Use Of Polyurethane Research Articles

Preparation and performance study of low heat storage flame retardant polyurethane for coal mines

In order to meet the requirements for the use of polyurethane for reinforcement in mines, the synthesis temperature of polyurethane needs to be lowered, and the flame-retardant and mechanical properties of polyurethane should also be considered comprehensively. Factors affecting the synthesis temperature of polyurethanes are investigated, low heat storage polyurethanes that meet the temperature requirements for use in plugging crushed coal bodies in coal mines are formulated, and the synthesized polyurethanes are characterised for their flame retardant properties by FTIR, SEM, TG-FTIR and CONE experiments. It was found that in this paper, a new type of polyurethane for coal mines was formed by flame retardant modification of polyurethane by adding nano-system flame retardant and phosphorus-system flame retardant, and the synthetic reaction temperature of the material could reach as low as 51.2 °C, and the pyrolysis onset temperature was increased to 286 °C. The experimental results show that the flame retardant property of this synthetic polyurethane has been significantly improved, and the heat accumulation effect of the synthesis process on the surrounding coal body has been greatly reduced. The physical properties and thermal stability of this synthetic polyurethane in the grouting process meet the safety requirements for use in underground coal mines.

Vibrational analysis of polyurethane-sandwiched bridge decks with variable skew angles

Bridge decks are the surface of bridges that carry the weight of the vehicles and pedestrians crossing over them. The design of bridge decks varies depending on the span, traffic volume, and material availability. But nowadays, the need for a sustainable approach is required. So, use of a sustainable material for construction and retrofitting purposes is the need of the hour. In the present study, a novel synthetic material polyurethane has been used in bridges. The study deals with the variation in skew angles to determine the response of the bridge deck. The response of natural frequencies on the bridge deck due to the variation in skewness and thickness of steel are analysed under simply supported and clamped boundary conditions. Further, the bridge deck is sandwiched using steel and polyurethane having different thicknesses, and the responses are recorded. Afterwards, a bridge deck is modelled using polyurethane as a special case, to pursue sustainability and justify the RRR (reduce, reuse, and recycle) concept of waste management. A comparative study is also performed between the isotropic steel deck and sandwiched deck by varying the skewness. The skew angle is varied from 0° to 60° with a difference of 10°, i.e., 0°, 10°, 20°, 30°, 40°, 50°, and 60°. The frequencies of the isotropic steel and sandwiched decks are increasing when the skewness is increased. Also, the decks may be modelled in a way to enhances the vibration behaviour by sandwiching the existing steel decks. The free vibration frequencies of the sandwiched decks are comparable to the steel deck of similar thickness, which shows the use of polyurethane as the core material does not affect the vibrational characteristics of the deck, while at the same time reducing the cost significantly. The research lays the groundwork for the creation of engineering recommendations that practitioners can use.

Flexible and washable MXene@PEDOT:PSS@CS@PU pressure sensors

Flexible electronics have attracted great interest because of their potential applications in healthcare monitoring and human-computer interaction. The performance of flexible electronics depends on the design of structure, materials, and mechanical responses. In this work, we explore the use of polyurethane (PU) sponge as the scaffold to form flexible piezoresistive pressure sensors with conductive networks made from conductive polymer PEDOT:PSS and MXene nanosheets. The sensitivity of the prepared pressure sensors reaches 0.2171 kPa−1 under mechanical pressure in a range of 1.8–6.15 kPa. The prepared pressure sensors are re-usable after washing. The applications of the prepared pressure sensors in the sensing of physiological behavior are demonstrated under the action of finger tapping, finger bending, vocal cord vibration, swallowing, and pulsing of radial artery. The prepared pressure sensors have great prospects for applications in human-machine interaction and physiological diagnosis.

Screening of polyurethane-degrading microbes using a quenching fluorescence probe by microfluidic droplet sorting

Excessive use of polyurethane (PU) polymers has led contributed to serious environmental pollution. The plastic recycling technology using microorganisms and enzymes as catalysts offers a promising green and low-carbon approach for managing plastic waste. However, current methods for screening PU-degrading strains suffer from drawbacks such as being time-consuming and inefficient. Herein, we present a novel approach for screening PU-degrading microorganisms using a quenching fluorescent probe along with the fluorescence-activated droplet sorting (FADS). The FPAP could specifically recognize the 4,4′-methylenedianiline (MDA) derivates released from PU degradation, with fluorescence quenching as a response. Based on the approach, we successfully screen two PU-degrading strains (Burkholderia sp. W38 and Bacillus sp. C1). After 20 d of cultivation, strain W38 and C1 could degrade 41.58% and 31.45% of polyester-PU film, respectively. Additionally, three metabolites were identified during the degradation of PU monomer (2,4-toluene diamine, 2,4-TDA) and a proposed degradation pathway was established. Consequently, the fluorescence probe integrated with microfluidic droplet systems, demonstrates potential for the development of innovative PU-biocatalysts. Furthermore, the identification of the 2,4-TDA degradation pathway provides valuable insights that can propel advancements in the field of PU biodegradation.

Biodegradable and biocompatible nonisocyanate polyurethanes synthesized from bio-derived precursors

Despite the enormous use of polyurethanes (PUs) in multiple aspects of modern lifestyle, the industrial scale manufacturing of PUs uses toxic chemicals like isocyanates, phosgene till today. In addition, the non-biodegradability and non-biocompatibility of PUs and their debris are serious cause of concerns for the environment. To deal with these challenges, in the current work, a new approach is reported in which bio-derived non-isocyanate polyurethanes were synthesized by exploiting viable amino acid-based diamines and biscyclocarbonates from sebacoyl chloride and diglycerol derivatives in a readily doable process. The newly designed polyhydroxyurethanes (PHUs) exhibited remarkable biodegradability and biocompatibility (cell viability) in comparison with commercial diamine based PHUs. A series of PHUs were synthesized in bulk and solvent free green synthetic route by polycondensing library of amino acids (such as glycine, alanine, valine, and isoleucine etc.) based diamines consisting of varying alkyl chain lengths and biscyclocarbonates like sebacic biscyclocarbonate and diglycerol biscyclocarbonate etc. All the synthesized PHUs were thoroughly characterised by IR, NMR and HRMS spectroscopic techniques. The impact of chain length and molecular structure of the synthesized PHUs were also evaluated using DSC, TGA, SEC, water contact angle measurements and hydrolytic degradation studies. The molar masses of the PHUs obtained from the SEC analysis are in the range of ∼17,000–24,000 Da. The current study demonstrated that amino acids is one of the major degradation products and are biocompatible in in-vitro conditions. The PHUs and their degradable products showed excellent cell viability when studied in HEK293T cells that were carried out using microgram to milligram concentration of PHUs. The outcome of this work in comparison to conventional PHUs and polyurethanes clearly demonstrated good biocompatibility and hence drawing attention to potential applications in bio-adhesives, bio-implants, drug delivery, and green coatings etc. in the near future.

Biodegradation of polyurethanes by Staphylococcus warneri and by microbial co-culture

With the increasing production and use of polyurethanes (PUs), it is necessary to develop sustainable techniques for the remediation of plastic pollution. The use of microorganisms capable of biodegrading PUs may be an environmentally desirable solution for controlling these plastic contaminants. To contribute to the discovery of alternatives for the mitigation of plastics in the environment, this study aimed to explore the potential of StaphylococcuswarneriUFV_01.21, isolated from the gut of Galleria mellonellalarvae, for biodegradation of PU in pure culture and microbial co-culture with Serratia liquefaciensL135. S. warneri grew using Impranil® PU as the sole carbon source in pure culture and co-culture. With six days of incubation, the biodegradation of Impranil® in Luria Bertani broth was 96, 88 and 76%, while in minimal medium, it was 58, 54 and 42% for S. warneri, S. liquefaciens, and co-culture, respectively. In addition, S. warneri in pure culture or co-culture was able to biodegrade, adhere and form biofilms on the surfaces of Impranil® disks and poly[4,4′-methylenebis (phenyl isocyanate)-alt-1,4-butanediol/di(propylene glycol)/polycaprolactone] (PCLMDI) films. Scanning electron microscopy also revealed biodegradation by detecting the formation of cracks, furrows, pores, and roughness on the surfaces of inoculated PU, both with pure culture and microbial co-culture. This study is the first to demonstrate the potential of S. warneriin PU biodegradation.

The effect of moisture on abrasive wear of urethane-containing elastomers

An increasing demand for the materials used in the mining industry necessitates extending the service life of polyurethane-type elastomers. This challenge can partially be met through optimal use of these elastomers, with their properties taken into account as dependent on moisture. The problem formulated like that implies the use of polyurethanes under conditions of a wide range of the relative air humidity values during different climatic seasons in different countries. This paper presents the results of a study in the changes in abrasive wear of urethane-containing elastomers (polyurethanes and polyurethane ureas) under moisture conditions. The purpose of the work being to study comparative resistance of different elastomers, chemically structured differently, to abrasive wear, the experiments were carried out as per the techniques standard for rubbers. An increase in stability of abrasive resistance of the elastomers under study, when moistened, was established to be ensured by a higher content of hard segments in polymer chains and stability of domain structures to the action of water. The effect produced by moisture on the properties of the elastomers under study is of nature of temporary plasticization. Generally, the oligoethers-based urethane-containing elastomers are more resistant to moisture than those based on oligoesters, but if the domain structure of an elastomer is unstable by reason of a steric hindrance, the pattern of the phenomenon can vary.

Cost‐effectiveness of Resonance® metallic ureteral stent compared with standard polyurethane ureteral stents in malignant ureteric obstruction: A cost‐utility analysis

AbstractBackgroundMalignant ureteral obstruction (MUO) is a frequent challenge for urologists. Patients have poor prognoses, treatment aims to improve quality‐of‐life while optimising renal function. Standard practice in the United Kingdom is to use polyurethane stents, which require frequent surgical replacements for blockages and encrustation. More durable metallic stents are available, although these incur an increased initial purchase price.AimsWe aim to assess whether the use of polyurethane double‐J (JJ) or metallic stent, Resonance® is more cost‐effective for managing MUO in the UK healthcare setting.MethodsA Markov model was parameterised to 5 years with costs and health‐related quality‐of‐life consequences for treating MUO with Resonance metallic stent (Cook Medical), versus standard JJ stents, from the UK care system perspective, with 3.5% discounting. Deterministic and probabilistic sensitivity analyses were undertaken to assess the effect of uncertainty.ResultsOver 5 years, approximately four fewer repeat surgical interventions were estimated in the metallic stent arm compared with the JJ stent, driving a 23.4% reduction in costs. The mean estimates of costs and benefits indicate that treatment of MUO with Resonance for 5 years is dominant over JJ stents. Over 5 years a cost‐saving of £2164.74 and a health gain of +0.046 quality‐adjusted life years (QALYs) per patient is estimated. With a maximum willingness to pay of £20 k per QALY, a net monetary benefit (NMB) of £3077.83 is estimated. Probabilistic sensitivity analysis at a willingness to pay threshold of £20 000 indicates an 89.3% probability of Resonance being cost‐effective over JJ stents. Within 1‐year savings of £726.53 are estimated driven by a reduction of two fewer repeat surgical interventions when using the metallic stent.ConclusionsResonance metallic stents for the treatment of MUO reduce the number of repeat procedures and could be a cost‐effective option for the treatment, potentially offering efficiencies to the healthcare system.

The RPUF Composite’s Physical and Mechanical Properties with Ramie Stem Particle Reinforcement

Rigid polyurethane foam (RPUF) is a common insulation material that has low thermal conductivity and good mechanical properties. The qualities of RPUF may be enhanced by adding natural fiber reinforcing. The purpose of this work is to examine how the mechanical and physical characteristics of RPUF composite are affected by the amount of ramie stem particles present. Japanese Industrial Standard (JIS) A 5908-2003 is the basis for the mechanical test (modulus of elasticity, modulus of rupture, compressive strength, internal bond) and the physical test (density, moisture content, water absorption). The study's findings suggest that the physical properties of the RPUF composite were affected by the addition of ramie particles for reinforcement. The density increase in particle content 2.5% – 7.5% range, is not statistically significant. The MC and WA increased statistically significantly. The values of MOE and MOR were not significantly different. In fact, with the addition of 2.5% and 5% ramie particles, the compressive strength value was higher than the RPUF composite without ramie particle filler. Then overall, the IB value was increased by increasing the ramie particles in the RPUF composite. The addition of 2.5-5% ramie particles into the RPUF composite showed optimum results in mechanical properties. Thereby, the addition of ramie particles in the RPUF composite means reducing the use of polyurethane. Therefore, it can reduce production costs. Then the product is more environmentally friendly

Polyurethane as a versatile polymer for coating and anti-corrosion applications: A review

The development of polyurethane materials and process optimization are currently the subjects of extensive study. Polyurethane is characterized by high physicochemical and operational properties. Polyurethanes have high wear resistance, and oil and gasoline resistance. They have excellent thermophysical and elastic properties. This allows the use of polyurethanes in many industries where materials with high-performance properties are required. Polyurethanes are widely used in many industrial applications, protective coating manufacturing, and anti-corrosion agent applications. A significant number of studies have been conducted to improve the physical, mechanical, and operational properties of polyurethane polymers, in particular the anti-corrosion properties of modified polyurethane coatings. The properties of polyurethane polymers for various applications can be improved by changing monomers and their ratios and the process of preparations. Preparation of polyurethane polymers based on polyols and isocyanate monomers using a polyaddition process in the presence of a catalyst as well as solvents including toluene, xylene, and acetone. There are different factors affecting the physical and mechanical properties of polyurethane polymers were investigated by different techniques. The factors were types of isocyanates, polyols, OCN/OH ratios, solvents, catalysts, and temperatures. Generally, the polyols are responsible for the flexibility of the polyurethane polymers and isocyanates are responsible for the rigidity of the polyurethane polymer and crosslinking between the backbone of the polymer. Because of the flexibility of its chemistry, they may modify the coating's characteristics based on the intended use. The effects of different polyols and polyisocyanates' chemistry are assessed. The hydrophobicity, thermal stability, and mechanical and anti-corrosion properties of polyurethane polymers were investigated. As a result, the properties of polyurethane polymers such as hydrophobicity, thermal stability, and mechanical and anti-corrosion properties were all enhanced when all the above factors. An outline of the most modern, financially successful methods for creating protective polyurethane coatings and using them as anti-corrosion agents is given in this review article.

Polyurethane as an alternative support media to low-density polyethylene in fermentative-sulfidogenic reactors: Beneficial or indifferent?

Sporadically addressed in previous studies, the removal of sulfate during fermentation has been a matter of great interest in new applications of fixed-film two-stage biodigestion as the most efficient strategy to boost methane production from a low-sulfate fermented substrate. This study assessed the use of polyurethane (PU) as the support material in a thermophilic (55 °C) fermentative/sulfidogenic fixed-film reactor subjected to different operating conditions based on the variation of the sulfate loading rate (SLR = 8.0–4.0 kg-SO42− m−3 day−1), HRT (12.0–16.0 h) and liquid upflow velocity (3.42–7.90 m h−1). A maximum sulfate removal efficiency of only 46.8 % was achieved when applying SLR and HRT of 4.0 kg-SO42− m−3 day−1 and 16.0 h, respectively, reaching a total dissolved sulfide concentration of 275 mg L−1. This poor performance resulted from two factors: the interspaced arrangement of PU pieces and the use of ethanol as the only carbon source. While the first triggered excess biomass accumulation, the latter favored the establishment of a very restricted microbial community. Only some Clostridia-like bacterial classes, Proteobacteria, and other non-SRB bacteria belonging to phyla Synergistetes and Thermotogae were identified. Hence, under the studied conditions, using PU did not enhance sulfidogenesis in the fermentative reactor.

ПОЛУЧЕНИЕ, СВОЙСТВА И ПРИМЕНЕНИЕ ПОЛИУРЕТАНОВ, МОДИФИЦИРОВАННЫХ ДОБАВКАМИ РАСТИТЕЛЬНОГО ПРОИСХОЖДЕНИЯ (ОБЗОР)

This review discusses the synthesis, properties and applications of polyurethanes. Polyurethanes are materials that combine high hardness and stiffness with the flexibility of rubber, making them versatile and multifunctional materials. The article describes in detail the process of synthesis of various types of polyurethane compositions from polyols and isocyanates, as well as their basic physicochemical properties. Special attention is paid to the diverse applications of polyurethanes, including the automotive, biomedical, coatings, adhesives and sealants industries. The relevance of the study and development of this material is due to its high service life and economic efficiency. The purpose of this work is to compare the advantages of obtaining and the possibilities of using polyurethanes in various industries, as well as their impact on technological processes and the environment. The ability to modify polyurethanes allows manufacturers to create materials with a variety of properties and adapt them to different types. Progress in the use of polyurethanes is clearly manifested in the use of biocompatible polyols. The article presents the advantages and disadvantages of using various types of polyols in the production of PU. The latest achievements and trends in the use of polyurethanes, including the use of biocompatible polyols and nanomaterials, are reviewed. Possessing excellent mechanical strength, biodegradability and biocompatibility, PUs are widely used in various medical fields. Thus, PU is included in nanotubes, catheters and bactericidal wound dressings. The use of renewable resources of plant origin as PU components makes it possible to create new environmentally friendly polymer building materials. Analysis of the relevance of the use of polyurethanes allows us to better understand their prospects and opportunities for further development of the industry.

Development of porous asphalt mixture based on the synthesis of PTEMG and MDI polyurethane asphalt

Polyurethane-modified asphalt (PA) stands out as an environmentally sustainable road material, renowned for its exceptional performance that significantly extends road surface lifespans while reducing maintenance costs. This study focuses on the preparation of PA using a single-component blending method that incorporates polyether polyol PTEMG (Poly-(tetra methylene ether glycol)) and isocyanate MDI (4,4′-diphenylmethane diisocyanate) as primary raw materials. Various analytical techniques, including Fluorescence Microscopy, Fourier-transform Infrared Spectroscopy (FTIR), Thermogravimetric analysis (TG), Differential Scanning Calorimetry (DSC), Viscosity Testing, Tensile Testing, and Bending Beam Rheometer (BBR), were employed to investigate PA's microstructure, modification mechanism, thermal properties, viscosity characteristics, curing properties, and low-temperature stability. A porous polyurethane-modified asphalt mixture, targeting a void content of 20%, was designed and compared to a high-viscosity modified asphalt mixture with the same void content in terms of performance. The results indicate a combination of chemical and physical processes in PA modification. Through TG and DSC experiments, it was ascertained that polyurethane-modified asphalt commences decomposition at 252 °C, exhibiting an exothermic peak within the temperature range of − 19.98–2.73 °C. The introduction of polyurethane substantially enhances the thermal performance and cryogenic stability of the asphalt binder. Viscosity tests and tensile experiments indicate that the curing reaction of polyurethane-modified asphalt is protracted and irreversible. Consequently, it is recommended to prepare polyurethane-modified asphalt mixtures employing a compaction temperature of 175 °C and a maximum resting time of 100 min. Additionally, specimens should rest at room temperature for at least 3 days. Comparatively, the porous asphalt incorporating polyurethane exhibits notable advantages over the high-viscosity modified asphalt mixture. It demonstrates superior high-temperature stability, excellent resistance to low-temperature cracking, reduced sensitivity to strains, prolonged fatigue life, and improved flexibility. However, its fatigue resistance and resistance to dynamic loads are slightly inferior. This study offers valuable insights into the use of polyurethane in porous asphalt mixtures, making it a promising option for sustainable road construction.

The Use of Polyurethane Composites with Sensing Polymers as New Coating Materials for Surface Acoustic Wave-Based Chemical Sensors—Part I: Analysis of the Coating Results, Sensing Responses and Adhesion of the Coating Layers of Polyurethane–Polybutylmethacrylate Composites

The sensing layers for surface acoustic wave-based (SAW) sensors are the main factor in defining the selectivity and reproducibility of the responses of the sensor systems. Among the materials used as sensing layers for SAW sensors, polymers present a wide range of advantages, from availability to a large choice of chemical-sensing environments. However, depending on the physical–chemical properties of the polymer, issues about the chemical and mechanical stability of the sensing layer have been reported that can compromise the application of sensor systems in the long-term. The sensor properties are defined basically by the properties of the coating material and the quality of the coating process. The strategy used to improve the properties of polymeric coating layers for SAW technology involved the use of polyurethane (PU) in combination with a second polymer that is responsible for the sensing properties of the resulting layer; this is obtained by a reproducible and robust coating procedure. In this first part of our research, we used polymer composites of different compositions of polybutylmetacrylate (PBMA) as the sensing polymer with polyurethane. The analysis of the coating (ultrasonic parameters), the relative sensor responses and the adhesion results for the PU–PBMA composites were determined. The ultrasonic analysis and the relative sensor responses showed very reproducible and precise results, indicating the reproducibility and robustness of the coating process. Accurate correlations between the results of the ultrasonic parameters due to the coating and the relative sensor responses for the organic analytes analyzed were obtained, showing a precise quantitative relationship between the results and the constitution of the composite coating materials. The composites show practically no significant sensor responses to water. The PU–PBMA composites substantially enhanced adhesion to the surface of the piezoelectric sensor element in comparison to the coating with pure PBMA, without loss of its sensing properties. Other PU–polymer composites will be presented in the future, as well as an analysis of the selectivity for the organic analytes for these types of coating materials.

The Effect of Concentration of Titanium Dioxide Nanoparticles on Their Antibacterial Activity in the Synthesis of Polyurethane Biopolymers

In the health sector, the use of polyurethane (PU) as a basic material for medical devices still causes problems related to local and systemic infections. One of the most appropriate ways to overcome this problem is to synthesize PU biopolymer with titanium dioxide (TiO2) nanoparticles. The use of nano-shaped materials in this synthesis has many advantages, including being easier to synthesize and being antibacterial. Meanwhile, starch is the result of isolation from banana weevils, where banana weevils are agricultural waste that has not been utilized properly. Particle size and the use of agricultural waste are a form of modification and innovation in PU synthesis, as well as a novelty in the development of this research. In PU synthesis, several characterization techniques are carried out, including polymer tests, namely strain and stress, functional group analysis using (Fourier Transform Infra-Red), and antibacterial tests. Based on the results of the FTIR test analysis, it show that at a wave number of 1724.36 cm-1, the N-H functional group is visible, and the absorption of urethane and TiO2 groups is in the range of 513.07 cm-1. The mechanical properties test shows the strain (28.92 - 21.88% GL) and young's modulus in the interval (5.484-3.268 MPa). The antibacterial test showed that the inhibitory power of test samples A1 and A4 with diameters of 8 mm and 8 mm proved to be very effective in killing E. Coli bacteria, while test samples A1¹, A2¹, A3¹, and A4 were not able to kill E. Coli bacteria. S. Aureus. bacteria. The characterization results show that PU biopolymer can be used as a basic material for making bacterial decontaminant medical devices.

The Effect of Titanium Dioxide Nanoparticle Composites as an Antibacterial in Synthesizing Polyurethane Biopolymers

Abstract. In the health sector, the use of polyurethane (PU) as a basic material for the manufacture of medical devices also creates problems related to local and systemic infections. One of the most appropriate ways to overcome this problem is to add titanium dioxide (TiO2) nanoparticles to the urethane polymer to produce a biodegradable polymer and bacterial decontamination. In synthesizing decontaminating polyurethane bacteria, several characterization techniques were carried out, including polymer test, namely strain and stress, functional group analysis using Fourier Transform Infra-Red (FTIR), and antibacterial test. Based on the results of the FTIR test analysis, shows a change in the functional group. At wave number 1724.36 cm-1, the N-H functional group appears, this absorption is the absorption of the urethane group and TiO2 is in the range of 513.07 cm-1. Mechanical properties test showed strain (28.92 - 21.88% GL) and young modulus at intervals (5,484-3,268 MPa). and the antibacterial test showed that the inhibitory power of test samples A1 and A4 with resistance diameters of 8mm and 8mm proved to be very effective in killing E.Coli bacteria while A1¹, A2¹, A3¹, and A4 killed could not kill S. Aureus bacteria inhibitors. The characterization results show that the polyurethane biopolymer can be used as a medical device with bacterial decontamination properties.

Resistance of Chip Block Pallet from Teak Wood Particle against Decay Fungi and Subterranean Termites

Wood biomass such as sawdust, particles, and chip obtained wood industry can be used as raw material for chip block pallets (CBP). This study evaluated the resistance of chip block pallets made from teak-sawn waste and polyurethane adhesive against decay fungi (white-rot and brown-rot fungi) and subterranean termites. The CBPs with dimensions of 9 × 9 × 9 cm and a target density of 0.6 g/cm3 were cold pressed at 9.8 MPa for 4 h using several polyurethane concentrations and composition of particle sizes. The termite and decay resistance tests were conducted following JIS K 1571 2004. The results showed that CBP treated with different polyurethane concentrations and composition of particle sizes was resistant to subterranean termite attacks. However, the CBP manufactured were not resistant to white-rot and brown-rot fungi attacks, showing more than 3% mass loss percentage. Considering the efficiency of polyurethane use, the study suggested the best content for using polyurethane in the manufacture of CBP is 4.5% with a particle size composition of 50 (4-14 mesh): 50 (> 60 mesh). Keywords: Biodeterioration, chip block pallet, polyurethane, teak wood particles

Performance evaluation of crumb rubber and bio-based polyurethane compound in terms of rheological and aging properties of asphalt binder

This study explored the effects of the combined use of CR and polyurethane (PU), whose use in bitumen modification is still in its infancy. The polymeric 4.40-diphenylmethane diisocyanate (MDI) and palm-oil-based polyol were used for the PU modification. A 4:1 M ratio of NCO/OH was found to be successful in forming urea bonds in the CR-modified binder. The performance of CR and CR + PU-modified bitumen was compared with the most widely used SBS modification. The binders were subjected to conventional and rheological tests. Fourier transform infrared spectroscopy was utilized to evaluate the effect of aging. The use of 8 %CR and 4% PU together provided a considerable performance improvement over the use of CR alone and that this combined binder provided better plastic deformation resistance, and low-temperature behavior than the 4 %SBS modification. The chemical reaction between PU and CR prevented the decomposition and had a significant effect on increasing the storage stability. The use of PU with CR was found to reduce chain scission, condensation and oxidation caused by aging.

ВЛИЯНИЕ ЖЕСТКОСТИ НАВЕСНОЙ СИСТЕМЫ НА УСТОЙЧИВОСТЬ КРИВОЛИНЕЙНОГО ДВИЖЕНИЯ МАШИННО-ТРАКТОРНОГО АГРЕГАТА

The search for constructive solutions to reduce the influence of inertial forces on the process of curved movement of a machine-tractor unit during curved movement is an urgent problem associated not only with reducing dynamic loads on the tractor and equipment aggregated with it, but with maintaining the stability of movement. A circular loop-free turn was chosen as the object of research. An experimental hinged system is designed to solve the tasks set in the work. It differs from the basic one in that between the hinged frame of the Belarus-1221.2 tractor and the hinged frame of the STV-12 seeder, an elastic element made of polyurethane is installed, which has the most suitable physical and mechanical properties. Nonlinear approximation of the array of abscissas and ordinates of the turn entry trajectory curve, calculated using the parametric form of equations for a circle of constant radius of the steady turn section, made it possible to describe the two considered stages of the theoretical turn trajectory by explicit non-linear functions. Analysis of arrays of theoretical and experimental values of the coordinates of the curves of the trajectories gave a constant value of the shift coefficient of the theoretical trajectory for the studied operating conditions of the unit 1.12, multiplying by which the explicit theoretical function obtained a parametric function of the actual trajectory of rotation. The comparison of trajectories showed the expediency of using elastic elements at the points of articulation of the tractor with the equipment, the use of polyurethane leads to the preservation of the trajectory, since the deviation of the actual trajectory from the theoretical one with the basic configuration in the height of the turning strip is 1.6... 2.25 m, and with the experimental one – 0.6 ... 1.13 m, the length of the theoretical curves is 8.21...10.82 m, and valid: with a base hitch of 11,223...12,792 m, with an experimental one – 9,652 ...11,854 m. A comparison of the results of theoretical studies with experimental data showed that their greatest difference does not exceed 4%, which allows us to conclude that they are correct.

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