Polyurethane Binder Research Articles

Urethane-Functionalized Graphene Oxide for Improving Compatibility and Thermal Conductivity of Waterborne Polyurethane Composites

This study provides an effective interface modification strategy for preparing graphene-based composite. Urethane-functionalized graphene oxide (FGO) was prepared by in situ polymerization and then was incorporated into a polyurethane binder (PUB) matrix to fabricate composites. The surface chemical composition and structural properties of FGO were systematically characterized by a series of measurements. It was found that urethane chains were covalently attached onto the graphene oxide surface, and the FGO possessed a comparatively regular lamellar structure and a larger interlayer distance. Additionally, amphipathic urethane chains on the FGO sheets not only improved the compatibility and interfacial interaction between the stiff FGO and the soft PUB matrix, but also alleviated the modulus mismatch between them. The most effective improvements in mechanical and thermal transport properties were achieved when 0.5 wt % FGO was incorporated into the PUB matrix, leading to improvement of tensile strength, e...

Kinetic Research on the Curing Reaction of Hydroxyl-Terminated Polybutadiene Based Polyurethane Binder System via FT-IR Measurements

Polyurethane binder systems based on hydroxyl-terminated polybutadiene (HTPB) possess several superior properties such as superior adhesion, high solid-loading capacity, outstanding mechanical performance, etc. They have been widely used in coatings and adhesives as well as in medical and military industries. The cure reaction between hydroxyl-terminated polybutadiene (HTPB) and diisocyanates plays a key role in the properties of final products as well as the adjustment of process parameters. FT-IR spectroscopy is applied to investigate the kinetics of the curing reaction of HTPB and isophorone diisocyanate (IPDI) in the presence of a low toxic and low viscosity catalyst, stannous isooctoate (TECH). The concentrations of the isocyanate groups (NCO) characterized by FT-IR during the cure reaction with respect to time were recorded at different temperatures and at constant stoichiometric ratio Rn[NCO]/n[OH] = 1.0. The kinetic parameters, i.e., activation energy (Ea), pre-exponential factor (A), activation enthalpy (ΔH) and activation entropy (ΔS) were determined. In addition, the curing process and mechanism of the HTPB-IPDI reaction are discussed.

EPDM Rubber Modified by Nitrogen Plasma Immersion Ion Implantation.

Ethylene-propylene diene monomer rubber (EPDM) was treated by plasma immersion ion implantation (PIII) with nitrogen ions of 20 keV energy and fluence from 1013 to 1016 ions/cm2. The Fourier-transform infrared attenuated total reflection spectra, atomic force microscopy and optical microscopy showed significant structure changes of the surface. The analysis of an interface of PIII treated EPDM rubber with polyurethane binder showed a cohesive character of the adhesion joint fracture at the presence of solvent and interpreted as covalent bond network formation between the PIII treated rubber and the adhesive.

A Polyurethane Coating Based on Hydroxyethylated Diphenylolpropane

To improve the thermal resistance of a coating, a polyurethane binder has been synthesized with the use of hydroxyethylated diphenylolpropane. The influence of the catalyst concentration, solvent nature, and structure and molar ratio of the initial reagents on the properties of the coatings is studied. The composition, corresponding to the polyurethane coating with high physicomechanical properties combined with thermal and chemical resistance, is established.

Development of polyurethane based anti-scratch and anti-algal coating formulation with silica-titania core-shell nanoparticles

In this present study, anti-scratch and anti-algal coating formulations were developed with silica and silica-titania core-shell nanoparticles individually in polyurethane binder. This core-shell nanoparticle was synthesized in house to utilize the mechanical property of core silica and photo-catalytic activity of thin titania shell on silica core. High mechanical property of silica improves the strength and anti-scratch property of polyurethane film whereas photo-catalytic activity of titania provides anti-algal property of the film. Silica nanoparticles were prepared through sol-gel process. TiO2 nanoparticles and core-shell nanoparticles were prepared through peptization process. The prepared nanoparticles – silica, titania and silica-titania core-shell nanoparticles were characterized by Dynamic light scattering, UV-visible spectrophotometer, scanning electron microscopy, FTIR and X-Ray Diffraction. Polyurethane coating formulations were developed with polyurethane binder, thinner and above prepared nanoparticles, where percentage of nanoparticles were kept at 4 wt% of total formulation. Dry films were casted on glass substrate with these coating formulations after applying with brush and heated at 100 °C. Scratch testing were carried out for these dried films with dry film thickness of 100 μm on glass substrate at different load from 3N to 9N. The same coating formulations were applied on small pieces of bricks for anti-algal testing against green algae and mixed algae. This core-shell formulation successfully improved the scratch resistance of coatings up-to 5N load and also provided good anti-algal property.

Laboratory evaluation on performance of porous polyurethane mixtures and OGFC

The application of open grade friction course (OGFC) is limited by problems such as mixture disintegration and relatively poor fatigue performance. In this study, polyurethane (PU), a polymer binder, and PU-bonded mixtures were studied for overcoming the limitations of traditional asphalt-bond OGFC mixtures. The viscosity-time and mechanical properties of two PU binders were characterized using Rheometer, tensile test and dynamic mechanical analysis (DMA). Then a laboratory evaluation of the PU-bonded porous mixtures (PPM) and asphalt-bonded porous mixtures (APM) were undertaken using the Marshall stability test, the Cantabro Loss test, and the fatigue test. The test results show the PPM obtained three times higher stability and over one order of magnitude greater fatigue life than APM. When compared with the low glass-transition temperature (Tg) PU binder, the high Tg PU binder significantly improved resistance to moisture damage and lowered Cantabro loss of PPM in the 60 °C immersion conditions. Results of this study will provide an important reference for utilizing PU porous mixtures as OGFC surface layer, and discover ways to improve OGFC durability.

High self-dispersibility carbon black particles prepared via hydroxylation and urethane chains encapsulation for enhancing properties of waterborne polyurethane composite films

Carbon black (CB) is a preferred nano-reinforcer for conventional polymers, but it exhibit poor dispersibility, which makes it difficult for further application in the coating industry. Here we prepared hydroxylated carbon black (OCB) by a mild oxidation process and then covalently encapsulated with a urethane chains shell via in situ polymerization, and thus encapsulated carbon black (EOCB) particles were achieved. Surface chemical composition of the EOCB particles was thoroughly characterized by FT-IR, TGA, XPS, and EA techniques, and its dispersion properties in aqueous medium were studied by DLS, natural sedimentation, and TEM analyses. It was found that EOCB possessed a high encapsulation percentage, and showed excellent self-dispersibility and prominent stability in aqueous medium. Furthermore, intensive investigation demonstrated that PUB/EOCB composite, that prepared by blending EOCB particles with a polyurethane binder (PUB), exhibited improved mechanical property, water resistance and matting appearance, which probably due to the strong hydrogen bonds between the EOCB particles and the PUB matrix. This work provides a potential avenue for designing CB-based microcapsules and makes it promising application in waterborne coatings.

Water as Significant Factor Having Influence on Composite Material Properties Based on Scrap Tyres and Polyurethane Binder

Composite materials based on scrap tires and polyurethane type polymer binder with defined reactivity were investigated to underline the influence of water (varying air humidity, special treatment of rubber crumb with water) during the production on selected mechanical properties. Compressive stress and modulus of elasticity E at 10% deformation, Shore C hardness and apparent density were investigated. Strong correlation between the above-mentioned mechanical properties of the composite materials and the crosslinking conditions of the polymer (presence of water during the production of composite materials) were observed. It has been confirmed previously that the crosslinking degree of polyurethane type binder separately and, therefore, at the same time mechanical properties of binder was strongly dependent on water as a significant factor during the hardening of the polymer.

Enhanced thermal and mechanical properties of PW‐based HTPB binder using polystyrene (PS) and PS–SiO2 microencapsulated paraffin wax (MePW)

ABSTRACTPolystyrene (PS) microencapsulated paraffin wax (MePW) and PS–SiO2 MePW were used to improve the form‐stability of PW in hydroxyl‐terminated polybutadiene‐derived polyurethane (HTPB) binder. HTPB matrix containing different contents of PS MePW, PS–SiO2 MePW, and PW were prepared. The chemical composition, crystallinity, microstructure, heat capacities, thermal stabilities, thermal reliabilities, leakage, and mechanical properties of the composites were compared using Fourier transforms infrared spectroscope, X‐ray diffractometer, scanning electronic microscope, differential scanning calorimeter, thermo‐gravimetric analyzer, thermal cycling test, leaking test, compression, and tensile tests, respectively. The results showed that the MePW/PW/HTPB composites were prepared without chemical reaction. The thermal stability and mechanical properties of PS–SiO2 MePW/PW/HTPB increased more dramatically than that of PS MePW/PW/HTPB. With the increasing contents of MePWs, the PW leakage of the composites decreased, especially for PS MePW/PW/HTPB. Consequently, the MePW/PW/HTPB composites possess a potential application for PW‐based polymer‐bonded explosive system. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46222.

Re-utilization of Finished Leather Waste (scraps) Blended with Different Plant Fibers Using Polymer Resins: A Waste to Wealth Approach of the Ethiopian Case

In the process of tanning significant amount of solid, liquid and gaseous wastes are generated. The waste generated from the tanning industry then causes negative health effects on the environment which in turn leads to health issue of the local community. The present study then is focused on making of leather composites using solid leather waste, different plant fibers namely enset (Ensete ventricosum), hibiscus (Hibiscus cannabinus), jute (Corchorus trilocularis L), palm (Phoenix dactylifera) and sisal (Agave sisalana) and two polymer resins i.e., Resin Binder (RB) and Poly Urethane Binder (PUB) in various proportions. Composites containing leather fiber incorporated with hibiscus, sisal and palm fibers along with resin binder exhibited better tensile strength values than their respective controls. This shows the compatibility of the resin binder with plant fibers and leather fibers. Composites prepared using sisal fibers gave better tensile strength values compared to others prepared in this study. SEM pictures of the products in this study showed composite nature. FTIR studies have shown the functional groups of collagen protein, cellulose and binders. In the DSC study, the composite sheets of jute (LF-JS), palm (LF-PS) and sisal (LF-SS) exhibited higher melting points than the control, however, enset (LF-ES) and hibiscus (LF-HS) samples showed lower melting temperature than their respective controls. Based on these results, all composite sheets that meet the set standard can be used for preparation of products such as light hand bags, false roofing coverage, mouse pads, key chains, wallets, components of furniture and other interior decorations.

Synthesis of bromo-cardanol novolac resins and evaluation of their effectiveness as flame retardants and adhesives for particleboard

The synthesis of bromo derivatives cardanolic novolac resins (BCNR) using infrared, thermogravimetric analysis, differential scanning calorimetry, gel permeation chromatography, nuclear magnetic resonance 1H and 13C methods was studied. The mechanism of thermal degradation of BCNR is proposed. It is shown, that particleboards manufactured using PU-(BCNR) as an adhesive are materials with enhanced flame retardant properties, meeting the requirements of P7 class to EN 312 (especially durable moisture-resistant particleboards) and the requirements of the emission class Super E0. The bromine in the structure of the cardanol-containing polyurethane binder allows achieving both high physical and mechanical characteristics of the particleboards and resistance to flame. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45322.

Surface Properties of Silane-Treated Diatomaceous Earth Coatings: Effect of Alkyl Chain Length.

Modification of diatomaceous earth (DE) was performed using alkyltrimethoxysilanes of different chain lengths (C3, C8, C12, C16, and C18), and their resultant properties were determined. The thermal properties of these alkyltrimethoxysilane-treated DE powders were probed using thermogravimetric analysis and temperature-modulated differential scanning calorimetry, and the surface/porosity was studied using nitrogen adsorption and electron microscopy. Crystallinity of the hydrocarbon tails occurred when the chain lengths were C12 or larger, and the adsorbed hydrocarbon amounts were 1.6 mg/m2 or more. The wettability of functionalized DE-containing surfaces was studied using water contact angle measurements. At larger adsorbed amounts of 2.2 mg/m2 or more, the treated DE formed superhydrophobic coatings (with water contact angles ≥150°) with a polyurethane binder. These coatings required a minimum of 30% particle loadings, which allowed the DE particles to dominate the surface. At loadings larger than approximately 50%, there was a decrease in the contact angles corresponding to a reduction in roughness on the surface. Samples with adsorbed amounts less than 2.2 mg/m2 or chain lengths shorter than C12 were only hydrophobic. These results were in agreement with scanning electron microscopy and Brunauer-Emmett-Teller specific surface area and pore volume measurements.

Flexible and wrinkle-free electrode fabricated with polyurethane binder for lithium-ion batteries

Flexible and wrinkle-free electrodes for lithium-ion batteries (LIBs) have been developed by using polyurethane as a binder. The electrodes provide LIBs with robust mechanical properties and good electrochemical performances along with MWNT.

Boundary-Layer Detection at Cryogenic Conditions Using Temperature Sensitive Paint Coupled with a Carbon Nanotube Heating Layer.

Detection of flow transition on aircraft surfaces and models can be vital to the development of future vehicles and computational methods for evaluating vehicle concepts. In testing at ambient conditions, IR thermography is ideal for this measurement. However, for higher Reynolds number testing, cryogenic facilities are often used, in which IR thermography is difficult to employ. In these facilities, temperature sensitive paint is an alternative with a temperature step introduced to enhance the natural temperature change from transition. Traditional methods for inducing the temperature step by changing the liquid nitrogen injection rate often change the tunnel conditions. Recent work has shown that adding a layer consisting of carbon nanotubes to the surface can be used to impart a temperature step on the model surface with little change in the operating conditions. Unfortunately, this system physically degraded at 130 K and lost heating capability. This paper describes a modification of this technique enabling operation down to at least 77 K, well below the temperature reached in cryogenic facilities. This is possible because the CNT layer is in a polyurethane binder. This was tested on a Natural Laminar Flow model in a cryogenic facility and transition detection was successfully visualized at conditions from 200 K to 110 K. Results were also compared with the traditional temperature step method.

Effect of thermal processing temperature on the microphase separation and mechanical properties of BAMO/THF polyurethane

Abstract This paper describes the influence of thermal processing temperature on the microphase separation, hydrogen bonding, phase transitions and mechanical properties of 3,3-bis(azidomethyl)oxetane (BAMO)/tetrahydrofuran (THF) polyurethane binder, which is used for propellant. Fourier transform infrared (FTIR) spectroscopy confirmed that the intended polyurethane was synthesized and was used to determine the state of the local hydrogen bonding in these polyurethanes. The results showed that the thermal processing clearly imparts significant changes to the H-bonded environment and this was confirmed in a quantitative fashion using small-angle X-ray scattering (SAXS). The dynamic mechanical analysis (DMA) revealed rather significant changes in dynamic segmental relaxations and storage moduli for this series of BAMO/THF polyurethanes, which are in keeping with the findings from other experiments.

Rheokinetic analysis on the curing process of HTPB-DOA- MDI binder system

Polymer bonded explosives (PBXs) are a kind of rubbery explosives, in which the explosive components are bound together by a polymeric binder. The hydroxyl terminated polybutadiene (HTPB)-based polyurethane binder systems possess a unique combination of properties, including superior adhesion, excellent mechanical properties and have been widely used in rocket propellants, PBXs and other weapons. The cure reaction between HTPB and diisocyanates in the castable PBXs plays an important role in the adjustment of process parameters as well as properties of explosive formulations. In this paper, viscosity measurements were carried out at different temperatures (15oC, 25oC, 35oC, 45oC, 55oC) to a series of systemic studies on the viscosity build-up and rheological reaction rate constant during the curing process of the of HTPB- dioctyl adipate (DOA)-diphenyl methane diisocyanate (MDI) binder system, discovered and explained the phenomenon that the pot-life of the binder system was prolonged when the curing temperature raised and the curing reaction rate was accelerated. And the rheology kinetic model of the HTPB-DOA-MDI binder system was established.

The Exponentiated Hencky Strain Energy in Modeling Tire Derived Material for Moderately Large Deformations

This work presents a hyperviscoelastic model, based on the Hencky-logarithmic strain tensor, to model the response of a tire derived material (TDM) undergoing moderately large deformations. The TDM is a composite made by cold forging a mix of rubber fibers and grains, obtained by grinding scrap tires, and polyurethane binder. The mechanical properties are highly influenced by the presence of voids associated with the granular composition and low tensile strength due to the weak connection at the grain–matrix interface. For these reasons, TDM use is restricted to applications involving a limited range of deformations. Experimental tests show that a central feature of the response is connected to highly nonlinear behavior of the material under volumetric deformation which conventional hyperelastic models fail in predicting. The strain energy function presented here is a variant of the exponentiated Hencky strain energy, which for moderate strains is as good as the quadratic Hencky model and in the large strain region improves several important features from a mathematical point of view. The proposed form of the exponentiated Hencky energy possesses a set of parameters uniquely determined in the infinitesimal strain regime and an orthogonal set of parameters to determine the nonlinear response. The hyperelastic model is additionally incorporated in a finite deformation viscoelasticity framework that accounts for the two main dissipation mechanisms in TDMs, one at the microscale level and one at the macroscale level. The new model is capable of predicting different deformation modes in a certain range of frequency and amplitude with a unique set of parameters with most of them having a clear physical meaning. This translates into an important advantage with respect to overcoming the difficulties related to finding a unique set of optimal material parameters as are usually encountered fitting the polynomial forms of strain energies. Moreover, by comparing the predictions from the proposed constitutive model with experimental data we conclude that the new constitutive model gives accurate prediction.

Polyurethane encapsulated carbon black particles and enhanced properties of water polyurethane composite films

Abstract Polyurethane-encapsulated carbon black (ECB) particles were synthesized successfully through a facile method by encapsulating carbon black (CB) particles in the presence of an amphiphilic isocyanate-terminated polyurethane pre-polymer. Fourier transform infrared spectroscopy demonstrated the existence of a polyurethane layer on the surface of encapsulated CB, and thermo-gravimetric analysis indicated the encapsulation percentage reached 15.77 wt.%. The results of dynamic light scattering, transmission electron microscopy, and UV–vis spectroscopy analyses revealed that the ECBs exhibited better dispersibility and stability in water in comparison with the dispersant-dispersed carbon black (DCB) prepared by simply dispersing CB particles using a polymer super-dispersant. In particular, scanning electron microscope observation of PUB/ECB composite films obtained by blending ECB particles with a waterborne polyurethane binder (PUB), showed enhanced dispersibility and compatibility of the ECBs in the PUB matrix. Therefore, as test results demonstrated, PUB/ECB composite films showed better mechanical, water resistance, and color properties compared with those of PUB/DCB composite film. It is expected that this effective encapsulation method for preparing functional CB dispersions will be used to make waterborne coatings in the leather and textile finishing fields.

Microstructuring of metal effect pigments in functional coatings on textile substrate

A coating system for polyester fabrics is developed containing metal effect pigments and a polyurethane binder. The metal pigment is made of copper, is of microscaled size and anisotropic shape. It is originally used for optical modification but can also be used to introduce other functional properties. The polyurethane binder is needed to fix the pigments on the textile surface. The aim of the current investigation is to present that the binder has not only the task to fix the pigment but can be also used to structure the pigment surface. The binder application leads to formation of microstructures on top of the pigment surface, probably as a result of a dewetting process. Based on this microstructured pigment surface, in future, textile coatings for improvement of water-repellent, antimicrobial, and antistatic properties could be developed.

Reactive Energetic Plasticizers for Energetic Polyurethane Binders Prepared via Simultaneous Huisgen Azide‐Alkyne Cycloaddition and Polyurethane Reaction

AbstractReactive energetic plasticizers (REPs) for use in glycidyl azido polymer (GAP) based polyurethane (PU) energetic binders were investigated. These REPs consisted of an activated terminal alkyne group that was expected to give rise to Huisgen azide‐alkyne 1,3‐dipolar cycloaddition within the specific pot life for a PU formulation to prevent the migration of plasticizers, and with a gem‐dinitro group as an energy resource. A quantitative miscibility investigation between the plasticizers and uncured GAP showed that REPs exhibited better miscibility than conventional energetic plasticizers. The plasticization effect of the REPs on the GAP prepolymer with respect to the reduction of the viscosity illustrated REPs can effectively reduce the viscosity of the GAP prepolymer from 6,015 cP to 150–240 cP at the processing temperature when 50 wt‐% of REP was added. A comparison of the click reactivity and activation energies (Ea) of REPs and GAP prepolymer elucidated that the reactivity of azide‐alkyne cycloaddition depended on the dipolarophilicity of REPs which could be controlled by adjusting the length of methylene spacer between electron‐withdrawing groups (EWG) and neighboring alkynes in REPs. Thermogravimetric analysis manifested REP/GAP‐based PU binders maintained the thermal stability of the control GAP‐based PU binder. The mechanical properties and impact insensitivity of the GAP‐based PU binders were also improved by the incorporation of REPs.