Characterization Of Polyurethane Research Articles

Preparation and Characterizations of Silver Incorporated Polyurethane Composite Nanofibers via Electrospinning for Biomedical Applications

We report on the preparation and characterization of polyurethane (PU) nanofibers containing silver (Ag) nanoparticles were synthesized by using electrospinning. Two different approaches were adopted to incorporate the Ag nanoparticles in to PU nanofibers. In the first approach, a homogeneous solution of 10 wt% PU containing silver nitrate was electrospun to obtain PU-Ag composite nanofibers. And in the second approach, the pristine PU nanofibers were initially electrospun and then Ag nanoparticles were coated via wet casting method. The surface morphology, structure, bonding configuration, optical and thermal properties of the resultant products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, UV-vis spectroscopy and thermogravimetric analysis. The antibacterial activity was tested against four common food borne pathogenic bacteria, namely, Staphylococcus aureus, Escherichia coli, Salmonella typhimurium and Klebsiella pneumoniae by minimum inhibitory concentration (MIC) method. Our results demonstrated that no bactericidal activity was detected for the pristine PU nanofibers. Further on, antibacterial activity was observed to be more pronounced for the composite nanofibers which were attributed to the presence of Ag nanoparticles in the composite nanofibers. Overall, this study demonstrates the fabrication of cheap, stable and effective nanofiber mats with excellent antimicrobial activity that can be utilized to inhibit the microbial growth associated with food stuff.

Polyurethanes from Isosorbide‐Based Diisocyanates

Benign building blocks: Stereochemically pure diisocyanates were prepared on a multigram scale from succinic anhydride and isosorbide or isomannide. Characterization of polyurethanes that were produced from these diisocyanates revealed low polydispersity, high thermal stability, and stereochemistry-dependent morphology. If biobased succinic anhydride is used, then no stoichiometric petroleum-derived reagents are required in the synthesis of these materials.

Polyurethane-based drug delivery systems

Polyurethanes (PUs) are formed by a reaction between isocyanates and diols to yield polymers with urethane bonds (-NH-COO-) in their main chain. A great variety of building blocks is commercially available that allows the chemical and physical properties of PUs to be tailored to their target applications, particularly for the biomedical and pharmaceutical fields. This article reviews the synthesis and characterization of PUs and PU-copolymers, as well as their in vitro and in vivo biodegradability and biocompatibility. Particular emphasis is placed on the use of PUs for the controlled release of drugs and for the (targeted) delivery of biotherapeutics.

Multipurpose polyurethane antimicrobial metal composite films via wet cast technology

We report on the preparation and characterization of polyurethane (PU) film containing metal particles and their antibacterial activity. The utilized PU films containing metal particles were prepared by a simple solvent evaporation method. The surface morphology, structure and optical properties of the resultant products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and UV-vis spectroscopy. The antibacterial activity was tested against four common food borne pathogenic bacteria, namely, Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, and Klebsiella pneumoniae by minimum inhibitory concentration (MIC) method. Our results demonstrated that no bactericidal activity was detected for the pristine PU film. Further on, antibacterial activity was observed to be more pronounced for the PU films containing metal particles which were attributed to the presence of metal in the PU thin films. Overall, this study demonstrates the fabrication of cheap, stable and effective material with excellent antimicrobial activity that can be utilized to inhibit the microbial growth associated with food stuff. Open image in new window

Antibacterial ciprofloxacin HCl incorporated polyurethane composite nanofibers via electrospinning for biomedical applications

Abstract We report on the preparation and characterization of polyurethane (PU) composite nanofibers by electrospinning. Two different approaches were adopted to obtain the PU composite nanofibers. In the first approach, a homogeneous solution of 10 wt% PU containing ciprofloxacin HCl (CipHCl) drug was electrospun to obtain PU/Drug composite nanofibers. And in the second approach, the PU with ciprofloxacin HCl drug and ceramic hydroxyapatite (HA) particles were electrospun to obtain the PU/Drug and PU/Drug/HA composite nanofibers. The surface morphology, structure, bonding configuration, optical and thermal properties of the resultant products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and UV–vis spectroscopy. The antibacterial activity was tested against common food borne pathogenic bacteria, namely, Staphylococcus aureus , Escherichia coli by the minimum inhibitory concentration (MIC) method. Our result results demonstrate that these composite nanofibers possess superior characteristics which can utilized for variety of applications.

Synthesis and characterization of polyurethane–urea microcapsules containing galangal essential oil: statistical analysis of encapsulation

Galangal essential oil (GEO) is known to possess antimicrobial activity (e.g. against Staphylococcus aureus). A way to increase oil lifetime in plants is encapsulation in polyurethane–urea (PUU) microcapsules. In this study, PUU microcapsules with GEO were synthesized by interfacial polymerization at oil–water interface in oil–water emulsion. A statistical analysis of the microcapsule size was successfully applied for characterization of the encapsulation process. Using the model of reversible aggregation, it was shown that the process of encapsulation takes place in the conditions of thermodynamic control. The polymerization conditions (agitation rate in the range 2000–10 000 rpm/min) are the key factors that affect the mean microcapsule size of primary capsules formed during encapsulation. Two complementary processes were determined the mean capsule size during a transformation of these primary microcapsules: break-up and coalescence of oil droplets in the oil-in-water emulsion. The agitation rate does not influence the coalescence of the oil droplets, but the threshold value of agitation speed (in this system 4000 rpm/min) does exist and that is what strongly increases break-up of oil droplets. The higher agitation rate resulted in smaller size of microcapsules (mean diameter decreasing from 5.6 to 4.9 µm for primary capsules and from 13.8 to 9.8 µm for secondary capsules) and with a narrower size distribution. The last mode of encapsulation allows the more effective use the shell material for encapsulating of larger amount of oil.

Characterization of Polyurethanes from Vegetable Oils by TG/DTG, DMA and FT‐IR

AbstractSummary: Given the demand for renewable resources by industries and the promising potential of vegetable oils for this purpose, the current study aims to evaluate the properties of polyurethanes (PUs) obtained from linseed (Linum usitatissimun L.) oil (PULO) and passion fruit (Passiflora edulis Sims f. flavicarpa Degener) oil (PUPFO), by thermogravimetry (TG), derivative thermogravimetry (DTG), dynamic mechanical analysis (DMA) and Fourier transform infrared (FT‐IR). The results showed that PULO is more thermally stable than PUPFO, suggesting that the first presents more urethane linkages. The DMA analysis showed that both prepared PUs have uneven porosity, causing the loss of the elastic plateau. It was found as well that PUPFO exhibits a higher value of glass transition temperature (Tg), signifying that it seems to be more crosslinked than PULO. The analysis by FT‐IR showed that the curing reaction of PUs was successful.

Microencapsulation of 2‐octylcyanoacrylate tissue adhesive for self‐healing acrylic bone cement

Here, we report the first phase of developing self-healing acrylic bone cement: the preparation and characterization of polyurethane (PUR) microcapsules containing a medical cyanoacrylate tissue adhesive. Capsules were prepared by interfacial polymerization of a toluene-2,4-diisocyanate-based polyurethane prepolymer with 1,4-butanediol to encapsulate 2-octylcyanoacrylate (OCA). Various capsule characteristics, including: resultant morphology, average size and size distribution, shell thickness, content and reactivity of encapsulated agent, and shelf life are investigated and their reliance on solvent type and amount, surfactant type and amount, temperature, pH, agitation rate, reaction time, and mode of addition of the oil phase to the aqueous phase are presented. Capsules had average diameters ranging from 74 to 222 μm and average shell thicknesses ranging from 1.5 to 6 μm. The capsule content was determined via thermogravimetric analysis and subsequent analysis of the capsules following up to 8 weeks storage revealed minimal loss of core contents. Mechanical testing of OCA-containing capsules showed individual capsules withstood compressive forces up to a few tenths of Newtons, and the contents released from crushed capsules generated tensile adhesive forces of a few Newtons. Capsules were successfully mixed into the poly(methyl methacrylate) bone cement, surviving the mixing process, exposure to methyl methacrylate monomer, and the resulting exothermic matrix curing.

Synthesis and characterization of polyurethanes containing glucose for selective determination of epinephrine in the presence of a high concentration of ascorbic acid

AbstractPolyurethane (PU) films were prepared from glucose, ethylene glycol and diphenylmethane diisocyanate and used to construct a novel polymer electrode for the detection of epinephrine (EP) in the presence of a high concentration of ascorbic acid (AA). The NCO:OH molar ratio was kept constant at 1 and the saccharide content was varied. The PUs were characterized using Fourier transform infrared spectroscopy, differential scanning calorimetry and differential thermal and thermogravimetric analyses, with intrinsic viscosity and adhesive properties also being evaluated. The PUs exhibited high glass transition temperature, good thermal stability and good adhesive properties. The incorporation of saccharides into the PU structure resulted in a higher crosslinking density and a higher content of hard segments. Medium‐ to high‐molecular‐weight polymers were obtained, with inherent viscosities near or higher than 0.98–2.14 dL g−1. The solubility of the PUs was much better than that of aromatic PUs. The modified polymer electrodes were then used to determine EP in the presence of a high concentration of AA using differential pulse voltammetry. From the amperometric results for the PU electrode, it is concluded that a PU film containing 5 wt% glucose can be used as a membrane for EP detection in the presence of a large concentration of AA, because of its strong adherence to the electrode surface, easy preparation, chemical stability, selectivity and very high statistical confidence (R = 0.9994). © 2012 Society of Chemical Industry

Preparation and Characterization of Polyurethanes from Spinifex Resin Based Bio-Polymer

In this paper we explore the preparation of polyurethanes from spinifex resin biopolymer. Polyurethanes were prepared by both one-shot and pre-polymer (two step) processes. Attenuated total reflection—Fourier transform infrared analysis revealed urethane bond formation in both processes, and the peak intensity for N–H stretching was more sharp when the network was prepared by the pre-polymer method. Gel permeation chromatography revealed that the molecular weight of synthesized polyurethane increased with respect to the resin starting material, and the molecular weight was further increased when polyurethane was synthesized by the pre-polymer method. The glass transition temperature was also increased for the polyurethanes as compared with the starting resin. Thermo-gravimetric analysis revealed that the thermal stability of the PU-spinifex resin was reduced at intermediate temperatures due to the urethane bond formation. However, thermal degradation properties were superior at higher temperatures due to the cyclization degradation reaction of spinifex-polyurethane.

Thermal Characterization of Polyurethane from Castor Oil Reinforced Sugarcane Straw Composites

The development in the area of natural-fibre-reinforced composites has greatly increased in recent years. Using castor oil polyurethane (PU) as matrix for composites reinforced with lignin and cellulose from sugarcane straw is in tune with economical and environmental interests. The aim of this work was the thermal degradation study of castor oil-polyurethane composites reinforced with cellulose from sugarcane straw. For the obtainment of cellulose, sugarcane straw was pretreated by steam explosion, followed by a delignification with NaOH. For the production of the PU, the polyol (castor oil) to diisocyanate mass ratio was 1.5:1.0. Reinforcement of the matrix was done changing the concentration of cellulose fibres (5,10,15,20% w/w). Thermogravimetric analysis of the materials was carried out. The results obtained showed that the process of decomposition of the matrix occurs in one step, while for the composites it occurs in two steps. The addition of reinforcement in the matrix basically did not change the thermal stability of the composite.

Synthesis and characterization of polyurethane – Treated waste milled light bulbs composites

In this study, polyurethane (PU)-milled light bulbs glass composites were synthesized and characterized. The main interest in this study that the polyurethane derived from renewable resources and waste glass are used to form the composite constituents as an attempt towards environmental preservation. Castor oil and polymeric diphenyl methane di-isocyanates (PMDI) were used in NCO/OH ratio=2 for polyurethane synthesis. Milled glass with average particles size less than 300μm were prepared based on waste light bulbs. Silane A1100 (as a compatibilizer) was used in order to improve the value of recycled milled glass beads. The adhesion force between polyurethane matrix and milled glass beads was evaluated using mechanical and physical tests. Scanning electron microscopy (SEM) was used to investigate dispersion and fracture surfaces of the composites. Infrared spectrum (IR), Differential scanning calorimetry (DSC) behavior, and Thermogravimetric analysis (TGA), were employed to characterize the developed composite materials in details. Chemical resistance (weight change, thickness swelling) was measured in oil, water and dilute acetic acid media. Furthermore, tensile strength and hardness were investigated using universal materials testing machines. A slight increase in the hardness values was reported along with the increasing in particulate fillers loading up to 10% as a considerable improvement has been detected when milled glass reached 20%. The DSC analysis showed the presence of treated milled glass beads influences the thermal behavior of pure PU and composites. This can be attributed to enhancing the physical bonding between PU and silica group. Waste milled glass showed a significant effect on the thermal degradation of the composites in the presence of coupling agent. Further analysis on the tensile strength of the composites indicated that such improved mechanical properties may be attributed to the presence of coupling agent.

Preparation and characterization of polyurethane foam/activated carbon composite adsorbents

A polyurethane foam (PU)/activated carbon (AC) composite was prepared by adding granular AC during the synthesis of PU foam, and subsequent carbonization. Nitrogen adsorption–desorption isotherms and scanning electron microscopy were used to ascertain the pore structure and surface morphology of the samples. The prepared composite foams possess well-developed open cell structures. Under the conditions investigated, a higher carbonization temperature promoted development of porous structures. Thermogravimetric and derivative thermogravimetric analyses revealed the thermostability of the PU foam precursor/AC composites. The adsorption performance of the composites was evaluated using phenol, iodine and methylene blue (MB) as model compounds. A PU foam/AC composite with a maximum specific surface area of 655.0 m2/g, maximum iodine number of 525.2 mg/g, and maximum adsorption capacity of MB and phenol of 100 and 66.5 mg/g, respectively, was achieved.

Characterization of Polyurethanes Containing Different Chain Extenders

Several waterborne polyurethane adhesives containing different chain extenders were prepared by using the acetone process. Concretely, the polyurethane dispersions were synthesized by the prepolymer method based on three chain extenders: two diols and one diamine: 1,4-butanediol, 1,6-hexanediol and hydrazine. The adhesive solutions were characterized by flow rheology, pH measurements, particle size and solids content. The solid adhesive films were characterized by plate-plate rheology, dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). The adhesion properties were measured from T-peel test of leather/polyurethane adhesive/SBR rubber joints. As a result, the chosen chain extender influences significantly the polyurethane synthesized properties, specially determines the crystallinity of the polymer, as well as thermal and adhesive properties. Particularly, the molecular weight of the chain extender determines the structure of the synthesized polyurethanes.

Synthesis and Characterization of Polyurethanes Based on Oligo(ϵ-caprolactone) Prepared by Free-Metal Method

The oligoester diols were synthesized via ring-opening polymerization of ϵ-caprolactone in the presence of creatinine and diethylene glycol or 1,4-butanediol as initiator systems. Thus, obtained oligomers were successfully used in the synthesis of segmented polyurethanes. The oligoester diols (poly(ϵ-caprolactone) and dihydroxy(polyethylene adipate)) were reacted with 4,4′-methylenebis(phenyl isocyanate) in the presence of 1,4-butanediol as the chain extender to obtain polyurethanes. The physical and mechanical properties of polyurethanes were determined. The structures of the oligoesters and polyurethanes were elucidated by means of NMR, IR and MALDI-TOF MS studies.

Synthesis and characterization of polyurethane-block-poly(2-hydroxyethyl methacrylate) hydrogels and their surface modification to promote cell affinity

Physically crosslinked hydrogels based on poly(2-hydroxyethyl methacrylate) (PHEMA) and polyurethane macroiniferter (PUMI) were prepared. The synthesis of polyurethane- block-poly(2-hydroxyethyl methacrylate) (PU-b-PHEMA) was verified by spectroscopic analyses. Due to the low fibronectin adsorption from culture media, cell attachment on PU-b-PHEMA surface was poor compared with the PUMI control. To improve the cell affinity of PU-b-PHEMA, fibronectin was conjugated via surface hydroxyl groups. These biomimetic PU-b-PHEMA hydrogel surfaces were tested for tissue engineering applications. A short-term cell culture study revealed that, compared with the unmodified PU-b-PHEMA, fibronectin-conjugated PU-b-PHEMA hydrogel showed more uniform and dense cell attachment and spreading, indicating a potential use for tissue engineering applications.

Finite Deformation and Viscoelasticity Modeling and Test

A model is considered as a representation of compressive and incompressive elastomeric materials in nonlinear behavior. Applications are done on one hand by the characterisation of polyurethane 60 - 65 shore A (a compressive material), and on the other hand by the characterisation of polyurethane 95 shore A and fluorosilicone, both incompressive materials. The Rivlin energy expression is used for incompressive materials. Linear vibrations superposed on static large deformation, which is most often the real using state of elastomeric materials, are studied. Relative experimental and numerical results presented show good predictions.

Synthesis and characterization of polyurethane

Polyurethane was synthesized by the copolymerization with isocyanate and diols. The structure and properties of the copolymers were characterized by infrared spectrometer (IR), differential scanning calorimetry (DSC) and thermogravimetry (TG). The rabbit blood samples was dripped on the polyurethane, which was prepared by drying and die, and the contact angle was measured by contact angle measurement, then infiltration phenomenon was observed by electron microscopy. The results showed that the contact angle of blood samples and polyurethane was decreased with increasing time, and the platelets on the polyurethane would gradually increase and more rules. Thus the polyurethane coating had good hydrophilic property and anticoagulant activity.

Synthesis and characterization of polyurethane cationomer/MMT hybrid composite

AbstractBACKGROUND: The development of polymeric nanocomposites incorporating intercalated or exfoliated layered silicate clays into the organic matrix has been substantially motivated by the significant improvements induced by the presence of the inorganic component. Moreover, understanding and controlling the dispersion of inorganic layers into segmented polyurethane matrices by means of ionic interactions, and exploiting these interactions to enhance physicomechanical behaviour, could be of great interest in the field of polymer nanocomposites.RESULTS: New cationic polyurethane elastomers were prepared starting from poly(butylene adipate)diol (Mn = 1000 g mol−1), 4,4′‐diphenylmethane diisocyanate, 1,4‐butanediol and N‐methyldiethanolamine or N,N′‐β‐hydroxyethylpiperazine, used as potential quaternizable moieties. The characterization of the polymers was achieved using specific analyses employed for the macromolecular samples (Fourier transform infrared and 1H NMR spectroscopy, thermogravimetric analysis (TGA), gel permeation chromatography). An extension of our research on polymers reinforced with organically modified montmorillonite (OM‐MMT) in order to prepare hybrid composites with improved properties was performed and the resulting materials were characterized using TGA, X‐ray diffraction, atomic force microscopy and scanning electron microscopy. Also, the mechanical properties of the cationic polyurethane/OM‐MMT composites were investigated in comparison with the pristine ionic/non‐ionic polymers and their composites containing non‐ionic polymer blended with OM‐MMT or ionic polymer and unmodified MMT.CONCLUSION: The insertion of the organically modified clay into the polymeric matrix gave an improvement of the mechanical properties of the polyurethane composites, especially the tensile strength and stiffness of the hybrid materials. Copyright © 2009 Society of Chemical Industry

Synthesis and characterization of iodinated polyurethane with inherent radiopacity

The synthesis and characterization of polyurethane (PU) with excellent radiopacity for medical and allied applications are reported. Bisphenol-A (BPA) was iodinated to obtain 4,4′-isopropylidinedi-(2,6-diiodophenol) (IBPA) which was used as a chain extender for the preparation of a radiopaque PU. The PU was prepared by reacting 4,4′-methylenebis(phenyl isocyanate) (MDI), poly(tetramethylene glycol) (PTMG) and IBPA in 2.2:1.2:1 molecular ratio and is characterized by infrared spectroscopy (IR), thermogravimetry (TGA), dynamic mechanical analysis (DMA), energy dispersive X-ray analysis (EDX), gel permeation chromatography (GPC) and X-radiography. X-ray images showed that the PU prepared using IBPA as the chain extender is highly radiopaque. An in vitro cytotoxicity test using L929 mouse fibroblast cells shows that the PU is non-cytotoxic. The outlined synthesis of a PU with radiocontrast properties opens up the possibility of synthesizing many different kinds of radiopaque PUs with desirable range of physical properties exploiting the versatility in their chemical synthesis.