Cast Polyurethane Research Articles

Experimental guide wire placement for total shoulder arthroplasty in glenoid models: higher precision for patient-specific aiming guides compared to standard technique without learning curve

BackgroundPatient-specific aiming devices (PSAD) may improve precision and accuracy of glenoid component positioning in total shoulder arthroplasty, especially in degenerative glenoids. The aim of this study was to compare precision and accuracy of guide wire positioning into different glenoid models using a PSAD versus a standard guide.MethodsThree experienced shoulder surgeons inserted 2.5 mm K-wires into polyurethane cast glenoid models of type Walch A, B and C (in total 180 models). Every surgeon placed guide wires into 10 glenoids of each type with a standard guide by DePuy Synthes in group (I) and with a PSAD in group (II). Deviation from planned version, inclination and entry point was measured, as well as investigation of a possible learning curve.ResultsMaximal deviation in version in B- and C-glenoids in (I) was 20.3° versus 4.8° in (II) (p < 0.001) and in inclination was 20.0° in (I) versus 3.7° in (II) (p < 0.001). For B-glenoid, more than 50% of the guide wires in (I) had a version deviation between 11.9° and 20.3° compared to ≤ 2.2° in (II) (p < 0.001). 50% of B- and C-glenoids in (I) showed a median inclination deviation of 4.6° (0.0°-20.0°; p < 0.001) versus 1.8° (0.0°-4.0°; p < 0.001) in (II). Deviation from the entry point was always less than 5.0 mm when using PSAD compared to a maximum of 7.7 mm with the standard guide and was most pronounced in type C (p < 0.001).ConclusionPSAD enhance precision and accuracy of guide wire placement particularly for deformed B and C type glenoids compared to a standard guide in vitro. There was no learning curve for PSAD. However, findings of this study cannot be directly translated to the clinical reality and require further corroboration.

New Hybrid Sublayers for Heat- and Water-Resistant Adhesive Joints of Cast Polyurethane with Metals

New Hybrid Sublayers for Heat- and Water-Resistant Adhesive Joints of Cast Polyurethane with Metals

STUDY OF THE PERFORMANCE OF PLUNGER PUMP VALVES OPERATED IN AGGRESSIVE ENVIRONMENTS

Reciprocating plunger pumps are crucial for various industrial sectors, including chemical processing, well cementing, oil and gas production, and wastewater management. These pumps play a vital role in handling a range of fluids, making them indispensable for maintaining efficient and reliable operations in these demanding applications. These environments often involve handling aggressive fluids that can cause significant wear and corrosion to pump components, particularly the valves. Selection the right materials for valve manufacturing is essential to maintain the reliability, performance, and durability of plunger pumps operating in harsh environments. This ensures that the pumps can withstand extreme conditions while maintaining their efficiency over time. This research offers an in-depth review of the materials typically used for manufacturing plunger pump valves, with a focus on their performance in demanding environments. The research highlights the importance of material properties such as wear resistance, corrosion resistance, hardness, and mechanical strength. It evaluates various materials, including cast polyurethane, industrial ceramics such as silicon nitride and silicon carbide, and advanced coating techniques with nickel, chromium, and ceramic layers, to determine their effectiveness in harsh environments. Cast polyurethane is recognized as an optimal material due to its superior physical and mechanical properties, minimal shrinkage, and excellent chemical resistance. It excels in managing abrasive media and high-viscosity fluids, making it highly suitable for diverse industrial applications. Industrial ceramics, such as silicon nitride and silicon carbide, are distinguished by their ability to withstand high temperatures, resist corrosion, and offer low friction coefficients. Materials like silicon nitride and silicon carbide demonstrate exceptional performance in conditions where traditional metals and polymers fail. Moreover, applying advanced coatings, such as nickel-chromium-ceramic layers, to steel components significantly improves the durability and corrosion resistance of plunger rods and other critical parts. Keywords: plunger pump valves, aggressive environments, operational efficiency, material selection.

Effect of Water Immersion on the Seismic Isolation Performance of Castable Polyurethane Bearing

This study performs a 120-day water aging simulation on castable polyurethane (CPUE) bearings and tests them at 30-day intervals for vertical load-bearing performance and 100% horizontal shear performance. The results indicated that the CPUE bearings achieved full water aging after 120 days of water immersion. Besides, the vertical stiffness, horizontal shear stiffness, and equivalent damping ratio decreased by 10.3%, 16.8%, and 10.0%, respectively. Moreover, the study investigates the hydrolysis mechanism of CPUE bearings using Atomic force microscopy (AFM) and cross-linking density (NMR) tests. Subsequently, it develops models for unaged CPUE bearings (CPUE-un) and fully water-aged bearings (CPUE-aged), selecting unaged test results for CPUE-un and the test results from 120 days of water immersion for CPUE-aged. Within the study context, a representative high-pier continuous girder bridge serves as the basis for evaluating the effects of seismic conditions on the CPUE-un and CPUE-aged bearing bridge systems. The findings demonstrate that water-aged CPUE experiences significant material softening, with bearing deformations increasing by 14.99%, 34.06%, and 46.65% at 0.3, 0.6, and 0.9 g peak ground acceleration (PGA), respectively. The likelihood of damage to water-aged bearings increased under seismic influence, while the impact on piers was less pronounced. This research provides a valuable reference for the application of CPUE bearings in humid environments.

Measurement of the Dynamic Viscosity of Filled Composites on the Basis of Thermosetting Cast Polyurethane

Measurement of the Dynamic Viscosity of Filled Composites on the Basis of Thermosetting Cast Polyurethane

Optimization of Mass-spring Model Parameters by ICA for Assessing Compressional Behavior of Warp-knitted Spacer Fabrics Reinforced Polyurethane Cast Elastomer Composites

Optimization of Mass-spring Model Parameters by ICA for Assessing Compressional Behavior of Warp-knitted Spacer Fabrics Reinforced Polyurethane Cast Elastomer Composites

Preparation of polyurethane coating formulation based on dihydropyridine derivatives as an insecticide and antifungal additives for surface coating applications

Pyridine derivatives are prepared and evaluated before being incorporated into polyurethane coating formulations to create antifungal and insecticidal coating compositions. Different analyses, including Fourier transform infrared (FTIR), mass, proton nuclear magnetic resonance (1HNMR), and carbon-13 nuclear magnetic resonance (13C NMR) spectra, were used to confirm the synthesized compounds. The material has been coated using a polyurethane coating mixture. Gloss, scratch resistance, flexibility, and adhesion are some of the coating attributes investigated; mechanical capabilities include impact resistance and shore hardness, and physicochemical properties such as chemical resistance of coated polyurethane (PU) samples are also investigated. PU coatings were applied to substrates to measure coating properties. The mechanical properties of the PU cast films were measured. The results of the experiments revealed that all PU coatings based on dihydropyridine derivatives had good scratch resistance which varied from > 1.5 to > 2 kg. While reducing gloss value varied from 65 to 85, there is no effect of the prepared compounds in the other mechanical test. These PU coatings have excellent chemical resistance except the alkali resistance as evidenced by their physicochemical properties. The observed antifungal and insecticide activities indicated that dry wood coated with PU based on dihydropyridine derivatives is promising for resistance to these insects and fungi, in comparison with the paint as blank. The results revealed that the inhibition zones diameter by compound 2 were 25.1 ± 0.69, 23.2 ± 0.94, 20.16 ± 0.62, 20 ± 0.80, and 18 ± 0.81 mm against A. terreus, A. niger, A. flavus, C. albicans, and A. fumigatus, respectively, whereas the inhibition zones (IZ) diameter by compound 3 were 22.56 ± 0.30, 21.03 ± 0.49, 21.03 ± 0.61, 21 ± 0.66, and 20 ± 0.78 mm versus A. niger, A. fumigatus A. flavus, C. albicans, and A. terreus, respectively. The ordering activity against insects increased as the dose concentration of the pyridine derivatives was increased.

Study on properties of polyurethane elastomers prepared with different hard segment structure

AbstractFour different systems of cast polyurethane elastomers were prepared through two‐step method by adjusting different isocyanates and amine chain extenders. The blocked polyurethane prepolymer synthesized by the reaction of methyl ethyl ketoxime (MEKO) and the prepolymer weakens the reactivity with the amine chain extender. The mechanical and thermal properties of cast polyurethane prepared by different combinations were analyzed through comparison. The microphase separation of hard and soft segments structure in different systems were observed by using atomic force microscope (AFM). Through dynamic mechanical analysis (DMA), the influence of various structures on the loss factor is discussed. Studying the dynamic endogenous heat of cast polyurethane (CPU) by changing the hard segment structure provides a novel idea for the construction of polyurethane with low‐damping structure.

Effect of splinting scan bodies on trueness of complete-arch implant impression using different intraoral scanners: an in vitro study.

To evaluate the trueness of seven different intraoral scanners (IOSs) in making a complete-arch digital scan with and without splinting the scan bodies. A polyurethane cast of an edentulous mandible with four dental implant analogs was prepared. A reference scan was made using a laboratory scanner. The reference model was scanned with each of the seven investigated IOSs (control groups, n = 10 per scanner), and scanned again after splinting the scan bodies (study groups, n = 10 per scanner). Each scan was exported as a standard tessellation language (STL) file and transferred to a comprehensive metrology software program (Geomagic Control X). In order to measure the trueness, four points (A, B, C, and D) were determined on the scan bodies, and the distance between point A and the other points (DAB, DAC, and DAD) was measured. The measurements were tested for normality using the Kolmogorov-Smirnov test and probability plots. Trueness was compared using three-way analysis of variance (ANOVA), and pairwise comparisons were performed using the post hoc Tukey and paired sample t tests. Statistical analyses were two-sided, and the significance level was set at 5%. Splinting the scan bodies improved the trueness values of the digital scans, while increasing the interimplant distance decreased them. A significant association was found between the trueness values and all three tested variables, including splinting the scan bodies, type of IOS, and interimplant distance (P < 0.001). Based on the present findings, splinting the scan bodies can improve the trueness of complete-arch digital implant scans due to the improvement in morphologic landmarks by the stitching process, regardless of the type of IOS or the interimplant distance. (Int J Comput Dent 2023;26(1): 19-0; doi: 10.3290/j.ijcd.b2599297).

Study of the Aging of Cold-Cured SKU-PFL Type Polyurethane Filled with Waste Products

The article describes the results of aging of samples of cold-cured molded polyurethanes of SKU-PFL brand filled with zeolite and silica gel - wastes of petrochemical production. The samples were aged under normal climatic conditions for 5 years. Filling of the samples varied from 10 to 50 %wt. Investigations of physical and mechanical properties of the samples before and after aging were carried out, the basic indicators of material quality were calculated using Microsoft Office Excel package. As a result of researches it was established that after aging the basic physical and mechanical properties of cast polyurethanes of SKU-PFL brand of cold curing filled with zeolite and silica gel change insignificantly, however the best resistance to aging are in samples with 20 %wt. zeolite and 10 %wt. silica gel filling both before and after aging that allowed to recommend them for long-term use of articles.

Novel Cast Polyurethanes Obtained by Using Reactive Phosphorus-Containing Polyol: Synthesis, Thermal Analysis and Combustion Behaviors.

Phosphorus-containing polyol applications in polyurethane synthesis can prevent volatilization of flame retardants and their migration on the surface of a material. In this work, novel cast polyurethanes were prepared by a one-step method with the use of different amounts of phosphorus-containing polyol, 4,4′–diphenylmethane diisocyanate and 1,4-butanediol. The chemical structure, thermal, physicochemical and mechanical properties and flame resistance of the prepared materials were investigated. The results obtained for cast flame-retarded polyurethanes were compared with cast polyurethane synthesized with commonly known polyether polyol. It has been shown that with an increasing amount of phosphorus content to polyurethane’s chemical structure, an increased flame resistance and char yield were found during combustion tests. Phosphorus polyol worked in both the condensed (reduced heat and mass exchange) and gas phase (inhibition of flame propagation during burning). The obtained materials contained phosphorus polyol, indicating higher thermal stability in an oxidative environment than an inert atmosphere.

ВЫБОР МАТЕРИАЛОВ, ПРИМЕНЯЕМЫХ ДЛЯ ИЗГОТОВЛЕНИЯ ДИАФРАГМ МЕМБРАННО-ПОРШНЕВЫХ НАСОСОВ В АГРЕССИВНЫХ СРЕДАХ

Abstract. Wear of the diaphragm-piston pump may occur due to a reduction in the cross-section of the suction circuit (caused by an unsuitable pipe diameter, a dirty fi lter, pumping of high-viscosity liquids, etc.), the use of very aggressive chemicals, high operating temperature, abrasive particles, and high pressure in the pneumatic line. The paper considers various types of materials used for the manufacture of diaphragm piston pumps: rubbers, thermoplastic elastomers, thermoplastics and thermoset materials. The physical and mechanical, technological and operational characteristics of materials and the corresponding requirements for chemical resistance, temperature range of operation and abrasiveness were taken into account using an example of soybean cultivation. It was found that the optimal material that meets the above criteria is cast polyurethane. It has high physical and mechanical characteristics, a wide range of hardness (from 30 A to 90 В by Shore), low shrinkage, which implies long-term use of the material. Polyurethane products are manufactured by free casting, in which the liquid polymer composition is cured in a form that does not require complex and expensive injection molding rigs, unlike thermoplastics and elastomers. Injection polyurethane has suffi cient chemical resistance in contact with the pump’s working fl uids and features wear resistance when pumping abrasive media. Therefore it is suitable for working in the climatic conditions of the Central region of Russia, and is also aff ordable, cheap and technologically advanced.

Characterization of 3-Dimensional Printing and Casting Materials for use in Computed Tomography and X-ray Imaging Phantoms.

Imaging phantoms are used to calibrate and validate the performance of medical computed tomography (CT) systems. Many new materials developed for three-dimensional (3D) printing processes may be useful in the direct printing or casting of biomimetic and geometrically accurate CT and X-ray phantoms. The X-ray linear attenuation coefficients of polymer samples were measured to discover materials for use as tissue mimics in phantoms. This study included a cohort of polymer compounds that were tested in cured form. The cohort consisted of 101 standardized polymer samples fabricated from: two-part silicones and polyurethanes used in commercial casting processes; one-part optically cured polyurethanes used in 3D printing; and fused deposition thermoplastics used in 3D printing. The testing was performed with a commercial micro-CT imaging system from 40 kVp to 140 kVp. The X-ray linear coefficients of the samples and human tissues were plotted with error bars to allow the reader to identify suitable mimics. The X-ray linear attenuation coefficients of the tested material samples spanned a wide range of values, with a small number of them overlapping established human tissue mimic values. Twenty 3D printer materials and one castable polyurethane tracked nylon and polymethyl methacrylate (PMMA) as established X-ray mimics for fat. Five 3D printer materials tracked water as an established X-ray mimic for muscle.

Marginal fit of CAD-CAM monolithic zirconia crowns fabricated by using cone beam computed tomography scans

Statement of problemInformation regarding the precision of monolithic zirconia crowns fabricated by using a standard computer-aided design and computer-aided manufacturing (CAD-CAM) workflow is available. However, information on the effect of a modified workflow using 3D laboratory scanning and/or cone beam computed tomography (CBCT) for monolithic zirconia crown fabrication is lacking. PurposeThe purpose of this in vitro study was to evaluate the effect of different scans on the marginal fit of CAD-CAM monolithic zirconia crowns fabricated by 3D laboratory scanning and CBCT. Material and methodsAn extracted maxillary left first molar was prepared and digitized by using a 3D laboratory scanner (D900; 3Shape A/S) (control group). The tooth was also scanned by CBCT (i-CAT; Imaging Sciences) to generate a second virtual 3D model (CBCTscan group). A tooth cast out of polyurethane (PU) (Zenotec Model; Wieland) was reproduced from the CBCT data by using a CAD software program (Dental System 2.6; 3Shape A/S) and milling machine (CORiTEC 550i; imes-icore) and further scanned by using the 3D laboratory scanner to generate a third virtual 3D model to represent a clinical scenario where a patient's cast is needed (PU3DLab group). A monolithic zirconia crown design (cement space: margin 40 μm, 1 mm above 70 μm) was used on the virtual models, and crowns were fabricated out of presintered zirconia blocks (ZenostarT4; Wieland) by using a 5-axis milling machine (CORiTEC 550i; imes-icore). The crowns were sintered (Sinterofen HT-S Speed; Mihm-Vogt), and the vertical marginal discrepancy (VMD) was measured by ×100-magnification microscopy. Measurements were made at 384 points in 3 groups of 16 specimens. The measurements for each specimen were averaged, and VMD mean values were calculated. The Kruskal-Wallis test was used for the statistical analysis (α=.05). The Mann-Whitney U test and Bonferroni adjustment were further used to compare the pairs (α=.017). ResultsThe mean VMD value was 41 μm (median: 38 μm) for the control group, 44 μm (median: 42 μm) for the CBCTscan, and 60 μm (median: 58 μm) for the PU3DLab. No significant difference was found between control and CBCTscan groups (P=.274). However, there was a significant difference between control and PU3DLab and CBCTscan and PU3DLab groups (P<.001). ConclusionsMarginal fit of the crowns fabricated by using the 3D laboratory scanner and through the direct use of CBCT was better than that of the crowns fabricated by using the workflow that combined the use of CBCT, PU cast, and 3D laboratory scanner. All tested protocols enabled the fabrication of monolithic zirconia crowns with a marginal discrepancy smaller than 120 μm.

New composites for neutron radiation shielding

A castable polyurethane (PUR) with soft segment made by polytetrahydrofuran polyol (or polytretramethylene ether glycol = PTMEG) derived from renewable sources was used as polymer matrix to prepare neutron shields. The PUR polymer matrix was filled with 20.4% of amorphous boron or with 20.9% by weight of hexagonal boron nitride (h-BN). The PUR composites were cast in foils 2 mm thick and tested as thermal neutron shields against reference unfilled PUR foils. The method of sandwitched copper wire activation till saturation was used for the determination of the neutron shielding effectiveness. Both the linear and massic attenuation coefficient of the two PUR composites were determined. Making 100 the linear attenuation coefficient μ of unfilled PUR, the μ value of 20.4% amorphous boron filled composite was found at 224 while that of 20.9% filled BN was found at 182. Making 100 the mass attenuation coefficient μ/ρ of the unfilled PUR the amorphous boron PUR filled composite was found at 311 while the BN filled PUR composite stopped at 178. Unfilled PUR and PUR composites were studied with FT-IR spectroscopy and DSC before and after neutron processing with a total dose of 1.5 × 1013 cm−2. No significant changes were detected neither in the FT-IR spectra nor in the DSC thermal behaviour confirming the excellent radiation resistance of PUR and its suitability as polymer matrix for neutrons and more in general radiation shielding.

Organogels containing immobilized shear thickening fluid and their composites with polyurethane elastomer

This article concerns investigation on immobilization of shear thickening fluids (STFs) in form of organogel obtained with the use of oligo(propylene glycol) diacrylate (PPGA) as a cross-linking monomer. The STF used was a suspension of nanosilica in oligo(propylene glycol). Organogel particles were prepared by dropwise addition of the STF containing PPGA into silicone oil followed by thermal cross-linking of the monomer. Organogel particles were used to prepare PUR-matrix composite. The rheological properties of organogels and composites were studied by oscillatory measurements. The measurements showed significant changes in internal structure of the samples, which are most likely connected with shear thickening. It was demonstrated that manufactured composites exhibited 20% higher impact absorption than that of cast polyurethane elastomer. Presented method of STF immobilization allows to obtain organogel particles that can be widely used for intelligent materials preparation due to their good stability and impact absorption ability.

Characterization and Neutral Atom Beam Surface Modification of a Clear Castable Polyurethane for Biomicrofluidic Applications

Polyurethanes (PU) are a broad class of polymers that offer good solvent compatibility and a wide range of properties that can be used to generate microfluidic layers. Here, we report the first characterization of a commercially available Shore 80D polyurethane (Ultraclear™ 480N) for biomicrofluidic applications. Studies included comparing optical clarity with Polydimethylsiloxane (PDMS) and using high-fidelity replica molding to produce solid PU structures from the millimeter to nanometer scales. Additionally, we report the first use of NanoAccel™ treatment in Accelerated Neutral Atom Beam (ANAB) mode to permanently roughen the surface of PU and improve the adhesion of breast cancer cells (MDA-MB-231) on PU. Surface energy measurements using Owens-Wendt equations indicate an increase in polar and total surface energy due to ANAB treatment. Fourier-transform infrared (FTIR) spectroscopy in attenuated total reflectance (ATR) mode was used to demonstrate that the treatment does not introduce any new types of functional groups on the surface of Ultraclear™ PU. Finally, applicability in rapid prototyping for biomicrofluidics was demonstrated by utilizing a 3D-printing-based replica molding strategy to create PU microfluidic layers. These layers were sealed to polystyrene (PS) bases to produce PU-PS microfluidic chips. Ultraclear™ PU can serve as a clear and castable alternative to PDMS in biomicrofluidic studies.

Dynamic response and fatigue life of Vacuum cast Polyurethane polymer material

The objective of this paper is to measure the dynamic response transmissibility and fatigue life of vacuum cast Polyurethane (PU) polymer material used in the construction of automotive lamps. Polymers used in automotive lamps, if mass produced, are injection moulded. For ultra-low volume production, however, the cost of tooling for these traditional manufacturing methods is often very high. Hence, alternative approaches such as Silicone Tool – Vacuum (STV) casting are used. The parts produced using alternative approaches may have inferior dynamic performance. The specimens for dynamic response and fatigue testing were cut-out from a vacuum cast polyurethane plate. An instrumented beam was mounted on a shaker table and using sine sweep base excitation the dynamic response was measured. Using measured acceleration, response transmissibility was calculated. The bending fatigue properties were measured on a vibration shaker using a 4-point bending based resonance test apparatus. A series of tests were carried out to obtain average performance parameters. The dynamic response shows nonlinearity, as expected of polymers, and a large variation in dynamic properties is observed. The obtained fatigue life curve shows significant scatter at 40% fatigue load level. The assessed fracture surface micrograph of the fatigued specimens at three load levels shows surface tear at 80% and 60% load levels. Overall, the Vacuum cast polyurethane shows less fatigue performance than the conventional polymers of automotive lamps.

Physical correlation between abrasive wear performance and scratch resistance in model polyurethane elastomers

Wear behaviors of a series of model cast polyurethane elastomers (CPU) under linear reciprocating sliding and fretting conditions were investigated and physically compared with their corresponding scratch behavior. It is found that the sliding wear and scratch damages of the model systems are both governed by abrasive wear mechanism, which involves tensile tear induced cracking along with material removal on the surface. The scratch resistance against tensile tear induced cracking/material removal of the model CPU systems correlates well with their abrasive wear performance, which can then be linked to their material properties, i.e., a higher tensile strength improves abrasive wear resistance. On the other hand, the fretting wear damage of the model systems is found to be dominated by adhesive-fatigue wear mechanism, and thus cannot be correlated with the scratch performance. Temperature rise measurement of the model CPU systems during wear was also performed to further understand the observed wear behaviors. The present study provides fundamental insights into understanding of complex abrasive wear behavior of polymers through their corresponding simpler scratch behavior.

The influence of different glycerine purities on chemical recycling process of polyurethane waste and resulting semi‐products

Chemical recycling is the most favourable recycling method due to the possibility of polyol recovery. This work is dedicated to the utilisation of crude glycerine and polyurethane waste. It aims at determining the impact of the use of glycerine from the production of biodiesel with various degrees of purity as a cleavage agent on the decomposition process of polyurethane foam. The influence of glycerine purity on the chemical structure of recycling products was analysed using Fourier transform infrared and 1H NMR spectroscopies and gel permeation chromatography. Hydroxyl and amine values were determined, and rheological measurements were performed. Glycerolysates showed minor structural differences due to the presence of amine groups and exhibited heterogeneous structure compared to original polyols. The ones obtained in decomposition using 84 and 99.5% glycerine had a lower viscosity below 0.45 Pa s at 50 °C and higher hydroxyl number of 183 and 220 mg KOH g−1, respectively, compared to the ones obtained with glycerine purity of 40 and 62% due to a different chemical structure. All of the products of decomposition were defined as non‐Newtonian fluids, where viscosity depended on the shear rate. Selected glycerolysates were used in the production of cast polyurethanes with satisfactory mechanical properties. © 2018 Society of Chemical Industry