PCL–PEG–PCL triblock ester–ether copolydiol-based waterborne polyurethane. II. Effect of NCO/OH mole ratio and DMPA content on the physical properties

This article was focused on the effects of the NCO/OH molar ratio and 2,2-bis(hydroxyl methyl) propionic acid (DMPA) content during prepolymerization on the physical properties of synthesized waterborne polyurethane (WBPU) by using the polycaprolactone–poly(ethyl glycol)–polycaprolactone triblock copolydiol (PCL–PEG–PCL) as the soft segment. The results showed that the particle size of the WBPUs' dispersion decreased with a decreasing NCO/OH molar ratio or increasing DMPA content. Regarding thermal and mechanical properties, the WBPUs had a higher T_g's and lower T_m's and a higher breaking stress and a lower breaking strain of film with the NCO/OH molar ratio or DMPA content increase. The increasing NCO/OH molar ratio was advantageous to the water vapor permeability (WVP)-breaking stress balance, but the effect of the DMPA content on the WVP was not significant. The WBPU with PCL–PEG–PCL as the soft segment had a smaller particle size in dispersion and a better WVP-breaking stress balance than those of WBPU with the blending PCL and PEG as the soft segment. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1301–1311, 1998     

Effects of a soft segment component on the physical properties of synthesized waterborne polyurethanes by using triblock ester-ether copolydiol as the soft segment

This paper examines the effect of an ester-ether soft segment structure on the physical properties of synthesized WBPUs. The CET series, CPT series, and CMT series anionic waterborne polyurethane (WBPU) were prepared with PCL-PEG-PCL, PCL-PPG-PCL, and PCL-PTMG-PCL triblock copolydiol as the soft segment. These copolydiols were synthesized from polyethylene glycol (PEG), polypropylene glycol (PPG), or polytetramethylene glycol (PTMG), respectively, by end capping with caprolactone (CL). Particle size and its distribution, solvent absorption, thermal properties, and the mechanical properties of the WBPUs were studied. The particle size of WBPU dispersion was in the sequence of CET > CPT > CMT series. The CET series WBPU had better phase mixing between the soft and hard segment, whereas the CMT series WBPU had good phase separation and better mechanical properties. In addition, both the phase mixing and mechanical properties increased with PCL content, except for the CMT series WBPU.     

Preparation and properties of waterborne polyurethane‐urea/sodium alginate blends for high water vapor permeable coating materials

To improve the water vapor permeability of coating materials, aqueous sodium alginate (SA) solution was blended with waterborne polyurethane‐urea (WBPU) dispersions synthesized by prepolymer mixing process. The content of SA for stable WBPU/SA dispersions was found to be below 30 wt %. As the SA content increased, the number and density of total micropores (tunnel‐like micropores/isolated micropores) formed after dissolution of SA in water increased, and the water vapor permeability of coated Nylon fabric also increased remarkably. These results clearly demonstrate that utilizing WBPU/water soluble polymer SA blends as coating materials and then dissolving SA in water surely facilitate obtaining prominent breathable fabrics. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Effects of polyaminosiloxane on the structure and properties of modified waterborne polyurethane

A waterborne polyurethane (WPU) prepolymer was synthesized with poly(tetramethylene glycol) to form the soft segment, dimethylolpropionic acid as a hydrophilic chain extender, and isophorone diisocyanate. Moreover, the graft and block copolymer emulsification of WPU–polysiloxane and their films was carried out through reactions between the WPU prepolymer, aminoethyl aminopropyl dimethicone (AEAPS), and a linear polyether-blocked amino silicone (LEPS), respectively. The properties of the structure and formed films of the WPU were characterized with Fourier transform infrared spectrometry, gel permeation chromatography, X-ray diffraction, thermogravimetric analysis, dynamic thermomechanical analysis, and X-ray photoelectron spectroscopy; the measurement of the water contact angle; the testing of the water absorption; and so on. The WPU–polysiloxane emulsion showed a high stability, and the molecular weight of WPU increased. Moreover, the glass-transition temperature (T_g) of the soft segment of polysiloxane that was incorporated into the WPU shifted to a lower temperature range, whereas the T_g of the hard segment shifted to a higher temperature range, and the crystallinity of the WPU–polysiloxane film was reduced. There was a greater degree of crosslinking and accumulation of polysiloxane segments on the surface of the WPU emulsion that was modified with AEAPS in comparison to the LEPS-modified WPU emulsion. Therefore, the water resistance of the AEAPS-modified WPU was higher than that of the LEPS-modified WPU. The rigidity and elasticity of the WPU–polysiloxane film improved, whereas its tensile strength did not change much after AEAPS was used. However, this was not true after LEPS was used, as the tensile strength decreased significantly. Nevertheless, the flexibility and plasticity of the WPU–polysiloxane film were enhanced after LEPS was used. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47226.     

Effects of mixing procedure on the structure and physical properties of ester–ether-type soft segment waterborne polyurethane

The effects of the mixing procedure for the preparation of ester-ether-type waterborne polyurethane (WBPU) on the structure and properties of the cast film are studied here. The following three types of WBPU processing are examined: film formed from WBPU mixing ether-type WBPU with ester-type WBPU (CEM series), film formed from WBPU synthesized with PEG2000 and PCL2000 polydiol as the soft segments (CEB series), film formed from WBPU synthesized with triblock ester-ether copolydiol (PCL-polyethylene glycol-PCL) as the soft segment (CET series). The water vapor permeability (WVP) for the application to nylon fabrics is also studied. The results show that the mixing procedure greatly affects the properties of the ester-ether-type WBPU. The CEB series has better phase mixing than the CET series, and the CEM series has a phase boundary between the ester-and ether-type WBPU. The CEM series has a better Young's modulus and breaking stress and poorer breaking strain than the CEB and CET series. In addition, samples with lower ethylene oxide (EO) content have better phase mixing and mechanical properties. On the other hand, the ester-ether-type WBPU has a higher WVP than the ester-type WBPU and the WVP increases with the EO content. The order of the mixing procedures for WVP is CET > CEB > CEM. © 1996 John Wiley & Sons, Inc.     

Hierarchical structure of phase‐separated segmented polyurethane elastomers and its effect on properties

Polyurethanes were prepared from 4,4′‐methylenebis(phenyl isocyanate), 1,4‐butanediol and poly(1,4‐butanediol adipate) polyester polyol. The hydroxyl functional group ratio of polyol/total diol was kept constant at 0.4, while the ratio of the isocyanate and hydroxyl groups (NCO/OH ratio) changed between 0.90 and 1.15. The polymers were prepared by one‐step bulk polymerization in an internal mixer. They were characterized using a number of methods including Fourier transform infrared spectroscopy, wide‐ and small‐angle X‐ray scattering, differential scanning calorimetry, dynamic mechanical analysis, light transmittance and tensile testing. Changing the stoichiometry modifies the molecular weight in accordance with the laws of stepwise polymerization, and the relative concentration of end groups also changes at the same time. Competitive interactions among various groups including chain‐end functional groups lead to the formation of slightly ordered phases of sub‐nanometre size at both ends of the composition range. These structures assemble into larger units at the 10 nm level, which associate further to even larger entities of micrometre size causing scattering of light and a decreased transparency of the samples. The order of the primary units, together with the number and size of assemblies at both higher levels, decrease as the composition approaches equimolar stoichiometry. The amount of less ordered amorphous phase has a maximum in this range. The stiffness of the polymers is determined by the amount of this phase, while ultimate properties are influenced also by molecular weight and the number of physical crosslinks formed. Copyright © 2010 Society of Chemical Industry     

Effects of molecular weight and arm number on properties of star‐shape styrene–butadiene–styrene triblock copolymer

A star‐shape styrene–butadiene–styrene triblock copolymer SBS (802) was synthesized and fractionated into four fractions coded as 802‐F1 (four arms), 802‐F2 (two arms), 802‐F3 (one arm), and 802‐F4 by repeating fractional precipitation. Their weight‐average molecular weight (M_w) was measured by size‐exclusion chromatography combined with laser light scattering to be 16.0 × 10⁴, 8.2 × 10⁴, 4.3 × 10⁴, and 1.19 × 10⁴, respectively. The samples were, respectively, compression‐molded and solution‐cast to obtain the sheets coded as 802C, 802‐F1C, 802‐F2C, and 802S, 802‐F1S, 802‐F2S. The structures and mechanical properties of the sheets were characterized by ¹H‐NMR, scanning electron microscope, wide‐angle X‐ray diffractometer, tensile testing, and dynamic mechanical thermal analysis. The results indicated that the compression‐molded 802‐F1C exhibited the higher tensile strength (σ_b, 28.4 MPa) and elongation at break (ε_b, 1610%), and its optical transmittance is much higher than those of 802C and 802‐F2C. This work revealed that the star‐shape SBS with four arms could be helpful in the enhancement of the properties as a result of good miscibility of the compression‐molded SBS sheets. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 832–840, 2005     

Studies of the water permeability and mechanical properties of a film made of an Ethyl Cellulose–Ethanol–Water ternary mixture

A water permeability study of ethyl cellulose (EC) film made from an EC–ethanol–water ternary mixture is presented. EC films were prepared by pouring the solution onto a polycarbonate plate and by spraying. The results reveal that the permeability of water, estimated by diffusion experiments, increases as the amount of the nonsolvent increases in the liquid–liquid demixing process. In addition, a relative decrease in the evaporation rate of ethanol compared to that of water following an increase in casting temperature or a higher EC concentration produces a membrane with lower permeability. A mechanical evaluation of the films is also presented. Addition of water to the solvent leads to decreases in the modulus of elasticity, stress, and elongation, due to changes in the morphology of the film. The surface of the film was visualized by SEM photomicrography. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2056–2062, 1999     

Effect of chemical crosslinking on the structure and mechanical properties of polyurethane prepared from copoly(PPO–THF) triols

Copoly(PPO–THF) (oxypropane–tetrahydrofuran) diol and triol were synthesized by cationic copolymerization of PPO–THF in the presence of 1,4-butanediol (BD) or 2,2′-dihydroxymethyl butanol (DHMB). The results of proton nuclear magnetic resonance verified the chemical structure of the obtained diol and triol. The amounts of the end hydroxyl group for the obtained triol and diol were measured by the end group analysis method. Linear (B-series) and crosslinked (T-series) polyurethanes were prepared from the diol and triol, respectively. The weight ratio of hard segment in the soft domain was calculated with Fourier transform infrared spectroscopy. Differential scanning calorimetry technology was used to investigate the structure of hard domains in B- and T-series polyurethanes. Mechanical properties studies of B- and T-series polyurethanes were carried out. Higher ultimate strength of T-series polyurethane than that of the B-series one was discussed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:2163–2169, 1998     

Preparation and properties of waterborne polyurethane–urea anionomers. I. The influence of the degree of neutralization and counterion

Two series of waterborne polyurethane–urea anionomers were prepared by a polyaddition reaction with isophorone diisocyanate, poly(tetramethylene oxide) glycol (weight‐average molecular weight = 1000), dimethylol propionic acid (DMPA), and ethylene diamine as chain extenders. Triethylamine (TEA) or 28:1 mol/mol ammonium hydroxide (NH₄OH)/cupric hydroxide [Cu(OH)₂] was used as a neutralization agent [NH(C₂H₅) or NH/Cu²⁺ counterion] for the pendant COOH group of DMPA. The effects of the degree of neutralization and counterion on the particle size of the dispersions, the conductivity, and the antibacterial and mechanical properties of polyurethane–urea anionomer films were investigated. The particle sizes of the two sample series dispersions decreased with an increasing degree of neutralization. Aqueous dispersions of polyurethane–urea anionomers with particle sizes of 30–120 nm were stable for about 3 months. By infrared spectroscopy, it was found that TEA‐based samples (T series) had higher fractions of hydrogen‐bonded carbonyl groups in the ordered region than NH₄OH/Cu(OH)₂‐based samples (S series). However, the fractions of hydrogen‐bonded carbonyl groups in the disordered region of the S‐series samples were higher than those of the T‐series samples. The conductivities of the S‐series film samples were higher than those of the T‐series samples. However, the T‐series film samples commonly had higher tensile strengths and initial moduli than the S‐series samples. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2375–2383, 2002     

Hydraulic resistance of rigid polyurethane foams. I. Effect of different surfactants on foam structure and properties

Foams used in buoyancy applications must resist penetration by water at significant depths of immersion. The behavior of water blown rigid polyurethane foam at different water pressures from 0 to 3 MPa are studied in this work. The effects of different surfactants on the cell structure and hydraulic resistance of the foams are examined. The foams have densities in the range of 145 to 160 kg/m³. With increasing applied hydraulic pressure, it is found that the foams have very small buoyancy losses at low pressures but beyond a threshold pressure, buoyancy losses increase rapidly. The threshold pressures of the foams increase with decrease in cell window area. A cell window is the lamella of the foam material that separates two adjacent cells. The cell sizes of the foam are found to correlate with the size of the air bubbles entrained during initial mixing. Surfactants, which reduce the surface tension of the polyol to the greatest extent, are found to give the finest initial bubbles, smaller cells, and foams with the highest hydraulic resistance. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2821–2829, 2004     

Study on the microphase structure and mechanical properties of the blends of acrylonitrile–butadiene–styrene and sodium sulphonated styrene–acrylonitrile ionomer

The tensile properties of the blends containing neat acrylonitrile–butadiene–styrene (ABS), styrene–acrylonitrile (SAN) and the sodium sulphonated SAN ionomer have been investigated as a function of ion content of the ionomer in the blend. The tensile toughness and strength of the blends showed maximum values at a certain ion content of the ionomer in the blend. This is attributed to the enhanced tensile properties of the SAN ionomer by introduction of ionic groups into SAN and the interfacial adhesion between the rubber and matrix phase in the blend. The interfacial adhesion was quantified by NMR solid echo experiments. The amount of interphase for the blend containing the SAN ionomer with low ion content (3·1mol%) was nearly the same as that of ABS, but it decreased with the ion content of the ionomer for the blend with ion content greater than 3·1mol%. Changing the ionomer content in the blends showed a positive deviation from the rule of mixtures in tensile properties of the blends containing the SAN ionomer with low ion content. This seems to result from the enhanced tensile properties of the SAN ionomer, interfacial adhesion between the rubber and matrix, and the stress concentration effect of the secondary particles. © 1998 SCI.     

Effects of different catalysts on the structure and properties of polyurethane/water glass grouting materials

Polyurethane/water glass (PU/WG) grouting materials were prepared in presence of different proportions of catalyst. The effects of catalyst on the mechanical properties, thermal properties, and chemical cross‐sectional morphologies of the grouting materials were also investigated. Catalyst addition can significantly increase the chemical reaction rate, reduce the gel time and curing time, and improve the thermal stability of PU/WG grouting materials. It was found that the grouting material containing 0.1 wt % BDMA + 0.1 wt % DBTDL demonstrated high fluidity, short curing time, and high early‐stage and late‐stage (up to 66.1 MPa) compression strengths. However, when the content of the added catalyst was equal to 0.5 wt %, fine cracks were formed in the material structure accompanied by the detachment of spherical particles from the PU matrix, which significantly deteriorated its mechanical properties. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46460.     

Polyurethane/acrylate hybrids: Effects of the acrylic content and thermal treatment on the polymer properties

Polyurethane (PU)/acrylate hybrids with different acrylic contents (10, 30, 50, 70, and 90 wt %) were prepared by the polymerization of acrylic monomers in the presence of preformed PU chains with polymerizable terminal vinyl groups. Films obtained by the casting of polymer dispersions before and after thermal annealing were characterized by dynamic light scattering, Fourier transform infrared spectroscopy, transmission electron microscopy (TEM), TEM electron energy‐loss spectroscopy, differential scanning calorimetry, and gel fraction determination. Small‐angle X‐ray scattering (SAXS), wide‐angle X‐ray scattering, mechanical properties testing, atomic force microscopy, water contact angle testing, Buchholz hardness testing, and roughness testing of the films were also performed. The effects of the acrylic content and thermal treatment on the structure and properties were determined. TEM showed that a core–shell morphology was formed during polymerization. When the acrylic content increased, smaller particles without core–shell morphologies were observed. TEM energy‐loss spectroscopy studies confirmed this observation. Systems with up to 50 wt % acrylic component were homogeneous, as determined by SAXS, before and after thermal annealing. An attempt to incorporate a higher amount of acrylic component led to phase‐separated materials with a different morphology and, therefore, different properties. The relationship between the acrylic content and properties did not follow linear behavior. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of the reagent molar ratio on the phase separation and properties of waterborne polyurethane for application in a water‐based ink binder

Waterborne polyurethane (WPU) dispersions with a high solid content and low viscosity were prepared successfully by a two‐step polymerization with isophorone diisocyanate, poly(propylene glycol), and dimethylol propionic acid as the main raw materials. The molar ratio of hard segments to soft segments was controlled to investigate its influence on the particle size, particle morphology, stability of dispersions, and final properties of the WPU films. Measurements including attenuated total reflectance/Fourier transform infrared spectroscopy, transmission electron microscopy, differential scanning calorimetry, thermogravimetric analysis, X‐ray diffraction, polarizing optical microscopy, and contact angle tests were used to characterize the bulk structures, phase separation, thermal stability, crystallinity, and wettability of the WPU dispersions. The results indicate that all of the WPU dispersions with a high solid content (ca. 40 wt %) and low viscosity (ca. 20–50 mPa s) displayed excellent stability. The prepared WPU dispersions with acetone contents of 5–7 wt % could be used directly as an ink binder without removing the acetone; this is beneficial to industrial applications of water‐based ink binders. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45406.     

High-density polyethylene (HDPE) hollow fiber membrane via thermally induced phase separation. I. Phase separation behaviors of HDPE–liquid paraffin (LP) blends and its influence on the morphology of the membrane

Phase separation behaviors of the blends that consist of high-density polyethylene (HDPE) and LP was investigated by means of thermal analysis. The miscibility of the two components was evaluated in terms of the Flory–Huggins interaction parameter, determined from the Hoffman–Weeks plot, gave a value of 0.36. This leads us to a conclusion that this blend system is applicable to the preparation of microporous hollow fiber membrane by melt spinning of the blend. The homogeneous blends in the molten state become heterogeneous systems to yield microporous HDPE membranes in the course of cooling due to thermally induced phase separation. The influence of the phase separation on the membrane morphology was also discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2135–2142, 1999     

Relationships between rheological properties,morphological characteristics,and composition of bitumen–styrene butadiene styrene copolymers mixes. I. A three-phase system

The variation, with temperature, of the dynamic mechanical properties (at 5 Hz) of bitumen–SBS mixes has been established. Typical features of the storage modulus, the loss modulus, and the loss angle variations with temperature could be attributed to the different phases that compose the mix. Finally, relationships between viscoelastic measurements and morphological characteristics (number of phases, phase composition, and phase content in the blend) have been proposed. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1595–16, 1997     

Quantification of shish–kebab and β‐crystal on the mechanical properties of polypropylene

The oriented “shish–kebab” structure and β‐crystal can enhance the mechanical properties of polypropylene products. In this regard, equipment and β‐nucleation agents have been developed or modified to form shish–kebab and β‐crystal. However, the effect of shish–kebab/β‐crystal proportion on the mechanical properties of polypropylene remains unclear. The answer is crucial but remains a challenge because of the difficulty in manipulating the shish–kebab proportion. In this work, we used a self‐made multiflow vibrate‐injection molding, which can provide a controllable shear flow, to produce samples with different shear‐layer thicknesses. The shish–kebab proportion was represented by R, which is the thickness ratio of the shear layer to that of the whole sample. Results showed that the tensile strength exponentially increased, whereas the elongation at break exponentially decreased, with R. The impact strength remained constant with R, indicating that the shish–kebab and β‐crystal possessed similar toughening effects. This work proposes a schematic to interpret the strengthening mechanism involved and presents a method of establishing and controlling the mechanical properties of polypropylene samples by using shish–kebab structures and β‐crystals. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45052.     

Hydrogen bonding and morphological structure of segmented polyurethanes based on hydroquinone– bis(β-hydroxyethy)ether as a chain extender

Two series of polyether polyurethanes based on hydroquinone bis(β-hydroxyethy) ether (HQEE) or 1,4-butanediol (BDO) as a chain extender were prepared by a one-step bulk polymerization process. Their hydrogen bonding and morphological structure were studied by means of Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). Compared with BDO-based polyurethanes, HQEE-based polyurethanes showed better phase segregation and higher extent of ordering in the hard domain. Besides short-range hydrogen bonds, a considerable amount of long-range hydrogen bonds existed in amorphous phase of the hard domain. The soft segment was easier to crystallize, and the melting temperature of the hard domain was elevated in HQEE-based polyurethanes. Its hard domain displayed a banded structure, rather than spherulitic structure in BDO-based polyurethanes. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2895–2902, 1999     

Effects on the structure and properties of membranes formed by blending polydimethylsiloxane polyurethane into different soft‐segment waterborne polyurethanes

Polydimethylsiloxane polyurethane (PDMS‐PU), which was synthesized from PDMS as the soft segment, was blended into a variety of ester‐ or ether‐based soft‐segment waterborne polyurethanes with different concentrations to investigate the crystallization, thermal, and physical properties of the membrane formations. According to X‐ray analysis, the ether‐based PUs, synthesized from soft segments of poly(propylene glycol) (PPG1000) or poly(ethylene glycol) (PEG2000), were found to have maximum crystallinity at a 5% blending ratio of PDMS‐PU, but the ester‐based PU, synthesized from soft segments of polycaprolactone (PCL1250), had decreased crystallinity at a 5% blending ratio. Differential scanning calorimetric analysis revealed that the T_g,s values of PUs were highest when the blending ratio of PDMS‐PU was 5%–10%, except for PU from PCL1250. Moreover, ether‐based PUs showed maximum T_m,h values, but the T_m,h of the ester‐based PU was greatly reduced when PU with PCL1250 was blended with PDMS‐PU. In addition, the PU from PEG2000 had the highest melting entropy. Mechanical property analysis showed that the stress of ether‐based PUs would be increased when PUs were blended with a small amount of PDMS‐PU and that the stress of PU from poly(tetramethylene glycol) (PTMG1000) increased to its greatest value (20–30 MPa). On the other hand, the ester‐based PU, from PCL1250 blended with PDMS‐PU, would have reduced stress. On the whole, the stress and strain of PU from PEG1000 had excellent balance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 210–221, 2006