Search

Novel eco-friendly sulfonated polyurethane/polyacrylate (SPUA) emulsions were synthesized by surfactant-free emulsion polymerization method using PU as seeds. The sodium sulfonate modified polyester polyol (SDNP) was used as internal emulsifier to make the PU emulsion disperse in deionized water. Effects of the SDNP content on the properties of the emulsions and membranes were studied. Dynamic light scattering (DLS) result showed that the average particle sizes of SPUA emulsions decreased first from 124.1 nm to 102 nm when the SDNP content was lower than 40 wt% and then increased to 138 nm. Transmission electron microscopy (TEM) morphology showed that the particle sizes were all spherical and an apparent core-shell structure was observed. Fourier transform infrared spectroscopy (FT-IR) result ascertains that SPUA was successfully prepared. X-ray photoelectron spectroscopy (XPS) analysis demonstrates that the carbon, oxygen, nitrogen, sulfur, and sodium peaks were all revealed and the polyurethane component was rich in the upper surface. Thermo gravimetric analysis (TGA) of the membranes showed that the thermal stability of the SPUA membranes was enhanced by increasing the SDNP content. Scanning electron micrograph (SEM) results demonstrates that the coexistence of a dual phase. The SPUA could be used as adhesives in footwear industry, and the T-peel strength of the SPUA membranes increased from 5.98 N/mm to 12.06 N/mm when the SDNP content was up to 40 wt%. The wettability of SPUA emulsions on the rubber surface results showed that the emulsions could wet the rubber surface well. [ABSTRACT FROM AUTHOR]

Novel polyurethane/polyacrylate (PUA) composite emulsions were synthesized by soap-free emulsion polymerization method from methyl methacrylate (MMA), butyl acrylate (BA), and 2-Hydroxyethyl acrylate (HEA) in the presence of PU as seeds and a polymerizable emulsifier-Allyloxy hvdroxyl propanesulfonic salt (AHPS). Effects of the AHPS content on the properties of the emulsions and films were studied. Dynamic light scattering (DLS) result showed that the average diameters and polydispersity were decreased with the increment of AHPS content. Fourier transform infrared spectroscopy (FT-IR) result shows that AHPS was introduced into the PUAS chains. Their thermal stability and Tg of the films increased gradually with augment of AHPS amount in polymer. X-ray photoelectron spectroscopy (XPS) analysis showed that sodium was preferably enriched on the surface of latex particles. Atomic force microscopy (AFM) observation performed the extremely flat membrane. [ABSTRACT FROM AUTHOR]

Waterborne cationic fluorinated polyurethane (WCFPU) micro-emulsion was prepared by the reaction of isophorone diisocyanate (IPDI), polytetramethyleneether glycol (PTMG1000), 1,4-butanediol (BDO), N-methyldiethanolamine (MDEA), trimethylolpropane (TMP) and perfluoroalkylethyl octanol (FEOH), and then the films of the WCFPU were prepared. The influence on the mechanical properties and water absorption of the films, such as the molar ratio of NCO to OH, the dosage of MDEA, TMP and FEOH, was investigated. Their structure, morphology and heat performance were characterized by fourier transform infared spectrometer (FT-IR), dynamic light scattering (DLS), transmission electron microscope (TEM), X-ray diffraction (XRD), differential scanning calorimeter (DSC) and thermogravimetry (TG). The results revealed that the best mechanical properties and water resistance could be obtained under the condition that NCO/OH molar ratio was 1.25, w(TMP) was 1.1%, w(MDEA) was 7.29% and w(FEOH) was 22.3%. In addition, WCFPU was endowed with low surface energy of its film and the membrane surfaces had excellent water and oil repellency. Furthermore, the thermal stability of the waterborne cationic fluorinated polyurethane increased with the incorporation of perfluoroalkyl chain. And XRD, DSC and TG showed that micro-crystallinity of polyurethane increased with the increase of FEOH, which was benefit to the micro-phase seperation. [ABSTRACT FROM AUTHOR]

Self-crosslinkable polyurethane emulsion containing active carbonyl group was obtained using dihydroxyketon N-[(1,1-dimethyl-2-acetyl)ethyl]-β-dihydroxyethylamino propanamide(DDP) and 1,4-butanediol as chain extenders, isophorone diisocyanate (IPDI), polyether polyol (PTMG1000), dimethylol propionic acid (DMPA) and trimethylol propane (TMP) as main materials, γ-aminopropyltriethoxysilane (APTES) as end capping agent. Then adipic dihydrazide was added into the emulsion. The structure and composition of DDP and the films were confirmed by means of FTIR and H nuclear magnetic resonance (H-NMR) spectrometer, the test results indicated that the reaction between ketone carbonyl and hydrazine has happened during the film curing. The effects of n(NHNH-)/ n(C=O) and DDP content on the properties of the films were studied. The results show that water absorption of the films decreases from 39.3% to 18.9%, crosslinking degree increases from 51.5% to 90.2%, tensile strength increases from 20.1 MPa to 28.3 MPa and pencil hardness is 2H when the DDP content increases from 0% to 6.13%. TGA analysis indicates that the Ketone-Hydrazide crosslinking structure can improve thermal stability of the films. [ABSTRACT FROM AUTHOR]

Waterborne polyurethane prepolymer was prepared by the reaction of isophorone isocyanate(IPDI), polyether polyol(PTMG), dimethylol propionic acid(DMPA) and trimethylol propane(TMP), which was modified by silicane coupling agent(APTES) to form highly crosslinked polyurethane emulsion. The films of the waterborne polyurethane were prepared. The structure of the polyurethane was characterized by Fourier transform infared spectrometer (FTIR), X-ray diffraction (XRD) and differential scanning calorimeter (DSC). The mechanical properties and water absorption of the films were measured. FT-IR indicates that APTES reacted with -NCO of polyurethane. XRD and DSC shows that crystallinity of polyurethane decreased with the increase of w(APTES). Tensile strength increases as the NCO/OH ratio increases. Tensile strength of films increases with increase of w(DMPA) and elongation at break decreases. The water absorption decreases with the increase of w(TMP) when w(TMP) is lower than 1.8%. As the mass fraction of APTES increases from 0% to 10%, the tensile strength of PU films increased from 18 MPa to 28 MPa, water absorption and ethanol absorption decreased. [ABSTRACT FROM AUTHOR]

The anionic hydrophobic association polyacrylamide (AFPAM) modified with fluorinated acrylate have been synthesized of acrylamide (AM), 2-acrylamide-2-methyl propanesulfonic acid (AMPS) and 2-(perfluorooctyl)ethyl acrylate (FEA) by free radical micellar copolymerization in aqueous solution utilizing sodium dodecyl sulfate(SDS) as the surfactant and potassium persulfate(KPS)/sodium bisulfite(SBS) as the redox initiator. The solution properties of these polymers were investigated. The results show that there are strong hydrophobic associations in the AFPAM aqueous solution. The intrinsic viscosity decreases and Huggins constant increases with the increase of hydrophobic FEA content. The addition of NaCl and CaCl2 results in an increase of solution viscosity which indicate the good salt-resistant performance. The polymers exhibit good temperature tolerance property, shear-thickening and thixotropy behavior. Additionally, the AFPAM has higher surface activity in salt solution than in water. [ABSTRACT FROM AUTHOR]

Self-crosslinkable aqueous polyurethane (PU)/polyacrylate (PA) composite emulsion was obtained by radical copolymerization. Fourier transform infrared spectroscopy (FT-IR) result shows that the cross-linking reaction between the carbonyl group and the hydrazine group has happened. The influence of the hydrazide-carbonyl molar ratio and the PA content on the properties of the composite emulsions and their films were investigated. The results show that, under the optimal hydrazide-carbonyl molar ratio ( n (hydrazine group)/ n (carbonyl group) =1:1), the water absorption is 10.56 %, and the mechanical properties and thermal stabilities are both improved. As the PA content increases from 0 wt% to 15 wt%, the tensile strength increases from 5.7 MPa to 7.3 MPa and the gel content increases from 70.3 % to 87 %. [ABSTRACT FROM AUTHOR]

Through ultrasonic assisted radical polymerization, hydrophobically associating polyacrylamide (U-HAPAM) was prepared by acrylamide (AM), 2-acrylamido −2- methyl propane sulfonic acid (AMPS), and hydrophobic monomer octadecyl acrylate (ODA). The effects of concentration of initiator, ultrasonic frequency power and concentration of total monomers, had great influences on total monomer conversion, relative molecular mass and the viscosity of its aqueous solution. The macroscopic and microscopic self-assembly behaviors of the product was studied through apparent viscometry, fluorescence spectroscopy(FS) and atomic force microscope(AFM) respectively. The results showed that, the ultrasound possessed the certain ability of initiating and 0.3 % of initiator was advisable to use during the ultrasonic assisted radical polymerization to enhance the efficiency without substantially affecting the M; the thickening ability of the product was best under120W ultrasonic frequency power, of which the apparent viscosity attained 153.3 mPa · s as the concentration of U-HAPAM was 0.30 wt.%. Weighting the reaction efficiency and M, the concentration of total monomers was set as 10 % optimally. U-HAPAM achieved more excellent self-assembly performance and the critical association concentration of U-HAPAM prepared under these conditions was 0.27 wt.% (CAC) obtained from apparent viscometry and 0.23 wt.% (CAC') from FS. [ABSTRACT FROM AUTHOR]

The self-assembly of a fluorinated hydrophobically associating polyacrylamide (UFPAM) prepared by emulsifier-free ultrasound-assisted radical polymerization was studied using fluorescence spectroscopy (FS), rheological measurements, and dynamic light scattering (DLS). The effects of the degree of mineralization ( M), temperature, and the concentrations of ionic surfactants-sodium dodecyl sulfate (SDS) and cetyltrimethyl ammonium bromide (CTAB)-on the self-assembly behavior of UFPAM were explored in detail. The results showed that 2,2,3,4,4,4-hexafluorobutyl methacrylate (FA) was effectively incorporated into the UFPAM. As the concentration of UFPAM increased, the hydrophobic self-assembly behavior of UFPAM increased the apparent viscosity and enhanced the structural network of UFPAM, as indicated by the Ostwald-de Waele power-law model, FS, dynamic rheological measurements, and DLS. The maximum apparent viscosity of the UFPAM solution occurred when the polarity of the solution was enhanced in mineralized solution and the polymer coils were expanded at increased temperature. Provided that the concentration of the ionic surfactant was below its CMC, the addition of CTAB promoted the self-assembly of UFPAM, but this did not occur upon the addition of SDS. When the concentration of the surfactant was above the CMC, the aggregation number increased in the UFPAM-CTAB system, whereas it exhibited a minimum value in the UFPAM-SDS system. [ABSTRACT FROM AUTHOR]