Liquid‐type nucleating agent for improving thermal insulating properties of rigid polyurethane foams by HFC‐365mfc as a blowing agent

The effects of liquid‐type additives on the morphology, thermal conductivity, and mechanical strength of polyurethane (PUR) foams were investigated. The PUR foams synthesized with perfluoroalkane showed a smaller average cell diameter and a lower thermal conductivity than PUR foams prepared with propylenecarbonate or acetone. The average cell diameter of the PUR foams decreased from 228 to 155 μm and the thermal conductivity decreased from 0.0227 to 0.0196 kcal/mh °C when the perfluoroalkane content was 0.0 to 2.0 php (parts per hundred polyol by weight). The perfluoroalkane likely acted as a nucleating agent during the formation of the PUR foams. The addition of perfluoroalkane induced the smaller cells size of the PUR foams probably due to lower surface tension of the polyol and perfluoroalkane mixture, resulting in high nucleation rate. The smaller cell size appears to be the main reason for the improvement in the thermal insulating and the mechanical properties of these PUR foams. The compressive strength of the PUR foams prepared with perfluoroalkane was higher than the PUR foams prepared with the propylenecarbonate and acetone. Based on the morphology, thermal conductivity, and compressive strength, it is suggested that the perfluoroalkane is an efficient liquid‐type additive for the improving the thermal insulation of PUR foams. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43557.     

Effects of liquid‐type silane additives and organoclay on the morphology and thermal conductivity of rigid polyisocyanurate‐polyurethane foams

This article investigates the effects of liquid‐type silane additives and organoclay as a solid‐type additive on the morphological, mechanical and thermal insulating properties of polyisocyanurate‐polyurethane (PIR‐PUR) foams. The organoclay likely acted as nucleating agents during the formation of PIR‐PUR foams. When the liquid silane additives and organoclay were added, the cell size and thermal conductivity of the PIR‐PUR foams appeared to be decreased. However, organoclay did not contribute to reduce the cell size distribution of the foam. PIR‐PUR foams synthesized with tetramethylsilane as a liquid‐type additive showed a smaller average cell size and lower thermal conductivity than that of PIR‐PUR foams synthesized with the other silane additives or with organoclay as a solid‐type additive. For the PIR‐PUR foam with organoclay/TEMS (1.5/1.5 php) mixture, cell size and thermal conductivity of the foam showed similar to the foam with TEMS. These results suggest that smaller cell size appears to be one of the major factors in the improvement of thermal insulation properties of the PIR‐PUR foams. Silane additives did not seem to have a strong effect on the flammability of the PIR‐PUR foams. However, heat resistance was more dominant for the foam with the organoclay at the higher temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Expandable graphite in polyurethane foams: The effect of expansion volume and intercalants on flame retardancy

Several expandable graphites (EGs), differing in expansion volume but with the same mean size, are compared as flame retardants in polyurethane (PUR) foams. Not only common sulfur‐intercalated graphites are investigated but also a new one intercalated with phosphorus. The main aim of this article is to understand which properties of EG are important for its flame retardancy effectiveness in PUR foams. Thermal stability, flammability, and fire behavior are analyzed through limiting oxygen index and cone calorimeter tests. Detailed characterization of the phosphorus‐intercalated graphite is also provided as well as physical–mechanical characterization. The results show that the well‐known sulfur‐intercalated graphites and the one with phosphorus both enhance the residue yield, induce a protective layer, and thus efficiently flame‐retard PUR foams. While the expansion volume of the EGs had a surprisingly limited influence on the performance of the foams, at least in the range tested, the most important feature controlling the effectiveness of EG in terms of flame retardant PUR foams was the type of intercalant. The presence of EG affected the physical–mechanical properties of the foams; however, no significant effect of the expansion volume or intercalant type has been revealed on the physical–mechanical properties of the foams. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45173.     

Effect of different concentration of rapeseed‐oil‐based polyol and water on structure and mechanical properties of flexible polyurethane foams

Flexible polyurethane foams (FPURFs) with varied concentration of water from 3.2 to 4.2% and rapeseed oil based polyol (ROP) in the range of 13–22% in polyol premix were obtained. Effects of changes in polyurethane (PUR) formulation on the foaming process and mechanical properties of FPURFs were analyzed. It was found that the change of water content in PUR formulation influences its foaming process. Higher water content in the PUR formulation increases the growth velocity and the temperature of reaction mixture. In the case of foams modified with ROP, an opposite effect can be observed, where higher content of that component resulted in overall downturn of the foaming process and decreases of registered temperature inside the foams core. An addition of ROP beneficially influences on foams cellular structure favoring creation of finer cells. Such modification of PUR formulation with ROP increased apparent density, reduced hardness, and resilience of flexible foams. What is more the support factor of FPURFs with ROP was higher in comparison to the reference foam. Along with higher water content in the PUR formulation, apparent density and hardness has decreased and foams ability to absorb energy has been increased. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42372.     

New compounds for production of polyurethane foams

A method of boroorganic compound preparation with boric acid, 1,3‐propanediol, 2,3‐butanediol, and 1,4‐butanediol is described in this article. The obtained compounds were characterized with respect to their usability as polyol components for the production of polyurethane (PUR) foams. New boroorganic compounds were applied as polyol components for the foaming of rigid PUR–polyisocyanurate (PIR) foams. The method of preparation, foaming parameters, and physicochemical properties of the PUR–PIR foams and their results are presented. Application of the prepared borates as polyol components in the production of foams had a favorable effect on the properties of the foams. The obtained rigid foams were characterized by lower brittleness, higher compressive strength, content of closed cells, and considerably reduced flammability in comparison with standard foams. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5918–5926, 2006     

Modifications of the rigid polyurethane–polyisocyanurate foams

The method of boroorganic compounds preparation by esterification of boric acid and glycols has been presented. The obtained compounds tri(2‐hydroxybutyl)borate, tri(hydroxythiodiethylene)borate, tri[(3‐chloro‐2‐hydroxy‐1‐propoxy)‐1‐methylpropyl]borate, and tri[3‐chloro‐2‐hydroxy‐1‐propoxy)thiodiethyl]borate were used to produce the rigid polyurethane–polyisocyanurate (PUR‐PIR) foams. The foams were prepared by one‐stage method and the amount of borates added varied, within the range from 0.0 to 0.4 of chemical equivalent. The method of preparation, determination of foaming parameters, and methods of testing of the physicochemical properties of PUR‐PIR foams as well as their results have been presented. A special emphasis was put on reduction of the foam flammability. It was found that application of the obtained compounds as polyolic components has a favorable effect on the properties of the produced rigid PUR‐PIR foams. The obtained rigid PUR‐PIR foams were characterized by a higher compressive strength, lower brittleness, considerably reduced flammability, and higher content of the closed cells. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2020–2029, 2006     

Properties of rigid polyurethane foams prepared from recycled aircraft deicing agent with hexamethylene diisocyanate

Polyurethane (PUR) rigid foams were prepared from recycled aircraft deicing agent (aircraft deicing fluid) with reaction of hexamethylene diisocyanate at temperature of 55°C. The effect of [NCO]/[OH] ratio on properties of microscopic structure, cell size distribution, compressive strength, apparent density, as well as thermal conductivity (k) was studied. Higher [NCO]/[OH] ratio helped achieve better micromorphology, higher apparent density, and compressive strength of the PUR foams. With the [NCO]/[OH] ratio of 0.75 and 0.8, some shrinking happened during foam rising, causing a decrease in total volume of the PUR foam, and leading to higher apparent density as well as sharply increased compressive strength. All PUR foams displayed good thermal insulation properties in this study. With [NCO]/[OH] ratio increased from 0.7 to 0.8, the k value increased significantly from 34.3 to 42.2 mW m^?1 K^?1. The k value here was chiefly governed by the apparent density of the foams, which was in turn a function of the ratio of [NCO]/[OH]. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci., 2013     

不同原料对合成PUR弹性体性能的影响

采用相同官能度、不同分子量的聚醚多元醇和甲苯二异氰酸酯(TD I)及扩链剂反应合成了系列聚氨酯(PUR)弹性体,同时对所合成的PUR弹性体进行了表征。结果表明,聚醚多元醇的相对分子质量对PUR弹性体的性能有较大影响,相对分子质量越大,柔性链段含量就越多,弹性体的拉伸强度、断裂强度和硬度就减小,断裂伸长率则相对提高。同时也进一步证明了软硬链段之间的均匀分布和较强的相互作用更有利于弹性体力学性能的提高。     

Electrical conductivity of polyurethane/MWCNT nanocomposite foams

Polymeric foams with electrical conductivity represent a novel and very interesting class of materials rather sporadically studied. In this study, the feasibility to prepare electrically conductive Rigid Polyurethane (PUR) foams at various densities using multiwall carbon nanotubes (MWCNT) at varying contents was investigated. The produced PUR/MWCNT foams exhibited electrical conductivity over a wide range of densities and nanofiller contents. The effect of these two parameters on the electrical conductivity of the final foam system was studied. To explain the behavior, Statistical Percolation laws were employed. Model parameters were elaborated for both cases showing that the percolation model can adequately describe the behavior. The foaming process is analyzed in further detail to assist in the explanation and understanding of theexperimental observations. Finally, a material design map is proposed for the preparation of electrically conductive foams. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

In vitro comparative biodegradation analysis of salt‐leached porous polymer scaffolds

This study presents a comprehensive, side‐by‐side analysis of chemical, thermal, mechanical, and morphological changes in four polymers used in tissue engineering: poly(glycerol‐sebacate) (PGS), poly(lactic acid) (PLA)/poly(ε‐caprolactone) (PCL) blend, poly(lactic‐co‐glycolic acid) (PLGA), and Texin 950, a segmented polyurethane resin (PUR). Polymer foams were created using a salt‐leaching technique and then analyzed over a 16‐week period. Biodegradation was analyzed by examining the morphology, thermal properties, molecular weight, chemical, and mechanical properties using scanning electron microscopy, differential scanning calorimetry, gel permeation chromatography, attenuated total reflectance‐Fourier transform infrared spectroscopy, thermogravimetric analysis, and compression testing. PGS underwent the most rapid degradation and was hallmarked by a decrease in compressive modulus. PLA/PCL blend and PLGA both had rapid initial decreases in compressive modulus, coupled with large decreases in molecular weight. Surface cracks were observed in the PUR samples, accompanied by a slight decrease in compressive modulus. However, as expected, the molecular weight did not decrease. These results confirm that PUR does not undergo significant degradation but may not be suitable for long‐term implants. The biodegradation rates of porous PGS, PLA/PCL blend, and PLGA found in this study can guide their use in tissue engineering and other biomedical applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

New polyol for production of rigid polyurethane‐polyisocyanurate foams,Part 2: Preparation of rigid polyurethane‐polyisocyanurate foams with the new polyol

The method of preparation, determination of foaming parameters, and methods for the determination of physicochemical properties of polyurethane‐polyisocyanurate (PUR‐PIR) foams prepared with the use of N,N′‐di(methyleneoxy‐2‐hydroxyethyl)urea and boric acid derivatives are presented in this paper. It was found that application of the borate as a polyol component and simultaneously as a flame retardant in the recipe for production of PUR‐PIR foams was very favorable. The foams prepared were characterized by reduced brittleness, higher compressive strength and content of closed cells, as well as considerably lower flammability in comparison with standard foam. The results show that the new polyol prepared on the basis of N,N′‐di(methyleneoxy‐2‐hydroxyethyl)urea and boric acid can be applied for production of rigid PUR‐PIR foams, and it improves their physicochemical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Properties of rigid polyurethane‐polyisocyanurate foams modified with the selected fillers

Rigid polyurethane‐polyisocyanurate foams (PUR‐PIR) containing from 2.5% to 20% w/w of fillers (talc, aluminum hydroxide, chalk, starch and borax) were the subject of our studies; a reference sample was PUR‐PIR foam with no filler added. Apparent density, compressive strength, brittleness, content of closed cells, retention (flammability) and softening point of foams were determined and the products were analyzed by thermogravimetric method. These parameters were the basis to determine effect of type and participation of the fillers studied on physicochemical, heat, and thermal properties of foams. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Ultrasound devulcanization of unfilled natural rubber networks,studied via component molecular mobility

¹³C NMR solids spectroscopy and transverse relaxation, and ¹H relaxation and pulsed‐gradient spin‐echo self‐diffusion measurements at 70 °C were used to study molecular and segmental mobilities in natural rubber before and after sulfur crosslinking, and after subsequent devulcanization using intense ultrasound. NMR relaxation does not clearly distinguish between entangled and crosslinked network mobility, but unentangled sol and oligomeric species are separable within the longer T₂ decay components. Ultrasound reactor settings affect the amount of extractable sol generated. Some two‐thirds of the sol is entangled, with number‐average molecular weights (M_n) above 10 000 g mol^?1. Samples also contain near 2 wt% of inert light species (M_n < 400 g mol^?1); ultrasound is relatively ineffective in producing additional oligomeric material. All proton mobilities increase as more sol is produced, but ¹³C relaxation, reflecting intramolecular effects, indicates a slight decrease in backbone mobility. In contrast with other rubbers, in natural rubber, neither the glass transition nor the sol diffusion rate is greatly affected by the extent of ultrasound exposure. Comparisons with previous similar work of this laboratory, particularly styrene‐butadiene rubber, are useful in confirming the molecular mechanisms involved. Copyright © 2007 Society of Chemical Industry     

Biobased Polyurethane Composite Foams Reinforced with Plum Stones and Silanized Plum Stones

In the following study, ground plum stones and silanized ground plum stones were used as natural fillers for novel polyurethane (PUR) composite foams. The impact of 1, 2, and 5 wt.% of fillers on the cellular structure, foaming parameters, and mechanical, thermomechanical, and thermal properties of produced foams were assessed. The results showed that the silanization process leads to acquiring fillers with a smoother surface compared to unmodified filler. The results also showed that the morphology of the obtained materials is affected by the type and content of filler. Moreover, the modified PUR foams showed improved properties. For example, compared with the reference foam (PUR_REF), the foam with the addition of 1 wt.% of unmodified plum filler showed better mechanical properties, such as higher compressive strength (~8% improvement) and better flexural strength (~6% improvement). The addition of silanized plum filler improved the thermal stability and hydrophobic character of PUR foams. This work shows the relationship between the mechanical, thermal, and application properties of the obtained PUR composites depending on the modification of the filler used during synthesis.     

Enhanced fire behavior of rigid polyurethane foam by intumescent flame retardants

Using expandable graphite (EG) and ammonium polyphosphate (APP) as flame retardants, we prepared two series of polyisocyanurate–polyurethane (PIR–PUR) foams (i.e., EG foams filled with different amounts of EG alone and APEG foams containing different amounts of expanded EG and APP) and evaluated the effect of the additives on the physical–mechanical property, fire behavior and thermal stability of the foams based on compressive strength test, limiting oxygen index (LOI), cone calorimeter test, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The addition of EG alone or both EG and APP into the foam greatly influences the physical–mechanical property. The compressive strength of APEG foams is closely related to the apparent density. The LOI value showed good improvement in both EG and APEG foams. The addition of APP in APEG foams gave better fire behavior than the EG foams with an obvious decrease in PHRR and increase in residue. In addition, the TGA curves illustrated that APP might be an effective charring agent to promote char formation. The SEM results showed that the incorporation of APP and EG allowed the formation of a cohesive and dense char layer, which inhibited the transfer of heat and combustible gas and increased the thermal stability of PIR‐PUR. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

氮磷协效阻燃剂对软质聚氨酯泡沫热解特性的影响

选用两组不同的氮磷协效阻燃剂配制不同磷氮比例的阻燃剂溶液,用浸渍阻燃的方法制备了阻燃软质聚氨酯(PUR)泡沫,利用热重分析仪分析不同种类和磷氮比例的阻燃剂对软质PUR泡沫热解特性的影响,找出较优阻燃剂种类及其最适磷氮比例.结果表明,利用NH4H2PO4/(NH4)2SO4阻燃软质PUR泡沫时,其最佳磷氮比例为P:N=1...     

Thermal resistance of polyurethane adhesives containing aluminum hydroxide and dealkaline or alkaline lignin

For the sustainability of the polyurethane resin (PUR) industry, petroleum-based materials must be replaced with renewable resource and economic aspects must be considered. Lignin is a renewable, thermostable biomass consisted with a phenolic polymer. As a thermostable bio-filler for PUR adhesives, acidic or basic lignin was blended with an amphiprotic inorganic filler, to reduce the resins and product costs due to cheap, unmodified materials. The thermal resistance of the PUR adhesives was evaluated by measuring adhesion before and after heating and with and without a mechanical effect caused by substrate penetration. The results show that after heating at 200°C, the PURs containing 7.5 or 15 wt% of dealkaline lignin or 7.5 wt% of alkaline lignin decomposed more slowly than the lignin-free PUR. The properties of the PURs were also analyzed using Fourier-transform infrared spectroscopy and differential scanning calorimetry. Additionally, the PURs containing over 30 wt% of dealkaline lignin show potential as environmentally friendly water-blown PUR foams.     

聚氨酯改性环氧树脂的研究

用分子量分别为600、1000、1500、2000的聚乙二醇(PEG)与甲苯-2,4-二异氰酸酯(TDI)反应,合成了不同种类的聚氨酯(PUR)预聚物,用来改性环氧树脂(EP),考察了由不同分子量PEG合成的PUR预聚物用量对改性EP力学性能、耐热性能的影响.结果表明,采用分子量为1500的PEG与TDI合成的PUR且其含量为10%时,改性EP材料的弯曲强度达到108.02 MPa,拉伸强度达到78.25 MPa,综合力学性能较好.     

The effect of surface energetics and molecular interdiffusion on adhesion in multicomponent polymer systems

The interfacial region of coated plastics is an example of a multicomponent polymer system. Practical adhesion, as determined by the peel test, has been found to be strongly dependent on the composition of the system and the degree of interaction between its components. Several interactions are possible during the coating process of polypropylene (PP)/ethylenepropylene-diene-monomer (EPDM) blends with chlorinated polyolefin (primer) and polyurethane (PUR) paint. Wettability, a necessary but not sufficient condition alone for molecular interdiffusion, was found to be good in all cases. The lack of interfacial adhesion between PP and PUR and between EPDM and PUR was explained by high interfacial tensions calculated from surface energetics, which, in turn, were determined by contact angle and inverse gas chromatography (IGC) measurements. The improvement of interfacial adhesion between PUR and PP by chlorinated polyolefin was explained by acid-base interactions detected by IGC. The creation of surface topography by extraction of low molecular weight fractions during the coating process does not influence the adhesion. Molecular interdiffusion was shown to be facilitated by solvents.     

Thermal stability of polyurethane elastomers before and after UV irradiation

In this work, we investigated the thermal degradation behavior of segmented polyurethane (PUR) elastomers before and after UV irradiation. The thermal degradation of PUR elastomers was studied over the temperature range of 25–600°C in an atmosphere of nitrogen using thermal gravimetric analysis (TGA). Four series of PUR elastomers derived from poly(oxytetramethylene)glycol (PTMO) of 1000 and 2000 molecular weight and poly(caprolactone glycol) (PCL) of 1250 molecular weight, 4,4′‐diphenylmethane diisocyanate (MDI), and 4,4′‐dicyclohexylmethane diisocyanate (H₁₂MDI) and 1,4‐butanediol as an chain extender were synthesized by the prepolymer method. The derivative thermogravimetric (DTG) peaks observed in the experiments indicated that PUR elastomers degraded through two steps. We attributed the first step to degradation of the hard segment. The second degradation step could be ascribed to degradation of the soft segment. We found that the PUR elastomers based on poly(ester polyol) and aromatic diisocyanate exhibit better thermal stability than that of PUR elastomers based on the poly(ether polyol) soft segment in both steps of degradation. The thermal degradation is more prevalent in PUR elastomers based on cycloaliphatic diisocyanate. The higher values of the temperature of initial decomposition (Tⁱ) indicate a higher thermal stability of UV‐exposed elastomers on the beginning of degradation. This may be due to the formation of a crosslinking structure in the presence of UV irradiation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 864–873, 2001