Smart secondary polyurethane dispersions

Secondary dispersions of cationic segmented polyurethanes (PUs) with thermoresponsivity (upper critical solution temperature (UCST) in water), high solid contents and antibacterial properties are highlighted in this paper. PUs were prepared by polyaddition reactions and subsequent quaternization with methyl iodide. No additional stabilizers, organic solvents or special procedures were required to obtain stable aqueous dispersions containing up to 10 wt% PU; in contrast, stable dispersions were straightforwardly accessed by a combination of UCST behavior and repulsive electrostatic forces among the positively charged segments, which meets the requirements of a green chemistry process. Particle size and UCST strongly depended on the solid content of the dispersions and the content of poly(ethylene glycol) segments in the copolymers. The dispersions exhibited fast‐acting antibacterial properties against Escherichia coli. © 2013 Society of Chemical Industry     

High‐performance waterborne coatings based on epoxy‐acrylic‐graft‐copolymer‐modified polyurethane dispersions

Polyurethane dispersions (PUDs) have been an active area of research since the early 1940s because of legislative restrictions on the use of organic solvents in conventional solvent‐based products and also because PUDs exhibit almost the same high performance levels as solvent‐borne polyurethanes. In the present study, properties of conventional waterborne PUDs are modified with epoxy‐acrylic graft copolymer blocks. The epoxy‐acrylic graft copolymers were first modified with ethylene diamine to give amine‐terminated blocks which in turn reacted with isocyanate‐terminated prepolymer (prepolymer mixing process) to give modified PUDs. Several experimental sets were prepared with varying compositions. The experimental sets were also prepared using conventional poly(ethylene glycol) blocks and ethylene diamine chain‐extenders. The physico‐chemical properties and film characteristics of the experimental sets show the dramatic improvement in important mechanical properties of PUDs due to grafting with epoxy‐acrylic copolymer blocks. Copyright © 2004 Society of Chemical Industry     

Modification of aqueous polyurethane dispersions via tetraphenylethane iniferters

Aqueous polyurethane (PU) dispersions containing tetraphenylethane iniferter groups were prepared from 4,4′‐diphenylmethane diisocyanate, poly(propylene oxide)glycols, dimethylol propionic acid, and 1,1,2,2‐tetraphenylethane‐1,2‐diol. To improve the water resistance of the dispersions, methyl methacrylate monomers were added into these dispersions and block‐copolymerized onto the main PU chain. The viscosity and particle size of the dispersions were determined. Dispersion‐cast films were characterized in terms of the contact angle, the swell in water, and the mechanical properties. Contact‐angle and water‐swell measurements showed that the hydrophilicity of the films was decreased significantly when methyl methacrylate was polymerized in the presence of tetraphenylethane containing aqueous PU dispersions. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2993–3000, 1999     

MWNTs/PUR复合材料的制备与气敏响应性研究

将端羧基丁二烯丙烯腈橡胶(CTBN)改性为多端羟基橡胶(f-CTBN)后,掺杂功能化多壁碳纳米管(MWNTs),与4,4′-二环己基甲烷二异氰酸酯(H12MDI)反应得到预聚物,再加入聚乙二醇(PEG6000)共聚合,得到一系列聚氨酯复合材料MWNTs/PUR;采用扫描电镜(SEM)、热失重(TG)等手段进行表征;考察了MWNTs含量、固化温度等因素对聚氨酯复合材料气敏响应能力的影响。结果表明,掺杂纳米管不仅提高了聚氨酯复合材料的力学和热学性能,更增强了其对有机溶剂饱和蒸汽的气敏响应能力;当固化温度为80℃时,聚氨酯复合材料的气敏响应能力最强。     

f-CTBN/PEG聚氨酯材料的合成及性能研究

以三乙醇胺得到的功能化丁腈橡胶（f-CTBN）和不同相对分子质量聚乙二醇（PEG）为基本物质,逐步聚合得到一系列高支化嵌段聚氨酯材料。探究f-CTBN、PEG的用量和固化剂（HDI与H12MDI）的不同对材料性能的影响,通过形貌观察、力学性能测试、毒性试验来综合评价,发现物料比m（f-CTBN）/m（PEG）为3∶7聚氨酯有望成为医用薄膜。     

共混改性废旧聚氨酯的再生研究

采用聚甲基丙烯酸甲酯(PMMA)与热塑性聚氨酯(PUR-T)共混改性废旧聚氨酯(PUR),探讨了PMMA与PUR-T用量对PUR再生料的力学性能、加工性能的影响,并分析了树脂与CaCO3的界面相容性.结果表明,添加PMMA或PUR-T共混改性废旧PUR均能使材料的力学性能有所改善;但添加PMMA使再生料的加工性能有所下降,而添加PUR-T使再生料的加工性能提高,通过扫描电子显微镜观察发现,其共混体系中树脂与CaCO3的界面接合性要比PMMA共混体系好.     

Crystallization of poly(ethylene oxide) in i-polypropylene–poly(ethylene oxide) blends

A two-stage stable system of isotactic polypropylene–poly(ethylene oxide) blend, in which poly(ethylene oxide) can be permanent either in molten or in crystallized states in the temperature range from 280 to 327 K, was described. The behavior of that blend was explained in terms of fractionated crystallization. A fine dispersion of poly(ethylene oxide) inclusions is required for efficient suppression of crystallization initiated by heterogeneous nuclei. The application of a thin film of polypropylene-poly(ethylene oxide) 9 : 1 blend obtained by quenching for multiuse erasable and rewritable carriers for visible information has been demonstrated. The same sample exhibits different dynamic mechanical properties when poly(ethylene oxide) inclusions are molten or crystallized. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2047–2057, 1997     

硅溶胶/苯乙烯-丙烯酸酯共聚物无机-有机杂化水分散液的制备和表征

A stable silica sol with 3-5 nm in diameter, which can form homogeneous film without crack, was prepared and characterized. Then, the inorganic-organic hybrid aqueous dispersion composed of such a silica sol and an emulsion of styrene （St） and acrylate （Ac） copolymer was prepared and the hybrid effect between the silica sol and poly（St-co-Ac） was observed by Fourier transform infra-red （FT-IR） spectroscope. The toughness of the film prepared by this kind of hybrid aqueous dispersion was excellent, as it was enhanced appreciably by commixing with a small amount of poly（St-co-Ac） emulsion. Some amino-polysiloxane modified hybrid aqueous dispersions were also prepared and the properties of the modified dispersions and their films were investigated. The experimental results showed that the film prepared with such an amino-polysiloxane modified hybrid dispersion exhibited excellent hydrophobicity and low surface energy after heat treatment for 1.5 h, during which the formation of the graft copolymer was observed. The surface energy of this film decreases as a result of the enrichment of siloxane segments on the film surface.     

Influence of the addition of PEG into PCL-based waterborne polyurethane-urea dispersions and films properties

In this work, segmented waterborne polyurethane-urea (WBPUU) dispersions containing hydrophobic polycaprolactone (PCL) and hydrophilic poly(ethylene glycol) (PEG) in different molar ratios are synthesized and used for the subsequent preparation of films by casting. The molar ratio of PEG is gradually increased up to 0.20 in order to analyze the effect of low hydrophilic PEG content (from 1.7 to 7.1 wt %) on the properties of resulting dispersions and films. Regarding the dispersions, the addition of PEG results in an increase of the particle size, from 86 ± 1 in the case of pure PCL-based system to 112 ± 15 for systems containing 7.1 wt % of PEG, as well as in the formation of a core–shell structure in the particles. Films show different behaviors depending on their PEG content. WBPUUs containing just PCL or very low content of PEG in the soft segment present higher stiffness. However, the addition of PEG in a content of 3.4 wt % or higher hinder the ability of the short-range ordering of the hard segment, increasing the elongation at break from 842 ± 102 MPa for PCL-based WBPUU to 1312 ± 84 MPa for the system with the highest PEG content. Systems with higher PEG content form nanoparticles with more segregated core–shell structures inducing to the film a higher hydrophilicity. Hence, the addition of PEG to a PCL-based WBPUU allows to tune the properties of the resulting film increasing the range of application of these materials. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48847.     

Chitosan modified by poly(ethylene oxide): Film and mixture properties

Chitosan + poly(ethylene oxide) mixtures and films prepared from these mixtures were studied by rheological, absorption of solvent vapors, SANS, and mechanical testing methods. At a stoichiometric chitosan:poly(ethylene oxide) monomer:monomer composition, the mechanical properties of chitosan + poly(ethylene oxide) film are the best as compared with those of the initial components or of other compositions. This film composition is shown to be less heterogeneous. Chitosan and poly(ethylene oxide) are proved to be slightly incompatible polymers. This is supposed to induce the two components to align and to order at their stoichiometric composition, leading to the improvement in the mechanical properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1114–1122, 2002; DOI 10.1002/app.10319     

混凝一光催化氧化法处理合成胶废水的研究

以硫酸亚铁和过氧化氢作为催化剂,采用混凝一光催化氧化法,通过混凝、Fenton试剂和紫外光照射处理合成胶废水。考察了混凝剂种类及加量、FeSO。·7H：O加量、处理时间、pH值、HzO2加量及投加方式对合成胶废水COD去除率的影响,确定最佳处理条件如下：以硫酸铁为混凝弃3、其加量2500mg·I^-1,FeSO。·7Hz0加量为5．0g·L^-1。,处理时间为120rain,pH值为5．5,H2O。加量为10．0mL·I^-1’、分2次投加。此时,合成胶废水COD去除率达92．31％．     

Thermal stability of polyurethane elastomers before and after UV irradiation

In this work, we investigated the thermal degradation behavior of segmented polyurethane (PUR) elastomers before and after UV irradiation. The thermal degradation of PUR elastomers was studied over the temperature range of 25–600°C in an atmosphere of nitrogen using thermal gravimetric analysis (TGA). Four series of PUR elastomers derived from poly(oxytetramethylene)glycol (PTMO) of 1000 and 2000 molecular weight and poly(caprolactone glycol) (PCL) of 1250 molecular weight, 4,4′‐diphenylmethane diisocyanate (MDI), and 4,4′‐dicyclohexylmethane diisocyanate (H₁₂MDI) and 1,4‐butanediol as an chain extender were synthesized by the prepolymer method. The derivative thermogravimetric (DTG) peaks observed in the experiments indicated that PUR elastomers degraded through two steps. We attributed the first step to degradation of the hard segment. The second degradation step could be ascribed to degradation of the soft segment. We found that the PUR elastomers based on poly(ester polyol) and aromatic diisocyanate exhibit better thermal stability than that of PUR elastomers based on the poly(ether polyol) soft segment in both steps of degradation. The thermal degradation is more prevalent in PUR elastomers based on cycloaliphatic diisocyanate. The higher values of the temperature of initial decomposition (Tⁱ) indicate a higher thermal stability of UV‐exposed elastomers on the beginning of degradation. This may be due to the formation of a crosslinking structure in the presence of UV irradiation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 864–873, 2001     

透明聚氨酯胶片的成型与应用研究

研究透明聚氨酯（PUR）浇铸料的合成，并用三种不同的方法成型出PUR胶片，对胶片的外观质量、光学性能及力学性能进行了比较。结果表明，离心浇铸法制出的胶片综合性能最好，进一步研究了离心浇铸法的各影响因素，将PUR胶片用于制造防弹玻璃，并全面测试了光学性能和防弹性能。该防弹玻璃防弹效果优于传统的以聚乙烯醇缩丁醛为粘接层的纯化无机层合防弹玻璃。     

以聚乙烯醇为保护胶体的乳液与部分官能团的接枝反应研究

主要研究了在以聚乙烯醇为保护胶体的醋酸乙烯乳液聚合中,乳液与环氧丙烯酸酯、聚氨酯、硅烷等官能团的接枝反应.在以过硫酸铵为引发剂、以聚乙烯醇为保护胶体的醋酸乙烯乳液聚合中,乳液与上述各类官能团间发生的接枝反应直接影响乳液的黏度、固体含量、剪切强度等宏观性质.研究发现官能单体脂肪醇聚氧乙烯醚、丙烯酸异辛酯(2-EHA)等单体和丙烯酸(AA)与乙烯基三乙氧基硅烷共同作用时对乳液的宏观性质影响显著.     

Glycolyzed products from PET waste and their application in synthesis of polyurethane dispersions

Soft drinks poly(ethylene terephthalate) (PET) bottles were depolymerized by glycolysis with different molar ratio of glycol, such as propylene glycol (PG), triethylene glycol (TEG) and poly(ethylene glycol) (PEG 400), in the presence of a zinc acetate catalyst. These glycolyzed products were characterized by hydroxyl value (HV) determinations. The obtained glycolyzed products were reacted with isophorone diisocyanate (IPDI), dimethylol propionic acid (DMPA), as potential ionic center for water dispersibility, and mixed with ethylene diamine (EDA) as extender chain to prepare polyurethane dispersions. The PET glycolyzed products and polyurethane formation were characterized using Fourier transform infrared spectroscopy (FTIR). The molecular masses distribution of oligoester polyol and polyurethane dispersions were determined by using gel permeation chromatography (GPC). The effect of different PET/glycol molar ratio, on the physico-mechanical properties, such as hardness, adhesion test and gloss of polyurethane films were investigated. Thermal properties were investigated by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC).     

Emulsifyable air drying urethane alkyds

A novel monomer, acrylamido (A) tertiary (T) butane (B) sulfonic (S) acid (ATBS) a commercially available ionic moiety was used as a replacement of dimethylol propionic acid (DMPA) in synthesis of polyurethane dispersion. IR technique was used to confirm the chemical structure and formation of polyurethane dispersions. Polyurethane dispersions were investigated for various coating properties, such as drying times, pencil hardness, adhesion, chemical and solvent resistance. Polyurethane dispersion based on ATBS showed better thermal, chemical and coating properties than those prepared by DMPA anionomer.     

Electrospinning of Technical Lignins for the Production of Fibrous Networks

Abstract

Electrospinning is an effective strategy to produce micron and sub-micron diameter fibrous networks from a variety of polymeric systems. Using seven different technical lignins the effect of lignin structure on fiber formation by electrospinning was studied. Surprisingly, none of the technical lignins could be electrospun into continuous fibers, although beaded fiber formation was observed for the softwood Kraft lignin system at high concentration (>50 wt%). However, the addition of poly(ethylene oxide) dramatically affected the electrospinning behavior and fiber formation. For all of the technical lignins a clear transition from electrospray or beaded fibers to uniform fibers was observed upon addition of poly(ethylene oxide); the lignin concentration dependent on poly(ethylene oxide) content. In all of the systems a linear increase in fiber diameter with increasing lignin concentration was observed. At the same concentration, the various lignin solutions had varying viscosities and different electrospinning behavior, that is, fiber diameter and ability to form uniform fibers, suggesting lignin specific structures and intermolecular interactions are influencing solution properties and electrospinning behavior. In fact, specific viscosity versus concentration plots reveal scaling exponents’, η ～ c^7.4–7.8 consistent with a branched polymer participating in intermolecular interactions such as hydrogen bonding or association complexes.     

Synthesis and characterization of high solid content aqueous polyurethane dispersion

Aqueous polyurethane (APU) dispersions having a solid content of 50% were synthesized using dimethyol propionic acid (DMPA) as the stabilizing moiety. The principal diols used were poly‐1,4‐butylene adipate glycol (PBA). The diisocyanates used in this study were a 30:70 blend of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI). All these samples were neutralized using triethylamine (TEA) and chain‐extended using ethylene diamine (EDA). The effects of the COOH content, NCO/OH molar ratio, and molecular weight (M_n) of PBA on the properties of APU dispersion and its cast film were studied. Dynamic light scattering results revealed that these high solid content dispersions shown broad particle size distributions as well as bimodal. Differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMA) results showed that as the hard segment content increased, the melting point (T_m) of the APU cast film increased, but the glass transition temperature (T_g) did not show significant alteration, when a PBA lower than 1000 M_n was used, the APU exhibited faint soft‐segment crystallization and tended to form amorphous polymer. Tensile and T‐peel strength tests attained excellent mechanical properties, such as a maximum Young's modulus of 166 MPa and the elongation at break reached to 2000%. T‐peel strength test (PVC/PVC) yielded a maximum peel strength value of 8.8 N/mm. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Pneumatic bursting characteristics of plastics films

The bursting strength and inflated deflection of linear low density polyethylene (LLDPE), oriented polypropylene (OPP), flexible poly(vinyl chloride) (PVC), poly(ethylene terephthalate) (PET), and polyurethane (PUR) films of different thicknesses were investigated with the pneumatic bursting method. The study showed the bursting air pressure is directly proportional to the thickness of LLDPE, OPP, and PET films. The effect of different membrane diameters on the change of the bursting properties in OPP and PUR film was also investigated. The results showed that the bursting properties are inversely proportional to the membrane diameter. Furthermore, biaxial stress-strain exerted on the pole region of the tested films was studied. The results denoted that the relationship between the biaxial and uniaxial tensile stress-strain was considered for two types of film: (1) Film that presented an isotropic tensile behavior showed that the tangential stress-strain is higher than the tensile stress-strain. (2) Film that presented an anisotropic tensile behavior showed that the tangential stress-strain is determined by the weaker tensile stress-strain values between two directions.     

The drag reduction of chrysotile asbestos dispersions

The drag reduction (DR) of dispersions of Chrysotile asbestos fibers in aqueous solutions of Aerosol OT and in ethylene glycol, and of glass microfibers in water at a pH of 3 were studied as a function of concentration and temperature with a rotating disc apparatus. Only the dispersions of asbestos in aqueous Aerosol OT showed DR comparable to poly(ethylene oxide) WSR 35 (～500,000 MW), and these dispersions were more fully studied. As was the case with Polyox WSR 35, the asbestos dispersions achieved maximum DR at a concentration of about 200 ppm. They showed no DR temperature dependence at constant Reynolds number at high concentrations but displayed a decreasing DR with increasing temperatures at low concentrations. However, the temperature effect was much smaller for the asbestos dispersions than for Polyox. The asbestos dispersions also showed a much smaller decrease of DR with time at a given disc rotation than was previously measured for poly(ethylene oxide). Electron microscope evidence indicated that less than 10% of the fibers were fully separated, and it is probable that these were the fibers which were primarily active in DR. Hence, if complete separation and dispersion could be accomplished without breaking the fibers, Chrysotile asbestos would be a most potent, not very shear-degradable DR species.