Mechanical properties of polyurethane film exposed to solutions of nonoxynol‐9 surfactant and poly(ethylene glycol)

Mechanical properties of two polyether urethane films (Estane and Tecoflex) were studied after exposure to solutions of nonoxynol 9 (N9) surfactant and poly(ethylene glycol) 400 (PEG) for various times. Large amounts of N9 were absorbed from N9/PEG solutions, resulting in soft‐segment plasticization and lower mechanical properties. As the N9 concentration increased, Estane absorbed more liquid and its mechanical properties decreased more compared to Tecoflex, although the mechanical properties of Estane were higher than Tecoflex at low concentrations of N9. Hard‐segment domain disruption is probably not occurring because the relationship between the elastic modulus and polymer volume fraction followed Flory's theory for swollen elastic rubber networks and the liquids do not fully dissolve the polymers. The diffusion behavior of N9 and PEG was observed to follow Fickian behavior. Most of the absorption and decrease in mechanical properties occurred within the first 20 h after soaking, implying that additional loss in strength over longer times would be minimal. Mechanical property anisotropy suggests that condoms should be cut from Estane film in an orientation that optimizes the property–orientation relationship for specific end uses. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1086–1096, 2004     

Synthesis and characterization of photopolymerizable hydrogels based on poly (ethylene glycol) for biomedical applications

Hydrogels are polymeric materials widely used in medicine due to their similarity with the biological components of the body. Hydrogels are biocompatible materials that have the potential to promote cell proliferation and tissue support because of their hydrophilic nature, porous structure, and elastic mechanical properties. In this work, we demonstrate the microwave-assisted synthesis of three molecular weight varieties of poly(ethylene glycol) dimethacrylate (PEGDMA) with different mechanical and thermal properties and the rapid photo of them using 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184) as UV photoinitiator. The effects of the poly(ethylene glycol) molecular weight and degree of acrylation on swelling, mechanical, and rheological properties of hydrogels were investigated. The biodegradability of the PEGDMA hydrogels, as well as the ability to grow and proliferate cells, was examined for its viability as a scaffold in tissue engineering. Altogether, the biomaterial hydrogel properties open the way for applications in the field of regenerative medicine for functional scaffolds and tissues.     

Thermal and mechanical properties of polyisobutylene‐based thermoplastic polyurethanes

We investigated thermal and mechanical properties of thermoplastic polyurethanes (TPUs) with the soft segment comprising of both polyisobutylene (PIB) and poly(tetramethylene)oxide (PTMO) diols. Thermal analysis reveals that the hard segment in all the TPUs investigated is completely amorphous. Significant mixing between the hard and soft segments was also observed. By adjusting the ratio between the hard and soft segments, the mechanical properties of these TPUs were tuned over a wide range, which are comparable to conventional polyether‐based TPUs. Constant stress creep and cyclic stress hysteresis analysis suggested a strong dependence of permanent deformation on hard segment content. The melt viscosity correlation with shear rate and shear stress follows a typical non‐Newtonian behavior, showing decrease in shear viscosity with increase in shear rate. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 891‐897, 2013     

Mechanical and thermal properties of polyurethane elastomers based on hydroxyl‐terminated polybutadienes and biopitch

Biopitch is a renewable source of polyol obtained from Eucalyptus tar distillation, which was studied as an active component of polyurethane (PU). The polymerization occurred in one step, with a mixture of biopitch and hydroxyl‐terminated polybutadiene polyols reacted with 4‐4′‐diphenyl methane diisocyanate in the presence of dibutyltin dilaurate. Solid‐state ¹³C‐NMR, IR spectroscopy, elemental analysis, and thermal analysis [thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC)] were used to characterize the biopitch. The biopitch sample showed an aromatic and oxygenated structure with great thermal stability at high temperatures. Multiphasic PUs were synthesized and characterized by IR spectroscopy (attenuated total reflectance), elemental analysis, thermal analysis (TGA and DSC), mechanical assays (tensile strength, elongation at break, toughness, hardness, and resilience), and water absorption resistance (ASTM D 570‐81). In a comparative study of the synthesized elastomers, biopitch content increased tensile strength and hardness and decreased thermal stability, elongation at break, and water absorption. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 759–766, 2003     

Synthesis and properties of novel biodegradable poly(ε‐caprolactone)/ poly(ethylene glycol)‐based polyurethane elastomers

Elastomeric polyurethanes with tunable biodegradation properties and suitable for numerous biomedical applications were synthesized via reaction of epoxy‐terminated polyurethanes (EUPs) with 1,6‐hexamethylenediamine as curing agent. The EUPs themselves were prepared from glycidol and isocyanate‐terminated polyurethanes made from poly(ε‐caprolactone) (PCL) or poly(ethylene glycol) (PEG) and 1,6‐hexamethylene diisocyanate. All the polymers were characterized by conventional methods, and their physical, mechanical, thermal, and degradation properties were studied. The results showed that the degradation rate and mechanical properties of the final products can be controlled by the amount of PEG or PCL present in the EUP. Increasing the PEG content causes an increase of hydrolytic degradation rate, and increasing the PCL content improves the mechanical properties of the final products. Evaluation of cytotoxcicity showed nontoxic behavior of the prepared samples, but the cytocompatibility of these polymers needs to be improved. Copyright © 2006 Society of Chemical Industry     

Study on the properties of crosslinking of poly(ethylene oxide) and hydroxyapatite–poly(ethylene oxide) composite

This study covers the crosslinking of poly(ethylene oxide) (PEO) and its composite with calcium hydroxyapatite (HA), their mechanical and swelling properties, and morphology. Sheets of the composites of PEO (two different grades with M_v: 5 × 10⁶ and 2 × 10⁵) and HA and neat PEO were prepared by compression molding. The prepared composite and PEO (0.1‐mm‐thick) sheets were crosslinked with exposure of UV‐irradiation in the presence of a photoinitiator, acetophenone (AP). This simple method for crosslinking, induced by UV‐irradiation in the presence of AP, yielded PEO with gel content up to 90%. Gel content, equilibrium swelling ratio, and mechanical and morphological properties of the low molecular weight polyethylene oxide (LMPEO)–HA crosslinked and uncrosslinked composites were evaluated. Although the inclusion of HA into LMPEO inhibits the extent of crosslinking, the LMPEO–HA composite with 20% HA by weight shows the highest gel content, with appreciable equilibrium swelling and mechanical strength. The growth of HA in simulated body fluid solutions on fractured surfaces of LMPEO and also LMPEO–HA was found to be very favorable within short times. The dimensional stability of these samples was found to be satisfactory after swelling and deposition experiments. The good compatibility between the filler hydroxyapatite and poly(ethylene oxide) makes this composite a useful tissue‐adhesive material. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 488–496, 2003     

Effect of difunctional acids on the physicochemical,thermal, and mechanical properties of polyester polyol‐based polyurethane coatings

Polyester polyol (PP)‐based polyurethanes (PUs) consisting of two difunctional acids [1,4‐cyclohexanedicarboxylic acid (CHDA) and 1,6‐adipic acid (AA)] and also two diols [1,4‐cyclohexanedimethanol (CHDM) and 1,6‐hexanediol (HDO)] were synthesized by a two‐step procedure with a variable feed ratio of CHDA to AA but fixed ratio of CHDM and HDO. The prepared PPs and/or PUs were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction spectroscopy, and atomic force microscopy. The effects of difunctional acids on the thermal, mechanical, and dynamic mechanical thermal properties of PPs or PU films were investigated by thermogravimetry analysis, differential thermogravimetry and dynamic mechanical thermal analysis. The results show that PP exhibits a lowest viscosity with the mole fraction of CHDA and AA at 3 : 7 whereas it delivers a lowest melting point with the mole fraction at 9 : 1. After PPs being cross‐linked by isocyanate trimers, the impact resistance, shear strength and glass transition temperature increase the mixed‐acid formulations with increasing the content of CHDA. In detail, the resultant PU almost simultaneously exhibits the best mechanical and thermal properties when the mole fraction of CHDA and AA is kept constant at 9 : 1, thus giving rise to a high glass transition temperature of 56.4°C and a onset decomposition temperature of 350°C, and also delivering a balanced toughness and hardness with an impact resistance of 100 J/g and storage modulus as high as 10⁹ Pa. This path for synthesis of PP‐based PU provides a design tool for high performance polymer coatings. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41246.     

pH‐ and thermal characteristics of graft hydrogels based on chitosan and poly(dimethylsiloxane)

Graft copolymerization of epoxy‐terminated poly(dimethylsiloxane) (PDMS) onto chitosan was reacted without using a catalyst. pH‐sensitive hydrogels were obtained that are based on two different components: a natural polymer and a synthetic polymer. These PDMS substitutents provide the basis for hydrophobic interactions that contribute to the formation of hydrogels. Various graft hydrogels were prepared from different weight ratios of chitosan and PDMS. Swelling behavior of these hydrogels was studied by immersion of the gels in various buffer solution. Photocrosslinked hydrogels exhibited a high equilibrium water content (EWC). Particularly, the sample CP31 of the highest chitosan–PDMS weight ratio showed the highest EWC in time‐dependent, temperature‐dependent, and pH‐dependent swelling behavior. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2661–2666, 2002     

pH and thermo‐responsive poly(N‐isopropylacrylamide) copolymer grafted to poly(ethylene glycol)

pH and thermo‐responsive graft copolymers are reported where thermo‐responsive poly(N‐isopropylacrylamide) [poly(NIPAAm), poly A ], poly(N‐isopropylacrylamide‐co‐2‐(diethylamino) ethyl methacrylate) [poly(NIPAAm‐co‐DEA), poly B ], and poly(N‐isopropylacrylamide‐co‐methacrylic acid) [poly(NIPAAm‐co‐MAA), poly C ] have been installed to benzaldehyde grafted polyethylene glycol (PEG) back bone following introducing a pH responsive benzoic‐imine bond. All the prepared graft copolymers for PEG‐g‐poly(NIPAAm) [ P‐N1 ], PEG‐g‐poly(NIPAAm‐co‐DEA) [ P‐N2 ], and PEG‐g‐poly(NIPAAm‐co‐MAA) [ P‐N3 ] were characterized by ¹H‐NMR to assure the successful synthesis of the expected polymers. Molecular weight of all synthesized polymers was evaluated following gel permeation chromatography. The lower critical solution temperature of graft copolymers varied significantly when grafted to benzaldehyde containing PEG and after further functionalization of copolymer based poly(NIPAAm). The contact angle experiment showed the changes in hydrophilic/hydrophobic behavior when the polymers were exposed to different pH and temperature. Particle size measurement investigation by dynamic light scattering was performed to rectify thermo and pH responsiveness of all prepared polymers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Characterization of the mechanical and thermal properties and morphological behavior of biodegradable poly(L‐lactide)/poly(ε‐caprolactone) and poly(L‐lactide)/poly(butylene succinate‐co‐L‐lactate) polymeric blends

Two series of biodegradable polymer blends were prepared from combinations of poly(L ‐lactide) (PLLA) with poly(?‐caprolactone) (PCL) and poly(butylene succinate‐co‐L ‐lactate) (PBSL) in proportions of 100/0, 90/10, 80/20, and 70/30 (based on the weight percentage). Their mechanical properties were investigated and related to their morphologies. The thermal properties, Fourier transform infrared spectroscopy, and melt flow index analysis of the binary blends and virgin polymers were then evaluated. The addition of PCL and PBSL to PLLA reduced the tensile strength and Young's modulus, whereas the elongation at break and melt flow index increased. The stress–strain curve showed that the blending of PLLA with ductile PCL and PBSL improved the toughness and increased the thermal stability of the blended polymers. A morphological analysis of the PLLA and the PLLA blends revealed that all the PLLA/PCL and PLLA/PBSL blends were immiscible with the PCL and PBSL phases finely dispersed in the PLLA‐rich phase. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of interpenetrating polymer networks from polyurethane and poly(ethylene glycol) diacrylate

Interpenetrating polymer networks (IPNs) combining polyurethane (PU) and poly(ethylene glycol) diacrylate (PEGDA) networks were prepared with simultaneous polymerization. PU was synthesized from biocompatible and biodegradable poly(ε-caprolactone) diol, and the hydroxyl group of poly(ethylene glycol) was substituted with a crosslinkable acrylate group. The effects of the PU/PEGDA compositions and the crosslink density of PU and PEGDA on the thermal properties, swelling ratio, surface energy, mechanical properties, and morphologies were investigated. The mechanical properties of PEGDA networks were improved by the presence of PU networks, particularly in the 75% PU/25% PEGDA IPNs. All PU/PEGDA IPNs showed a microphase-separated structure with cocontinuous morphology, as observed by atomic force microscopy, which was in agreement with the results of swelling ratio and dynamic mechanical thermal analysis measurements. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Development and characterization of thermosensitive hydrogels based on poly(N‐isopropylacrylamide) and calcium alginate

This work refers to the synthesis and characterization of thermosensitive hydrogels based on interpenetrating polymer networks (IPNs) of poly(N‐isopropylacrylamide) (PNIPAAm) and calcium alginate in the form of films. The influence of the crosslinking degree of PNIPAAm and alginate content on thermal, swelling, mechanical, and morphological properties of hydrogels is investigated in detail. Characterization of pure PNIPAAm hydrogels and IPN hydrogels was performed by FTIR, DSC, DMA, and SEM. In addition, the studies of equilibrium swelling behavior as well as swelling, deswelling, and reswelling kinetics are performed. The results obtained imply the benefits of synthesizing IPNs based on PNIPAAm and calcium alginate over pure PNIPAAm hydrogels. The presence of calcium alginate contributes to the improvement of mechanical properties, the deswelling rate of hydrogels, and the network porosity, without altering the thermosensitivity of PNIPAAm significantly. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Poly(ethylene glycol)‐based hydrogels as cartilage substitutes: Synthesis and mechanical characteristics

Cartilage substitutes are needed to replace cartilage tissue, damaged in accidents or by pathologies (e.g., osteoarthritis). Treatment by total hip replacement has disadvantages, particularly due to immunological reaction to the implant's wear debris. One promising alternative is to replace damaged cartilage with substitutes based on hydrogel‐type material, designed to mimic the structure and properties of cartilage. The development of such a substitute must consider a wide spectrum of requirements. In this study, we addressed one aspect of this development namely the preparation and investigation of hydrogels exhibiting the required mechanical characteristics. To this aim, poly(ethylene glycol) (PEG) hydrogels and amphiphilic interpenetrating polymer networks (IPNs) of PEG with poly(methyl methacrylate) (PMMA) were prepared and characterized for their mechanical and swelling properties. Twenty‐seven types of hydrogels were synthesized, differing in their composition: PEG molecular weight, crosslink density, and PMMA volume fraction. The properties measured were water content, compression modulus, strength, fatigue durability, and poroelastic properties (hydraulic permeability and equilibrium modulus). All were investigated as functions of hydrogel's composition. Results show that lower PEG M_w, higher crosslink densities and higher PMMA fraction, all lead to higher modulus and lower water content, and that these properties can be controlled independently by proper choice of ingredients. Introduction of IPN greatly improved the hydrogels' strength. No reduction in the compression modulus resulting from fatigue damage was evident. Poroelastic properties varied nonmonotonously with structural characteristics. Seven types of the hydrogels were found to fit cartilage in their water content, modulus, and poroelastic properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Biodegradable polyetheresteramides synthesized from ϵ‐caprolactone, 6‐aminocaproic acid,and poly(ethylene glycol)

Biodegradable aliphatic polyetheresteramides copolymers (PEEAs) were synthesized from ϵ‐caprolactone, 6‐aminocaproic acid, and poly(ethylene glycol) (PEG) by melt‐polycondensation method. FTIR, ¹H NMR, differential scanning calorimeter, wide‐angle X‐ray diffraction, and thermogravimetric analysis/differential thermogravimetry were used to characterize the PEEAs. The tensile testing, water absorption and hydrolytic degradation behavior were also studied. With the increase in PEG content, the water absorption increased. The rate of hydrolytic degradation depended on the copolymers' hydrophilicity and crystallinity. PEEAs with a relatively low content of PEG still retain good tensile properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Flexible aliphatic poly(isocyanurate–oxazolidone) resins based on poly(ethylene glycol) diglycidyl ether and 4,4′‐methylene dicyclohexyl diisocyanate

New flexible aliphatic oxazolidone‐isocyanurate networks (AISOX) are obtained by reacting a low molecular weight diisocyanate (4,4′‐methylene dicyclohexyl diisocyanate, H₁₂MDI) and a macro‐diepoxyde (poly(ethylene glycol) diglycidyl ether, M_n = 526, PEGDGE) in different molar ratio. The curing reaction, carried out from 25 °C to 200 °C, is studied by using DSC and FTIR. The effect of the molar ratio of the two monomers on thermal and mechanical properties of AISOX resins is investigated by DSC, thermogravimetric analysis, stress?strain measurements and optical microscopy. Independently from the feed composition, it is observed that the reaction steps are: (i) partial hydrolysis of isocyanate caused by water traces, (ii) incomplete trimerization of isocyanate to give isocyanurate, and (iii) formation of oxazolidone and complete conversion of isocyanate. At the highest concentration of the soft macrodiepoxyde (PEGDGE), the AISOX resin is in the rubbery state at room temperature and shows an elastomeric behavior. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43404.     

Effects of TDI and FA‐703 on physico‐mechanical properties of polyurethane dispersion

A series of water dispersion polyurethanes dispersions (PUDs) were prepared by polyaddition reaction using isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), poly(oxytetramethylene) glycol (PTMG), dimethylol propionic acid (DMPA), and triol (trade name FA‐703). Various formulations were designed to investigate the effects of process variables such as TDI and FA‐703 on the physico‐mechanical properties of PUD. IR spectroscopy was used to check the end of polymerization reaction and characterization of polymer. Evolution of the particle size distribution, contact angle, T_g, molecular weight, viscosity, and mechanical properties of the emulsion‐cast films were significantly affected by variable content of TDI and FA‐703. Average particle size of the prepared polyurethane emulsions and contact angle decrease with increase of content of FA‐703 and TDI. Molecular weight, T_g, tensile strength, tear strength, hardness, viscosity and elongation at break increase with increase of content of FA‐703 and TDI. The increase of molecular weight, tensile strength, tear strength and elongation at break properties are interpreted in terms of increasing hard segments, chain flexibility, and phase separation in high content of FA‐703 and TDI‐based polyurethane. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Mechanical properties of crosslinked polyurethane elastomers based on well‐defined prepolymers

This article presents research findings for selected mechanical properties of polyurethane elastomers. The studied elastomers were synthesized with the prepolymer‐based method with the use of controlled molecular weight distribution (MWD) urethane oligomers and with the classical single‐stage method. Prepolymers with defined MWDs were obtained with the use of a multistage method, that is, step‐by‐step polyaddition. To produce elastomers, isocyanate oligomers were then crosslinked with triethanolamine, whereas hydroxyl oligomers were crosslinked with 4,4′,4′′‐triphenylmethane triisocyanate (Desmodur RE). The tensile strength of the obtained elastomers ranged from 1.0 to 7.0 MPa, the ultimate elongation approached 1700%, the Shore A hardness varied from 40 to 93°, and the abrasion resistance index fell within 15–140. The effects of the types of raw materials used, the chemical structures, the production methods, and the supermolecular structures on the mechanical properties of the obtained polyurethane elastomers were examined. When the obtained findings were generalized, it was concluded that the structural changes in the polyurethanes, which were favorable for intermolecular interactions, improved the tensile strength, hardness, and abrasion resistance of the materials and impaired their ultimate elongation at the same time. More orderly supermolecular structures and, therefore, superior mechanical properties were found for polyurethane elastomers produced with the prepolymer method. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Structure‐mechanical properties relationship of poly(ethylene terephthalate) fibers

The correlation between the fiber structure and mechanical properties of two different poly(ethylene terephthalate) fiber types, that is, wool and cotton types produced by three producers, was studied. Fiber structure was determined using different analytical methods. Significant differences in the suprastructure of both types of conventional textile fibers were observed, although some slight variations in the structure existed between those fibers of the same type provided by different producers. A better‐developed crystalline structure composed of bigger, more perfect, and more axially oriented crystallites was characterized for the cotton types of PET fibers. Crystallinity is higher, long periods are longer, and amorphous domains inside the long period cover bigger parts in this fiber type in comparison with the wool types of fibers. In addition, amorphous and average molecular orientation is higher. The better mechanical properties of cotton PET fiber types, as demonstrated by a higher breaking tenacity and modulus accompanied by a lower breaking elongation, are due to the observed structural characteristics. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3383–3389, 2003     

Poly(2‐hydroxyethyl acrylate) hydrogels reinforced with graphene oxide: Remarkable improvement of water diffusion and mechanical properties

A series of hybrid hydrogels of poly(2‐hydroxyethyl acrylate), PHEA, and graphene oxide, G? O, with G? O content up to 2 wt % has been prepared by in situ polymerization. Because PHEA has been used as biomaterial in various applications, has a side chain with the hydroxyl functional group and its mechanical properties are poor, it is a good candidate for reinforcement with G? O. Fourier transform (infrared) spectroscopy, atomic force microscopy, differential scanning calorimetry, the thermal, mechanical, and water sorption properties of neat PHEA and PHEA/G? O composites have been studied in order to elucidate the dispersion and interaction between both components. An increase in the water diffusion coefficient and dramatic changes in its mechanical properties are the most remarkable results. Thus, at a nanofiller load of 2 wt %, the novel materials present an increased diffusion coefficient higher than 380% and the elastic modulus is enhanced by more than 650% in dry state and by more than 100% in swollen state, both compared to neat PHEA. These results have been attributed to the excellent interaction between the matrix, PHEA, and the reinforcement, G? O, and could open the door to new applications in the field of biomaterials with higher structural requisites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46158.     

Novel kind of functional gradient poly(ε‐caprolactone) polyurethane nanocomposite: A shape‐memory effect induced in three ways

Multiwalled carbon nanotube (MWCNT) crosslinked polyurethane nanocomposites filled with iron (Fe) powders were synthesized by an in situ polymerization method. The Fe powders were deposited on one side of the nanocomposites during sample formation. Because of the gradient distribution of the Fe powders, the polymer part was affected little; this resulted in good mechanical properties of the nanocomposites. The electrical conductivities on each side of the nanocomposites were different. Because of the good magnetic properties and high electrical conductivities of the nanocomposites, the shape‐memory effect could be induced by temperature heating (temperature = 45°C), electrically resistive Joule heating (voltage (U) = 30 V), and magnetic field heating (frequency (f) = 45 kHz, intensity of magnetic field (H) = 46.5 kA/m). The shape‐memory properties were dependent on the location of the side that contained the most Fe powders (Fe side), and the nanocomposites showed better shape‐memory properties when the Fe side was located inside of the folded samples. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40220.