Search

A series of polyurethanes (PU) were synthesised via one-step polymerisation without a chain extender, using toluene diisocyanate as well as a variety of soft segments composed of different macrodiols. Poly(D,L-lactide) (PDLLA) and polycaprolactone diol (PCL) were synthesised as a polyester type polyols to obtain soft segments. The process of varying the molar ratio of newly synthesised PDLLA in soft segments has been confirmed as a powerful tool for fine-tuning the final properties of PU. Fourier-transformed infrared spectroscopy was used for evaluation of molecular structures of synthesised PDLLA polyol and final PU. Nuclear magnetic resonance spectrometry was used to confirm the presumed structure of PU. The influence of soft segment composition on polyurethane thermal characteristics was examined using thermogravimetric analysis and differential scanning calorimetry. The composition of soft segments had little impact on the thermal stability of PU materials, which is explained by the comparable structures of both polyester polyols. Wide-angle X-ray scattering was utilised to evaluate the effect of amorphous PDLLA on the degree of crystallinity of PCL in soft PU segments. It was discovered that not only did the PDLLA ratio in the soft segment have a substantial influence on the degree of microphase separation in the soft and hard segments, but it also influenced the crystallisation behaviour of the materials. Furthermore, the restriction of crystallisation of the PCL soft segment has been verified to be dependent on the hard segment concentration and the ratio of PDLLA/PCL polyols. The sample with pure PCL as the polyol component achieved the highest degree of crystallinity (34.8%). The results demonstrated that the composition of soft segments directly affected the properties of obtained polyurethane films. These results can be utilised to easily achieve a desirable set of properties required for application in biomaterials. [ABSTRACT FROM AUTHOR]

Two series of polyurethanes (PUR) were synthesized in a one-step procedure, using a polydimethylsiloxane (Mn ~ 2000 g/mol) in different molar ratios (10, 15, and 20 mol%) as soft segments, hexamethylene diisocyanate, and isophorone diisocyanate as a part of hard segments. Butane-1,4-diol was used as a chain extender in polyurethane synthesis. Obtained PURs were thoroughly studied and used for the preparation of blends with commercial thermoplastic polyurethane elastomer. In combination with commercial PUR, some synthesized samples behave as plasticizers, increasing the breaking strain and decreasing the Young's modulus values. Blends with commercial PUR and 10 wt% of sample synthesized using an isophorone diisocyanate have shown an increase in strain values, but also values of break and Young's modulus, resulting in materials with fully improved mechanical properties, and mostly higher hydrophobicity. The greatest values of breaking strain (1712.72%) and max strain (1637.09%) were recorded for the blend which contains 10 wt% of PUR sample based on isophorone diisocyanate and 20 mol% of polydimethylsiloxane, while blend which contains 10 wt% of PUR sample synthesized using isophorone diisocyanate and 10 mol% of polydimethylsiloxane has the greatest value of Young's modulus (3.55 N/mm2). Prepared blends possess a lower surface tension values in comparison with the commercial PUR. The lowest value of surface tension (13.23 mN/m) was recorded for blend which contains 30 wt% of PUR sample synthesized using the isophorone diisocyanate and 20 mol% of polydimethylsiloxane. [ABSTRACT FROM AUTHOR]

The paper describes the chemical depolymerization of the polyethylene terephthalate (PET) waste from postconsumer soft drink bottles and a search for the way to use this product. The depolymerized oligoester obtained from glycolysis of PET waste using tiethylene glycol was transesterified with castor oil which resulted in the formation of hydroxyl-functional polyester polyol, with hydroxyl value of 391 mg KOH g−1. In the presented paper, series of castor oil-based waterborne polyurethane (CPU)/silica hybrid dispersions were prepared using dimethylolpropionic acid as an ionic center. The polyurethane prepolymers with pendent castor oil groups were prepared first, and then different concentrations of hydrophilic fumed silicas (0, 0.5, 0.75, 1.0 and 2.0 wt%) were added. For waterborne polyurethane dispersions of hydrophilic fumed silica with the surface area (50 ± 15 m2/g) and a primary particle size of 40 nm in the polymer matrix, ultrasound waves were used. The hybrid dispersions were prepared by adding the required amount of triethylamine and water. The molecular structures and mass of glycolyzed PET oligoesters, castor oil-based polyol and castor oil-based polyurethane-silica hybrid dispersions were estimated by FTIR method and gel permeation chromatography.The incorporation effect of SiO2 nanoparticles into the PU matrix on the thermal and mechanical properties of resulting polyurethane films has been examined by Fourier transform infrared spectroscopy (FTIR), thermogravimetry analysis, differential scanning calorimetry (DSC), SEM microscope, and measurement of the coatings properties. The DSC data results suggest that hard segment glass temperature decreases, but mixed-phase glass transition temperature increases with increasing SiO2 content. The FTIR deconvolution result of the degree of phase separation between oxide nanoparticles and hard segment supports to the DSC analysis. The addition of silica oxide caused the increase in the thermal stability. The T10% and T50% of CPU films (the temperatures where 10 and 50% weight loss occurred) increased with increasing the SiO2 content. UV-Vis spectrophotometry showed that introduction of nanosilica particles into polyurethane enhanced the shielding property of obtained films for UV light. The hardness, adhesion, and gloss quality of the polyurethane films were also determined considering the effect of the phase separation and the SiO2 content, so this paper confirmed the suitability of using these castor oil-based waterborne polyurethane/silica hybrid dispersions as new materials with high-performance coatings materials. [ABSTRACT FROM AUTHOR]

Novel biobased poly(ester-urethane)s (PUDs) were synthesized by solvent free homogeneous solution polymerization of poly(caprolactone) diol (PCL), castor oil-based polyols (COLs), dimethylolpropionic acid (DMPA), isophorone diisocyanate (IPDI) and 1,4-butane diol (BD) as the chain extender. The polyurethane dispersions were prepared by adding required amount of triethylamine (TEA) and water. In this work, castor oil-based polyols have been synthesized using the depolymerized oligoester obtained from glycolysis of PET waste with poly(ethylene glycol) (PEG 400) and castor oil. The effects of the soft segments content on the thermal and coatings properties of resulting polyurethane films have been examined by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and measurement of the coatings properties. Phase separation of polyurethane shows a strong correlation with crystallization behaviour of the polyurethane prepared. It is established that all PUD samples containing PCL as a part soft segment with different molar ratio of castor-oil polyol are crystallisable polymers. The results from XRD analysis have showed that highest degree of crystallinity (23 and 22%) is reached in polyurethanes based on the largest content PCL diol (CPU77 and CPU73). The thermal stability of samples based on (COL/PCL molar ratio 0.25:0.75) possesses the best thermal properties but less values hardness coatings which can be ascribed to a decrease of the hard segment i.e. DMPA content in polyurethane dispersions. The long-term stability of polyurethane dispersions has been investigated using UV–vis spectroscopy. The physico-mechanical properties such as hardness adhesion test and gloss of the dried films have also been determined considering the effect of soft segment content on coating properties. [ABSTRACT FROM AUTHOR]

Castor oil polyols (COLs) have been synthesized from glycolyzed oligoester polyol in order to produce waterborne polyurethane (WPU)/silica hybrid dispersions. Soft drinks poly(ethylene terephthalate) (PET) bottles were depolymerized by glycolysis with different molar ratio of poly(ethylene glycol) ( PEG 400), in the presence of zinc acetate as catalyst. The obtained glycolyzed products were reacted with castor oil (CO) to attain castor oil polyols by the process of transesterification. Five castor oil polyols were used with hydroxyl values of 255, 275, 326, 366 and 426 mg KOH g −1 . Several castor oil-based, polyurethane/silica hybrid dispersions having soft segment content of 39.6% to 28.2% and two concentrations of SiO 2 nanoparticles (0.5 and 1.0) have been prepared. The incorporation effect of SiO 2 nanoparticles into the PU matrix and the hydroxyl functionality of the COLs on the thermal and mechanical properties of resulting polyurethane films has been examined by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermal gravimetric analysis (TG) and measurement of the mechanical properties. The degree of phase separation (DPS) between oxide nanoparticles and hard segment, and particle size in the polyurethane, depends to some extent on nanosilica content and the hydroxyl functionality of the polyols employed in the polyurethane preparation process. Thermal stability of obtained hybrid materials depends on the hydroxyl functionality of the COLs and nanosilica content. The T 10% and T 50% (the temperature where 10 and 50% weight loss occurred) of WPU films decreased with the rise of OH functionality of castor oil polyols, caused by the increase of hard segment content. Glass transition temperature increased with increasing OH functionality and SiO 2 content. The hardness, adhesion and gloss quality of the polyurethane films were also determined with a view to assessing the effect of mole ratios of PET to glycol in glycolyzed products, the hydroxyl functionality and the SiO 2 content. [ABSTRACT FROM AUTHOR]

Glycolysis of poly(ethylene terephthalate) (PET) waste using different molar ratio of poly(ethylene glycol) (PEG400), was used to produce saturated hydroxyl-functional polyester polyols with castor oil (CO) by transesterification process. The waterborne polyurethane (WBPU) adhesives were synthesized from these saturated polyester polyols, isophorone diisocyanate (IPDI), dimethylolpropionic acid (DMPA), and hexamethoxymethyl melamine (HMMM) as cross-linking agent by a conventional prepolymer process. The glycolyzed polyols and polyester polyos formations were characterized using Fourier transform infrared spectroscopy (FTIR) and the molecular weights were determined using gel permeation chromatography (GPC). The cross-linking reaction between WBPU and HMMM was verified using FTIR and 1 H NMR analysis. Thermal properties were investigated by thermogravimetric analysis (TG). Thermal stability of cross-linked WBPU significantly increased with decreasing castor oil content in the process of transesterification to obtain polyester polyol as a soft segment. The T 15% and T 50% (the temperature where 15 and 50% weight loss occurred) of WBPU increased with the decreasing of castor oil content in the obtained polyester polyols, caused by the steric hindrance of polyester polyol with higher castor oil content, in the process of cross-linking reactions with HMMM. The physico-mechanical properties of WBPU, such as hardness, adhesion test, and gloss of the dried films were also determined considering the effect of participation of HMMM in cross-linking reactions with polyurethane, on coating properties. [ABSTRACT FROM AUTHOR]

Abstract: Polyurethane anionic adhesives were synthesized as waterborne polyurethane dispersions (PUDs) by modified dispersing procedure, using isophorone diisocyanate, dimethylol propionic acid, ethylenediamine as a chain extender and a range of soft segments with various macrodiols proportions. The soft segment was formed by replacing poly(propylene glycol) (PPG) as polyether polyol with polycarbonate diol (PCD), as polyester polyol. The effect of the macrodiols proportions of soft segment on the thermal properties of polyurethane films was measured by thermogravimetry analyses (TGA) and differential scanning calorimetry (DSC) methods. The infrared spectroscopy (FTIR) was used for evaluating the degree of phase separation. The results showed that phase separation between hard and soft segments of poly(ester–urethane) is more significant than of poly(ether–urethane). The phase separation degree of polyurethane dispersion significantly affected the glass transition temperature (T g) and film properties. While the phase separation degree increased, T g proportionally decreased, but the hardness and gloss of the dried films increased, as expected. However, thermal stability was influenced by the molecular weight of used polyols and chemical structure of the polyols, and it was described by the effect of oxygen content, and interaction between the soft and hard segment, and the soft segment composition. The soft segment can be achieved with a proper selection, in order to fine-tune the performance of waterborne polyurethane dispersion, considering certain practical application. [Copyright &y& Elsevier]

Preparation of the series of polyurethane elastomers and its nanocomposites from castor oil (a vegetable triglyceride) and different isocyanates (aromatic: toluene diisocyanate, TDI and aliphatic: isophorone diisocyanate, IPDI) is described. The synthesis was carried out in bulk and without catalyst by a one-step reactive process. Different elastomers were prepared by using several stoichiometric imbalances. For polyurethane nanocomposites based on TDI, titanium(IV) oxide nanoparticles was used. The thermal properties of the materials are discussed on the basis of simultaneous TG-DSC measurements results and TMDSC data. TMDSC results show that T increases with increasing r = NCO/OH ratio. Namely, with increasing NCO/OH ratio the cross-linkage density increases and as a consequence, the chain mobility decreases, resulting in a higher T. It was estimated that the T of the samples decreased as the nanofiller content increased due to the changes in the segmental mobility in polyurethane materials. Thermal data refers to increased stability of nanocomposites compared with that of the unfilled elastomers. [ABSTRACT FROM AUTHOR]

Copyright of Chemical Industry / Hemijska Industrija is the property of Association of Chemical Engineers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chemical Industry / Hemijska Industrija is the property of Association of Chemical Engineers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: The goal of this work was to investigate the properties of environmentally friendly, castor oil based polyurethane hybrid materials with titanium(IV) oxide nanoparticles, as a filler, and different types of diisocyanate (toluene diisocyanate and isophorone diisocyanate). In the sample synthesis, different ratios of the reactive groups (NCO/OH), r, were used (1, 1.15 and 0.92). In the composite preparation, only toluene diisocyanate was used, and the filler particles were premixed in a glass vessel with the castor oil polyol before the reaction with diisocyanate. For all the composite samples, the r value was 1. Polyurethane formation was confirmed by ATR-FT-IR by detecting the urethane band at 1515cm−1. It was determined that the hydroxyl groups had reacted because the broad band corresponding to the OH groups (3400cm−1) was not detected or detected at a reduced intensity depending on the r value. As was expected, the presence of the unreacted NCO groups was detected only for samples with r >1 (band at 2300cm−1, which corresponds to the existence of these groups). The dynamic mechanical measurements were performed at a temperature range from −50°C to 100°C at different frequencies. For investigation of reinforcement effect of filler on polymer matrix, tensile testing was applied. The glass transition temperature, T g , was determined by DSC measurement. It was estimated that the T g of the samples decreased as the nanofiller content increased due to the changes in the segmental mobility influenced by the interaction between the nanoparticles and polymer chains. [Copyright &y& Elsevier]

Abstract Waterborne castor oil-recycled polyol based polyurethane-silica nanocomposite adhesives (WPU) with polymer matrix and silica nanoparticles chemically bonded have been successfully prepared through a sol-gel process. A series of waterborne polyurethane adhesives with hard segment contents from 71.3 to 74.5 wt%, were synthesized using an isophorone diisocyanate, 2-bis(hydroxymethyl) propionic acid, recycled castor oil-based as soft segments and (3-aminopropyl)triethoxysilane (APTES) as chain extender. The depolymerized oligoester obtained from glycolysis of poly(ethylene terephthalate) (PET) waste using triethylene glycol (TEG), was transesterified with castor oil (CO) which resulted in the formation of hydroxyl-functional polyester polyol, with hydroxyl value of 414 mgKOH g−1. The molecular structures and mass of glycolyzed PET oligoesters, castor oil-based polyol and castor oil-based polyurethane-silica nanocomposite adhesives were estimated by Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The structure and properties of the resulting films were investigated by FTIR, wide angle X-ray diffraction measurement (XRD), thermogravimetry (TG) and differential scanning calorimetry (DSC). TG analysis indicated that APTES can improve the thermal stability of WPU. XRD showed that the crystallinity of WPU decreased with the increase alkoxysilane content. The extent of crosslinking was investigated to show a dependence on silica concentration, which increased the glass transition temperature and particle size of polyurethane nanocomposites with increasing alkoxysilane content due to the condensation of the alkoxysilane groups. The hardness, adhesion and gloss quality of the polyurethane films were also determined considering the effect of APTES content, so this paper confirmed the suitability of using these castor oil-based waterborne polyurethane-silica nanocomposites as new adhesive materials with high performance coatings materials. The experimental results reveal that the APTES and the hard segment content play a key role in controlling the structure and properties of the PU cast films based on castor oil-recycled polyols. [ABSTRACT FROM AUTHOR]

Abstract: Three water-based polyurethane dispersions (PUD) were synthesized by modified dispersing procedure using polycarbonate diol (PCD), isophorone diisocyanate (IPDI), dimethylolpropionic acid (DMPA), triethylamine (TEA) and ethylenediamine (EDA). The ionic group content in the polyurethane-ionomer structure was varied by changing the amount of the internal emulsifier, DMPA (4.5, 7.5 and 10 wt.% to the prepolymer weight). The expected structures of obtained materials were confirmed by FTIR spectroscopy. The effect of the DMPA content on the thermal properties of polyurethane films was measured by TGA, DTA, DSC and DMTA methods. Increased DMPA amounts result in the higher hard segment contents and in the increase of the weight loss corresponding to the degradation of the hard segments. The reduction of hard segment content led to the elevated temperature of decomposition and to the decrease of the glass transition temperature and thermoplasticity. The atomic force microscopy (AFM), results indicated that phase separation between hard and soft segment of PUD with higher DMPA content is more significant than of PUD with lower DMPA content. The physico-mechanical properties, such as hardness, adhesion test and gloss of the dried films were also determined considering the effect of DMPA content on coating properties. [Copyright &y& Elsevier]

A series of nontoxic acrylated waterborne polyurethane/silica hybrid composites were synthesized from 1,6-hexamethylene diisocyanate (HDI), polycaprolactone diol (PCL), dimethylolpropionic acid (DMPA), a mixture of 3-aminopropyltriethoxysilane (APTES) and 2-hydroxyethyl methacrylate (HEMA) as chain extender. To control crosslink density the mono-functional HEMA was incorporated into the biodegradable polyurethanes. Different amounts of nanosilica were incorporated into acrylic-based polyurethanes to prepare polyurethane/silica hybrid composites. The structures of the acrylated waterborne polyurethane/silica hybrid composites were characterized by Fourier-transform infrared spectroscopy (FTIR), 1H NMR,13C NMR analysis and scanning electron microscopy (SEM). The effect of the amount of nanosilica on the thermal properties of polyurethane nanocomposite films was investigated by means of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Wide-angle X-ray scattering (WAXS) was used to investigate the degree of crystallinity of PCL as a soft segment into polyurethane hybrid composites. It is established that all samples containing PCL as a part soft segment with different silica loading are crystallisable polymers. The results from WAXS analysis have shown that the highest degree of crystallinity (37%) is reached in polyurethanes based on 1 wt% content of Aerosil OX50. The highest crystallization enthalpy (Δ Hc) value for the sample with 1% nanosilica was 9.77 J/g confirmed by DSC analysis. The decrease of crystallinity of the PCL soft segment in polyurethanes indicates that the restriction of the crystallization of the PCL soft segment depends on the silica content. The incorporation of nanosilica into waterborne polyurethanes increases the thermal stability of the hybrid composite films. It was found that greater thermal and mechanical properties of waterborne polyurethane-silica hybrid composites were obtained due to a condensation process between triethoxysilane groups in the side chains of polyurethane molecules and silanols group on the surface of nanosilica. [ABSTRACT FROM AUTHOR]

Polyurethane hydrogels were prepared in open and closed system, in reaction of polyethylene glycol (PEG) with different molar mass (2000, 6000 and 10,000 g/mol) and poly[(phenyl isocyanate)- co -formaldehyde] (PPIF) in order to investigate the influence of different synthesis conditions on the hydrogel structure and consequently swelling properties. The PEG molar mass was varied in order to investigate the correlation between PEG chain length, hydrogel hydrophilicity and absorption capacity. Scanning electron microscopy (SEM) and porosity studies have shown that hydrogels prepared in open system have cellular, sponge-like structure, while preparation in closed system have resulted in hydrogels with compact structure. Morphological differences were reflected on swelling kinetics and compressive properties. Swelling ratio in distilled water increases with increasing in PEG molar mass in both series, but swelling behavior of hydrogels synthesized in open system follows second-order kinetics and in closed system first-order kinetics, slower response in first 180 min, but greater capacity to retain water. Compressive modulus increases with increasing in PEG molar mass and has greater values for hydrogels synthesized in closed system. Granulated PU-PEG hydrogels have demonstrated ability to retain and deliver water in soil and contribute to tomatoes growth. Addition of hydrogel in 1 wt% in soil has resulted in higher and more developed plant. Applying the procedure of preparation in open and closed system using the same compounds give hydrogels with a different morphology, swelling and mechanical properties, which implies different application. However, comminution of both type of hydrogels to the level under the pore size, when the morphological differences disappears, give the granules (diameter around 2 mm) with the same swelling properties and potential application in agriculture. [Display omitted] • Polyurethane hydrogels were synthesized in one-step procedure, in open and closed system, using PEG with different molar mass. • Synthesis in open and closed system have resulted in hydrogels with different structural and morphological properties and consequently different swelling kinetic. • Obtained hydrogels have demonstrated a great potential in agricultural applications. [ABSTRACT FROM AUTHOR]