Properties Of Polyurethane Films Research Articles

Synthesis of self‐healing soybean oil‐based waterborne polyurethane based on Diels–Alder reaction

AbstractIn order to endow water‐based polyurethane with special functionality, vegetable oil‐based waterborne polyurethane with self‐healing properties is synthesized. Firstly, soybean oil‐based emulsifier (GA‐ESO) was prepared by epoxy soybean oil and glutaric acid without solvent and catalyst. Then, two Diels−Alder (DA) diols were prepared by the DA reaction between N,N′‐(4,4′‐methyldiphenyl) bismaleimide, 4‐maleimide phenol and furfuryl alcohol, respectively. Finally, GA‐ESO and DA diols used as the raw material was reacted with isophorone diisocyanate to synthesize a series of soybean oil‐based waterborne polyurethane with self‐healing behavior. The effects of DA diol on the properties of polyurethane films and the self‐healing process and mechanism of polyurethane membrane were investigated. The results showed that after the addition of DA diol, the particle size of polyurethane emulsion increased from 28.8 to 85.3 nm, the tensile strength was improved from 0.3 to 12.6 MPa, and the water contact angle was enhanced from 68.5° to 84.2°. In addition, it can be observed that with the addition of DAdiol, the polyurethane film had self‐healing behavior at high temperature, and the highest self‐healing efficiency can reach 100%.

Preparation and properties of polyurethane film with photothermal conversion and energy storage capability

Purpose This paper aims to provide a flexible polyurethane (PU) film with visible light trapping ability, photothermal conversion and energy storage performance by covalently bonded a visible light absorbing dye into the polymer through copolymerization. Design/methodology/approach For this target solution copolymerization of diphenyl-methane-diisocyanate (MDI), poly(1,4-butylene adipate) (PBA2000), polyethylene glycol (PEG) of different molecular weight, self-made dye, 1,4-butanediol (BuOH) was carried out in a flame-dried flask under an inert nitrogen (N2) atmosphere. First, an isocyanate-terminated prepolymer of dried PEG, MDI and PBA2000 was prepared in dimethylformamide and stirred for 1 h at 35°C. Then, self-made dye and 1, 4-butanediol (BuOH) were added and heated at 85°C for 3 h to get photothermal conversion polyurethane (PTPU) solution. Allowed the solution to dry at room temperature for seven days and then at 65°C for 12 h to get PTPU films. Findings The flexible PU films with photothermal conversion and energy storage performances were successfully synthesized and the functional films presented both excellent energy storage and mechanical property when the molecular weight of PEG was in the range of 6,000∼10,000. Research limitations/implications The materials that were used in this research paper had a reasonably low cost. Also, the procedures for the synthesis of dye and polymers were extremely easy because there was no need for high pressure or temperature and no dangerous solvents were used. Practical implications The photothermal conversion property and mechanical performance of the synthesized flexible PU films were characterized. The results have proved that these films were soft and elastic, and have certain photothermal conversion and energy storage ability, thus can be used in the surface finishing of special fabric and leather. Originality/value Visible light trapping photothermal conversion PU flexible film with energy storage capability was prepared for the first time.

Synthesis and characterization of polyethylene glycol-phenol-formaldehyde based polyurethane composite

A series of phenol-formaldehyde-polyethylene glycol polyether polyols (PF-PEGs) were synthesized through the condensation polymerization and etherification of phenol, formaldehyde, and poly(ethylene glycol) (PEG) under alkaline conditions and subsequently reacted with 1,6-hexamethylene diisocyanate to obtain polyurethane (PU) films using acetone as solvents. The influence of phenol and formaldehyde to PEG mass ratio ((P + F)/PEG) on the hydroxyl number of PF-PEGs and mechanical properties, thermal stabilities, crystallization behaviors, as well as microstructure of polyurethane composite films were studied using chemical analysis, mechanical tests, thermogravimetric analyses (TGA), dynamic mechanical analyses (DMA), X-ray diffraction (XRD), scanning and transmission electron microscopies (SEM and TEM), respectively. Results demonstrated that PF-PEGs with (P + F)/PEG of 50/50 had the highest hydroxyl number of 323 mg K(OH)/g. The incorporation of phenol and formaldehyde into PEG improved the mechanical properties of polyurethane films, glass transition temperature (Tg), and thermal properties but resulted in the brittleness characteristic of the composite films and low crystallization properties. Moreover, the synthesis mechanism of PF-PEGs polyurethane composite films was revealed, which would provide a theoretical base for the preparation of the rigid polyurethane foams based on phenolic resins.

Preparation and Properties of Polyurethane Films with Spent Coffee Grounds

In this study, a method of recycling spent coffee grounds (SCG) is introduced. The SCG was dried and crushed into micron-sized coffee particles. The coffee particles could be used to prepared polyurethane (PU) films with different contents (0wt.%, 5wt.%, 10wt.%, 15wt.%, 20wt.%, 25wt.% and 30wt.%). The anti-ultraviolet property, thermal comfort performance and mechanical property of different PU films were measured. The results showed that after the blending of coffee particles, the films exhibited excellent anti-ultraviolet property and thermal comfort performance, and the mechanical properties were also retained. This study also provided an effective approach to reuse SCG, which is consistent with the environmental-friendly society principle.

Enhancement in Corrosion Barrier Properties of Polyurethane Films on Steel by Embedding MgO Nanoparticles

The effect of nanosized MgO loading on the corrosion barrier characteristics of polyurethane (PU) films on mild steel has been investigated. It was found that small amount of MgO loading even as low as 0.03 vol% significantly improved the corrosion retardation ability of PU films. Both the enhanced adhesion strength and the formation of chemically strong -NCO radicals between nano-MgO and PU matrix seem to be responsible for the enhancement.

Effect of Solvent Interactions on the Properties of Polyurethane Films

A series of segmented polyurethanes were synthesized by the reaction of poly (ethyleneadypate) diol, 4,4’-methylene-bis(phenyl isocyanate) and ethylene glycol. Various solvents were used as reaction media: N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF) and mixtures of NMP with DMF, toluene, and ethyl acetate (at a rate 80/20 weight). These polyurethanes exhibited different behaviors due to different interactions between solvents and macromolecular chains or solvents and water. These phenomena in combination with the phase segregation in polyurethanes arising from the incompatibility between the hard and soft segments were utilized to produce a variety of polyurethane membranes by immersion precipitation. The type of solvent has a strong effect on the properties and morphology of polymers when they are cast using different solvents, which was confirmed by thermal and mechanical measurements.

Effects of calcium ion on polyester‐type polyurethane emulsion and properties of polyurethane film

AbstractPolyurethane (PU) emulsions were prepared from polytetramethylene adipate diol, toluene diisocyanate, dimethanol propionic acid, and so forth. The effects of calcium ion on the stability of PU emulsion as well as on the water‐resistance property, tensile strength, and tensile yield of PU film were discussed. The results show that calcium ion can quickly damage the stability of PU emulsion. Meanwhile, calcium ion can distinctly counteract the unfavorable effects water has on the tensile properties of PU film. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1285–1288, 2004

Network structures and thermal properties of polyurethane films prepared from liquefied wood

Network structures and thermal properties of polyurethane films prepared from liquefied wood

Study of the long-term strength and fatigue properties of polyurethane films

1. During deformation the cross section varies up to 45–50%, the stresses increasing. 2. With an increase in temperature of the breaking stress the relative deformation and relative contraction in the cross section decrease, and the mechanism of their variation is given a tentative physical explanation. 3. With an increase in temperature the polymer loses work capacity due to an acceleration in the relaxation process, which is characterized by an activation energy equal to 28 kcal/mole for the polymer concerned. 4. For cyclic loading the breaking stress is 30% lower, while the time to fracture is ten times lower than for static loading.