Epoxy Polyurethane Research Articles

Effects of moisture absorption analysis of kevlar/carbon/glass/polyurethane epoxy hybrid sandwich composites with nano silicon particles

ABSTRACT Hybrid sandwich polymer composites are widely used in aviation applications due to their attractive properties, such as their excellent strength capability, high modulus values, excellent stiffness properties, and greater wear resistance. This study aims to analyse the mechanical properties of degraded hybrid sandwich specimens exposed to moisture and investigate the moisture behaviour of the degraded sandwich panels. These panels are reinforced with woven fabrics made of kevlar, carbon, and glass fibres. The hand layup technique was employed to create the structures. The hybrid sandwich composite samples are submerged in normal seawater at ambient temperature for varied duration’s to measure the fibres’ water absorption characteristics. The study investigated the mechanical characteristics of an ageing moisture hybrid sample during tensile, flexural, and compressive tests. Novel stacking sequence arrangements (01 K/01 C/01 G/PUR/01 G/01 C/01 K) were used to enhance the stiffness, load-carrying capacity, yield strength, and other mechanical characteristics of the sandwich structures. The degraded sandwich panels demonstrated that water absorption significantly influences the tensile, flexural, and compressive properties of degraded sandwich structures compared with the results of regular sandwich panels. The tensile (31.67%, 40.40%, and 47.089%), flexural (63.13%, 66.05%, and 70.14%), compressive (33.14%, 39.37%, and 38.40%), and water absorption (3.75%, 3.97%, and 4.71%) test results were analysed.

ORGANIZATIONAL AND TECHNOLOGICAL SOLUTIONS FOR THE REPAIR AND RESTORATION OF SEWAGE TUNNELS IN THE PLACES ADJACENT TO EXPLORATION MINES

The analysis of the occurrence of typical accidents of water drainage networks indicates a number of reasons for their failure, namely: a 2-3 times decrease in the amount of sewage over the last 20 years; increase in aggressiveness of wastewater, decrease in flow rate and increase in rainfall. During operation beyond the regulatory term, the reinforced concrete vault of the tunnel is almost completely destroyed as a result of biogenic corrosion. The listed reasons for the destruction of sewage tunnels built more than 50 years ago are generally similar in nature. From the above, it follows that the specifics of the operation of sewer tunnels can be highlighted - the cross-section diameter is more than 1500 mm and the laying depth is more than 5-7 m. It should be noted that the sections of the tunnels at the points of connection with inspection shafts, as well as the structure of inspection shafts, experience the greatest corrosion. A significant role in the repair and restoration of water drainage structures is played by the selection of materials and structures capable of counteracting the aggressive effects of hydrogen sulfide and other gases. In Ukraine and abroad, considerable experience has been accumulated in the repair and restoration of drainage network structures using materials and structures with high acid and alkali resistance. Conducted research has shown that products based on basalt have a number of advantages: high strength, fairly low weight, reliability during operation in a wide temperature range, they are not prone to corrosion and have high chemical resistance. The experience of working with pneumatic formwork gives them special importance, because they ensure the following requirements:quick installation and dismantling of the formwork; the possibility of using it for curved spatial surfaces forms, even with large spans;multiple reversibility of the formwork. The technology for the construction of the vaulted part of the sewer tunnel with internal finishing with stone casting tiles involves the following stages:dismantling of emergency sections of the tunnel (vaults, walls);clearing the tray part of the tunnel;restoration of the section of the tunnel part of the tunnel (if the tunnel is destroyed);cleaning of the existing fittings to ensure the joint operation of the tray and the protective coating of the vault being erected;installation of pneumatic formwork for the construction of the tunnel vault with internal finishing with stone casting tiles;laying stone casting tiles;installation of the necessary fittings for the protective lining of the vault made of monolithic reinforced concrete;creation of inventory formwork;laying the concrete mixture of the monolithic part of the vault;dismantling of pneumatic and inventory formwork after gaining strength of concrete;backfilling of the trench with compaction. The main period of restoration of the observation shaft with the help of lining the walls with stone-cast basalt tiles: dismantling of floor slabs; cleaning of walls from corrosion products; injection of anti-corrosion concrete on a small filler of space at the junctions of the tunnel; reinforcement of the mine walls (in case of deep corrosion of the walls); facing the walls of the observation shaft with stone-cast basalt tiles; treatment of the inner surface of operational areas and stairs with anti-corrosion epoxy polyurethane compound "AQUAKHIM". To justify the feasibility of using the proposed technology, two options for restoring the destroyed tunnel were considered: the method using stone casting tiles; the method of replacing destroyed pipes with polyethylene ones (an open method of restoration with dismantling of the destroyed tunnel). The option of restoring the sewer tunnel using stone casting tiles is almost 3 times more economical and expedient in terms of the cost of materials compared to the use of SPIRO PE pipe. The advantage of restoring sewage tunnels in this way is the durability and resistance of this material to aggressive effects, a sufficient amount of natural material in the country, and low cost. Keywords: sewage tunnel, inspection shaft, basalt, pneumatic formwork, technological solutions, open method.

Bisphenol A Diglycidyl Ether-Primary Amine Cooligomer-poly(ε-caprolactone) Networks: Synthesis and Characterization.

In this work, the preparation and systematic investigation of cross-linked polyurethane-epoxy (PU-EP) polymer systems are reported. The PU-EP polymers were prepared using a reaction of isocyanate (NCO)-terminated PU-prepolymer with diglycidyl ether of bisphenol A (DGEBA)-amine cooligomer. The oligomerization of DGEBA was carried out by adding furfurylamine (FA) or ethanolamine (EA), resulting in DGEBA-amine cooligomers. For the synthesis of NCO-terminated PU-prepolymer, poly(ε-caprolactone)diol (PCD) (Mn = 2 kg/mol) and 1,6-hexamethylene diisocyanate (HDI) were used. The cross-linking was achieved by adding DGEBA-amine cooligomer to PU-prepolymer, in which the obtained urethane bonds, due to the presence of free hydroxil groups in the activated DGEBA, served as netpoints. During cross-linking, ethanolamine provides an additional free hydroxyl group for the formation of a new urethane bond, while furfurylamine can serve as a thermoreversible coupling element (e.g., Diels-Alder adduct). The PU-EP networks were characterized using attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), dynamical mechanical analysis (DMA) and scanning electron microscopy (SEM). The DMA curves of some PU-EPs (depending on the compositions and the synthetic method) revealed a plateau-like region above the melting temperature (Tm) of PCD, confirming the presence of a cross-linked structure. This property resulted in a shape memory (SM) behavior for these samples, which can be fine-tuned in the presence of furfurylamine through the formation of additional thermoreversible bonds (e.g., Diels-Alder adduct).

Biologically active polyurethane compositions for bone plastic operations of the facial skeleton

The problem of scientific investigations in the selection of fixators for osteosynthesis in treating ailments with fractures and deformities of the facial skeleton bones, which will require reconstructive surgery, is considered. Literature data on the use of various types of materials for osteosynthesis are given. It was established that the development of new biologically active composite materials for the production of bone plates for osteosynthesis, which would meet the basic requirements of bone surgery: biocompatibility, strength, flexibility, ability to biodegrade, stimulation of tissue regeneration and prolonged therapeutic action, is an urgent direction of modern science and practical medicine. To solve this problem, the use of fixation structures for osteosynthesis based on biodegraded epoxy polyurethane (EPU) composite material with bioactive action (EPU-HAP-LEV) is proposed. Biological activity is ensured by the presence of hydroxyapatite and levamisole fillers in the EPU composite. Representative results of physical-mechanical, physical-chemical, and medical-biological studies, which preceded clinical trials of the composite material EPU–HAP–LEV in the form of osseous plates for osteosynthesis, are given. According to the obtained results, the EPU–HAP–LEV composite material is non-toxic, biocompatible and bioactive, capable of biodegradation and prolonged release of levamisole, has the necessary strength characteristics (flexural strength - 27.1 MPa, tensile strength - 24 MPa, relative elongation at break 5.3 MPa), which made it possible to manufacture fixators for osteosynthesis in the maxillofacial area and allowed to recommend them for clinical use. In the clinic, 76 patients with facial skull fractures were treated with polymer plates with screws, which are made of the EPU-HAP-LEV composition. An example of the clinical use of bone plates for osteosynthesis made of EPU-LEV-HAP is presented and their compliance with the medical purpose, effectiveness in the surgical treatment of maxillofacial fractures in areas that do not bear a significant masticatory load, as well as in biomechanically stable fractures is established.

Smart epoxy/polyurethane/carbon quantum dots hybrid coatings: Synthesis and study of UV-shielding, viscoelastic, and anti-corrosive properties

ABSTRACT This project was performed to synthesize and investigate the properties of the smart hybrid coatings based on epoxy/polyurethane (EP/PU) reinforced with carbon quantum dots (CQDs) with multipurpose applications. To do this, flexible and transparent polymer coatings were prepared by mixing epoxy resin and PU pre-polymer. Strengthening of hybrid coatings by CQDs (1–3 wt%) led to preparing fluorescent coatings with high protection against UV rays (85–98%), and improved tensile strength, flexibility (10–35%), and viscoelastic properties such as storage modulus and Tg. Findings of salt spray test approved that increased CQDs concentration in the coatings resulted in improved anti-corrosive behavior.

Water transport in epoxy/polyurethane interpenetrating networks

AbstractDiffusion of water in epoxy–polyurethane (PU) interpenetrating networks was investigated using gravimetry, time‐resolved ATR‐FTIR, and 2D correlation analysis. In this study, the amount of PU component and the length of polyethylene oxide soft block in them were systematically varied to determine their influence on water uptake. The diffusion coefficients were calculated and anomalous water diffusion is well described by the Carter and Kibler model. Water molecules of four different states were identified in the network volume, and sequence of their formation was determined by 2D‐IR spectroscopy. One of them could be confined into free volume (microvoids) or molecularly dispersed with hydrogen‐bonding at cluster formation (bulk dissolved), while the others could be attributed to the bound water forming strong hydrogen bonds with hydrophilic entities of networks. These results were supported by solid‐state 2H NMR data. The influence of water uptake on thermomechanical behavior of epoxy/PU networks was determined. It was shown that the increase of PU content in composites leads to the changes of the effect of water uptake from plasticizing to the anti‐plasticizing as a result of the formation of new networks of interchain hydrogen bonds.

Synthesis and characterization of 1 K waterborne non-isocyanate polyurethane epoxy hybrid coating

Non-isocyanate polyurethanes (NIPU) attract more attention these days due to the increasing environmental concerns from the traditional polyurethanes that involve isocyanates in the synthesis. Herein we prepared a novel one-package (1 K) waterborne non-isocyanate polyurethane in this study. A series of 1 K waterborne epoxy hybrid coatings were synthesized from bio-based amine, cyclic carbonate, internal emulsifier, and epoxy resin. Different formulations of the 1 K waterborne NIPU epoxy hybrid coatings were designed including different ratios of soft and hard segments, different urethane contents, and different functionalities and structures of the hybridized epoxy. The chemical structure of the NIPU polymers was analyzed by Fourier transform infrared spectroscopy and nuclear magnetic resonance. The thermal stability and mechanical property of the 1 K waterborne NIPU coatings were investigated by thermogravimetric analysis and tensile tests, respectively. One glass transition temperature studied by differential scanning calorimetry was found for each coating which demonstrated that the soft segments and the hard segments were mixed well in the 1 K waterborne NIPU coating systems. The coatings with different formulations can achieve a broad range of thermal and mechanical properties. In addition, the general coating properties, such as hardness, adhesion, and chemical resistance, were evaluated to demonstrate the practical application of the 1 K waterborne NIPU in coatings.

A REVIEW ON RECYCLING OF THERMOSETS

Thermosets are a type of plastics that pose a major problem when it comes to easy reusability and recycling because they become irreversibly rigid when subjected to progressive increase in temperatures. Epoxy resins, Phenol Formaldehyde, and Polyurethanes are a few of the many thermosets that are widely employed in several different fields. The rigid, brittle, opaque thermosets, in general, possess qualities like good mechanical strength at elevated temperatures, good chemical resistance in addition to even being self-extinguishing at times (mostly with the help of additives), with low smoke emissions, as highlighted by the British Plastics Federation. However, these properties which serve as an advantage to the end product also affect their recyclability, which is difficult and limited, because of their ability to undergo cross-linking on heating, which ultimately results in the formation of strong covalent bonds that cannot be broken easily. Several commercial techniques are now available for recycling thermosets, which include - Mechanical Processing, Thermal Processing and Chemical Processing. These methods demand higher amount of energy for offering feasible results. There are several studies that have focused on degradation (which is the essential first step that progressively leads to recycling) of thermosets. This review highlights the importance of such studies, techniques and methodologies on aspects including feasibility, cost, sustainability and technological innovation.

Preparation and Application of Polyurethane Coating Material Based on Epoxy Cyclohexane Protective for Paper

Paper is important to most historical and cultural relics, however, these paper heritages are facing a crisis of disappearance, damage and aging. For increasing the paper strength, delaying the paper aging, and improving the weak stability and permeability of former resins used for paper, another material is necessary to be produced on preservation and protection of the paper items. The synthesis of epoxy cyclohexane polyetherpolyol was as follows: Epoxy cyclohexane was as the starting material, ethylene glycol was as the initiator, boron trifluoride ether was as catalyst, and dichloromethane was as the solvent. The synthesized homopolyether was characterized by infrared (IR) spectroscopy and proton nuclear magnetic resonance (1HNMR) spectroscopy to determine the structure. Then the epoxy cyclohexane homopolyether reacted with the hexamethylene diisocyanate (HDI) trimer, and the polyurethane was obtained. With the tests of the physical and chemical properties of paper samples, it showed that the paper processed with 10% polyurethane liquid had excellent performance, the increase in the tensile strength was from 1105 to 2317 N/m, and the increase in the folding endurance was from 20 to 504 times. What’s more, the paper processed with 10% polyurethane liquid had good brightness and gloss. The results of the paper samples for the test have shown that the synthesized material simultaneously has the advantages of epoxy cyclohexane homopolyether and polyurethane, possessing excellent performance in paper reinforcement. Thus, the synthesized polyurethane material has broad application prospect in paper protection field.

ИССЛЕДОВАНИЕ АДГЕЗИИ ФУНКЦИОНАЛЬНЫХ ЛАКОКРАСОЧНЫХ ПОКРЫТИЙ ДЛЯ ЗАЩИТЫ ПОВЕРХНОСТИ ПКМ

Adhesion and adhesive durability of functional systems of paint coatings on the basis of epoxy resin primer and polyurethane enamels to surfaces of polymeric composite materials with different geometrical and qualitative characteristics of surface on the basis of the epoxy binding are investigated. It is shown that the significant contribution to durability of coupling of film of paint coating in addition to mechanical forces is brought by also chemical nature of two components of adhesive interaction.

A laboratory study of epoxy/polyurethane modified asphalt binders and mixtures suitable for flexible bridge deck pavement

Asphalt binder is prone to thermal cracking, which limits its application in flexible bridge deck pavement. Binders of rubbery characteristics, such as polyurethane (PU) and epoxy resin (EP), having high strength, modulus and toughness, could be applicable to resolve cracking issues at low temperatures. This research proposes a novel approach of using PU and EP to prepare an epoxy/polyurethane (EPU) modified asphalt binder. Properties and microstructure of the EPU modified asphalt binder were explored, and the appropriate formula was determined. Besides, the technical properties of the EPU asphalt mixture were also studied. The results show that EPU modified asphalt binder has satisfactory mechanical strength, flexibility and storage stability. 8 wt% PU and 32 wt% EP is determined as the optimal content. The results of Fourier transform infrared spectrum testing show that PU inserts into the three-dimensional network structure of EP, which plays a positive role in improving the flexibility and heat resistance of the modified asphalt binder. The growth of viscosity is greatly affected by temperature and modifier content, and the construction retention time is shorter than the specification requirements. Besides, the low-temperature cracking resistance of EPU modified asphalt mixture is significantly improved compared to epoxy asphalt mixture, which exhibits a good application prospect in flexible bridge deck pavement engineering.

Mortar Lining as a Protective Layer for Ductile Iron Pipes

The objective of the study is to recognise whether epoxy resin or polyurethane internal linings of ductile iron (DI) pipes create visibly smaller head loss in flow than cement mortar linings. Some data reported by the Ductile Iron Pipes Research Association (DIPRA) was used in the calculations. Only the data from hydraulic tests performed no later than 30 years after the placing of the mortar lining were considered. The average values of the Hazen–Williams roughness coefficients C for each of the internal pipe diameters were calculated, and single experimental data neglected. Two different approaches were taken for interpreting the DIPRA experimental results and omitting the fact that the flow rates during these tests are unknown. The Hazen–Williams roughness coefficients C were used in both for computing the friction factor f from the Moody chart for three values of flow rate: being equal to the optimal value for a given diameter, and then by 50% larger and 50% smaller than this value. Next, the computed friction factors were compared with the values predicted from the Moody chart for smooth pipes. In the first approach, the friction factors f were computed using the Epanet2 software, and in the second approach, a general equation for calculating f from known C and flow parameters was applied. Both approaches resulted in friction factors f very close to those for smooth pipes for the whole range of Q. In conclusion, more smooth plastic linings of DI pipes do not result in a significantly more visible saving of energy for pumping.

Composite materials based on epoxy resins as implants for bone tissue (a review)

This review is devoted to implant materials for bone tissue. A variety of bone implants in termrs of their chemical nature (auto-, allo-, xenogenic, metallic and polymeric composite materials), their advantages and disadvantages are characterized. The relevance and prospects of using epoxy resins for medical applications are shown. Particularly the creation of composite materials based on epoxy resins with enhanced physical-mechanical properties is of great importance, since they are suitable for the production of bone implants. Composite materials prepared by the chemical modification of epoxy resins via polyurethane, which provides an increase in biocompatibility and elasticity, and by the physical modification via biologically active substances, which causes a local therapeutic effect of the composites, can be considered as an alternative to existing implants. Biocompatible biologically active fumarate-containing epoxy polyurethane composite materials filled with ferrocene exhibit an increased capacity for biodegradation due to introduction of oligooxypropylene fumarate into their structures, a prolonged therapeutic effect of ferrocene, which is manifested in the stimulation of bone regeneration, and improved physical-mechanical properties sufficient to perform the functions of under bone plates for osteosynthesis.

Preparation of Graphene-Modified Anticorrosion Coating and Study on Its Corrosion Resistance Mechanism

When aluminum alloy is present in a Cl−-rich environment, the surface oxide film is easily damaged, resulting in faster dissolution of the substrate. The application of graphene-modified anticorrosion coating can effectively prevent the occurrence of corrosion. In this study, to explore the corrosion resistance of graphene-modified anticorrosion coating on the surface of aluminum alloy, we prepared graphene-modified anticorrosion coating on the surface of aluminum alloy and investigated the corrosion resistance mechanism. Epoxy resin primer and polyurethane top coat were modified by predispersed reduced graphene oxide (rGO). Scanning electron microscope (SEM) and Raman spectrum were used to investigate the microstructure of graphene-modified anticorrosion coating, and it was found that the addition of rGO could effectively improve the porosity defect of epoxy resin primer. Electrochemical workstation was used to quickly characterize the corrosion resistance of graphene-modified anticorrosion coating, and the change of the electrochemical curve during soaking in 3.5% NaCl was investigated every 5 hours. It was found that the application of rGO to modify the anticorrosion coating could improve the corrosion resistance of the anticorrosion coating, and as the soaking time increased, the corrosion resistance of graphene-modified anticorrosion coating changed regularly. The study results indicated that when the content of rGO was 0.4%, the porosity of epoxy coating decreased from 1.54% to 0.33%, the porosity dropped by an order of magnitude, and the self-corrosion voltage was relatively positive (-0.72434 V). The self-corrosion current density was the lowest ( 1.948 × 10 − 6 A / c m 2 ), and at the low frequency, the impedance modulus was the highest (103). After the equivalent circuit fitting, the dispersion index was relatively high, the dispersion effect was relatively weak, and the corrosion resistance of the coating was improved. For graphene-modified anticorrosion coating, in the early stage of corrosion protection, the existence of pores and other defects in the coating might increase the dispersion effect, resulting in greatly decreased corrosion resistance of the coating. In the middle stage of corrosion protection, the pores in the coating would be completely filled by corrosive ions, resulting in a weakened dispersion effect. Therefore, the decrease in the corrosion resistance of the coating was slowed down and became stable.

Effect of Surface Modification and Fibre Content on the Mechanical Properties of Coconut Fibre Reinforced Concrete

In the past few decades, concrete has been the most widely used material for structural applications in the world and uses steel reinforcement as aide to meet the flexural, tensile and ductility demands required of concrete structures. Manufacturing of concrete and steel reinforced concrete structures is associated with millions of tons of carbon dioxide emissions and mineral waste. This activity is also responsible for the depletion of a large number of non-renewable resources. Reinforcing steel is also a high cost material, consumes a lot of energy in its production. Consequently, the use of natural fibres as an alternative for steel reinforcement is widely investigated, to promote the use of sustainable concrete structures. This study aims to investigate the effect on durability, flexural, compressive, tensile properties and workability of concrete by incorporating coir fibre at varying fibre content to find the fibre content which gives optimum results. The fibre contents used were 0%, 0.5%, 1.0%, 1.5% and 2.0% by weight of cement. Furthermore, the effect of modifying the surface of the coir fibres by alkali treatment (i.e. 5 wt.% NaOH solution) and coating the fibres with epoxy paint and polyurethane varnish on coir fibre reinforced concrete (CFRC) were also investigated. Tests conducted on the CFRC specimens included slump test and flexural, compressive and tensile strength tests. Water absorption and sorptivity tests were also conducted to investigate the durability. Slump (workability) and unit weight reduced with an increase in fibre content. The surface modification methods used, had resulted in an increased workability and a reduced unit-weight. A coconut fibre content of 1% produced the best combination of flexural, tensile and compressive properties. Water absorption and sorption rate per unit time, increased with an increase of coir fibre content. It is also found that epoxy paint and alkali treatment of the fibres has a positive effect on the mechanical strength properties and also the durability and workability of the CFRC specimens. However, polyurethane varnish coating had a detrimental effect on the mechanical strength properties of the CFRC specimens.

Investigation of The Thermal Conductivity of Binary Polymer Blends

In this research, binary polymer blends are formed from epoxy, unsaturated polyester and polyurethane. The concentration were chosen with varying percentages of components, resulting in three groups; polyurethane / epoxy (PU/EP), epoxy/unsaturated polyester (EP/UPE) and polyurethane/unsaturated polyester (PU/UPE) blends. Hand lay-up technique was used to prepare the samples with 6 mm thickness prepared from simultaneous mixing of the two constituents in the required percentages.Thermal conductivity K for these blends was carried out by using Lee’s disk method at room temperature. The experimental results showed that an increment and/or decrement of thermal conductivity depend on type and blend concentration. Also the experimental results indicated that the thermal conductivity has the highest values of (K) (0.78 J/m2.k) at ratios (PU 10% / EP 90 %), (0.70 J/m2.k) at ratios (EP 50% / UPE 50%) and (0.50 J/m2.k) at ratios (PU 40% / UPE 60%) respectively. This increment of (K) implies that the penetration of molecules of both polymer components in the same direct then a good transfer of energy by the vibration and rotation of the chain molecules.Also the experimental results indicated that the thermal conductivity has the lowest value of (K) (0.52 J/m2.k) at ratios (PU 40% / EP 60%), (0. 0.53 J/m2.k) has obtained at ratios (EP 30% / UPE 70%) and (0. 0.31 J/m2.k) has obtained at ratios (PU 60% / UPE 40%) respectively.

The Preparation and Characterization of an Epoxy Polyurethane Hybrid Polymer Using Bisphenol A and Epichlorohydrin

Epoxy polymers composed of bisphenol A (BPA) and epichlorohydrin (ECH) were grafted onto polyurethane (PU) using the graft-polymerization method to prepare the epoxy PU hybrid polymer. The main series contained the epoxy polymer grafted onto PU; however, the epoxy polymer was not bound to PU in the control series. The breaking tensile stress steeply increased at low BPA and ECH contents and then decreased as more BPA and ECH were included in the main series, whereas the control series did not display an incline in the breaking tensile stress irrespective of the BPA and ECH contents. The percent shape recovery also steeply increased after the grafting of epoxy polymer in the main series but increased at a slower rate in the control series. The flexibility of the main series at a freezing temperature was not enhanced compared with the plain PU because the grafted epoxy polymers did not effectively disrupt the molecular interaction between PUs. Therefore, the grafting of epoxy polymers noticeably enhanced the breaking tensile strength and percent shape recovery of PU.

Matt Polyurethane Coating: Correlation of Surface Roughness on Measurement Length and Gloss.

Matt polyurethane coating was successfully prepared through the synergistic effect of castor oil and phenolic epoxy resin into polyurethane backbone. The formation mechanism may be ascribed to the modulus mismatch between the partially modified epoxy polyurethane and partially unmodified polyurethane. Scanning electron microscopy (SEM) was used to observe the micro-rough surface morphologies. Atomic force microscopy (AFM) and three-dimensional (3D) surface profilometer were applied to calculate a series of surface roughness parameters in different dimensions, such as Sa, Sq, Sp, Sv, Sz, Sku, Ssk, etc. The exciting results of this paper—the correlation of surface roughness on measurement length and gloss—are explored in detail. It reveals the extrinsic property of measured roughness with measurement length and provides guidance for what kind of incident angle gloss meters (20°, 60°, and 85°) best describe the gloss of matt polyurethane coating.

Rheological Properties of Epoxy Urethane Oligomers and Сuring Kinetics of Polymer Composites on Their Basis

The rheological properties of epoxy urethane oligomers (EUOs) synthesized at different stoichiometric ratios of reaction groups NCO : OH have been examined over a wide range of temperatures and shear rates using rotational viscometry. The effect of the NCO : OH ratio on the kinetic parameters (dynamic viscosity increase constant and gelation time) of epoxy polyurethane compositions curing at a temperature of 25 ± 1°C have been revealed. Evaluation of the adhesion tensile strength of cold-cured adhesive EUOs joints is presented.

Waterborne isocyanate-free polyurethane epoxy hybrid coatings synthesized from sustainable fatty acid diamine

This study proposed an effective method to prepare environmental-friendly waterborne epoxy modified non-isocyanate polyurethanes.