Polyurethane Resin Research Articles

Applicability Evaluation of Modified Epoxy Resin in the Repair and Reinforcement of Ancient Building Timber Members

To investigate the potential of modified epoxy resin for repairing and strengthening historical wooden structures, this study utilized polyurethane and silicone-modified epoxy resin as the base, alongside a polyamine curing agent. The resin mixture was cured at ambient temperature, resulting in the creation of ten unique epoxy resin systems. Investigation into the chemical structure and alterations to the glass transition temperature were conducted. The study conducted tests and characterization of viscosity, curing rate, mechanical properties, stress failure mode, hygrothermal aging resistance, and bonding properties. The results reveal that the curing degree of the two modified epoxy resins is high after being cured at room temperature, and the chemical structure and curing rate show insignificant changes. The range of the glass transition temperature for the modified epoxy resin is between 61.31 °C and 70.51 °C. The incorporation of polyurethane and silicone molecular chains into the epoxy resin cross-linking curing system enhances the toughness of the epoxy resin. The modified resin achieves a maximum elongation at break that is 5.18 times greater than that of the unmodified resin, along with a maximum tensile strength and a compressive strength that are 7.94 and 1.74 times, respectively, higher than those in the Chinese technical specifications for the maintenance and reinforcement of ancient wooden structures. The increase in toughness changes the failure mode of the cured epoxy resin. The modified epoxy resin exhibits great bonding ability to aged wood, with a shear strength of up to 9.6 MPa along the grain. As a result, the modified epoxy resin meets the requirements for the reinforcement and repair of the timber members of ancient buildings.

Non-staining resistance to dyes and odors of synthetic leathers composed of polyurethane resins with different glass transition temperatures

The objective of this study was to develop a highly durable synthetic leather with excellent resistance to light discoloration and deterioration without the use of fluorine or silicon and a surface that is resistant to dyes and odors. Environment-friendly biomass feedstock was used as the reaction component. Firstly, polyurethane (PU) resins with varying glass transition temperatures ( Tg) were synthesized. Subsequently, these were used as surface treatment agents for synthetic leather, and the relationship between the non-staining performance of the PU resin and the Tg values was discussed. In addition, the physical durability over time was investigated. The non-staining performance of the synthetic leather surface against dyed clothing and the odor of ammonia evidently depended on the Tg of the PU resin used as the surface treatment agent. The Tg range that is the most convenient for practical purposes, and the related best light discoloration and degradation resistance and bending resistance, were confirmed, and serve as indicators that the material can be used as a highly durable interior material.

No‐organic solvent, no‐fluorinated waterborne superhydrophobic coatings based on SiO2 and IBTS

AbstractWaterborne superhydrophobic coatings have attracted widespread attention. However, organic solvents, fluorine‐containing compounds, and complex operational technologies hinder superhydrophobic coatings development severely. Herein, A simple method of preparing water‐based superhydrophobic coatings by one‐step spraying without organic solvent and fluorine is reported. The particles of silicon dioxide (SiO2) was modified by isobutyltriethoxysilane (IBTS), then combined with waterborne acrylic polyurethane (WPUA) and phenolic resin (PF), baked at 110°C to fabricate superhydrophobic coatings. According to the contact Angle (CA), hardness, adhesion, and other parameters, the ratio of SiO2 and PF of the composite coatings was optimized. Results showed that the superhydrophobicity and physical properties of the coating are the most exceptional at the content of SiO2 is 0.6 g, and the PF is 25%. In addition, related experimental results show that the coatings have good water resistance and self‐cleaning ability, the special nano/micro structure of the coatings also endows it excellent abrasion resistance. Exceptional hydrophobicity and physical properties meeting the actual application conditions of superhydrophobic coatings. Therefore, the simple method for preparing superhydrophobic coatings has great application prospects.

Multi-scale investigation on mechanical properties of wood joints bonded with a polyurethane adhesive in successive cycles of accelerated aging treatments

To gain a deeper understanding of the bond durability in adhesively bonded wood products, a multiscale investigation of the mechanical properties of wood joints bonded with a one-component polyurethane (PU) adhesive in successive cycles of accelerated aging treatment was conducted by combining nanoindentation (NI) and conventional tensile-shear techniques. The delamination ratio, shear strength, and wood failure ratio of the wood joints, as well as the reduced elasticity modulus (Er) and hardness (H) of the PU resin, cell walls in the interphase region (CW–I), and control cell walls (CW) were evaluated. The correlations between the macro shear strength and micromechanical properties were further established. The results showed that the average delamination ratios of the wood joints were 10%–26 % after eight cycles of hydrothermal treatment. Macromechanical and most micromechanical properties substantially decreased with an increase in the number of treatment cycles, with maximum reductions of 37 %, 24 %, 60 %, 56 %, 48 %, and 57 % for the shear strength, wood failure ratio, Er of PU, H of PU, Er of CW-I, and Er of CW, respectively. The linear regression for the mechanical properties and the number of treatment cycles indicated that the Er of PU, CW-I, and CW, as well as the H of PU, showed linear downward trends (with R2 values of 0.765–0.921) during successive aging treatments. Significant and positive linear correlations were found between the shear strength and micromechanical properties of PU, with correlation coefficients of 0.970 (P < 0.01) and 0.941 (P < 0.05) for Er and H of PU, respectively. The wood failure ratio showed significant positive correlations with the Er values of CW-I (P < 0.01) and CW (P < 0.05), whereas the proportion of wood failure in the interphase was significantly (P < 0.05) negatively correlated with the Er value of CW. The shear strength was positively correlated with the Er of the cell walls, with correlation coefficients of 0.861 and 0.868 for CW-I and CW, respectively. In summary, both the micromechanical properties of the PU resin and the elasticity of the wood cell walls in the wood-adhesive interphase were demonstrated to be key factors affecting the bond durability of wood bond joints.

Pengaruh variasi campuran serbuk kayu jati (tectona grandis l.) dan sekam padi pada pembuatan material komposit kampas rem

Brake pad composite materials are made from organic materials and are harmless to the environment. In this study, the brake pad composite material was made using teak wood powder, rice husk and aluminium. Comparison of variations A (23.5 grams of teak wood powder, 18.5 grams of rice husk and 7 grams of aluminium powder) B (27 grams of teak wood powder, 15 grams of rice husk and 7 grams of aluminium powder) C (30.5 grams of teak wood powder, 11.5 grams of rice husk and 7 grams of aluminium powder) and the addition of 21 grams of polyurethane resin then compressed for 30 minutes at 100 0C for 20 minutes. The test results of density, hardness, flexibility and wear were compared with SAE J661. Based on the test results, it was found that samples A, B and C met the SAEJ661 standard only in the flexure test with a value of 490.33 - 529.55 N/cm2. Teak wood powder can increase the value of flexibility while rice husk is used to increase the value of density, hardness and wear due to its silica content.

Mechanical investigation of compositing by resin filling in lattice structures manufactured with fused deposition modelling

Fused Deposition Modeling (FDM) is a widely used polymer additive manufacturing technique for polymer part manufacturing and prototyping. However, manufacturing speed, mechanical properties, and high costs, limit its suitability for industrial applications. In this study, researchers blended polyester and polyurethane resins with lattice structures to achieve a remarkable 70% reduction in production time and a 75% decrease in manufacturing costs. They explored five lattice structure geometries relevant to common literature applications. Lattice structures were manufactured using PA, PLA, PA-CF, and TPU filaments. The composite samples underwent comprehensive analysis, including SEM microscopic inspections, density measurements, and compression tests. Parameters such as density, yield strength, compressive strength, specific stress, modulus of elasticity, and toughness were evaluated. The findings revealed that polyester-based composites exhibited a remarkable 131% enhancement in mechanical properties, with toughness values increasing up to 12-fold. The results revealed significant mechanical advantages that the developed composites can offer in applications.

Numerical Simulation of Flow Characteristics for Supercritical CO2-Sprayed Polyurethane Resin.

Conventional paint spraying processes often use small molecule organic solvents and emit a large amount of volatile organic compounds (VOCs) that are highly toxic, flammable, and explosive. Alternatively, the spraying technology using supercritical CO2 (scCO2) as a solvent has attracted attention because of its ability to reduce VOC emissions, but the flow characteristics of coatings have not been thoroughly studied. Therefore, we numerically simulate the spraying process based on the actual process of scCO2 spraying polyurethane coatings by computational fluid dynamics (CFD). The effects of inlet pressure and volume fraction of scCO2 on the fluid motion parameters inside the nozzle as well as the atomization effect of droplets outside the nozzle are investigated. The simulated results show that a fluid with a large volume fraction of scCO2 will obtain a smaller density, resulting in a larger velocity and a larger distance for the spray to effectively spray. Higher coating content and bigger inlet pressures will result in higher discrete phase model (DPM) concentrations, and thus a bigger inlet pressure should be used to make the droplets more uniform across the 30° spray range. This study can provide theoretical guidance for the process of scCO2-sprayed polyurethane resin.

Experimental Study on Water-Plugging Performance of Grouted Concrete Crack.

In this paper, ordinary Portland cement, ultrafine cement, polyurethane, and epoxy resin were selected as typical grouting materials. Grouting simulation tests were first conducted to prepare the grouted concrete crack sample. The effect of concrete crack parameters (i.e., crack aperture and roughness), grout water-cement ratio, and grouting pressure on the water-plugging performance of different grouting materials was explored through the impermeability test. The microstructure of grouted concrete cracks was analyzed by means of scanning electron microscopy (SEM) and computed tomography (CT), and the difference in water-plugging performance of different grouting materials was explained at the micro level. The results show that the impermeability of the four grouting materials was ranked as follows: Epoxy resin > polyurethane > ultra-fine cement > ordinary Portland cement. The concrete cracks grouted by epoxy resin have the highest plugging failure water pressure and the lowest permeability, which is the optimal grouting material. The effectiveness of crack grouting in water-plugging was directly proportional to the grouting pressure, provided the pressure did not exceed a certain value. When the pressure surpassed the threshold, the increase in pressure did not have a significant impact on the water plugging performance. For the two cement-based materials, the threshold pressure was 1 MPa, while for the other two chemical grouts, it was 2 MPa. The two cement-based grouts with a water-cement ratio of 0.8 showed optimal water-plugging performance. The water-plugging performance of ordinary Portland cement paste, ultra-fine cement pastes, and polyurethane grout was negatively correlated with crack aperture and positively correlated with crack roughness. However, the water-plugging performance of epoxy resin grout was not affected by crack aperture or roughness.

Performance of castor oil polyurethane resin in composite with the piassava fibers residue from the Amazon

The use of castor oil in producing polyurethane resins has been identified as one of the most promising options for the industry. The piassava fibers waste generated by the industry on a large scale presents excellent properties as a reinforcing agent due to its high lignin content characterized by chemical tests and FTIR. Composite boards consisting of a higher content of mercerized piassava fibers (10 mm, 85 wt.%) reinforced polyurethane castor oil-based resin (prepolymer (PP) and polyol (OM)) exhibited excellent performance. Composites with these properties have strong potential for medium-density applications ranging from biomedical prosthetics to civil partition walls and insulation linings. Alkali treatment removed the superficial impurities of piassava fibers, activating polar groups, and physical characterization reported excellent performance for all composites. Among the composites, the CP3 sample (composite reinforced with piassava fibers (85 wt.% fibers; 1.2:1—PP:OM)) stood out with higher density and lower swelling and water absorption percentage than other composites. FTIR results indicated NCO traces after the resin cured in the PU3 (1.2:1—PP:OM), possibly contributing to the interaction with the fibers. DMA results reported relevant information about more flexibility to CP1 (composite reinforced with piassava fibers (85 wt.% fibers; 0.8:1—PP:OM)) and CP3 than CP2 (composite reinforced with piassava fibers (85 wt.% fibers; 1:1—PP:OM)). The results suggest that the proper combination with natural products must lead to composites with potential applications as engineering materials.

VO2 nano-rod coated mica composite pearlescent pigment for temperature control packaging

A temperature control mica/VO2 functional pearlescent pigment was designed for the packaging industry. Firstly, a layer of VO2 nanorod film was coated on the surface of flake mica powder by hydrothermal method. Then, the surface of pure mica was modified by silane coupling agent KH-570 and sandwiched between inorganic powders to strengthen the combination. Secondly, the mica/VO2 composite pearlescent powder with gray-green pearlescent effect were successfully obtained by thermal annealing. The crystal structure of the VO2 coating and the chemical valence state of vanadium were verified by X-ray diffraction and X-ray photoelectron spectroscopy. Finally, powders were mixed with polyurethane resin to obtain a functional film. The infrared transmittance of film at 28 °C and 70 °C showed that the composite film with mica content of 3 g had greater temperature control properties, and the difference between high and low temperature transmittance was about 16%. Most importantly, the shiny decorative effect of pearlescent pigment can be still be maintained after being endowed with temperature control property. This work proposes the preparation of functional mica/VO2 composite with pearlescent effect and temperature control property.

Tensile and Interfacial Mechanical Properties for Single Aramid III Fibers under Dynamic Loading.

In this study, the traditional mini split Hopkinson tension bar (SHTB) was enhanced for the dynamic mechanical performance testing of single fiber/resin interface of composites. Single Aramid III fibers were modified using a polyamine modification treatment. Quasi-static and dynamic tensile tests of modified single Aramid III fibers were conducted using an electronic tensile testing machine and mini SHTB. The test results indicated that the surface modification employing the Catechol-Tetraethylenepentamine (Cat-TEPA) approach had a negligible effect on the tensile mechanical properties of single Aramid III fibers. The microdroplet method was introduced to measure the dynamic interfacial shear strength (IFSS) of Aramid III fiber/waterborne polyurethane resin using a mini SHTB. The dynamic shear test results revealed an increase in the dynamic shear strength of the modified Aramid III fiber/resin interface from 36.16 MPa to 41.51 MPa. Furthermore, the Scanning Electron Microscope (SEM) photography of the modified single Aramid III fiber after debonding exhibited regular grid structures on the debonding area, which can prevent debonding between the single fiber and the microdroplet, thereby enhancing interfacial shear performance.

Development of Fire Resistant Composite Material Using Fire Retardant Filler for Electrical Application

Safety is paramount across diverse sectors, with a growing emphasis on dependability. Preventing fires in electrical contexts and employing fire-resistant techniques using additives have become crucial. This involves the development of composite materials, typically incorporating substances like Alumina Rehydrate (ATH), metal hydroxides, or specialized additives such as epoxies, polyester, or polyurethane resins within polymer matrices. These formulations include fire-retardant fillers, underscoring their significance in enhancing safety and reliability. Increasing the fire resistance of the composite can be achieved through various methods such as delaying ignition, reducing flame spread, mitigating smoke emissions when exposed to high temperatures, and employing fire-resistant compounds to quench potential electrical arcs, especially in electrical applications where combustible materials pose significant hazards. These items consist of electrical casings, wire pathways, insulation, and other crucial components for ensuring fire safety within various systems. These components are chosen based on their electrical characteristics, strength, and the necessity for fire resistance, all of which contribute to achieving a harmonious balance. Careful consideration is given to adhesive matrices during the selection and optimization process as part of the development procedure. Advanced manufacturing methods such as Compression Melding, Resin Transfer Melding, or filament winding are utilized to produce composite components with standardized properties, enhancing overall efficiency.

Mats Made from Recycled Tyre Rubber and Polyurethane for Improving Growth Performance in Buffalo Farms

This study focuses on anti-trauma mats designed for buffaloes’ comfort, using as raw materials rubber powder from end-of-life tyres (ELTs) and an isocyanate-based polyurethane resin binder. The first part of the study focused on mat formulation. Whilst it was possible to select a unique combination of raw materials and design features, it was necessary to investigate the relationship between three critical parameters affecting mat consistency and therefore buffalo comfort: binder quantity, mat thickness, and desired final mat density (bulk). In order to quantitatively assess the variation in hardness, various combinations were investigated within well-defined ranges based on the relevant literature. The results obtained from nine selected combinations indicate that increases in the three critical parameters do not induce a real phase transition in the final product consistency, although the hardness suggests an increasing trend. The mats consistently exhibited a moderately soft/hard consistency, offering environmental benefits in terms of increased rubber usage and potentially reduced chemical binder, depending on the desired thickness. The selected mixture showed excellent resistance to heavy chemical loads, suggesting reliability for frequent cleaning operations. The second part of the study involved field trials of the mats with calves. This involved monitoring their weight gain and appetite levels over a 90-day period. The results showed excellent growth performance compared to uncoated grids (i.e., weight gain was approximately 20% higher at the end of the observation period); this was similar to that achieved with the use of straw bedding. However, compared to straw bedding, the mats (i) exhibit long-term durability, with no signs of wear from washing or trampling over the months of the trial, (ii) allow for quick and efficient cleaning, and (iii) enable companies to save on labour, material (straw), and waste disposal costs, while maintaining (or even improving) the same welfare levels associated with the use of straw.

Investigation of Physical Properties of Polymer Composites Filled with Sheep Wool.

Sheep farmers are currently facing an oversupply of wool and a lack of willing buyers. Due to low prices, sheep wool is often either dumped, burned, or sent to landfills, which are unsustainable and environmentally unfriendly practices. One potential solution is the utilization of sheep wool fibers in polymer composites. This paper focuses on the study of mechanical vibration damping properties, sound absorption, light transmission, electrical conductivity of epoxy (EP), polyurethane (PU), and polyester (PES) resins, each filled with three different concentrations of sheep wool (i.e., 0%, 3%, and 5% by weight). It can be concluded that the sheep wool content in the polymer composites significantly influenced their physical properties. The impact of light transmission through the tested sheep wool fiber-filled polymer composites on the quality of daylight in a reference room was also mathematically simulated using Wdls 5.0 software.

Physical Properties of Polymer Concrete Utilizing Pahae Natural Zeolite, Corn Husk Fiber, and Polyurethane Resin Adhesives

This study aimed to determine the optimum composition in the manufacture of polymer concrete using Pahae natural zeolite, corn husk fiber, and polyurethane resin adhesives. This study used the hot-press method at 170℃ for 30 minutes. The compositions of zeolite and corn husk fiber tested were varied under three different additions of polyurethane resin of 15 g, 20 g, and 25 g, while the composition of sand was fixed at 60 g. The inclusion of corn husk fiber content reduces the density of the concrete and increases the porosity and water absorption. The physical properties analysis showed that the polymer concrete samples showed the highest density was 1.89 g/cm3 from 20 g of polyurethane resin and no addition of corn husk fiber; the highest porosity was 6.15% from 15 g of polyurethane resin and 10 g of corn husk fiber; and the highest water absorption was 5.85% from 15 g of polyurethane resin and 10 g of corn husk fiber. Because improved material quality and durability are linked to reduced water absorption rates in polymer concrete, the most favorable composition with minimal water absorption (0.51%) came from the sample utilizing 20 grams of polyurethane resin without incorporating corn husk fiber.

Polyethylene terephthalate (PET) as a recycled raw material for particleboards produced from pinus wood and biopolymer resin

Considering the significant demands for construction products and the increasing disposals of plastic and agroforestry residues, this research evaluated the influence of recycled particles of polyethylene terephthalate (PET) inserted in the manufacture of five particleboard prototypes based on Pinus elliottii wood and castor-oil-based polyurethane resin (CPUR). The following panel traits were obtained: 100% pine wood, 0% PET and 10% CPUR (M100P-0PET-10C); 70% pine, 30% PET, and 10% CPUR (M70P-30PET-10C); 50% pine, 50% PET, and 10% CPUR (M50P-50PET-10C); 70% pine, 30% PET, and 5% CPUR (M70P-30PET-5C); and, 50% pine, 50% PET, and 5% CPUR (M50P-50PET-5C). Panels were evaluated according to physical (density, moisture content, thickness swelling, and water absorption), mechanical (modulus of rupture, modulus of elasticity, perpendicular tensile), and morphological tests (scanning electron microscope). M50P-50PET-10C particleboards revealed the best performance in the physical and mechanical tests, as well as M70P-30PET-10C and M50P-50PET-5C panels showed equivalent results. The findings suggested a notable environmental contribution and a great economic feasibility. Thus, it is possible to obtain wood-based particleboards manufactured from recycled PET, reusing this highly discarded non-biodegradable plastic and using a smaller volume of adhesive, with physical-mechanical properties that meet the expected performance for this bioresource-based product.

Evaluation with a Coordinate-Measuring Machine of Dimensional Accuracy of the Abutment Duplication Technique in Cement- Retained Implant Restoration.

To evaluate the effectiveness and accuracy of a proposed duplication technique in terms of one- and three-dimensional discrepancies between an original abutment and polyurethane duplicates obtained through a conventional workflow in single-implant rehabilitation. A titanium, shoulderless abutment was chosen for a single-implant cemented rehabilitation. The master cast was made using a plastic-based die system, and the implant portion was separated. The implant section was consecutively duplicated eight times using a manual technique with polyvinyl siloxane and unfilled polyurethane resin as impression and die materials. The duplicates were analyzed with a coordinate-measuring machine (SmartScope Flash 200, Optical Gaging Products): one- and three- dimensional discrepancies were determined for each duplicate on 20 analysis points (A to T) located on the abutment surface. Changes in the abutment radius were also calculated to estimate the effects on cement thicknesses. One-dimensional discrepancies were -0.5 Å} 61.2 μm, -6.6 Å} 39.7 μm, and -19.4 Å} 47.8 μm on the X, Y, and Z axes, respectively; three-dimensional variation was -66.4 Å} 60.1 μm. Friedman test showed no significant difference between duplicates' one-dimensional variations on X (P = .059), Y (P = .156), or Z (P = .223) axes; a significant difference was found regarding three-dimensional changes (P < .001). Dunn test showed higher discrepancies on the X axis and on the abutment head. Mean variation of the abutment radius was -12.09 μm. The abutment duplication technique was shown to be an accurate and repeatable procedure for single cementable restorations.

Physical-mechanical properties of MDP panels with the addition of melamine paper in the internal layer

Particleboard panels find extensive application in the furniture sector, but their low stability in contact with water hinders their utilization. Simultaneously, the trimmings of melamine paper, exhibiting hydrophobic properties, used in panel finishing, represent unused industrial waste. This study aimed to evaluate the physical-mechanical properties of MDP (Medium Density Particleboard) panels produced with Pinus taeda and castor oil-based polyurethane resin with the addition of different proportions of melamine paper (0, 5, and 10%). The properties of density, moisture content, thickness swelling, water absorption, static bending, internal bonding, and screw withdrawal resistance, on face and top, were evaluated, following normative documents. At the end of the tests, statistical analysis was conducted at a 5% significance level to check any statistical differences among the means. The addition of melamine paper caused to an increase in panel density and moisture content, but all treatments remained within the ideal range. Thickness swelling and water absorption decreased, while all mechanical properties improved with an increase in the quantity of added melamine paper. Therefore, the use of melamine paper in MDP panels is viable and beneficial, notably the treatment with a 10% addition of melamine paper.

Evaluation of OSB panels using residual wood with low contents of castor oil polyurethane resin

Evaluation of OSB panels using residual wood with low contents of castor oil polyurethane resin

Synthesis of unsaturated polyurethane oligomer and its application in the 3D printing of composite solid propellants

Propellants are the main source of energy for internal ballistic processes. The use of 3D printing technology is expected to produce propellants with complex geometries. However, limited by the properties of existing printable resins, the mechanical properties of 3D-printed propellants make it difficult to meet the requirements for use. This study deals with the structural design, synthesis, and properties of an unsaturated polyurethane resin (PUA). A photoinitiator was added to this polyurethane resin and a photo-curable elastomer was successfully prepared under UV irradiation with tensile strength and elongation at break of 21.06 MPa and 1119 %, respectively. Then, the resin was mixed with active diluent, initiator, NH4ClO4, and Al particles to prepare the propellant slurry, and the rheological properties of the slurry were investigated. The results show that the propellant pastes have good flowability at 40 °C and are suitable for 3D printing. Finally, solid propellant and insulation samples with complex structures were effectively generated using UV-curable 3D printing technology, in which the tensile strength and elongation at break of the propellant samples were 0.923 MPa and 63.2 %, respectively. The fabrication of the grains with high precision and performance demonstrated the feasibility of the PUA binder in the 3D-printed propellant.