Polyurethane Polymer Research Articles

A feasibility study on production and optimization of PVDF/PU polyblend nanofiber layers using expert design analysis

Different polymer blends are electrospun to produce nanofibers with novel combined features. In this study, the feasibility of combining polyurethane (PU) and polyvinilidine floride (PVDF) polymer was evaluated to produce an adequate nanoscale layer. This scale would increase the β-phase in PVDF; the lowest beads in the nanolayers, to achieve a smooth layer with more uniform strength. To manufacture PVDF/PU, the PVDF was combined with PU components for elastic behavior. Eighteen experimental design points were performed using Design-Expert software, based on electrospinning variables, including solution concentration, applied voltage, and the needle to collector distance. SEM study was carried out to assess the fiber diameter and the bead numbers to characterize the surface morphology of nanofibers. Chemical reactions between the two polymer components and the fibers inner structure were investigated through FTIR and XRD. According to the experiment design, 14% (wt) solution concentration, 18 kV voltage, and 24 cm distance between the needle tip and the collector were considered as the optimum conditions during electrospinning. FTIR test revealed that there was no chemical reaction between the TPU and PVDF components. Also, several β-phases were formed during the electrostatic drafting of a polyblend solution. Moreover, the XRD results showed that the PVDF/TPU composite had low crystallinity compared to pure TPU and PVDF. Finally, it was concluded that providing uniform nanofiber mats by applying the optimum condition during electrospinning would result in PVDF/TPU polyblend higher piezoelectric features nanofibers.

Study of the interaction of ionizing radiation in polyurethane polymer films as biomaterial

New materials are being studied and widely applied in the health area, highlighting biocompatible polymers as the most versatile. Among these polymers, we developed the methodology for the manufacture of Thermoplastic Polyurethane films for application as Biomaterials. The proposed sterilization by ionizing radiation requires the study and characterization of the material to evaluate possible losses or modifications, due to the influence that the radiation can cause in the polymer chains, losing the characteristics for the purpose used. Therefore, the present work evaluates, through chemical and physical-chemical characterization, the possible extension of the changes caused by the radiation in the polyurethane film. The material is produced in an environment with controlled temperature and humidity and subjected to increasing doses of gamma (15, 25 and 50 kGy), ethylene oxide and plasma as comparative techniques. The techniques DSC (Differential Scanning Calorimetry), TGA (Thermogravimetry), FTIR-ATR (Fourier Transform Infrared Spectrometry), SEM (Scanning electron microscopy) and OCT (Optical coherence tomography), have proved that the material, after applied the sterilization techniques, maintains its physical-chemical characteristics and does not suffer any modifications after the treatment.

Therapy with new generation of biodegradable and bioconjugate 3D printed artificial gastrointestinal lumen.

Objective(s):Many patients die due to vascular, gastrointestinal lumen problems, and coronary heart diseases. Synthetic vessels that are made of biodegradable-nanofiber polymers have significant properties such as proper biodegradability and efficient physical properties such as high strength and flexibility. Some of the best options for supporting cells in soft tissue engineering and design are applications of thermoplastic polyurethane polymer in the venous tissue. In this study, the first nanoparticle-reinforced polymeric artificial prosthesis was designed and tested to be used in the human body.Materials and Methods: In this study, artificial gastrointestinal lumen were fabricated and prepared using a 3D printer. To improve cell adhesion, wettability properties and mechanical stability of elastin biopolymer with magnetic nanoparticles (MNPs) as well as single-walled carbon nanotubes (SWCNT) were prepared as separate filaments. MNPs were made in 5–7 mm sizes and then examined for mechanical, biological, and hyperthermia properties. Then, the obtained results of the gastrointestinal lumen were simulated using the Abaqus software package with a three-branch. The results were evaluated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) for morphology and phase analysis. Results:The obtained results of the designed vessels showed remarkable improvement in mechanical properties of the SWCNT vessels and hyperthermia properties of the vessels containing the MNPs. The results of computational fluid dynamics (CFD) analysis showed that the artificial vessels had lower shear stress at the output. Conclusion:Five-mm MNP containing vessels showed noticeable chemical and biological properties along with ideal magnetic results in the treatment of thrombosis and vascular obstruction.

Printable, Down/Up‐Conversion Triple‐Mode Fluorescence Responsive and Colorless Self‐Healing Elastomers with Superior Toughness

AbstractExpanding the practical application range of self‐healing materials has become an important challenge for developing smart materials. Herein, the synthesis of printable, triple‐mode fluorescence responsive, and colorless self‐healing elastomers, formed by the combination of disulfide cross‐linked polyurethane (PU) polymers, carbon dots (CDs) down‐conversion fluorescence materials, and lanthanide ions doped upconversion fluorescence materials. The PU elastomers with optimal mechanical properties and good restorability (recover large strain of 500% after relaxation at room temperature (R.T.) for 2 h) are selected to incorporate CDs for fabricating fluorescence responsive elastomers (denoted as PU‐CDs). Significantly, the prepared PU‐CDs exhibit not only superior tensile strength and toughness (20.95 MPa and 85.13MJ m–3, respectively) than the previously reported R.T. self‐healing elastomers but also show good self‐healing properties and achieve blue fluorescence emissions under the ultraviolet excitation. Furthermore, a series of dual‐mode fluorescence patterns based on formulated core@shell structural upconversion inks are prepared on the transparent PU‐CDs elastomers by a directly screen‐printing method. Self‐healing and integrating a series of fluorescence patterns and damaged electrical patterns can also be accomplished successfully. The designed self‐healing materials provide new ideas and important guidance for developing and applying the next generation of smart materials.

The Impact of a CO2 Laser on the Adhesion and Mold Resistance of a Synthetic Polymer Layer on a Wood Surface

In the wood industry, laser technologies are commonly applied for the sawing, engraving, or perforation of solid wood and wood composites, but less knowledge exists about their effect on the joining and painting of wood materials with synthetic polymer adhesives and coatings. In this work, a CO2 laser with irradiation doses from 2.1 to 18.8 J·cm−2 was used for the modification of European beech (Fagus sylvatica L.) and Norway spruce (Picea abies /L./ Karst) wood surfaces—either in the native state or after covering them with a layer of polyvinyl acetate (PVAc) or polyurethane (PUR) polymer. The adhesion strength of the phase interface “synthetic polymer—wood”, evaluated by the standard EN ISO 4624, decreased significantly and proportionately in all the laser modification modes, with higher irradiation doses leading to a more apparent degradation and carbonization of the wood adherent or the synthetic polymer layer. The mold resistance of the polymers, evaluated by the standard EN 15457, increased significantly for the less mold-resistant PVAc polymer after its irradiation on the wood adherent. However, the more mold-resistant PUR polymer was able to better resist the microscopic fungi Aspergillus niger Tiegh. and Penicillium purpurogenum Stoll. when irradiation doses of higher intensity acted firstly on the wood adherent.

Controlling magnetic properties of 3D-printed magnetic elastomer structures via fused deposition modeling

Several methods have been used to optimize performance of magnetic elastomers by controlling the microstructure, such as magnetic annealing. Another way to introduce anisotropy is Fused Deposition Modeling (FDM), which has been shown to manipulate the magnetic anisotropy of rigid printed parts. However, the use of flexible composite materials has not yet been explored due to additional processing challenges. The primary goal of this study is to demonstrate tunable anisotropy of these materials via 3D printed structures without post-processing as a viable means to tune the performance of magnetic elastomer materials. Here, FDM structures were printed with thermoplastic polyurethane (TPU) polymer and either iron, carbonyl iron, or magnetite particulate. In order to determine the relative effect of different parameters on the magnetic properties, a series of samples were printed combining each material type with different aspect ratios, infill percentages, and infill orientations. A Vibrating Sample Magnetometer (VSM) was used to obtain magnetic hysteresis loops in order to compare the magnetic susceptibility between samples. Results demonstrated that FDM provides a method of achieving the directional signature of magnetic annealing without requiring any post-processing; instead, this manifests through the anisotropy of the part’s internal structure. As such, this concept is referred to as infill magnetic annealing (IMA). These variables were found to form a continuum of tunable magnetic responses. Additionally, the chosen particulate transfers its magnetic signature to the composite material. Overall, the highly customizable and nuanced characteristics of 3D-printed magnetic elastomer structures will allow for its application in a broad range of emerging magneto-mechanical applications such as magnetic actuation and soft robotics.

Facile preparation of light‐weight biodegradable and electrically conductive polymer based nanocomposites for superior electromagnetic interference shielding effectiveness

AbstractHarmful electromagnetic radiations that are generated from different electronic devices could be absorbed by a light weight and mechanically flexible good electromagnetic interference (EMI) shielding polymer nanocomposite. On the other hand, different electronic wastes (“e‐wastes”) which are generally polymer building materials generated from wastes of dysfunctional electronic devices are not naturally biodegradable. Our recent effort has been employed to produce bio‐degradable EMI shielding polymer nanocomposite. For that purpose, we had prepared a 50:50 ratio polylactic acid/thermoplastic polyurethane polymer nanocomposite by mixing the conducting carbon black with the blend following the facile and industrially feasible solution mixing method. Morphological characterizations by scanning electron microscopy and transmission electron microscopy analysis revealed the co‐continuous morphology of the neat blend as well as polymer nanocomposites with the preferential distribution of conductive filler on a particular polymer phase. The polymer nanocomposites gave good mechanically with improved thermal properties. We got EMI shielding effectiveness around −27 dB with a low percolation threshold at around 30 wt% filler loading in the polymer nanocomposite at the X‐band frequency domain (8.2–12.4 GHz). Later we had studied the biodegradability of the PLA/TPU along with their composites (TXPXCX) by employing the respirometry method and got a satisfactory result to ensure their biodegradability.

Smart Nanocomposite Nonwoven Wearable Fabrics Embedding Phase Change Materials for Highly Efficient Energy Conversion-Storage and Use as a Stretchable Conductor.

Flexible and intelligent electronics are highly demanded in wearable devices and systems, but it is still challenging to fabricate conductive textiles with good stretchability, multifunctionality, and responsiveness to multistimuli. Therefore, kinds of smart conductive fabrics with high stretchability and thermal properties, good washability, excellent shape stability, rapid responsiveness to external stimuli (e.g., electrical and photonic), and outstanding energy conversion and storage properties were designed and prepared. The nonwoven smart fabrics were fabricated by electrospinning of a solution of multiwalled carbon nanotubes (MWCNTs)/lauric acid (LA)/thermoplastic polyurethane (PU) and dip-coating conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) on the obtained nanofibers. The smart textiles showed tunable temperature and phase change enthalpy that responded to external stimuli such as electrical voltage, infrared light, and sunlight. At the same time, they realized the storage and conversion of energy reversibly with a high efficiency. The elastic fabrics could also be used as a stretchable conductor in a range of deformation. The integrative functions of the smart fabrics promise them great potential in wearable systems and intelligent protective garments.

Polyurethane Versus Chitosan-Based Polymers Nasal Packs After Functional Endoscopic Sinus Surgery: A Prospective Randomized Double-Blinded Study.

Different packing materials are applied to the nose at the end of surgery to maintain drainage and sinus ventilation of the paranasal sinuses and avoid some complications such as bleeding, infection, crustations, adhesions in the middle meatus and lateralization of the middle turbinate. The study aims to compare the clinical outcomes of two absorbable packing materials, the synthetic polyurethane, and the naturally occurring Chitosan-based polymers (CBP) nasal packs, after functional endoscopic sinus surgery. Fifty patients with bilateral chronic rhinosinusitis with nasal polypi were operated with 100 surgical cavities. At the end of the surgery, one side was randomly packed with synthetic polyurethane and the opposite side with CBP nasal pack. Measure their outcomes at week 1, 2, 4, 8 and 12 as the presence of remnants materials in the middle meatus, crustations, adhesions, bleeding, granulations, infection, and general satisfaction of patients. CBP nasal pack shows a statistically significant advantage only in the first two weeks as regard remnants material, crusting and bleeding. All over the 12 weeks, there was no statistically significant difference between the two types of packs as regard granulations, adhesions and infection. In the first month, eight patients of the CBP group experienced bad smell and two patients had watery rhinorrhea as adverse reaction without a statistically significant difference. Patients were generally satisfied without a statistically significant difference between the two types of packs. Synthetic polyurethane and Chitosan-based polymers nasal packs are safe and efficient regarding; the mucosal healing, bleeding control, and the overall satisfaction of patients. The CBP showed a higher statistically significant advantage in the first two weeks only regarding the amount of the retained material, crusting as well as bleeding. Patients packed with CBP experienced fish-like smelly odor and watery rhinorrhea but there is no statistically significant difference.

Interface Bonding Properties between Nonwater Reaction Polyurethane Polymer Materials and Concrete

The concentric pushing method was used to study the bonding properties between polymer and concrete. This paper studied the influence of polymer density, environmental temperature, and moisture content of concrete between polymer and concrete on the bond strength. The results indicated that the bond failure of specimens occurred mainly when the polymer was pushed out. Furthermore, increasing the polymer density increases the bond strength at the polymer‐concrete interface but decreases as the moisture content of the concrete increases. The environmental temperature affects the curing time, and the bond strength increases with increasing temperature. Under the same condition, the bond strength was influenced by the roughness of the interface. This study provides references for the construction design and enhances polymer materials and matrix application for repairing cracks in concrete dams.

Silane Terminated Prepolymers: An Alternative to Silicones and Polyurethanes

Silane terminated prepolymers for adhesives, sealants and coatings are of great industrial importance. They are very important because of their low toxicity over polyurethanes, silicones, and solvent-based products. Hence, many pieces of literature which deal with the synthesis, properties and applications of this Silane terminated polymers hybrid system exist. Silylated polyether (MS polymers) and Silylated Polyurethane Polymers (SPUR) are the bases for numerous sealants, adhesives and coatings used worldwide. A hybrid system mixed with organic-polyurethane proportion and inorganic-alkoxysilane proportion combines the benefits of conventional polyurethane and silicone-based products. This article reviews the chemistry of MS polymers and SPUR and their advantages and disadvantages in silyl terminated prepolymer-based adhesives, sealants and coatings as well as provides information on different end applications.

Electrochemically Stable Poly (Vinylidene Fluoride)-Polyurethane Polymer Gel Electrolytes with Polar β-Phase in Lithium Batteries

The β-phase in polyvinylidene fluoride (PVDF) exhibits superior dielectric properties as compared to α-phase, with ionic conductivity in liquid electrolytes up to one magnitude higher than that of α-phase, providing excellent ion transportation performance when applied as polymer gel electrolytes (GPEs). However, the strong polarization effect affects the electrochemical stability of GPEs. To improve the electrochemical stability while maintaining high ionic conductivity, PVDF and PU are selected to be co-blended. Porous polymer membranes containing polar β phase are prepared by solution-casting phase separation, and then swollen and activated in the electrolyte to obtain PVDF-PU composite GPEs. The results show that PVDF0.8-PU0.2 GPE exhibits an ionic conductivity of 8.81 × 10-4 S cm-1 at room temperature and 1.88 × 10-3 S cm-1 at 65°C (the polyether segment in PU starts to melt). Li+ transference numbers (~ 0.84), electrochemical oxidation limit (~ 4.3 V) and charge-discharge performance satisfy the commercial requirements. Coulombic efficiency (~ 99%) and capacity retention (~ 96%) indicate that this GPE promises to be commercially available.

Experimental Study on the Mechanical Properties of the Fiber Cement Mortar Containing Polyurethane

Polymer is a kind of high molecular elastic material. The polymer cement mortar composite material formed by mixing it with cement mortar has the advantages of light weight, high strength, and good durability compared with traditional mortar materials. The effect of polyurethane polymer content on mechanical properties and microstructure of polyvinyl alcohol (PVA) fiber cement mortar was studied by compressive test, flexural test, and SEM analysis. The test results show that as the content of polyurethane increases, the compressive strength gradually decreases, and the flexural strength gradually increases. The addition of polyurethane helps to optimize the microstructure of PVA mortar, improve the compactness of the material, and enhance the bending resistance of the mortar. The mechanical properties of materials obtained from the experiment can provide references for engineering applications.

Molecular Rotors with Aggregation-Induced Emission (AIE) as Fluorescent Probes for the Control of Polyurethane Synthesis

In this work, the use of fluorescent molecular rotors such as 9-(2,2-dicyanovinyl)julolidine (DCVJ) and 2,3-bis(4-(phenyl(4-(1,2,2-triphenylvinyl) phenyl)amino)phenyl)fumaronitrile (TPETPAFN) was proposed for the real-time monitoring of polyurethane (PU) formation in a solution of dimethylacetamide starting with 4,4′-methylenediphenyl diisocyanate (MDI) and different polyethylene glycols (PEG400 and PEG600) as diols. Notably, relative viscosity variations were compared with fluorescence changes, recorded as a function of the polymerization progress. The agreement between these two parameters suggested the innovative use of a low-cost fluorescence detection system based on a LED/photodiode assembly directly mountable on the reaction apparatus. The general validity of the proposed experiments enabled the monitoring of polyurethane polymerization and suggested its effective applications to a variety of industrial polymers, showing viscosity enhancement during polymerization.

Investigation of Temperature Effect on Strength Properties of Polyurethane-Treated Sand

AbstractThis study focuses on the shear-strength properties of polyurethane polymer–treated sand stored at different temperatures. The triaxial test was performed at unconsolidated and undrained co...

Polyurethane polymers cured via azide-alkyne cycloaddition

Conventional thermoset polyurethane polymers are crosslinked by reaction of a polyisocyanate compound with a polyol. Herein are described alternative crosslinking polyurethanes (ACPUs) for coatings and related applications that cure by azide-alkyne cycloaddition. Commercial polyisocyanate resins including allophanate, isocyanurate, and biuret types were reacted with propargyl alcohol or 2-hydroxyethyl propiolate to yield polyurethane resins with terminal alkyne functionality. Various polyols, including polyether, polyester, and polyacrylic types were modified to convert their hydroxyl functionality to azide functionality. The best performance was obtained with an alkyne component based on Desmodur XP 2580 and an azidated polyol based on Setalux D A 870 BA. Clear, high-solids, two-component coatings were prepared with and without Cu(I) catalyst. The coating performance properties including pencil hardness, MEK double rubs, and glass transition temperature (Tg) were comparable to a conventional polyurethane control coating made from the precursor resins. Azide-alkyne formulations in the presence of copper catalyst exhibited faster curing kinetics than the polyurethane control. Propiolate-based systems showed significantly faster curing kinetics compared to the propargylated systems with or without Cu(I) catalyst. A study of azide:alkyne stoichiometry surprisingly showed that higher crosslink density of ACPUs may be obtained by formulating with 35–50 mol% excess azide component.

Permeation of water, ammonia and dichloromethane through graphene oxide/polymeric matrix composite membranes

The permeation of polar molecules (water and ammonia), non-polar dichloromethane and a mixture of ammonia and dichloromethane through graphene oxide (GO)/polymer matrix composite membranes was investigated. Results indicated that a hydrophilic poly(2-acrylamido -2 -methyl propane sulfonic acid) (PAMPS) based membrane had the highest permeability for water and ammonia due to the high hydrophilicity of the polymer matrix while a hydrophobic polyurethane (PU)-based membrane had the best permeation performance for dichloromethane and the worst performance for water and ammonia. Adding the GO to PU or PAMPS polymers increases the negative charge due to the negatively charged nature of GO caused by its oxygen-containing functional groups, which increases the amounts of absorbed water and ammonia due to the positive charge of the hydrogen atoms in these two molecules.

Microbial oversecretion of (R)-3-hydroxybutyrate oligomer with diethylene glycol terminal as a macromonomer for polyurethane synthesis

Poly((R)-3-hydroxybutyrate) (P(3HB)) is a polyester that is synthesized and accumulated in many prokaryotic cells. Recently, a new culture method for the secretion of the intracellularly synthesized (R)-3-hydroxybutyrate oligomer (3HBO) from recombinant Escherichia coli cells was developed. In this study, we attempted to produce microbial 3HBO capped with a diethylene glycol terminal (3HBO-DEG) as a macromonomer for polymeric materials. First, we prepared recombinant E. coli strains harboring genes encoding various polyhydroxyalkanoate (PHA) synthases (PhaC, PhaEC or PhaRC) that can incorporate chain transfer (CT) agents such as DEG into the polymer's terminal and generate CT end-capped oligomers. To this end, each strain was cultivated under DEG supplemental conditions, and the synthesis of 3HBO-DEG was confirmed. As a result, the highest secretory production of 3HBO-DEG was observed for the PHA synthase derived from Bacillus cereus YB-4 (PhaRCYB4). To evaluate the usability of the secreted 3HBO-DEG as a macromonomer, 3HBO-DEG was purified from the culture medium and polymerized with 4,4′-diphenylmethane diisocyanate as a spacer compound. Characterization of the polymeric products revealed that 3HBO-based polyurethane was successfully obtained and was a flexible and transparent noncrystalline polymer, unlike P(3HB). These results suggested that microbial 3HBO-DEG is a promising platform building block for synthesizing polyurethane and various other polymers.

Multi-scale coarse-grained molecular dynamics simulation to investigate the thermo-mechanical behavior of shape-memory polyurethane copolymers

Shape-memory polyurethanes (SMPUs) are smart semi-crystalline polymers with heat-induced shape memory. The segmented SMPU copolymer simulated in this study consisted of an isocyanate (hard segment) that acts as a netpoint to stabilize the network, and a polyol (soft segment) that, owing to polymer crystallization, acts as a molecular switch. The ratio of hard to soft segments is a determining factor in the thermo-mechanical behavior and shape-memory performance of SMPU copolymers. However, the limitations of the scale of the conventional all-atom molecular dynamics simulation makes it difficult to observe mesoscale phenomena such as the phase-segregated morphology and polymer crystallization. To address this problem, we have developed a coarse-grained (CG) molecular dynamics (MD) model with fewer degrees of freedom by treating multiple atoms as a single bead. We derived the CG intra- and inter-bead potentials of the CG MD model such that the structural and thermodynamic properties would be identical to those of the all-atom reference model. Consequently, polymer crystallization was verified to occur at room temperature with the developed CG potentials. We subsequently investigated the effects of hard-segment content (HSC) on the thermal transition at SMPU melting temperature. We also investigated the influence of HSC on the thermo-elastic behavior and shape-memory properties of SMPU copolymers by simulating a 4-step thermo-mechanical cycle. The results revealed that the microstructure significantly affects macroscopic shape-memory behavior. We expect that this study will be used to improve the prediction and design of the thermo-mechanical behavior of segmented polyurethane or other semi-crystalline polymers.

Biomimetic Polyurethane 3D Scaffolds Based on Polytetrahydrofuran Glycol and Polyethylene Glycol for Soft Tissue Engineering.

In this study, a novel polyurethane porous 3D scaffold based on polyethylene glycol (PEG) and polytetrahydrofuran glycol (PTMG) was developed by in situ polymerization and freeze drying. Aliphatic hexamethylene diisocyanate (HDI) as a nontoxic and safe agent was adopted to produce the rigid segment in polyurethane polymerization. The chemical structure, macrostructure, and morphology—as well as mechanical strength of the scaffolds—were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), and tensile tests. The results show that the HDI can react mildly with hydroxyl (–OH) groups of PEG and PTMG, while gas foaming action caused by the release of CO2 occurred simultaneously in the reactive process, resulting in a uniform porous structure of PU scaffold. Moreover, the scaffolds were soaked in water and freeze dried to obtain higher porosity and more interconnective microstructures. The scaffolds have a porosity of over 70% and pore size from 100 to 800 μm. The mechanical properties increased with increasing PEG content, while the hydrophilicity increased as well. After immersion in simulated body fluid (SBF), the scaffolds presented a stable surface structure. The gas foaming/freezing drying process is an excellent method to prepare skin tissue engineering scaffold from PTMG/PEG materials with high porosity and good inter connectivity.