Trimethylol Propane Content Research Articles

High solid content waterborne polyurethane with high foaming rate to artificial leather: Synthesis and characterization

A type of high solid content waterborne polyurethane (HSWPU) dispersions applied to foamed artificial leathers were designed and prepared by prepolymer method. The solid content of the waterborne polyurethane dispersions could reach 53 %, and the foaming ratio could reach an astonishing 2.50 by adjusting the parameters. The influence of synthesis parameters, including R value (molar ratio of -NCO/-OH), D value (hydrophilic group content), trimethylol propane (TMP) content (degree of crosslinking) and ethylenediamine (EDA) content (it was chain extender) on foaming ratio were investigated. Meanwhile, a series of properties of HSWPU dispersions, films and foamed artificial leathers were introduced in detail. The results demonstrated that R value, TMP content, D value and EDA content synergistically decided the foaming properties of HSWPU dispersions in three aspects: three-dimensional structure, surface tension and polarity, respectively. With optimized parameters of R = 2.0, TMP = 0.4 wt%, DMPA = 3.0 wt% and EDA = 60 wt%, the HSWPU dispersions had good appearance and stability, and the latex particles exhibited excellent water, acid and alkali resistance after films formation. The HSWPU dispersions with high foaming rate without collapsing in the foam-forming process and created uniformly bubble pores. In terms of application properties, the prepared foamed artificial leathers showed admirable air permeability and water vapor transmissions. All results distinctly demonstrate a feasible yet promising paradigm for applying the HSWPU on foamed artificial leathers had great potential applications.

Synthesis of a Reactive Cationic/Nonionic Waterborne Polyurethane Dye Fixative and Its Application Performance on Viscose Fiber Fabrics.

A series of cationic waterborne polyurethane (CWPU) emulsions was synthesized with isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI) as hard segments; polyol (N210) and polyethylene glycol (PEG-2000) as soft segments; N-methyldiethanolamine (MDEA) as a hydrophilic chain extender; and trimethylolpropane (TMP) as a crosslinker. Then, the effects of the R-value, MDEA content, and TMP content on the properties of the CWPU emulsion, film, and fabric treatment were investigated. The results indicated that when the R-value was 3.0, the MEDA content accounted for 4.0% of the solid and the TMP content accounted for 1.0% of the solid. CWPU has excellent storage stability. Applying it to the fixing treatment of the viscose fiber fabrics can effectively improve the color fastness to rubbing, elasticity, surface smoothness, and anti-static properties.

Preparation and Properties of a Novel Cross-Linked Network Waterborne Polyurethane for Wood Lacquer.

Waterborne polyurethane (WPU) is a waterborne coating with excellent physicochemical properties. Its deficiencies of water resistance, chemical resistance, staining, and hardness have limited the wide application of polyurethane in the wood lacquer market. In this study, polycarbonate diols (PCDL) were used as soft segments and WPCU was modified by cross-linking using Trimethylolpropane (TMP) to prepare polycarbonate type WPU (WPCU) with cross-linked network structure. The new wood lacquer was prepared by adding various additives and tested by applying it on wood board. The successful synthesis of WPCU was determined by FTIR testing, and the cross-linking degree of WPCU was probed by low-field NMR. The viscosity of the cross-linked WPCU emulsion showed a decreasing trend compared to the uncross-linked WPCU emulsion, and WPCU-2 had the smallest particle size. Compared with the uncrosslinked WPCU film, the crosslinked WPCU film had lower water absorption (2.2%), higher water contact angle (72.7°), excellent tensile strength (44.02 MPa), higher thermomechanical, and better water and alcohol resistance. The effect of crosslinker content on the microphase separation of WPCU chain segments on the surface roughness of the film was investigated by SEM. The wood paint prepared by WPCU emulsion has good dry heat resistance, chemical resistance, and adhesion, and the hardness of the wood paint when the TMP content is 3% reaches H. It also has good resistance to sticky stains, which can be used to develop new wood lacquer.

Examining the Effect of Trimethylol Propane Crosslinker on Butanetriol Trinitrate Plasticized Polycaprolactone Polymer Networks of Propellant Binder System

AbstractThe knowledge of polymer network characteristics is important to tune the properties of advanced energetic propellants based on nitrate ester plasticized polyol binder system. In this article, plasticized polyurethane networks of polycaprolactone (PCP) and hydroxyl‐terminated polybutadiene (HTPB) with different crosslinker content [0 to 0.20 parts] at various stoichiometric ratios (r‐value) [0.8 to 1.0] were studied. Five numbers of polyurethane networks of 1,2,4‐butanediol trinitrate (BTTN) plasticised PCP were formulated at each r value 0.8, 0.9 and 1.0 using 0, 0.05, 0.10, 0.15 and 0.20 parts of trimethylolpropane (TMP) crosslinker. Similarly, five numbers of dioctyl adipate (DOA) plasticized HTPB based polyurethane networks were formulated at r‐value of 0.8. FT‐IR spectra of these polyurethane networks (PUNs) were recorded for functional group identification. Stress‐strain behavior of PUNs was studied for understanding the effect of TMP content and r value on mechanical properties. Hard segment content of PUNs were calculated and its influence on network characteristics and mechanical properties was evaluated. CLD values (ν) increased with increase of hard segment content of PUN and the values quantified by different approaches followed the trend νe (by solvent swelling method) > νne2(by Initial modulus method)>νne1 (by Mooney Rivlin method).

Synthesis of highly branched water-soluble polyester and its surface sizing agent strengthening mechanism

Abstract Solvent-free and highly branched water-soluble polyester (WPET) is prepared through self-emulsification methodology, using dimethyl terephthalate (DMT), sodium dimethyl isophthalate-5-sulfonate (SIPM), trimethylolpropane (TMP), and ethylene glycol (EG) by the transesterification and polycondensation. The WPET were first utilized as surface-sizing agents for cellulose fiber paper. The structure, average molecular weights, and physical properties of the water-soluble polyester were characterized by FTIR, 1H NMR, gel permeation chromatography (GPC), dynamic light scattering (DLS), X-ray diffraction (XRD), and dynamic rheometer. The effects of polymer structure and properties, as well as the surface sizing of the paper, were investigated. WPET displayed better surface sizing properties when it was prepared under the following conditions: –COO/–OH molar ratio of 1:2, the SIPM content of 17.98%, and TMP content of 11.10%. The relationships between the WPET structure and sized paper were clearly illustrated. The mechanical properties and water resistance of sized paper did not only depend on multi-branched hydroxyl groups of the WPET chains but also relied on the interactions among polymers and fibers, as well as the high toughness of surface sizing agent. The sizing paper possesses excellent mechanical properties as well as water resistance.

Preparation and properties study of waterborne polyurethane synthesized by mixing polyester diols and isocyanates

AbstractIn view of environmental protection requirements, it is an inevitable trend for waterborne coatings to replace traditional coatings. Waterborne polyurethane (WPU), a kind of typical resin used in coatings, has become a research hot topic of waterborne coatings because of its advantages, such as non‐polluting, safe and reliable, excellent properties, good compatibility, and easy modification. In this article, solvent‐free WPU is prepared by mixing 4,4′‐dicyclohexylmethane diisocyanate/ isophorone diisocyanate (HMDI/IPDI) and polycarbonate diol/ Polycaprolactone diol (PCDL/PCL). Through the comparison of the properties of the polymer, the best amount of raw materials was determined. Specifically, R = 1.35 (R is NCO/OH ratio), the content of dimethylolpropionic acid (DMPA) is 5.5%, the content of trimethylol propane (TMP) is 2.5%, the mole ratio of HMDI/IPDI is 2:1, the mole ratio of PCDL/PCL is 2:1, and the preeminent WPU shows the excellent thermal stability, the contact angle of 118.04°, the hardness is H. The chemical structures and rough surface morphologies of the WPU films were characterized by FT‐IR, TG, AFM, and SEM, respectively. Therefore, considering the film properties, and the low cost, simple, and green process, this research will offer the possibility of application of this free‐solvent WPU in industrial production and large‐scale application.

Synthesis and characterization of alicyclic two-component waterborne polyurethane

PurposeThe purpose of this paper is to synthesize and characterize a series of alicyclic two-component waterborne polyurethane (2K-WPU) which is composed of non-ionic polyisocyanate aqueous dispersion and hydroxyl aqueous dispersion.Design/methodology/approachThe appearances of aqueous dispersions and 2K-WPU films were observed by photographs. The micromorphology of alicyclic polyisocyanate aqueous dispersion was examined by scanning electron microscopy (SEM). The molecule structures of WPU were studied by Fourier transform infrared (FTIR). The effect of NCO:OH molar ratio of two components and trimethylolpropane (TMP) content on the thermal stability, mechanical and water resistance properties of 2K-WPU films was studied.FindingsIt was found by SEM that alicyclic polyisocyanate particles in aqueous dispersion showed a kind of spherical particle appearance, in which hydrophobic polyisocyanate was encapsulated by hydrophilic ether linkages segment. FTIR showed that WPU was polymerized through mixture of polyisocyanate component and hydroxyl component and increasing NCO:OH molar ratio of two components from 1.1:1 to 1.5:1 had increased the content of urea, urethane and allophanate of 2K-WPU films. Increasing NCO:OH molar ratio had improved the mechanical and thermal properties of the 2K-WPU film, but the water resistance of the 2K-WPU film increased first and then weakened. Increasing TMP contents from 1 to 0.75 mol for 1:5 system had improved the mechanical, thermal and water resistance properties of the 2K-WPU film.Practical implicationsThe investigation established a method to prepare alicyclic 2K-WPU which is composed of non-ionic polyisocyanate aqueous dispersion and hydroxyl aqueous dispersion. The prepared 2K-WPU film could be applied in the field of waterborne surface coating, e.g. textile, wood and synthetic leather surfaces (Hasan et al., 2017; Akindoyo et al., 2016).Originality/valueThe paper established a method to synthesize alicyclic two-component 2K-WPU. The effect of NCO:OH molar ratio and TMP content on the thermal stability, mechanical and water resistance properties of 2K-WPU films were studied.

Effects of trimethylol propane and AAS salt on properties of waterborne polyurethane with low gloss

Abstract A series of waterborne polyurethane(WPU) dispersions containing different amounts of trimethylol propane(TMP) and/or 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt (AAS salt), were synthesized by prepolymer emulsification process. The effects of TMP and AAS salt on properties of WPU dispersions were discussed to find out the appropriate formulation of WPU dispersion with low gloss. The results showed the particle size of WPU increased as the TMP content increased, but a decrease to the gloss and transparency. Spherical granules emerged in the surface morphology of WPU films when the TMP content exceeded beyond 1% by weight via scanning electron microscope (SEM). In contrast, as the AAS salt content increased, the particle size of WPU decreased, and the gloss and transparency increased. It was most worth noting that the dispersion stability of WPU dispersions was enhanced dramatically with the increase of AAS salt content by measuring the Zeta potential of emulsion. Therefore, WPU dispersions with low gloss and high dispersion stability can be prepared successfully with the AAS content of 0.5% by weight and the TMP content of 1%–1.5% by weight when other influence factors were fixed to a suitable condition.

Preparation and properties of emulsifier-/solvent-free slightly crosslinked waterborne polyurethane-acrylic hybrid emulsions for footwear adhesives (III)–effect of trimethylol propane (TMP)/ethylene diamine (EDA) content

Stable emulsions of emulsifier-/solvent-free slightly crosslinked waterborne polyurethane-acrylic hybrids (WPU/AC-Ts) with a fixed acrylic monomer content (20 wt.%) and different trimethylol propane (TMP)/ethylene diamine (EDA) (0/0.20, 0.02/0.17, 0.04/0.14, 0.06/0.11, 0.08/0.08, the number indicated the mole% of TMP/EDA) for footwear adhesive materials were successfully prepared in this study. The as-polymerized hybrid emulsion containing 0.10/0.05 mole% of TMP/EDA content was found to be unstable, indicating that near 0.10/0.05 mole% of TMP/EDA content was beyond the limit value of crosslinkable TMP component for self-emulsifing. This study examined the effect of mole% of TMP/EDA on the stability and viscosity of hybrid emulsions, the tensile properties and dynamic mechanical thermal properties of hybrid film samples, and the adhesive strengths of formulated adhesives for footwear at both dry and wet states. As TMP content increased, the tensile strength/modulus/storage modulus/hardness of WPU/AC-Ts film samples increased, however, their elongation at break and water swelling% decreased significantly. The adhesive strength (peel strength) of formulated adhesives was found to be dependent upon the degree of drying, but almost not upon the TMP content in WPU/AC-Ts. The adhesive strength of footwear (EVA/leather) dried at room temperature for 24 h was higher than that of footwear dried for 30 min. However, the adhesive strength at wet state increased significantly with increasing TMP content. The optimum TMP/EDA contents were found to be 0.06/0.11 and 0.08/0.08 mole% to achieve the desired high performance adhesive properties such as high strength in wet state.

Preparation and properties of high storage stability polyester polyol dispersion for two-component waterborne polyurethane coating

A new type of polyester polyol dispersion with good storage stability was prepared based on a hydrophilic monomer 5-sodium sulfodimethyl isophthalate (5-SIPM), and frequently-used monomers such as neopentyl glycol (NPG), dimethyl terephthalate (DMT), dimethyl phthalate (DMP) and trimethylolpropane (TMP) by the transpolycondensation and polycondensation method. The polyester polyol dispersion was characterized by FTIR and GPC. The proper content of these monomers were determined by the performance of polyester dispersion: the content of TMP was 15wt%, the content of NPG was 7.5wt% and the hydrophilic monomer 5-SIPM content was 5wt%. Two-component waterborne polyurethane (2K-WPU) coatings were prepared by Bayhydur® XP2487/1 and polyester polyol dispersions, which were stored before and after at 40 ° for 6 weeks, the prepared films have no differences in drying time, adhesion, pencil hardness, gloss and chemical resistance, the result also reveals that the polyester polyol dispersion have excellent storage stability resistance.

Synthesis and Properties of Cationic Polyurethane Dispersions

A series of water dispersible polyurethanes containing quaternary ammonium group as the hydrophilic group with different content of trimethylolpropane (TMP) as inner crosslinker were prepared. IR spectroscopy was adopted to demonstrate the polymerization reaction and structure of polymer. The effects of TMP content on PU properties were investigated. Particle size distribution (PSD) analysis and morphology of PU observed by TEM showed that particle size of PU dispersions initially decreased and then increased with increasing TMP content. The viscosity of the PU dispersions with TMP addition was bigger than the PU dispersions without TMP. TG analysis indicated thermal stability and microphase separation degree of PU was enhanced with increasing TMP content. Contact angle and gel content of PU also increased as increasing TMP content. Meanwhile, tensile strength increased and then decreased with the increment of TMP content.

Synthesis of branched poly(butylene succinate): Structure properties relationship

A series of branched poly(butylene succinate) (PBS) were synthesized with several branching agents namely trimethylol propane (TMP), malic acid, trimesic acid, citric acid and glycerol propoxylate. The structure of the branched polymers was analyzed by SEC and 1H-NMR. The effect of branching agent structure on crystallization was also investigated and played a significant role. Isothermal studies showed that glycerol propoxylate could act as a nucleating agent. By contrast high content of TMP disturbed the regularity of the chain and hindered the crystallization of PBS. From the non-isothermal kinetic study, it was found that glycerol propoxylate increased noticeably the crystallization rate due to the flexible structure of the branching agent. A secondary nucleation was observed with glycerol propoxylate attributed to the crystallization of amorphous fraction included between crystallites formed at the primary crystallization. Chain topology was obtained through rheological investigations and the synthesized polymers showed a typical behavior of a mixture of linear and randomly branched PBS. The incorporation of branches improved the processability of PBS for film blowing application and the modulus and the stress at break of the resulting film were significantly increased.

Synthesis and characterization of waterborne polyurethane emulsions based on poly(butylene itaconate) ester

Waterborne polyurethane (WPU) prepolymer was synthesised by the reaction of poly(butylene itaconate) ester (PBI, Mn = 1109 g/mol), 1,6-hexanediol, dimethylol propionic acid (DMPA), 2,4-toluene diisocynate (TDI), hydroxyethyl acrylate (HEA), and absolute ethanol as blocking agent, triethylamine as neutralizer. Cross-linked WPU was synthesized by trimethylolpropane (TMP) as crosslinker. The influences of PBI, DMPA, and TMP content on WPU emulsions and films were investigated. The structure of WPU was determined by Fourier transform infrared (FTIR) spectra, thermal properties and glass transition temperature of WPU films were determined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), respectively, and morphology of the emulsion particles was observed by transmission electron microscopy (TEM). Through TGA, the heat resistance of the cross-linked WPU film was better than WPU film. By DSC analysis, glass transition temperature of cross-linked WPU film (21 °C) was higher than WPU film (10 °C).

Synthesis of aqueous and hydroxy-terminated polyurethanes: Impacts of formulation parameters by orthogonal matrix design

Abstract Aqueous and hydroxy-terminated polyurethanes (AHPUs) were synthesized using poly(caprolactone) glycol, isophorone diisocyanate, dimethylolpropionic acid (DMPA) as main raw materials, trimethylolpropane (TMP) as crosslinking agent, ethylenediamine (EDA) as chain extender, and tris(hydroxylmethyl) aminomethane as chain terminator. The optimum synthesis condition of AHPUs was elected by L 16 (4 5 ) orthogonal experiments with the content of DMPA ( A ) and TMP ( B ), molar ratio of isocyanate to hydroxyl in the prepolymerization step ( C ) and the molar ratio of amino groups in EDA to residual isocyanate groups of prepolymerization ( D ) as factors and the transmittance, relative viscosity and particle size of dispersions as evaluation index, and the tack-free drying time, gloss, hardness, adhesion and water resistance of coatings were discussed, too. The results demonstrate that the synthetic AHPUs have good physical properties, such as relative viscosity, transmittance and particle size, what's more, the two-component films have good air-drying ability, gloss, hardness, adhesion and water resistance when synthesis parameters are A = 7.0 wt%, B = 5.0 wt%, C = 1.6 and D = 0.2.

Effects of crosslinking on adhesion behavior of waterborne polyurethane ink binder

Abstract A series of waterborne polyurethanes (WPUs) with different crosslinking densities were synthesized by varying the amount of trifunctional crosslinker trimethylolpropane (TMP). The effects of the TMP content on the adhesion behavior of WPUs were investigated in terms of the cohesive strength of WPUs, and the interface adhesion strength between WPUs and the substrate–polyethylene glycol terephthalate (PET) film. It was found that with the increase of TMP content, the interface adhesion strength decreased due to the decreased mobility of PU molecular chains, the cohesive strength of WPUs films increased because of the increase in the crosslinking density (υe), and the T-peel strength (T) initially increased and then decreased with the change of debonding failure from a cohesive failure to an interface failure. An empirical equation, revealing the relation between peel strength and TMP content (x), was found to be T = 1.94 + 0.81x − 0.22x2, and another empirical equation, T = 1.59 + 750.44 υ e − 128313.62 υ e 2 , showing the relation between peel strength and crosslinking density was obtained. Moreover, crosslinking density was mainly determined by TMP content, and it was found that the relationship between υe and x could be showed by the equation υe = 0.00045 + 0.0013x or υe = 0.00050 + 0.0013x. On the whole, crosslinking played an important role in the adhesion behavior of WPUs, and an optimal crosslinking density was a key for preparing the WPUs with outstanding adhesion property. In this study, the optimal υe was 0.00292 mol/cm3.

EFFECT OF CROSSLINK DENSITY ON THE STRUCTURES AND PROPERTIES OF ALIPHATIC POLYURETHANE ELASTOMER

A series of crosslinked aliphatic polyurethane(PU) elastomers with various crossslink densities were synthesized by the reaction of isophorone diisocyanate(IPDI) with polyether diol,trimethylolpropane(TMP) and 1,4-butanediol(BDO) through one step method.The results showed that the crosslink density of PU elastomers exhibited a linear relationship to the content of TMP,while the content of hard segments of PU elastomers was fixed at 40 wt%.With the increase of the crosslink density of the PU elastomers,the glass transition temperature(Tg) value of the hard segment domains in the PU dropped significantly from 32℃ to 21℃,the Tg value of the soft segment domains in the PU dropped slightly form-47℃ to-48℃,and the degree of H-bonded urethane carbonyl in the PU decreased from 83% to 63%,which indicated that the micro-phase miscibility of the PU elastomers was enhanced.With the increase of the crosslink density of the PU elastomers,the TGA results showed that the onset decomposition and the maximum decomposition temperature of the PU elastomers increased from 285℃ to 319℃ and 325℃ to 349℃ respectively,which indicated that the thermal stability of the PU elastomers was also improved.The mechanical test indicated that the Young’s modulus,modulus at 100% extension and Shore A hardness of the PU elastomers significantly increased with the increase of the crosslink density of PU,while the elongation at break decreased.

폴리우레탄 평판 음향 원도우 제조와 수중에서 기계적 및 음향적 특성 연구

Polyurethane (PU) sheets were fabricated by the reaction of polypropylene glycol (PPG) and liquid diphenyl methane diisocyanate (L-MDI) with various trimethylol propane (TMP) contents. The value was varied from 34.8 to 49.9 according to the TMP content. As the content of TMP was increased from 4 to 12 wt%, the modulus of the PU sheet was increased from 322 MPa to 423 MPa, its tensile strength was increased from 10.6 MPa to 14.8 MPa, and its elongation was decreased from 62.8% to 49%. In case of acoustic properties, the sound speed of PU sheet was increased while its attenuation coefficient was decreased as the content of TMP was increased. The fabricated PU sheet was stable in water bath for 4 weeks.

Thermal stability of chemically crosslinked moisture‐cured polyurethane coatings

AbstractPolyurethane prepolymers are widely used in reactive hot melt adhesives and moisture‐cured coatings. The segmented moisture‐cured formulations, based on polytetramethylene glycol (PTMG‐1000)/trimethylol propane (TMP)/isophorone diisocyanate (IPDI) and PTMG/TMP/toluene diisocyanate (TDI), were prepared with NCO/OH ratio of 1.6 : 1.0. The excess isocyanate groups of the prepolymers were chain extended in the ratio of 2 : 1 (NCO/OH) with different aliphatic diols and 4 : 1 with different aromatic diamines. The surplus isocyanate groups of the formulations were completely reacted with atmospheric moisture, and the thermal stability of the postcured materials obtained as cast films were evaluated by thermogravimetric (TG) analysis. It was observed that initial degradation temperatures were above 270°C, with two‐ or three‐step degradation profiles. The degradation parameters were evaluated using the Broido and Coats–Redfern methods. The thermal resistance of moisture‐cured formulations using diisocyanates with the cycloaliphatic structures (IPDI) and the aromatic TDI, at the same NCO/OH ratio (1.6), and TMP content were compared from the isothermal TG experiments at different temperatures and dynamic TG experiments at different heating rates in nitrogen and oxygen environments. The observation suggests that polyurethane‐containing sulfone groups and straight‐chain diol chain extenders were more stable. It was also observed that at lower temperature polyurethane, prepared from aliphatic diisocyanates (IPDI), was more stable than the aromatic diisocyanate (TDI) containing polyurethanes. At high temperature, the stability order follows the reverse trend. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1509–1518, 2005

Shape-memorized crosslinked ester-type polyurethane and its mechanical viscoelastic model

A series of shape-memorized crosslinked ester-type polyurethanes (PUs), based on different compositions of 4,4′-diphenyl methane diisocyanate (MDI), poly(butylene adipate) glycol (PBAG) with different molecular weight (MW) and trimethylol propane (TMP), were synthesized. The morphology of samples was investigated by using DSC, WAXD, and dynamic mechanical analysis (DMA). It was found that the morphology of the soft segment, which was PBAG with a different MW, was in an amorphous state and no crystalline domain was found. By increasing the crosslinked density (varying the content of TMP) or decreasing the length of the soft segment (MW of PBAG), the glass transition temperature of studied samples increased. But the range of transition broadened and the modulus ratio E′−20°C)/E′+20°C) also decreased. The shape-memory behavior was studied by the bending test method adopted from the shape-memory alloy. The sample with high Tg showed not only a high recovered temperature (Tr) but also a high recovered rate (Vr) with a high modulus ratio. By introducing the chemical crosslinked structure, the deformed samples completely recovered their original shape and rendered shape-memory behavior under the complex deformation. The shape-memorized crosslinked ester-type PUs can be applied at different operating temperatures. A mechanical viscoelastic model is discussed for the shape-memory behavior of PUs, and the modified Bonart's viscoelastic model properly describes the mechanism of the shape memory of PUs. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1305–1319, 1999

Separation of aqueous phenol through polyurethane membranes by pervaporation. II. Influence of diisocyanate and diol compounds and crosslinker

The influence of diisocyanate and diol compounds of polyurethane and crosslinking agent on the separation of phenol aqueous solution by pervaporation was investigated. Polyurethanes were prepared by polyaddition of diisocyanate and diol compounds and trimethylolpropane (TMP) using dibutyltindilaulate as a catalyst. The polyurethane membrane was prepared by a casting method and was sandwiched with a porous polypropylene membrane (Celgard® 2500). Pervaporation measurement was carried out under vacuum on the permeate side, and the permeant was collected with a liquid nitrogen trap. Little influence of diisocyanate compounds on the phenol permselectivity through diisocyanate–polytetramethyleneglycol [PTMG(1000)] membranes was observed since the influence on the solubility and the diffusivity was small. The phenol permselectivity was increased with an increase in the molecular weight of PTMG and polycaprolactone diol (PCL) for the 1,6-diisocyanato hexane (HMDI)–PTMG and HMDI–PCL membranes. It was considered that the increase in phenol diffusivity can be attributed to an increase in phenol selectivity. The permeability and selectivity of HMDI–[PTMG(2900)–TMP] membrane was relatively constant below the 2% TMP content. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 439–448, 1999