides, the residual char was increased up to 27.7% displayed by TG test results. SEM shows that burned residues of EG/APP/SPUF present more compact char and worm-like structure. Furthermore, EG shows negative effect on the mechanical property of SPUF with 21.7% decrease in compression modulus, but the mechanical property can be improved by the addition of appropriate content of APP.

Compressive Behavior of Aluminum Microfibers Reinforced Semi-Rigid Polyurethane Foams.

Unreinforced and reinforced semi-rigid polyurethane (PU) foams were prepared and their compressive behavior was investigated. Aluminum microfibers (AMs) were added to the formulations to investigate their effect on mechanical properties and crush performances of closed-cell semi-rigid PU foams. Physical and mechanical properties of foams, including foam density, quasi-elastic gradient, compressive strength, densification strain, and energy absorption capability, were determined. The quasi-static compression tests were carried out at room temperature on cubic samples with a loading speed of 10 mm/min. Experimental results showed that the elastic properties and compressive strengths of reinforced semi-rigid PU foams were increased by addition of AMs into the foams. This increase in properties (61.81%-compressive strength and 71.29%-energy absorption) was obtained by adding up to 1.5% (of the foam liquid mass) aluminum microfibers. Above this upper limit of 1.5% AMs (e.g., 2% AMs), the compressive behavior changes and the energy absorption increases only by 12.68%; while the strength properties decreases by about 14.58% compared to unreinforced semi-rigid PU foam. The energy absorption performances of AMs reinforced semi-rigid PU foams were also found to be dependent on the percentage of microfiber in the same manner as the elastic and strength properties.

Effect of crosslinking agent on properties and morphology of water‐blown semirigid polyurethane foam

ABSTRACTIn this article, triethanolamine (TEOA) is used as crosslinking agent, water‐blown semirigid polyurethane foams with different crosslinking agent content were prepared. The crosslinking density of polyurethane foams (PUFs) were adjusted and designed by changing the content of TEOA. The influence of crosslinking agent content on foaming process, apparent density, cell structure, microphase separation structure, thermal properties, and mechanical properties of PUFs has been studied. The cell structure, apparent density, and mean size of foams are closely related to foaming and gelation process. The results show that the crosslinking density is increased with the content of TEOA, and the swelling ratio of foams decreased from 294.9 to 194.7%. Dynamic mechanical analysis indicates that the promotion of crosslinking density can effectively restrict the movement of molecular chains, results in the glass‐transition temperature (T g) of foams increased from −14.2 to −8.6 °C. Thermogravimetric analysis states that the carbon residue of foams has increased by 5%, because the addition of crosslinking density contributes to reducing and limiting the formation of volatile degradation products. Fourier transform infrared spectroscopy is shown that the introduction of TEOA is not conducive to the microphase separation of urea, resulting in the decrease of foam mechanical properties. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46753.

Influence of expandable graphite particle size on the synergy flame retardant property between expandable graphite and ammonium polyphosphate in semi-rigid polyurethane foam

Effect of the difference of expandable graphite (EG) particle size on the synergistic flame retardant effect between expandable graphite (EG) and ammonium polyphosphate (APP) in the semi-rigid polyurethane foam (SPUF) was studied for the first time. Three large-span particle sizes of EG were added into SPUF with different mass ratios of EG/APP. The synergistic effect between EG and APP on the flame retardant property of composites was investigated using the limiting oxygen index test, horizontal–vertical burning test, thermogravimetric analysis (TGA), scanning electron microscope (SEM), etc. Flammability performance tests indicated that the larger particle size the EG possessed, the more obvious will be the synergistic effect exhibited between EG and APP. SEM images and TGA results provided positive evidence for the combustion tests. Synergistic effect was strongly influenced by the compactness of united protective layer. The maximal rate of the degradation of the SPUF composite system further confirmed the relationship between the rate of the composites’ degradation and the compactness of united protective layer. Speculative reactions which were related to the changes of EG in the presence of APP under high temperature were discussed.

Semi-rigid polyurethane foams with rapeseed polyol of different viscosity

The subject of research presented in this article are the semi-rigid polyurethane foams (­SRFPUR) produced with a formula developed by the company FAMPUR. It consisted of replacing the petrochemical polyol with two types of rapeseed oil-based polyols of different viscosity. Foams were characterized using such techniques as infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry. With the use of scanning electron microscope changes in the structure of materials were analyzed. In addition, the apparent density, number of closed cells, and properties of materials during compression tests were determined.

Effect of zeolites on morphology and properties of water-blown semi-rigid ammonium polyphosphate intumescent flame-retarding polyurethane foam

Water-blown semi-rigid polyurethane foams (SPFs) were prepared by a one-shot, free-rise method. Effect of zeolites (ZEO) on morphology, flame retardancy, mechanical properties, damping properties, and thermal properties of ammonium polyphosphate (APP) intumescent flame-retarding SPFs was studied through the analysis of rotary viscosity test, limiting oxygen index (LOI), horizontal-vertical burning test, scanning electron microscopy (SEM) and mechanical test etc. Rotary viscosity test found that viscosity just enhanced a little when zeolites were added to the reaction matrix containing APP. With zeolites added, internal defects foams caused by the high loading of flame retardants could be effectively eliminated because the reaction heat could be partly taken by zeolites’ crystal water. The addition of zeolites did not increase the density of the APP intumescent flame-retarding SPFs. Meanwhile, with the presence of zeolites the APP intumescent flame-retarding SPFs exhibited better flame retardant property when APP content is high. Mechanical test showed that with the introduction of ZEO, compression strength and compression modulus of SPFs stably enhanced with the increasing APP loading and reached a maximum value when the APP content was 45 pphp. At a certain ZEO content (ZEO = 15 pphp), the APP intumescent flame-retarding SPFs with zeolites exhibited higher compression strength and modulus when the APP loading was over than 45 pphp.

Open cell semi-rigid polyurethane foams synthesized using palm oil-based bio-polyol

Semi-rigid polyurethane foams were successfully prepared by blending up to 70wt.% of a palm oil-based bio-polyol with a petrochemical polyether polyol. Due to the high viscosity of the bio-polyol derived from palm oil, polyol premixes were heated before mixing with an isocyanate component. Despite this, a slowdown in the foaming and gelling reactions was detected as the content of the palm oil-based bio-polyol in the formulation increased. The thermal conductivity of the modified foams was higher than that of the reference one, even when they exhibited a lower apparent density. In addition, their mechanical and dynamic mechanical properties decreased as the palm oil-based polyol content in the final foams increased. These effects are attributed to the foams’ cellular structure since the closed cell content decreased as the amount of the petrochemical polyol replaced by the bio-polyol increased. However, the water absorption decreased as the bio-polyol concentration in the polyurethane formulation increased and the modified foams exhibited excellent dimensional stability Taking into account potential applications of polyurethane systems, the formulation containing 30wt.% of the bio-polyol could be used in the preparation of a new generation open cell semi-rigid foams permeable to moisture and with higher content of biomass-derived constituents.

The Effect of Soluble Ammonium Polyphosphate on the Properties of Water Blown Semirigid Polyurethane Foams

Soluble ammonium polyphosphate (SAPP) is employed to prepare flame retardant semirigid polyurethane foam (SPUF) using water as blowing agent. The flame retardant property of SPUF is evaluated by limiting oxygen index (LOI) and horizontal burning test. Also the thermal degradation mechanism is studied by TG and Fourier transform infrared (FTIR). The results show that, with the increase of the content of SAPP, flame retardant property of SPUF improves obviously as the LOI value increases and the horizontal burning rate decreases. And residual char is increased up to 20% with 19 wt% SAPP. Moreover, the mechanical property of SPUF is enhanced dramatically.

Characterization of Biobased Polyurethane Foams Employing Lignin Fractionated from Microwave Liquefied Switchgrass

Lignin samples fractionated from microwave liquefied switchgrass were applied in the preparation of semirigid polyurethane (PU) foams without purification. The objective of this study was to elucidate the influence of lignin in the PU matrix on the morphological, chemical, mechanical, and thermal properties of the PU foams. The scanning electron microscopy (SEM) images revealed that lignin with 5 and 10% content in the PU foams did not influence the cell shape and size. The foam cell size became larger by increasing the lignin content to 15%. Fourier transform infrared spectroscopy (FTIR) indicated that chemical interactions occurred between the lignin hydroxyl and isocyanate revealing that lignin was well dispersed in the matrix materials. The apparent density of the foam with 10% lignin increased by 14.2% compared to the control, while the foam with 15% lignin had a decreased apparent density. The effect of lignin content on the mechanical properties was similar to that on apparent density. The lignin containing foams were much more thermally stable than the control foam as evidenced by having higher initial decomposition temperature and maximum decomposition rate temperature from the thermogravimetric analysis (TGA) profiles.

Performance study of flame-retardant semi-rigid polyurethane foam with modified expandable graphite

Purpose In this paper, boric acid was loaded on the surface of expandable graphite (EG), polyvinyl alcohol (PVA) and silane coupling agent (KH550) served as a bridge. The purpose of this study was to improve the flame retardant properties of semi-rigid polyurethane, meanwhile, the mechanical properties of the foam got ameliorated. Design/methodology/approach PVA was dissolved in hot water. EG was added to this solution. After stirring for 0.5 h at 85°C in ultrasonic agitation, the system was put at room temperature to cool. The silane coupling agent KH550 was added dropwise into the solution system, stirring to fully hydrolyze. Boric acid was added into the system, placing it in an oven at 90°C to dry after filtration. Changing of flame retardant properties and mechanical properties of semi-rigid polyurethane adding modified EG were characterized. Findings The flame retardant performance of the foam with EG has been improved, whereas the tensile strength decreased with an increase in the content of EG. After adding modified EG, compared to semi-rigid polyurethane with EG, flame retardant performance and tensile strength of the foam improved. Research limitations/implications In the study reported here, the surface of EG was modified by boric acid. The modified EG was added into semi-rigid polyurethane foam. The flame retardant performance and tensile strength of the foam after adding modified EG were discussed. Results of this research could benefit in-depth study of the influence of adding modified EG to semi-rigid polyurethane. The study could promote the application of flame-retardant polyurethane foam. Originality/value The flame retardant performance and tensile strength of the semi-rigid polyurethane were improved by adding modified EG. The effects of modified EG on the flame retardant performance and tensile strength of semi-rigid polyurethane were discussed in detail.

Production and characterization of polyurethane foams from a simple mixture of castor oil, crude glycerol and untreated lignin as bio-based polyols

Polyurethane foams from bio-based polyols have been studied to produce sustainable and eco-friendly materials from biomass industrial wastes. Semi-rigid polyurethane foams were synthesized from physical mixtures of kraft lignin, castor oil and residual glycerol. The influence of different lignin contents (10, 12.5, 15, 17.5, 20, 25, 30 and 40%) on the foam properties was evaluated. An increase in the density and a decrease in the thermal stability were observed upon an increasing amount of lignin. The foam synthesized with 17.5% lignin showed better dimensional and thermal properties as well as the best cell homogeneity and this formulation was chosen for further investigation of the effects of the castor oil content, isocyanate/hydroxyl molar ratio (NCO/OH) and the blowing agent type. Increased foam densities and compressive strengths were observed with increased castor oil content in the foams. Similar results were observed upon increasing the NCO/OH molar ratio due to the higher amount of crosslinking reactions. The evaluation of the blowing agent effect showed that using cyclopentane and n-pentane, the foams showed higher densities and lower compressive strengths in comparison to the foams synthesized with the chemical blowing agent (water). This result can be explained by the faster volatilization of these organic blowing agents, producing smaller cells in comparison to the CO2 generated by the reaction of water with isocyanate. Green polyurethane foams with good properties and industrial interest were produced using a mixture of residual raw materials (glycerol and lignin) and castor oil as bio-based polyols.

Effect of hard segments on the thermal and mechanical properties of water blown semi-rigid polyurethane foams

Water blown semi-rigid polyurethane foams with different ethylene glycol (EG) content were prepared. EG is used as chain extender to vary hard segments content of semi-rigid polyurethane foams. The effect of EG on foam molding process, hard segment structure and the relationship between structure and thermal, mechanical properties of foams has been investigated. Results indicate that the addition of EG contributes to preparing flawless foams, and reduces the apparent density of foams due to the increase in cell size. Fourier transform infrared analysis (FTIR) displays the existence of hydrogen bonds among polyurea segments, which is influenced by reactant activity. Dynamic mechanical analysis (DMA) manifests different phase mixing and soft domains Tg of foams with different EG content. Soft domains Tg is dependent on the purity of soft domains controlled by urethane hard segments and dissolved urea groups. Thermo gravimetric analysis (TGA) illustrates that thermal stability of foams is associated with hard segments content in foams. Mechanical tests demonstrate that improvements of mechanical properties of foams can be achieved by modifying foam formulation to increase microphase separation of polyurea segments.

NdCl3-Schiff Base Complex as Catalyst for Formation of Water-Blown Semi-Rigid Polyurethane Foam

NdCl3-Schiff Base Complex as Catalyst for Formation of Water-Blown Semi-Rigid Polyurethane Foam

Mechanical Properties of Automotive Instrument Panels with Semi-Rigid Foam

Semi-rigid polyurethane foam to soften the instrument panel has a lightweight, impact and energy absorption performance, while improving the texture of the surface of the instrument panel. This article was prepared by one-step car instrument panel with semi-rigid polyurethane foam, through the design of the four factors and three levels orthogonal test program, using Fourier infrared spectroscopy to characterize its structure, measuring its apparent density and hardness properties of transformation, the combination of research influence of the proportion of polyether foam system.

Study of different-sized sulfur-free expandable graphite on morphology and properties of water-blown semi-rigid polyurethane foams

In this paper, EG with different nominal particle sizes (70 μm, 430 μm and 960 μm) and different loadings from 0 to 50 pphp were considered to investigate the effect of expandable graphite on the morphology and properties of water-blown semi-rigid polyurethane foams (SPFs).

Effect of expandable graphite particle size on the flame retardant, mechanical, and thermal properties of water‐blown semi‐rigid polyurethane foam

ABSTRACTDifferent particle size of expandable graphite (EG) were incorporated into water‐blown semi‐rigid polyurethane foams (SPFs), which acted as the fire shield, in order to enhance the fire retardant properties. In this study, the particle size of EG was systematically varied from 70 µm to 960 µm. The effect of EG particle size on the density, mechanical properties, and thermal stability of SPFs was also investigated. Results showed that EG with smaller particle size showed almost no effect on the fire retardant properties of SPFs while the larger particle size of EG could effectively enhance it. It was observed that the flame retardancy of the composite improved with the increase of EG size which was attribute to the formation and densification of isolation layer with the increase in volume of expanded graphite. Limiting oxygen index (LOI) value of EG/SPF composites increased linearly by two steps with the increase in EG particle size. Horizontal burning test confirmed the above conclusion. Thermogravimetric analysis (TGA) indicated that EG particles and its size exhibited minor effect on the thermal stability of the SPF composites. Moreover, SPF filled with medium particle size of EG (about 400 µm) exhibited a poor compression performance compared with the others. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39885.