Polyol Blend Research Articles

Novel rubber-steel adhesive based on resole phenol formaldehyde/unsaturated polyester/soybean oil polyol blends with high thermal stability performance

One of the main challenges in rubber-metal adhesive is improving the adhesion strength performance with high thermal stability. A novel rubber-steel adhesives based on resole phenol formaldehyde/unsaturated polyester/soybean oil polyol blends were fabricated to tackle this challenge. SEM investigated the morphology of the fabricated blends, while the curing reaction and the components’ interactions were evaluated using FT-IR and XRD. The heat resistance and curing properties were studied by TGA and DSC. The adhesion properties for rubber-metal adhesive specimens were tested at room temperature. The impact of soybean oil polyol modifier addition was investigated on adhesion performance. The curing conditions (touch dry, full curing, and shelf life) and hardness were investigated. It is obvious that polyol improves the heat resistance of the prepared films and enhances their adhesion behavior. The fabricated adhesive exhibits good adhesion and thermal stability due to the integration of chemical cross-linking in the matrix. It can adhere extensively to substrate surfaces via intermolecular forces with small physical movements. Controlling the curing time and delaying the shelf life could be possible for samples that take a long time to cure completely. The designed fabricated adhesive appeared to desired properties of satisfactory rubber-metal adhesion and good thermal stability.

Understanding Starch Gelatinization, Thermodynamic Properties, and Rheology Modeling of Tapioca Starch–Polyol Blends Under Pre- and Post-ultrasonication

Understanding Starch Gelatinization, Thermodynamic Properties, and Rheology Modeling of Tapioca Starch–Polyol Blends Under Pre- and Post-ultrasonication

Investigating the Corrosion Inhibition Performance of a Novel Coconut Oil-Based Poly(urethane-urea) Hybrid Coating on Carbon Steel in 3.5% NaCl Solution

Polyurethane has been used for years as an anti-corrosion coating due to its intrinsic hydrophobic properties. However, its hydrophobicity is not enough to inhibit the permeation of corrosive agents; thus, incorporating it with polyurea would further enhance its hydrophobic properties. In this study, coconut oil, a saturated, low molecular weight vegetable oil, was employed as an eco-friendly precursor for synthesizing a novel poly(urethane-urea)- based hybrid coating. The synthesis process involved the utilization of a coconut oil-based polyol blend, triethanolamine (TEA) as an amine source, and hexamethylene diisocyanate (HDI). The resulting hybrid coating on carbon steel demonstrated remarkable anticorrosion performance in a 3.5 wt. % NaCl solution, owing to the intrinsic hydrophobic characteristics of coconut oil and polyurea. Significant corrosion rate reduction was observed with increasing amine content, accompanied by an enhancement in mechanical properties. Notably, an amine loading of 4% consistently exhibited superior corrosion resistance and mechanical performance in the hybrid coating. Chemical structural analysis revealed a hydrogen-bonding network in polyurea coatings, reducing porosity, enhancing barrier properties, and improving mechanical characteristics, highlighting its potential for sustainable corrosion protection.

TiO<sub>2</sub>- Polyurethane Cocopol Blend Nanocomposites as an Anticorrosion Coating for Mild Steel

Mild steels were the most frequently used materials in industries and factories since it possesses unique properties but due to weak environmental changes, these cause deterioration and corrosion to the materials’ surface. To prevent such, protective coatings were applied to protect against corrosion in which by incorporating titanium nanoparticles in polyurethane coatings. Titanium nanoparticles were synthesized using titanium butoxide as a precursor. The obtained nanoparticles were used as an inhibitor mixed with coconut oil-based polyurethane polyol blend against the corrosion on mild steel of 3.5% of sodium chloride solution which has been investigated using the Tafel polarization technique. The polarization curves of the corrosion potential for bare mild steel, along with different amounts of titanium nanoparticles coating, exhibit a positive shift. This shift indicates that the coating film effectively reduces the transport path for the corrosive solution, providing a protective barrier against corrosion. This observation is further supported by the results of the adhesive strength test, which demonstrates that the attachment of the coating films to the metal increases with higher amounts of titanium nanoparticles. This indicates improved adhesion and a stronger bond between the coating and the substrate, enhancing the overall corrosion resistance. The increase of contact angle test confirms the improvement of the coating’s hydrophobicity with the addition of titanium nanoparticles. This suggests that the coating repels water more effectively, further contributing to its protective properties against corrosion. Results also show that the addition of 4wt% of titanium nanoparticles has better anti-corrosion properties than the PU CCP alone, and 0.5, 1.0, and 2.0wt% of titanium added.

Synthesis of Silanated Coconut Oil-Based Waterborne Polyurethane Coating for Corrosion Protection

In this study, an eco-friendly coconut oil-based polyol blend was synthesized for bio-based waterborne polyurethane (WBPU) and WBPU-silane composite coatings. It was demonstrated that an increase in silane content incorporated into the WBPU matrix significantly enhanced the corrosion protection of WBPU coatings. Results also show a fourfold increase in the adhesion strength of WBPU-silane composite coatings as compared to that of bare WBPU coatings. Further, the water contact angle revealed that hydrophobic properties increase as the silane content incorporated into the WBPU matrix increases. This work provides a novel route for enhanced corrosion protection utilizing a bio-based polyol blend.

Increasing circular and bio-based content of a thermosetting polyurethane for encapsulation of optoelectronic devices: A multivariate investigation

Transparent thermosetting polyurethanes (PU) with increased circular and bio-based content have been developed with an effective and efficient approach based on the Design of Experiment. Starting from a commercial PU formulation for light-emitting diode encapsulation, the fossil-based polyol blend has been partially replaced with potentially recycled bis(2-hydroxyethyl) terephthalate (BHET) diol and bio-based polyol. BHET has been directly implemented in the polyol blend without requiring any additional solvent or treatment. The multivariate approach allowed to study formulative (i.e. BHET, bio-based and fossil-based polyols) and process factors (i.e. mixing time and temperature of polyol blend and PU blend) of the polymer preparation by using optical spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. The effect of each factor on the optical and thermal properties of the resulting polyurethane films have been observed and clearly quantified. Particularly, the implementation of BHET improved the thermal stability of PU but reduced the film transmittance as the concentration increases. Circular and bio-based components into the polyol blend have been increased up to 80%w/w and the formulation has been optimized by following a property-driven analysis. Polyurethane formulated with the selected polyol blend showed transparency, thermal behaviour, long-term stability, and cost comparable to the starting commercial formulation. Market-level properties and ease of preparation highlight that circular and bio-based PUs can be rapidly developed and implemented within current polyurethane production processes, promoting the shift towards Circular Economy with solid industrial symbiosis. At last, the present approach can be easily repurposed to further improve sustainability of polyurethanes, as well as to develop other classes of polymers.

Developing Materials for Biodegradable Otolaryngological Stents

Materials for otolaryngological stents have to be characterized by good tensile strength, wear resistance, biocompatibility, and specific degradation time. This work aimed to synthesize polyurethanes based on various biodegradable polyol blends. Their biodegradability and mechanical properties were tested and compared to commercial BIOFLEX material.

The Influence of Potassium Salts Phase Stabilizers and Binder Matrix on the Properties of Novel Composite Rocket Propellants Based on Ammonium Nitrate.

The environmental impact and availability of ingredients are vital for the new generation of rocket propellants. In this context, several novel composite propellants were prepared based on the "greener" oxidizer phase-stabilized ammonium nitrate (PSAN), a micronized aluminum-magnesium alloy fuel, iron oxide powder burn rate modifier, triethylene glycol dinitrate (TEGDN) energetic plasticizer and a polyurethane (PU) binder. The novelty of this study is brought by the innovative procedure of synthesizing and combining the constituents of these heterogeneous compositions to obtain high-performance "eco-friendly" rocket propellants. The polymorphism shortcomings brought by ammonium nitrate in these energetic formulations have been solved by its co-crystallization with potassium salts (potassium nitrate, potassium chromate, potassium dichromate, potassium sulphate, potassium chlorate and potassium perchlorate). Polyester-polyol blends, resulting from recycled post-consumer polyethylene terephthalate (PET) glycolysis, were utilized for the synthesis of the polyurethane binder, especially designed for this type of application. To adjust the energetic output and tailor the mechanical properties of the propellant, the energetic plasticizer TEGDN was also involved. The performance and safety characteristics of the novel composites were evaluated through various analytical techniques (TGA, DTA, XRD) and specific tests (rate of combustion, heat of combustion, specific volume, chemical stability, sensitivity to thermal, impact and friction stimuli), according to NATO standards, providing promising preliminary results for further ballistics investigations.

Effect of the aramid pulp on the physicochemical, viscoelastic properties and rheokinetics of polyurethanes

This publication highlights the effect of aramid pulp (1 wt.%) on equilibrium swelling, enthalpy reaction, solid viscoelastic properties, and rheokinetics of castor oil (CO) and polyether (PE) polyol blend (50/50 CO/PE) with polymeric isocyanate (pMDI). The CO-pMDI system showed a lower solubility parameter difference (Δδi) than the PE-pMDI and CO/PE-pMDI. Crosslink density values \({v}_{e}\) are higher for CO-pMDI, and when added to aramid pulp, there is a slight increase due to the possible restriction of swollen volume. Regarding the pseudo-solid behavior, AP restricts the macromolecular movement and confers reinforcing characteristics to PU systems. The Prout–Tompkins autocatalytic model satisfactorily described the reactions, resulting in activation energy values Ea within 45 − 54 kJ/mol. However, for the CO/PE blend, the difference between the reactivity of the polyols and the solubility parameter with pMDI results in a two-step reaction kinetics. Aramid pulp practically does not change the reaction mechanism, only the viscosity of the medium. Furthermore, the thermodynamic parameters (ΔS* and ΔH*) indicated that the PU with AP resulted in more ordered complexes. The adequate description of the polymerization reaction and the effect of the aramid pulp allowed for obtaining PU formulations with tunable characteristics for strict composite processing composites.

Surface modification of TiO2 nanoparticles with 1,1,1-Tris(hydroxymethyl)propane and its coating application effects on castor seed oil-PECH blend based urethane systems

Surface modification of peripheral hydroxyl groups of TiO2 with trimethylolpropane (TMP) was successfully carried out and characterized. This hybrid material (TiO2-TMP) was added in percentages to a polyol blend of castor seed oil (a renewable resource and nontoxic material) and poly(epichlorohydrin)-triol (PECH-triol) {a cross-linker}. After ultrasonication of the polyol blend with TiO2-TMP, through a one-pot synthesis, the mixture was made to react with polymeric 4,4′-methylene diphenyl diisocyanate (PMDI) using 4-Methyl-2-pentanone as a reacting solvent. The synthesized PECH-triol and composite coating films structural elucidation was carried out using FTIR, 1H NMR and 13C NMR. The pristine/undoped and composite films were subjected to specific coating evaluations such as morphology (FESEM), XRD, thermal stability, mechanical property (UTM), chemical resistance, antimicrobial activity and corrosion resistance (Tafel plot). The doped composites showed improved coating properties, especially PU-TiO2-TMP (1.0 wt%), which possesses the highest percentage of TiO2-TMP nanoparticle.

Dispersion Methodology for Technical Lignin into Polyester Polyol for High-Performance Polyurethane Insulation Foam

The incorporation of lignin into rigid polyurethane foam (RPUF) has been explored for the last two decades for replacing petrochemical polyols and producing sustainable high-performance insulation materials. However, to date, the issues associated with the dispersion of technical lignin in the commonly used polyols for RPUF have highly limited the improvement in mechanical and thermal insulation performance. This study reports the enhanced dispersion of kraft lignin (KL) up to 75 wt % in the glycerol-substituted aromatic polyester polyol blend. The influence of significantly well-dispersed KL on RPUF in terms of loading levels, the viscosity of the polyol, the microstructure, and the thermal and mechanical properties of RPUF is discussed. The KL incorporated (0.5–6.0 wt %) in polyol afforded a remarkable reduction in thermal conductivity (32%–34%) of the resultant RPUF with minimal variation in density and insignificant change in compressive strength. The scale of this improvement, to the best of our knowledge, has not been reported to date in lignin-incorporated RPUF systems. Furthermore, the presence of the KL in the RPUF also resulted in a mild improvement in the flame retardance performance. This study provides insights into producing KL-incorporated RPUF for thermal insulation application.

Study of castor oil‐based auxetic polyurethane foams for cushioning applications

AbstractThis work involves the study of mechanical and antibacterial properties of auxetic polyurethane (APU) foams synthesized using castor oil (CO) to ascertain their suitability as seat cushions in wheelchairs. Firstly, CO‐based PU foams (PU‐CO) were synthesized by substituting 25% synthetic polyol with CO in a polyol blend. Conventional PU foams and PU‐CO foams were then converted to auxetic foams using triaxial compression and heating. The chemical composition, microstructure and thermal, mechanical and antibacterial properties of the foams were analyzed. It was found that addition of CO improved the antibacterial and mechanical properties of the foams. CO‐based APU (CO‐APU) foams showed highest compression strength and storage modulus. An increase in thermal stability of PU‐CO was also observed as compared to PU foams. These CO‐APU foams could be a better alternative to conventional PU foams for wheelchair seat cushions and in hospital bed applications. © 2021 Society of Industrial Chemistry.

Bio-Based Polyurethane Foams with Castor Oil Based Multifunctional Polyols for Improved Compressive Properties.

Currently, most commercial polyols used in the production of polyurethane (PU) foam are derived from petrochemicals. To address concerns relating to environmental pollution, a sustainable resource, namely, castor oil (CO), was used in this study. To improve the production efficiency, sustainability, and compressive strength of PU foam, which is widely used as an impact-absorbing material for protective equipment, PU foam was synthesized with CO-based multifunctional polyols. CO-based polyols with high functionalities were synthesized via a facile thiol-ene click reaction method and their chemical structures were analyzed. Subsequently, a series of polyol blends of castor oil and two kinds of castor oil-based polyols with different hydroxyl values was prepared and the viscosity of the blends was analyzed. Polyurethane foams were fabricated from the polyol blends via a free-rising method. The effects of the composition of the polyol blends on the structural, morphological, mechanical, and thermal properties of the polyurethane foams were investigated. The results demonstrated that the fabrication of polyurethane foams from multifunctional polyol blends is an effective way to improve their compressive properties. We expect these findings to widen the range of applications of bio-based polyurethane foams.

The effect of PCL/PEG ABA block lengths on the crystallization of homo/block- based polyurethane/CNW nanocomposites

We report synthesis and characterization of a set of thermoset polyurethane (PU) bionanocomposites based on a polyol blend of poly(e-caprolactone)/ polyethylene glycol (PCL/PEG) ABA block copolymers and their homopolymers (Mw: 2000 D). ABA block copolymers of PCL/PEG, with variable block lengths, were blended with their homopolymers. The relative weight content of Homo: Block (HB) was set 1:1 and the blend was used to synthesize a PU bionanocomposite using HDI and cellulose nanowhisker (CNW). The change in PEG and PCL block lengths resulted in an extensive change in the crystallization of the soft domains. The results of dynamic and thermal analysis revealed an increasing trend in the crystallization of the PCL/PEG segments as their lengths increase in the block copolymer structure. The shape memory analysis of the PU specimens showed high recovery (84-100%) and fixity (93-100%) ratios. Specimens with about one-order of magnitude fall in the storage modulus in the plateau region showed the highest fixity ratios. The relatively stable storage modulus at the elevated temperature indicate lack of flow for the PU nanocomposites and their thermoset nature. The cytotoxity analysis of the specimens showed a great cytocompatibility, indicating their great potential in the field of tissue engineering as a new biomaterial model. HB6 was selected as the optimum sample with SR and SF of 100%, with the highest cell viability.

Effects of mixing sequence on epoxy/polyether polyol/organoclay ternary nanocomposites

ABSTRACT The effects of mixing sequence of the polyether polyol and curing agent (triethylenetetramine) on mechanical and thermal properties and morphology of epoxy/polyether polyol/organoclay ternary nanocomposites are investigated in this study. The polyether polyol domain size data are relatively unchanged with mixing order both in epoxy/polyether polyol blends and in ternary nanocomposites. Generally, impact strength data of the ternary nanocomposites prepared by the second addition order are higher than the ones produced by the first addition order. Flexural strength and strain at break may be accepted as unaltered generally for the ternary nanocomposites with respect to addition order. Except for the sample containing 3 wt-% Cloisite® 30B and 3 wt. % polyether polyol, flexural modulus data are close to each other in ternary nanocomposites. The highest flexural modulus is obtained for the 5 wt-% Cloisite® 30B and 3 wt-% polyether polyol sample prepared by the second addition order, as 2978 ± 27 MPa.

Evaluation of the effect of a hyperbranched polyester on the thermal, rheological, morphological and mechanical properties of polyvinyl chloride/hemp fiber blends

The aim of this study was to investigate the effect of the hyperbranched polyester polyol from second generation content on the structural, thermal, rheological, morphological and mechanical properties of recycled polyvinyl chloride/hemp fiber/hyperbranched polyester polyol obtained from second generation blends. In all blends, the amounts of recycled polyvinyl chloride and hemp fiber were 70 wt% and 30 wt% respectively. The blends were obtained in a torque rheometer. The proportions of hyperbranched polyester polyol regards to those of the polyvinyl chloride and hemp fibers were 5 wt%, 10 wt%, 15 wt% and 20 wt%. Additionally, a recycled polyvinyl chloride/hemp fiber blend was prepared to be used as control blend. Infrared analysis was then used to evidence the interaction between components of the blends. The thermal stability of the recycled polyvinyl chloride/hemp fiber/hyperbranched polyester polyol blends was lower than that of the polyvinyl chloride. Furthermore, it was not observed a trend in the thermal behavior of the recycled polyvinyl chloride blends. Hyperbranched polyester polyol increased the glass transition temperature of the blends. Additionally, rheological analysis results indicated that the hyperbranched polyester polyol reduced the viscosity of the blends.

Synthesis of Thermally Stable Reactive Polyurethane and Its Physical Effects in Epoxy Composites

A flame retardant polyol (EP-DOPO) with epoxy functional groups was synthesized by reacting a 1,6-hexanediol glycidyl ether with a flame retardant 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phospha-phenanthrene-10-oxide (DOPO). The polyurethane (EPPU) with enhanced heat resistance was prepared by the reaction of a polyol blend of EP-DOPO and polytetrahydrofuran (PolyTHF) at a ratio of 1:1 with isophorone diisocyanate. EPPU useful for the preparation of cables or coatings showed higher thermal decomposition temperature rather than that of reference polyurethane synthesized by the reaction between pure PolyTHF and isophorone diisocyanate by thermogravimetric analysis. Further study of the polyurethane as a toughening agent for epoxy polymers was carried out. Epoxy compositions consisting of bisphenol A epoxy resin and dicyandiamide as a hardener have a brittle property allowing crack propagation after cure. Polyurethane plays an important role as an impact modifier to prevent from cracks of epoxy polymers. Various contents of EPPU were added into epoxy compositions to measure the physical property changes of epoxy polymers. The tensile and flexural strengths of the cured specimen were compared with those of epoxy compositions including reference polyurethane. Furthermore, the crosslink density of the cured epoxy compositions was compared.

Surface Response Methodology-Based Mixture Design to Study the Influence of Polyol Blend Composition on Polyurethanes' Properties.

Polyurethanes are materials with a strong structure-property relationship. The goal of this research was to study the effect of a polyol blend composition of polyurethanes on its properties using a mixture design and setting mathematic models for each property. Water absorption, hydrolytic degradation, contact angle, tensile strength hardness and modulus were studied. Additionally, thermal stability was studied by thermogravimetric analysis. Area under the curve was used to evaluate the effect of polyol blend composition on thermal stability and kinetics of water absorption and hydrolytic degradation. Least squares were used to calculate the regression coefficients. Models for the properties were significant, and lack of fit was not (p < 0.05). Fit statistics suggest both good fitting and prediction. Water absorption, hydrolytic degradation and contact angle were mediated by the hydrophilic nature of the polyols. Tensile strength, modulus and hardness could be regulated by the PE content and the characteristics of polyols. Regression of DTG curves from thermal analysis showed improvement of thermal stability with the increase of PCL and PE. An ANOVA test of the model terms demonstrated that three component influences on bulk properties like water absorption, hydrolytic degradation, hardness, tensile strength and modulus. The PEG*PCL interaction influences on the contact angle, which is a surface property. Mixture design application allowed for an understanding of the structure-property relationship through mathematic models.

Synthesis and characterization of polyurethane foams derived of fully renewable polyester polyols from sorbitol

This work globally redesigns the conventional approach in obtaining polyurethane foams (PUF), from sorbitol. Fully biobased polyester polyols were synthesized from sorbitol, adipic or succinic acid and different renewable C2 to C12 diols as the first step towards the elaboration of PUF. Sorbitol-based polyester polyols were synthesized through a two-step esterification without catalyst. The absence of a catalyst limits some side reactions and focuses the reaction on the primary hydroxyl groups of the sorbitol, to obtain the linear molecular structure. The global yields of the corresponding esterifications were above 80%. Hydroxyl values and acid values of the corresponding linear biobased polyester polyols ranged from 440 to 683 mg KOH/g, and from 11 to 49 mg KOH/g, respectively. Acid values were decreased below 10 mg KOH/g by neutralization. PUF were prepared with polyols blends containing this biobased polyester polyol (up to 75wt%) and a conventional fossil based polyol e.g., oxypropylated glycerol, which present a high fossil content. The final biobased content of the PUF ranged up to 28wt% in contrast to 9wt% for the reference. Then the addition of neat glycerol to the polyol blend increased the final biobased contents of the PUF foams up to 31wt%. In contrast with the traditional approach consisting of modifying the catalyst content, the activation of the reactive foaming process was improved through initial polyols blends. The final biobased PUF foaming kinetic was similar to that of the polyether polyol, used as a reference. Finally, the effects of chemical and physical blowing agents (water vs. isopentane) were compared on the foaming rate and foam structure. The use of chemical blowing agent efficiently decreased the foam gel time of 33% and increased the foaming rate of 1mm/s with biobased systems. Besides, the polyols architecture has a strong influence on the foam tack free time which varied from 50 to 235s for the studied PUF.

The Use of Biodiesel Residues for Heat Insulating Biobased Polyurethane Foams

The commercial and biobased polyurethane foams (PUF) were produced and characterized in this study. Commercial polyether polyol, crude glycerol, methanol-free crude glycerol, and pure glycerol were used as polyols. Crude glycerol is byproduct of the biodiesel production, and it is a kind of biofuel residue. Polyol blends were prepared by mixing the glycerol types and the commercial polyol with different amounts, 10 wt%, 30 wt%, 50 wt%, and 80 wt%. All types of polyol blends were reacted with polymeric diphenyl methane diisocyanates (PMDI) for the production of rigid foams. Thermal properties of polyurethane foams are examined by thermogravimetric analysis (TGA) and thermal conductivity tests. The structures of polyurethane foams were examined by Fourier Transformed Infrared Spectroscopy (FTIR). Changes in morphology of foams were investigated by Scanning Electron Microscopy (SEM). Mechanical properties of polyurethane foams were determined by compression tests. This study identifies the critical aspects of polyurethane foam formation by the use of various polyols and furthermore offers new uses of crude glycerol and methanol-free crude glycerol which are byproducts of biodiesel industry.