Lignin-and molasses-based polyurethane (PU) foams with various lignin/molasses mixing ratios were prepared. The hydroxyl group
in molasses and lignin is used as the reaction site and PU foams with various isocyanate (NCO)/the hydroxyl group (OH) ratios
were obtained.
Thermal properties of PU foams were investigated by differential scanning calorimetry (DSC), thermogravimetry (TG) and thermal
conductivity measurement. Glass transition temperature (Tg) was observed depending on NCO/OH ratio in a temperature range from ca. 80 to 120°C and thermal decomposition temperature
(Td) from ca. 280 to 295°C. Mixing ratio of molasses and lignin polyol scarcely affected the Tg and Td. Thermal conductivity of PU foams was in a range from 0.030 to 0.040 Wm−1 K−1 depending on mixing ratio of lignin and molasses. 相似文献
Thermal properties of polyurethane (PU) films prepared from solvolysis lignin (SL), polyethylene glycol (PEG) and diphenylmethane diisocyanate (MDI) were examined by differential scanning calorimetry and thermogravimetry. In the SL—PEG—MDI system, the SL content, the molecular weight (Mn) of PEG and the NCO/OH ratio were changed in order to control the thermal properties. Glass transition temperatures (Tg's) of the prepared PU's were dependent on the SL content, the Mn of PEG and the NCO/OH ratio. However, the Tg of PU was significantly influenced by the SL content: the increment of Tg was ca. 150 K when the SL content in PEG increased from 0 to ca. 50%. The decomposition of the PU's was markedly dependent on the content of SL. Other factors, such as the NCO/OH ratio and the Mn of PEG, are less dominant compared with the SL content. This fact suggests that the dissociation between the isocyanate groups and the phenolic OH groups in SL may be the major factor in the whole process of the thermal decomposition of the PU containing SL 相似文献
This work presents thermal studies of nanocomposites based on the flexible polyurethane (PU) matrix and filled using montmorillonite organically modified with organophosphorus flame retardant compound. Flexible PU nanocomposite foams were prepared in the reaction carried out between reactive alcoholic hydroxyl and isocyanate groups with the ratio of NCO to OH groups equal to 1.05. The amount of an organoclay ranging from 3 to 9 vol% was added to the polyol component of the resin before mixing with isocyanate. The apparent density of PU foams was ranging from 0.066 to 0.077 g cm?1. Thermal properties of the flexible PU nanocomposite foams were investigated by thermogravimetry and dynamical mechanical analysis. Glass transition temperatures (Tg) were defined as maximum peak on tanδ curve. Thermal decomposition was observed at 310–320 °C (calculated from the onset of TG curve). Tensile strength of the PU foams was determined using mechanical test. The microstructure of the nanoparticles and the composites was investigated by X-ray diffraction. Finally, it was confirmed that the thermal and mechanical properties of flexible PU nanocomposite depend on the amount of nanoclay. 相似文献
A series of conducting interpenetrating polymer networks (IPNs), are prepared by sequential polymerization of castor oil based polyurethane (PU) with poly(methyl methacrylate) (PMMA) and polyaniline doped with camphor sulphonic acid (PAni)CSA. The effect of different amount of PAni (varies from 2.5-12.5%) on the properties of PU/PMMA (50/50) IPNs such as electrical properties like conductivity, dielectric constant and dissipation factor; mechanical properties like tensile strength and percentage elongation at break have been reported. (PAni)CSA filled IPNs shows improved tensile strength than the unfilled IPN system. The thermal stability and surface morphology of unfilled and (PAni)CSA filled PU/PMMA (50/50) IPN sheets were investigated using a thermogravimetric analyzer (TGA) and a scanning electron microscope (SEM). TGA thermograms of (PAni)CSA filled PU/PMMA (50/50) IPNs show a three-step thermal degradation process. SEM micrograms of filled PU/PMMA IPN system shows spherulitic structure at higher concentration of (PAni)CSA. 相似文献
Novel polyurethane (PU) composites whose matrix is derived from lignin, molasses polyol and filler from wood powder were successfully prepared. Two kinds of polyol were mixed 0/100 to 100/0 in seven steps, and filler content was varied from 50 to 100 mass % to polyol content. Decomposition behaviour of PU composites was investigated by thermogravimetry. Apparent density and mechanical properties of the above composites were also measured. Surface texture was observed by scanning electron microscopy. Thermal decomposition of PU composites was found to occur in two stages. The first decomposition observed at 570–580 K (DTd1, peak temperature of derivative curve) is attributed to the matrix of composites. The second stage decomposition depending on filler content, observed in a temperature range from 590 to 630 K (DTd2), is attributable to filler homogenously associated with PU matrix. Marked differences were not found, when the kinds of lignin and molasses polyol composition were varied. The above PU composites were found to be thermally stabilised by the introduction of filler. 相似文献
In this work thermal
transitions and thermal stability of polyurethane intermediates and polyurethanes
were investigated. The intermediates were obtained by glycolysis of waste
polyurethane (PUR) in the reaction with hexamethylene glycol (HDO). The excess
of HDO was not separated from the product after the glycolysis process was
finished. The effects of different mass ratio of HDO to PUR foam on selected
physicochemical properties (hydroxyl number, Brookfield viscosity and density)
were also determined.
The polyurethanes were synthesized from
the obtained intermediates by the prepolymer method using diisocyanate (MDI)
and glycolysis product of molecular mass in range 700/1000 g mol–1.
Hexamethylene glycol, 1,4-butanediol and ethylene glycol were used as chain
extender agents. Influence of NCO groups concentration in prepolymer on glass
transition temperature (Tg)
and storage and loss modulus (E’, E’’) of polyurethanes were investigated
by the DMTA method. Thermal decomposition of obtained glycolysates and polyurethanes
was followed by thermogravimetry coupled with Fourier transform infrared spectroscopy.
Main products of thermal decomposition were identified. 相似文献
Epoxy resin nanocomposites containing organophilic montmorillonite (oM) and polyurethane were prepared by adding oM to interpenetrating polymer networks (IPNs) of epoxy resin and polyurethane (EP/PU). The dispersion degree of oM in EP/PU matrix was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Fourier transform infrared spectrometry (FT-IR) showed that strong interactions existed between oM and EP/PU matrix, and oM had some effect on hydrogen bonding of these EP/PU IPNs nanocomposites. Positron annihilation spectroscopy (PALS) and differential scanning calorimetry (DSC) measurements were used to investigate the effect of oM and PU contents on free volume and glass transition temperature (Tg) of these nanocomposites. The PALS and DSC results clearly showed that the presence of oM led to a decrease in the total fractional free volume, which was consistent with increasing Tg upon addition of oM, ascribed to increasing hydrogen bonding in interfacial regions of oM and EP/PU matrix and enhancing the miscibility between EP phase and PU phase. In addition, with increasing PU content, the total fractional free volume increased, corresponding to decreasing Tg. 相似文献
This work studies the electrical, rheological, and thermal characteristics for polyurethane (PU) capped with tetraaniline
as a new material, tetraaniline-containing poly(urethane–urea) (TAPU). The conductivities can be increased from less than
10−10 S/cm for pure PU to 10−4 S/cm for TAPU, independently of the length of the soft segment in the TAPU backbone chain. The tensile strength and modulus
are increased when PU is copolymerized with tetraaniline. The viscoelastic creep can be effectively simulated using a Burgers
model. Additionally, TAPU has higher viscosity, higher retardation time, and lower compliance J1 than regular PU. Restated, TAPU exhibits less elastic but superior permanent deformation than PU because tetraaniline functions
as a chain holder. The thermogravimetric analytic (TGA) results reveal that TAPU has lower Td, smaller Tmw1 and Tmw2, and higher char yield because the dehydration of the urea-containing polymer produces a thin layer from a nitrogen compound
on the polymer’s surface, which insulates the underlying polymer from heat and oxygen. 相似文献
A series of polyurethane/polyaniline/silica organic/inorganic hybrids were synthesized via the conventional polyurethane (PU) prepolymer technique. Amine-endcapped polyaniline (PANI) with low molecular weight and higher solubility was firstly synthesized. This PANI oligomer was then used together with nano-silica bearing silanol groups as chain extenders to prepare the conducting polyurethane hybrids. The polyurethane hybrids were designated as PU-xPANI-ySiO2 (x + y = 1). For comparison, the urethane-aniline block copolymer and the PU/silica hybrid were designated as PU-PANI and PU-SiO2, respectively.The structures of PU-PANI, PU-SiO2 and conducting polyurethane hybrids were confirmed by FT-IR, solid-state 13C, and 29Si NMR spectra. In nano-silica containing organic/inorganic conducting polyurethane hybrids, UV-vis spectra revealed the maximum absorption bands similar to that of PU-PANI. X-ray diffraction patterns indicated that these samples are typical of semicrystalline/amorphous materials. SEM image of PU-0.5PANI-0.5SiO2 showed that PANI was dispersed homogeneously and interconnected continuously in the insulating PU-silica matrix. TGA results of the polymer hybrids exhibited higher thermal stabilities and lower decomposition rates than that of PU-PANI both in nitrogen and air. Differential scanning calorimetry (DSC) studies indicated that the polyurethane hybrids had higher glass-transition temperatures (Tg) with the increase of PANI, but lower than that of PU-PANI. Stress-strain curves for all of the polyurethane hybrids showed the elastomeric behavior of typical polyurethanes. The surface resistivity values of all hybrids were about 108 ∼ 1010 Ω/sq. and might meet the requirement of the anti-electrostatic materials. 相似文献
For the first time, through macromonomer radical copolymerization, a novel fluorinated polyurethane (FPU) was synthesized based on partly acrylate-endcapped polyurethane macromonomers with hexafluorobutyl acrylate (HFBA). Partly acrylate-endcapped polyurethane (PU) macromonomers were synthesized using isophronediisocyanate (IPDI), dimethylol propionic acid (DMPA), polyethylene adipate glycols (PEA) etc. The novel fluorinated polymer, which bore PU side chains and fluorinated side chains, was confirmed by F19 NMR spectroscopy, X-ray photoelectron spectroscopy (XPS), elemental analysis, scanning electron spectroscopy (SEM) etc. Copolymerization of polyurethane macromonomers with hexafluorobutyl acrylate (HFBA) was briefly investigated. The surface tension of FPU solution was measured and showed sharply decrease compared to that of pure polyurethane. Results from SEM showed a uniform size distribution of phase micro-domains on the fracture surface of FPU. 相似文献
The thermal degradation process of ethoxylated bisphenol A (BPA) and oxyalkylenated 2,6-toluylenediamine-based polyurethane (PU) foams blown with pentane and flame retarded by novel NaH2PO4 and NaHSO4 intumescent system (5:3, w/w) was studied by thermogravimetry coupled with mass spectrometry (TG–MS), thermogravimetry coupled with Fourier transform infrared spectroscopy (TG–FTIR), pyrolysis–gas chromatography coupled with mass spectrometry (Py/GC–MS) and diffuse reflectance Fourier transform spectroscopy (DRIFTS) methods. It has been found that NaH2PO4/NaHSO4 system is active both at the initiation stage of PU decomposition as well as it catalyses cross-linking reactions that lead to enhanced char formation during degradation; both effects contribute to the overall flame retardation effect. 相似文献
Differential Scanning Calorimetry (DSC), thermogravimetry/derivative thermogravimetry (TG/DTG) and infrared spectroscopy (IR) techniques were used to investigate the compatibility between prednicarbate and several excipients commonly used in semi solid pharmaceutical form. The thermoanalytical studies of 1:1 (m/m) drug/excipient physical mixtures showed that the beginning of the first thermal decomposition stage of the prednicarbate (Tonset value) was decreased in the presence of stearyl alcohol and glyceryl stearate compared to the drug alone. For the binary mixture of drug/sodium pirrolidone carboxilate the first thermal decomposition stage was not changed, however the DTG peak temperature (Tpeak DTG) decreased. The comparison of the IR spectra of the drug, the physical mixtures and of the thermally treated samples confirmed the thermal decomposition of prednicarbate. By the comparison of the thermal profiles of 1:1 prednicarbate:excipients mixtures (methylparaben, propylparaben, carbomer 940, acrylate crosspolymer, lactic acid, light liquid paraffin, isopropyl palmitate, myristyl lactate and cetyl alcohol) no interaction was observed. 相似文献
Summary: Octaaminophenyl polyhedral oligomeric silsesquioxane (OapPOSS) was used as a crosslinking agent together with 4,4′‐methylenebis‐(2‐chloroaniline) to prepare polyurethane networks containing POSS. Fourier transform infrared spectroscopy (FT‐IR), dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) were employed to characterize the POSS‐reinforced polyurethane. The POSS‐containing PU networks displayed enhanced glass transition temperatures (Tgs) and the storage moduli of the networks of the glassy state and rubber plateaus were also observed to be significantly higher than that of the control polyurethane although only a small amount of POSS was incorporated into the systems. The results can be ascribed to the significant nanoscale reinforcement effect of POSS cages on the polyurethane matrix. TGA results showed the thermal stability was also improved with incorporation of POSS into the system.
Dynamic mechanical spectra of PU and PU nanocomposites containing POSS. 相似文献
In the present work, lanthanum phenylphosphonate (LaPP)–based multilayered film was fabricated on the surface of flexible polyurethane (PU) foam by layer‐by‐layer self‐assembled method. The successful deposition of the coating was confirmed by scanning electron microscopy (SEM) and energy‐dispersive X‐ray (EDX). Subsequently, the thermal decomposition and burning behavior of untreated and treated PU foams were investigated by thermogravimetric analysis (TGA) and cone calorimeter, respectively. The TGA results indicated that Tmax2 of treated PU foams were increased by approximately 15°C to 20°C as compared with untreated PU foam. The peak heat release rate (PHRR) and total heat release (THR) of PU‐6 (with 19.5 wt% weight gain) were 188 kW/m2 and 20.3 MJ/m2, with reductions of 70% and 15% as compared with those of untreated PU foam, respectively. Meanwhile, the smoke production of treated PU foam was suppressed after the construction of LaPP‐based coating. 相似文献
Novel copolymers of polyurethane (PU) were prepared by direct transurethanetion reaction of a commercial PU with polydimethylsiloxanes (PDMS, MW 1000, 5000, and 10,000) containing hydroxyl end-groups. Transurethanetions with different mass ratios of hydrophobic PDMS to hydrophilic PU chains (PDMS1000–PU: 43:57, 67:33, 71:29, and 80:20; PDMS5000–PU: 37:63, and 51:49; PDMS10000–PU: 51:49) were carried out in solution at 65 and 100 °C. In catalyzed reactions, dibutyltin dilaurate (SnC32H64O4) was used to promote bond breaking in the PU chain and accelerate the reaction between hydroxyl end-groups of PDMS and regenerated isocyanates of PU. The chemical structures of the prepared copolymers were comprehensively characterized by 1H, 13C, and 29Si NMR spectroscopies. According to elemental analysis, the content of PDMS varied between 3 wt.% and 16 wt.%, and results obtained from the 1H NMR spectroscopy were in good agreement with the results of elemental analysis. Increased length of the hydrophobic chain increased the content of PDMS in the copolymer. The GPC results showed that molar masses of the PUPDMS copolymers were lower than the molar mass of the starting PU. The glass transitions (Tg) of the copolymers were shifted to lower temperature as compared with Tg of the starting polyurethane. ATR FTIR spectroscopy showed the surface of the copolymer films to be enriched with siloxane groups and, according to electron microscopy, it was textured with microspheres. The static contact angles for copolymer films measured with deionized water ranged from 94° to 117°. The different structural, thermal and surface properties of the PUPDMS copolymers as compared with PU indicated that transurethanetion had taken place. 相似文献
The kinetics of thermal decomposition of solid In(S2CNR2)3 complexes, (R=CH3, C2H5, n-C3H7,i-C3H7, n-C4H9 and i-C4H9), has been studied using isothermal and non-isothermal thermogravimetry. Superimposed TG/DTG/DSC curves show that thermal
decomposition reactions occur in the liquid phase, except for the In(S2CNMe2)3 and In(S2CNPri2)3 compounds.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
The thermal decomposition kinetics of composite modified double‐base (CMDB) propellants with a series of contents of hexogeon (RDX) was investigated by using parameters of Teo, Ti, Tp, Tf, Tb, Ta, E, lg A and ΔH, which were obtained from using a CDR‐4P differential scanning calorimeter (DSC) and Perkin‐Elmer Pyris 1 thermogravimetric analyzer (TG) analyses with heating rates of 5, 10, 15 and 20 K/min. Reliable activation energy was calculated using Flynn‐Wall‐Ozawa method before analyzing the thermal decomposition mechanism. TG‐DTG curves were treated with Malek method in order to obtain the reaction mechanisms. The obtained results show that the thermal decomposition mechanisms with the conversion from 0.2 to 0.4 was f(α)?1/2α, and with the conversion from 0.5 to 0.7 was f(α)?(1/4)(1?α)[?ln(1?α)]?3. 相似文献