Aliphatic Polyurethane Research Articles

Cross‐Linked Polymers as Solid‐State Media for Laser Dye‐Doped Elements

AbstractThe work presents investigation results on the main operation parameters of laser active elements, based on the xanthene dye and polyurethane matrices, different by their physical properties. The polyurethanes of various chemical contents are studied, in order to reveal the possibility for their efficient applications as active media in the solid‐state dye‐doped laser elements. Due to the solvation effects, the proposed high‐polar aliphatic polyurethane matrix provides a considerable growth of photostability, efficiency, and operation lifetime for the laser dye‐doped elements.

DEVELOPMENT OF SPECIALTY COATED FABRICS FOR CANOPY OF INFLATABLE MILITARY TENT (IMT) FOR FOREST AREA

The principal objectives of this present work were to develop novel coated fabrics in olive green (OG) colour to serve as canopy for inflatable military tent (IMT) for forest area. Two varieties of coated fabrics were developed by coating of specific grade aliphatic thermoplastic polyurethane (TPU) on Nylon fabrics and one more with coating of plasticized polyvinyl chloride (PVC) on Polyester fabric. The construction parameters and properties of the substrate basic fabrics used for coating were evaluated and reported. The various functional parameters such as breaking strength and elongation%, tear strength, bursting strength, waterproofness, flame retardancy, flexing, accelerated ageing (-400C and 700C), blocking, ultraviolet (UV) radiation protection and colour fastness to washing and light of the coated fabrics were measured and reported with details, along with an elaborate note on the preparatory process pursued for the development of these coated fabrics. The most suitable coated fabric for canopy of IMT was selected based on the evaluated functional features. Further, the thermal analysis was carried out for the selected coated fabric using Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) for assessing its heat resistance. The shelf-life of the selected coated fabric was assessed by evaluating the residual strength (tensile and bursting), measured by subjecting it to accelerated and natural weathering tests. A special device was fabricated to carry out natural weathering test. Statistical analysis was performed at 95% significance level to estimate the actual strength (tensile and bursting) loss upon weathering.

Effect of the cyclic structure content on aliphatic polycarbonate-based polyurethane

Aliphatic polycarbonate-based polyurethanes were successfully synthesized using two aliphatic polycarbonate polyols and hexamethylene diisocyanate (HDI) with 1,4-butanediol (1,4-BD) as the chain extender. One of the aliphatic polycarbonate polyols, named PBC-diol, was prepared from dimethyl carbonate (DMC) and 1,4-BD, while the other, named PCHC-diol, was derived by reacting DMC with 1,4-cyclohexanedimethanol (CHDM). The results of the thermogravimetric analysis (TGA) indicated that the cyclic structure improved the thermal stability of the polyurethanes. In addition, the differential scanning calorimetry (DSC) curves showed that the cyclic structure increased the glass transition temperature (Tg) of the polyurethanes but slowed their crystallization. Furthermore, the mechanical properties of the polyurethanes with different cyclic structure contents were analyzed using Instron. Although the elongation at break decreased, the tensile strength increased from 32.6 to 844.0 MPa when the PBC-diol was replaced with PCHC-diol in the polyurethanes. Finally, Fourier transform infrared (FTIR) analysis was conducted to investigate the formation of hydrogen bonds. The relationship between the hydrogen bonds and cyclic structure content was also shown in this study. A series of aliphatic polycarbonate-based polyurethanes with different content of cyclic structure was synthesized. There were more hydrogen bonds between soft and hard segments formed as the content of cyclic units increased. The mechanical and thermal properties of the environment-friendly polycarbonate-based polyurethanes can be enhanced and controlled by varying the content of the cycloaliphatic structures. These polyurethanes can be considered as high potential materials that can be used in different applications in the future.

Thermally stable biopolymer composites based on poly(3-hydroxybutyrate) modified with linear aliphatic polyurethanes – preparation and properties

Poly(3-hydroxybutyrate) (P3HB) is a biopolymer, but storing products from P3HB causes the deterioration of their properties leading to their brittleness. P3HB has also low thermal stability. Its melting point almost equals its degradation temperature. To obtain biodegradable and biocompatible materials characterized by higher thermal stability and better strength parameters than the unfilled P3HB, composites with the addition of polyurethanes were produced. The morphology, thermal, and mechanical property parameters of the biocomposites were examined using scanning electron microscopy, thermogravimetric analysis, standard differential scanning calorimetry, and typical strength machines. Aliphatic polyurethanes, obtained by the reaction of 1,6-hexamethylene diisocyanate and polyethylene glycols, were used as modifiers. To check the influence of the glycol molar mass on the properties of the biocomposites, glycols with a molecular weight of 400 and 1000 g/mol were used. New biocomposites based on P3HB were produced with 5, 10, 15, and 20 wt. % content of polyurethane by direct mixing using a twin-screw extruder. The following property parameters of the prepared biocomposites were tested: degradation temperature, glass transition temperature, tensile strength, impact strength, and Brinell hardness. Improvement of the processing property parameters of P3HB-biocomposites with the addition of aliphatic polyurethanes was achieved by increasing the degradation temperature in relation to the degradation temperature of the unfilled P3HB by over 30 °C. The performance property parameters have also been improved by reducing the brittleness compared to the P3HB, as evidenced by the increase in impact strength and the decrease in hardness with an increase in the amount of polyurethane obtained by the reaction of 1,6-hexamethylene diisocyanate and polyethylene glycol with a molecular weight of 400 g/mol (PU400) as modifier.

Melt-reprocessing of mixed polyurethane thermosets

Herein we have developed melt-reprocessing of mixed aromatic and aliphatic polyurethanes (PUR) thermosets. This study will enable post-consumer mixed PURs with immense benefits for science, the economy, and the environment.

Practical two‐step chain extension method to prepare sulfonated waterborne polyurethanes based on aliphatic diamine sulphonate

AbstractWe reported a novel synthesis route to fabricate sulfonated aliphatic waterborne polyurethane dispersions (SWPU) only based on 2‐[(2‐aminoethyl) amino] ethane sulphonate sodium (AAS‐Na) by two‐step chain extension method with the assistance of acetone and water cosolvent. When AAS‐Na was added, only less than 50% of AAS‐Na was incorporated into polyurethane chain in the first‐step chain extension and the residual AAS‐Na formed molecular aggregates which were insoluble in acetone due to the high polarity of AAS‐Na. Subsequently, the mixture of acetone and water was added, the residual AAS‐Na aggregates dissolved, undertaking the further second‐step chain extension reaction, and the ultimate reaction conversion of AAS‐Na rose to more than 90%. The mechanism for acetone and water cosolvent to affect the preparation of SWPU dispersions was studied, as well as the water resistance, mechanical properties and hydrolysis resistance of as‐prepared SWPU dispersions. With the decrease of AAS‐Na content from 2.0% to 1.2%, the peak area of the melting peaks for SWPU films increased, as well as the water resistance. And the as‐prepared polyester SWPU exhibited good hydrolytic stability.

Electro-mechanical properties of thermoplastic polyurethane films and tubes modified by hybrid carbon nanostructures for pressure sensing

Electrical and piezoresistive properties of hybrid nanocomposite films and tubes made of a segmented aliphatic polyurethane modified with multilayer graphene sheets (MLGSs), multiwall carbon nanotubes (MWCNTs), and hybrid mixtures of both, were investigated. Hybrid nanocomposites were fabricated at a total weight concentration () of 5 wt.%, with relative weight concentration of MLGSs with respect to MWCNTs ( of 25%, 50% and 75%. The electrical conductivity of these films is dominated by the MWCNT network, observing electrical MLGS-MWCNT collaborative effects only for = 25%. Dielectric impedance spectroscopy indicates that the nanocomposites display capacitive effects at frequencies higher than tens of Hz, which is explained by interfacial polarization. The burst pressure and circumferential stiffness of internally pressurized tubes fabricated from these films is slightly higher for tubes containing only MWCNTs. The strain fields in the pressurized tubes, determined by digital image correlation, showed localized strain gradients, and the piezoresistive response of the electro-conductive tubes was nonlinear. The highest pressure sensitivity factor (4.59 kPa−1) was obtained for hybrid nanocomposite tubes with = 25%.

New pivot for investigating flame‐retarding mechanism: Quantitative analysis of zinc phosphate doped aliphatic waterborne polyurethane‐based intumescent coatings for flame‐retarding plywood

The quantitative analysis of zinc phosphate (ZnP) on the flame resistance of intumescent flame retardant coatings (IFRCs) is presented including cone calorimeter (CC) and pyrolysis kinetics, using aliphatic waterborne polyurethane (AWP) as the coating binder. The CC results show that an appropriate dosage (2 wt%) of ZnP in the AWP‐based coating constitutes an improved flame resistance, evidenced by the fire performance index increased from 0.41 to 0.71 seconds m2 kW−1, as well as the reduced fire growth index. The characterization analysis determines the dehydrated ZnP facilitates the formed amorphous char‐residue with a heat‐sink effect, leading to an increase in heat absorption, which climbs from the 253.00to 351.30 J·g−1. Besides, the pyrolysis kinetics verifies that the 3D Jander model (n = 2) mainly governs the whole pyrolysis process of pure coatings by the modified Coats‐Redfern integral method. The ZnP‐containing coating exerts an improved Eα corresponding to 95–200°C, which climbs from 24.96 to 35.80 kJ mol−1, leading to the formation of a continuous and compact char layer. It explores an effective quantitative analysis of the flame resistance of organic–inorganic hybrid IFRCs, deepening the flame‐retarding mechanism.

Production of Biodegradable Palm Oil-Based Polyurethane as Potential Biomaterial for Biomedical Applications.

Being biodegradable and biocompatible are crucial characteristics for biomaterial used for medical and biomedical applications. Vegetable oil-based polyols are known to contribute both the biodegradability and biocompatibility of polyurethanes; however, petrochemical-based polyols were often incorporated to improve the thermal and mechanical properties of polyurethane. In this work, palm oil-based polyester polyol (PPP) derived from epoxidized palm olein and glutaric acid was reacted with isophorone diisocyanate to produce an aliphatic polyurethane, without the incorporation of any commercial petrochemical-based polyol. The effects of water content and isocyanate index were investigated. The polyurethanes produced consisted of > 90% porosity with interconnected micropores and macropores (37–1700 µm) and PU 1.0 possessed tensile strength and compression stress of 111 kPa and 64 kPa. The polyurethanes with comparable thermal stability, yet susceptible to enzymatic degradation with 7–59% of mass loss after 4 weeks of treatment. The polyurethanes demonstrated superior water uptake (up to 450%) and did not induce significant changes in pH of the medium. The chemical changes of the polyurethanes after enzymatic degradation were evaluated by FTIR and TGA analyses. The polyurethanes showed cell viability of 53.43% and 80.37% after 1 and 10 day(s) of cytotoxicity test; and cell adhesion and proliferation in cell adhesion test. The polyurethanes produced demonstrated its potential as biomaterial for soft tissue engineering applications.

Luminescent Solar Concentrators from Waterborne Polymer Coatings

This study reports for the first time the use of waterborne polymers as host matrices for luminescent solar concentrators (LSCs). Notably, three types of waterborne polymer dispersions based either on acrylic acid esters and styrene (Polidisp® 7602), acrylic and methacrylic acid esters (Polidisp® 7788) or aliphatic polyester-based polyurethane (Tecfin P40) were selected as amorphous coatings over glass substrates. Water soluble Basic Yellow 40 (BY40) and Disperse Red 277 (DR277) were utilized as fluorophores and the derived thin polymer films (100 μm) were found homogeneous within the dye range of concentration investigated (0.3–2 wt.%). The optical efficiency determination (ηopt) evidenced LSCs performances close to those collected from benchmark polymethylmethacrylate (PMMA) thin films and Lumogen Red F350 (LR) with the same experimental setup. Noteworthy, maximum ηopt of 9.5 ± 0.2 were recorded for the Polidisp® 7602 matrix containing BY40, thus definitely supporting the waterborne polymer matrices for the development of high performance and cost-effective LSCs.

Pyrolysis kinetics of ZrP-containing aliphatic waterborne polyurethane-based intumescent coating for flame-retarding plywood

The effect of zirconium phosphate (ZrP) on the fire resistance of aliphatic waterborne polyurethane (AWP)-based intumescent flame retardant coatings (IFRCs) has been preliminarily investigated by quantitative analysis including the cone calorimeter and pyrolysis kinetics of ZrP-containing AWP-based coating, respectively. It determines that an appropriate dosage (1 wt%) of ZrP in the AWP-based coating constitutes an improved fire resistance, evidenced by the fire growth index decreased from 0.49 to 0.32 kW m−2·s-1, and the risen fire performance index of 0.55 s m−2 kW-1 from 0.41 s m−2 kW-1. Because of the heat sink (Zr(HPO4)2⋅H2O→ZrP2O7) and catalytic charring of ZrP, the ZrP-containing AWP-based coating exhibits an enhanced flame resistance, evidenced by the formation of double-layer char residues. Furthermore, it clarifies that the 3D Jander model (n=2) mainly governs the whole pyrolysis process of the coating by modified Coats-Redfern integral method, the doped ZrP mainly makes the Eα of 310∼370 ℃ climb from 187.85 kJ mol-1 to 210.79 kJ mol-1, and the Eα during 95∼200 °C increases from 24.96 kJ mol-1 for S0 to 42.63 kJ mol-1. It provides a quantitative analysis of the flame-retarding mechanism of organic-inorganic hybrid coatings firstly.

Effect of oxalate unit on polycarbonate-based polyurethane and biodegradation by fungi

A series of aliphatic oxalate-polycarbonate polyols (AOPC) was synthesized from dimethyl carbonate, 1,6-hexanediol, and diethyl oxalate, made from oxalic acid that is a kind of bio-based material, via melting polycondensation. The aliphatic polycarbonate-based polyurethanes with oxalate units (AOPCUs) were successfully prepared using the AOPCs and hexamethylene diisocyanate (HDI) with 1,4-butanediol (1,4-BD) as the chain extender. The results of the 1H NMR analysis showed that the Mn of AOPCs was approximately 2900. Whereas, the Mw of the AOPCUs was ca. 48,200–53,000 from the gel permeation chromatography (GPC) measurement. The oxalate unit effectively impeded the crystallization of the AOPCUs as shown in the Differential scanning calorimetry (DSC) analysis. Based on the stress-strain curves, the AOPCUs with 10 M ratio of oxalate unit had best strength and elongation at break; however, their Young's modulus decreased from 130 MPa to 26 MPa. In addition, the biodegradation of the AOPCUs was studied using the fungi, Aspergillus sp. and Fusarium sp. The more oxalate units in the AOPCUs, the better biodegradability they presented after the 84-day degradation test. The characteristics of the biodegradation analysis for the AOPCUs presented the bulk erosion, and the oxalate unit played an important role in their biodegradability.

Facile preparation of aluminum triphosphate-containing intumescence flame-retarding coatings using aliphatic waterborne polyurethane as the binder

The effect of aluminum triphosphate (ATP) on the flame resistance of intumescent flame retardant coatings (IFRCs) has been explored, using the aliphatic waterborne polyurethane (AWP) as the binder, the quantitative analysis on the pyrolysis kinetics of ATP-containing AWP-based coating is investigated. It determines that an appropriate dosage (2 wt%) of ATP in the AWP-based coating exerts an enhanced flame resistance, evidenced by the fire growth index decreased from 0.49 to 0.34 kW m−2 s−1, and the shrunk heat release rate during the whole burning. Due to the heat sink, filling of Al(PO3)3 for reinforcing char residues, and the catalytic charring, the doped ATP contributes to the increased Eα from 26.33 to 39.38 kJ mol−1 corresponding to the stage of 95–215 ℃, according to the fitting 3D Jander model, which mainly governs the whole pyrolysis process of coatings. It identifies a quantitative evaluation on the flame resistance of AWP-based IFRCs modified by inorganic ATP.

Predicted Studies of Branched and Cross-Linked Polyurethanes Based on Polyhydroxybutyrate with Polycaprolactone Triol in Soft Segments.

The number of cross-links in the non-linear polyurethane structure is the basic factor affecting its properties. Selected properties of aliphatic polyurethanes with soft segments made of different amounts of polycaprolactonetriol, polycaprolactonediol and synthetic, telechelic poly([R,S]-3-hydroxybutyrate) were determined. On the basis of changes in polyurethane properties, the correlation between these properties and the construction of soft segments was found. The structure of polyurethanes, their morphology, hydrophilicity, thermal and mechanical properties were examined. These properties were changed linearly up to 15% content of polycaprolactonetriol in soft segments. A further increase in the amount of triol causes that these properties are mainly determined by the high number of cross-links.

Fabrication of Aliphatic Water-Soluble Polyurethane Composites with Silane Treated CaCO3.

In the present study, composites of water-soluble polyurethane/calcium carbonate (CaCO3) were prepared from a soft segment of hydroxyl-terminated polybutadiene (HTPB) and polyethylene glycol (PEG, average molecular weight = 4000) with aliphatic diisocyanates. The functionality of CaCO3 particles was modified using aminopropyltriethoxysilane (APTES), and was confirmed by Fourier-transform infrared spectroscopy (FTIR). The solubility, hydrophilic properties, and chemical structures of the composites were analyzed by water-solubility tests, contact angle measurements, and FTIR, respectively, and the successful production of the hydrophilic water-soluble polyurethane (WSPU) structure was demonstrated. The adhesion of surface-modified CaCO3 particles to the WSPU matrix and the thermal degradation properties of the neat WSPU and WSPU/CaCO3 composites were studied using field emission scanning electron microscopy (FE-SEM) and thermogravimetric analysis (TGA). The results demonstrated good adhesion of the surface-modified CaCO3 particles along with an improved thermal degradation temperature with the addition of CaCO3 particles to the WSPU matrix.

Multifunctional and fully aliphatic biodegradable polyurethane foam as porous biomass carrier for biofiltration

Water-blown fully aliphatic polyurethane foam was prepared at room temperature from trimer of hexamethylene diisocyanate and poly(diethylene glycol adipate) diol and post cured at 55 °C. In contrast to aromatic-based PUR foam analog, the produced flexible PUR foam exhibited highly porous structure with open cell content of 94% and average cell size of 700 μm. Therefore, it was subsequently tested as biodegradable cellular carrier of microorganisms (fungus Fusarium solani and bacterium Pseudomonas sp.) for biofiltration. Firstly, tests on enzyme activities (lipase, protease and urease) and utilization of PUR foam as the sole carbon and nitrogen source and determination of degradation products were carried out. Fusarium solani shown much higher both enzyme and degradation activities and higher spectrum of degradation products. Finally, the performance of a biofilter packed with the developed cellular carrier was investigated for removal of a mixture of acetone, propionic acid, ethyl acetate, toluene and α-pinene. Proven sorption properties of PUR foam against all pollutants and a high maximum elimination capacity of 218 ± 33 g m−3 h−1 make the new lightweight biofilm PU carrier suitable for this application due to their multi-functionality.

Sustainable Aromatic Aliphatic Polyesters and Polyurethanes Prepared from Vanillin-Derived Diols via Green Catalysis.

The design and preparation of polymers by using biobased chemicals is regarded as an important strategy towards a sustainable polymer chemistry. Herein, two aromatic diols, 4-(hydroxymethyl)-2-methoxyphenol and 2-(4-(hydroxymethyl)-2-methoxyphenoxy)ethanol, have been prepared in good yields through the direct reduction of vanillin and hydroxyethylated vanillin (4-(2-hydroxyethoxy)-3-methoxybenzaldehyde) using NaBH4, respectively. The diols were submitted to traditional polycondensation and polyaddition with acyl chlorides and diisocyanatos, and serials of new polyesters and polyurethanes were prepared in high yields with moderate molecular weight ranging from 17,000 to 40,000 g mol−1. Their structures were characterized by 1H NMR, 13C NMR and FTIR, and their thermal properties were studied by TGA and differential scanning calorimetry (DSC), indicating that the as-prepared polyesters and polyurethanes have Tg in the range of 16.2 to 81.2 °C and 11.6 to 80.4 °C, respectively.

Preparation and characterization of aliphatic polyurethane and modified hydroxyapatite composites for bone tissue engineering

Surfaces of nano-hydroxyapatite (n-HA) particles were modified by grafting of etidronic acid (ETD, 0.1 M) and were reinforced into polyurethane scaffolds prepared by foaming method to develop porous modified nano-hydroxyapatite/polyurethane (m-HA/PU) nanocomposite scaffolds for bone tissue engineering. Particle size and morphology of nanoparticles were studied using X-ray diffraction, transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. TEM and SEM results revealed that the surface of obtained modified hydroxyapatite (m-HA) particles was completely changed from grain- to plate-type structure with the size of 40 nm. Chemical structure, mechanical properties and biomedical application were studied using Fourier transform infrared spectroscopy (FTIR), universal testing machine and in vitro studies. In FTIR spectra, disappearance of peak around 2270 cm−1 confirmed the formation of polyurethane nanocomposite scaffolds and bands in the spectral range of 1400 and 800–900 correspond to the presence of calcium and phosphate groups due to hydroxyapatite. As the concentration of m-HA increased from 0 to 30 wt%, the compressive strength of the resulting PU/m-HA nanocomposites increased from 0.094 to 22.4 MPa. In vitro study with simulated body fluid (SBF) for 4 weeks indicated that surface was partially hydrolysed. Cell culture study showed that m-HA/PU nanocomposite scaffold is well suited for application in bone tissue engineering.

OPTIMISATION OF A CORROSION-PROTECTIVE COATING FOR A NEW BOAT LANDING SYSTEM USED IN OFFSHORE WIND TURBINES

Most of the maintenance operations in offshore platforms are performed by using service vessels approaching to boat landing systems, which are secondary structures attached to the main structure of the wind turbine. These systems guarantee certain structural integrity conditions thay may be jeopardised by the aggressive marine environment, which may cause corrosion processes if the structural material is not conveniently protected. The main strategy to avoid corrosion in this type of structures is to provide protective coatings, which in this particular case must have an adequate behaviour not only against the proper marine environment, but also against the abrasion and the impact loads generated by the violent contacts between the service vessel and the boat landing system. This work develops a comprehensive analysis to define a protective coating that provides simultaneously an adequate corrosion protection and a sufficient resistance against abrasion and impact loads. Based on industrial practice and a literature review, a number of tentative proposals were established, combining different metallization strategies, epoxy intermediate layers and external paints. The proposals were successively subjected to corrosion, abrasion and impact tests, discarding, after each set of tests, those providing unsatisfactory results. The final solution consists of 3 consecutive layers: thermal sprayed aluminium, a two-component polyamine cured pure epoxy, and a two-component chemically curing aliphatic acrylic polyurethane topcoat.

Polyurethane scaffold implants for partial meniscus lesions: delayed intervention leads to an inferior outcome

The purpose of this study was to assess the clinical outcomes of the implantation of an aliphatic polyurethane scaffold for the treatment of partial loss of meniscal tissue at a mean follow-up of 36months. A retrospective review on prospectively collected data was performed on patients who underwent implantation of an aliphatic polyurethane-based synthetic meniscal scaffold. Patients were evaluated for demographics data, lesion and implant characteristics (sizing, type and number of meniscal sutures), previous and combined surgeries and complications. Clinical parameters were rated using NRS, IKDC subjective, Lysholm, KOOS, and Tegner activity score, both preoperatively and at final follow-up. Sixty-seven patients were evaluated at a mean follow-up of 36months (48 M and 19 F; mean age 40.8 ± 10.6years; mean BMI 25.4 ± 4.3). The scaffold was implanted on the medial side in 54 cases, and on the lateral one in 13. Forty-seven patients had undergone previous surgical treatment at the same knee and 45 required combined surgical procedures. All evaluated scores improved significantly from the baseline. Among possible prognostic factors, a delayed scaffold implantation had lower post-operative clinical scores: IKDC subjective (P = 0.049), KOOS Sport (P = 0.044), KOOS total (p = 0.011), and Tegner (P = 0.03) scores at follow-up. The polyurethane meniscal scaffold implantation led to a significant clinical benefit in a large number of patients. A delayed intervention correlated with worse results. IV.