Synthesis of polymer materials by low energy electron beam. III. Effects of polymerization temperature in EB solid-state polymerization of semicrystalline urethane-acrylate film

In an electron beam (EB) polymerization of a urethane-acrylate prepolymer, the polymerization temperature greatly affected the structure and properties of the resulting gel film. Urethaneacrylate, which was synthesized by the reaction of poly(butylene adipate)diol, 4,4′-diphenylmethane diisocyanate, and 2-hydroxyethyl acrylate, was used as a prepolymer. The prepolymer was semicrystalline and showed a melting point in the region of 50–60°C. The maximum polymerization rate of the prepolymer was obtained when the prepolymer film was irradiated in the temperature range of 25–40°C. EB polymerization below the melting point (T_m) of the prepolymer produced semicrystalline polyurethane-acrylate gel films with a spherulitic texture. On the other hand, EB polymerization above the T_m destroyed the crystalline phase of the prepolymer to give transparent gel films. The gel film cured below the T_m had higher stress at yield, Young's modulus, and tensile strength than those cured above the T_m. Such temperature effects are attributed to whether or not the EB polymerization proceeds with retention of crystalline structure of the prepolymer.     

Curing and combustion properties of a PU‐coating system with UV‐reactive phosphazene

A UV‐curable polyurethane (PU)‐coating system containing phosphorus is formulated by the combination of photoinitiator, PU acrylate oligomer, and UV‐reactive phosphazene monomer. PU acrylate oligomer is prepared by the addition of 2‐hydroxyethylmethacrylate (HEMA) to NCO‐terminated PU prepolymer. UV‐reactive phosphazene monomer is derived from the HEMA substitution reaction to hexachlorocyclotriphosphazene (NPCl₂)₃. The curing reaction of this PU‐coating system is carried out by UV irradiation. The resultant UV‐cured PU‐coated films demonstrated better performance properties than those of original UV‐cured PU acrylate (UV‐PU) without UV‐reactive phosphazene monomer. Furthermore, their thermal properties are investigated by a thermogravimetric analyzer and a dynamic mechanical thermal analyzer, respectively. The combustion behaviors of these UV‐cured PU‐coated films are evaluated by the measurements of a limiting oxygen index and a cone calorimeter. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1980–1991, 2002     

PUA共聚乳液及其胶囊的性能研究

采用甲苯二异氰酸酯(TDI)、聚乙二醇(PEG)。丙烯酸为原料,通过分子设计合成了带有双键的PU预聚体。用此预聚体与丙烯酸酯类单体进行共聚,通过测定乳液的粘度、粒径分布、胶膜的机械性能和热性能等方法,讨论了此预聚体用量对乳液和胶膜性能的影响。结果显示：随着预聚体用量的增加,共聚乳液的稳定性、粘度逐渐下降、乳液粒径有较大的变化;PUA共聚乳液胶膜的光泽度、附着力在预聚体用量为4％时最好,其胶膜的抗冲击强度及硬度均好于相应的PA乳液胶膜。     

Preparation and properties of UV‐curable waterborne polyurethane–acrylate emulsion

Polyurethane–acrylate oligomer terminated with multiple unsaturated bonds was prepared using isophorone diisocyanate, (IPDI), methylene diphenyl diisocyanate, and polyols as monomers, using 2,2‐dimethylol propionic acid as hydrophilic chain extender, together with pentaerythritol triacrylate (PETA) as end‐capper. The UV‐curable waterborne polyurethane–acrylate (UV‐WPUA) composite emulsion was obtained by mixing the PUA oligomer with certain content of reactive diluents and then dispersing the mixture in water. The molecular structure of the polyurethane prepolymer, PUA oligomer, and UV‐cured polymer was investigated by Fourier transform infrared spectroscopy. The influence of the composition and content of the diluents and end‐capper on UV‐WPUA properties, including the emulsion stability, thermal property, water resistance, adhesion, hardness, glossiness of polymer film were studied. The results show that the WPUA emulsion has excellent stability, and the UV‐cured film features good hardness and remarkable water resistance when PETA is used as end‐capper and the end‐capping ratio of the polyurethane prepolymer is 70% and dipentaerythritol hexaacylate/dipropylene glycol diacrylate (mass ratio 1:1) is used as diluent. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45208.     

新型紫外线固化环氧树脂/丙烯酸酯改性水性聚氨酯的合成与性能

合成了一种新型的具有高交联密度和优异涂膜性能的环氧树脂和丙烯酸酯同时改性的紫外线（UV）固化水性聚氨酯（UV-EP-AC-WPUD）。通过环氧基团与以异氰酸酯基团（-N=C=O）封端的聚氨酯预聚体之间的反应引入质量分数为4%的环氧树脂E-20。同时,通过聚氨酯链的-N=C=O与二元丙烯酸酯（PEDA）以及季戊四醇三丙烯酸酯（PETA）的羟基之间的反应引入碳碳双键（C=C）,C=C的含量达到4.65 meq·g-1。 质量分数为3%的光引发剂Irgacure 2959被用于引发涂膜中C=C的聚合,涂膜的凝胶含量在12 s UV辐射之后达到91%,意味着C=C的聚合和交联速度快,同时所得到的涂膜的交联度非常高,不溶于溶剂丙酮,测试表明环氧树脂和两种丙烯酸酯单体已经成功嵌入聚氨酯链中,涂膜具有优异的力学性能和化学性能。     

羧基含量对UV固化PUA/EA核壳复合乳液性能的影响

以自制的亲水性聚氨酯丙烯酸酯(PUA)预聚体为高分子乳化剂,与自制的环氧丙烯酸酯(EA)树脂充分混合后,采用相反转乳化法制备了可UV固化的具有不规则核壳结构的PUA/EA复合乳液。利用傅里叶变换红外光谱对水性PUA合成过程以及复合乳液UV固化前后进行了表征,表明合成得到了目标产物且UV固化良好。透射电镜(TEM)测试表明,复合乳液呈不规则的核壳结构,且EA含量不同时核壳结构也不同。重点讨论了羧基含量对乳液相反转过程、PUA预聚体的乳化能力、复合乳液以及固化后涂膜性能的影响,结果表明,相反转过程中体系黏度与电导率有类似的变化趋势,最大值均随羧基含量的增加而增加,且出现得越来越晚;PUA预聚体的乳化能力随羧基含量的增加而增加,但超过2.3%后变化不再明显;此外,随羧基含量的增加,乳液的平均粒径变小、外观越来越透明、黏度变大、贮存稳定性变好,而相似文献   

不同官能度水性聚氨酯丙烯酸酯的合成及性能

以丙烯酸羟乙酯与季戊四醇三丙烯酸酯作为封端剂,分别合成了二官能度水性聚氨酯丙烯酸酯(WPUA2)和六官能度的水性聚氨酯丙烯酸酯(WPUA6),并用红外光谱、粒径仪、热重分析对合成产物结构和性能进行表征。研究表明,相比于使用低官能度WPUA2紫外光固化所得聚氨酯丙烯酸酯(PUA)涂膜,加入单体或使用多官能度WPUA6,都可使PUA固化膜凝胶率提高20%以上,吸水率降低30%;质量损失10%,分解温度增大82℃。提高预聚物官能度可有效提高涂膜交联密度和耐热性能,并具有与加入活性单体相似的应用效果。     

Syntheses and properties of UV-autocurable prepolymers. Semicrystalline urethane-multiacrylates

A series of UV-autocurable urethane-multiacrylate prepolymers, which were semicrystalline and showed melting points in the region of 40–50°C, was synthesized. Also, the effects of curing temperature and acrylic functionality on the structure and properties of the cured films were investigated. These prepolymers are solids and opaque at room temperature. In general, UV curing reactions of solid prepolymers are less efficient when compared with those of liquid prepolymers. UV curing reactions at curing temperatures below the melting point (T_m) of the prepolymers produced semicrystalline urethane-multiacrylate cured films. On the contrary, UV curing reactions above T_m destroyed the crystalline phase of the prepolymers and improved the transparency of the cured films. The films cured below T_m of the prepolymers had higher both breaking strength and Young's modulus, and a higher glass transition temperature (T_g), but a lower elongation at break than those cured above T_m. Such curing temperature effects were attributed to the retention or disappearance of the crystalline structure of the prepolymers during UV curing reaction. At curing temperatures below T_m, an increase in acrylic functionality of the prepolymer resulted in a fast curing rate and a higher crosslinking density of the cured films. Therefore, an increase in acrylic functionality of the prepolymers gave cured films with higher breaking strength and Young's modulus, but a lower elongation at break.     

Preparation and properties of UV‐curable fluorinated polyurethane acrylates

A series of UV‐curable polyurethane acrylates (PUA0, FPUA3, FPUA6, FPUA 9 FPUA12, FPUA15, where the numbers indicate the wt % of perfluoroalkyl acrylate), were prepared from a reactive oligomer [4,4 ?‐dicyclohexymethanediisocyanate(H12MDI)/ poly(tetramethylene glycol)(PTMG)/2‐hydroxyethyl methacrylate (HEMA): 2/1/2 molar ratio, prepolymer:40 wt %] and diluents [methyl methacrylate (MMA, 20 wt %)/ isobornyl acrylate (IBOA, 40–25 wt %)/heptadecafluorodecyl methacrylate (PFA, 0–15 wt), total diluents: 60 wt %]. This study examined the effect of PFA/IBOA weight ratio on the properties of the UV‐curable polyurethane acrylates for antifouling coating materials. The as‐prepared UV‐curable coating material containing a 15 wt % PFA content in diluents (MMA/IBOA/PFA) form a heterogeneous mixture, indicating that a PFA content of approximately 15 wt % was beyond the limit of the dilution capacity of diluents for the oligomer. In the wavelength range of 400–800 nm, the UV‐cured PUA0 film sample was quite transparent (transmittance%: near 100%). On the other hand, the transmittance% of the FPUA film sample decreased markedly with increasing PFA content. XPS showed that the film‐air surface of the UV‐cured polyurethane acrylate film had a higher fluorine content than the film‐glass dish interface. As the PFA content increased from 0 to 12 wt %, the surface tension of the UV‐cured urethane acrylates decreased from 26.8 to 15.6 mN/m, whereas the water/methylene iodide contact angles of the film–air surface increased from 90.1/63.6° to 120.9/87.1°. These results suggest that the UV‐curable polyurethane acrylates containing a PFA content up to 12 wt % have strong potential as fouling‐release coating materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40603.     

Morphology and mechanical properties of radiation-polymerized urethane–acrylates. I. Pure oligomers

The morphology of electron beam cured polyacrylo–urethane films based on polyethylene adipate and toluene diisocyanate was characterized to explain their mechanical properties. The polyacrylo–urethane films have a one-phase morphology in which the hard urethane segments and the soft polyester segments are homogeneously mixed. The films obtained from 1000-molecular-weight oligomer are hard and somewhat brittle due to their one-phase morphology in which hard glassy segments play a dominant role. The films obtained from 4600- and 6000-molecular-weight oligomers are soft and tough, once again due to their one-phase morphology in which soft rubbery segments are more effective. The original crystalline structure of 6000-molecular-weight oligomer is retained in the precrystallized γ-irradiated film, but electron-beam-irradiated films showed partial melting of the crystallites due to the heat of polymerization. The solid state polymerized films have a lower eleongation, a higher modulus, and a higher breaking strength due to their crystallinity.     

Comparison of properties of acrylic–polyurethane hybrid emulsions prepared by batch and semibatch processes with monomer emulsion feed

Aqueous acrylic–polyurethane hybrid emulsions were prepared by batch and semibatch polymerization of acrylic monomer mixtures (butyl acrylate, methyl methacrylate and acrylic acid) in the presence of polyurethane dispersion. The acrylic component was introduced in the monomer emulsion feed. The weight ratio between acrylic and polyurethane components was varied to obtain different emulsion properties, microphase structure and mechanical film properties. Scanning electron microscopy, average particle size and molecular weight measurements were performed to characterize the latex systems. Mechanical properties were examined by measuring Koenig hardnesses of dried films. The average particle size increased with the acrylic/polyurethane ratio. Particles of larger than average size and, to some extent, higher than average molecular weights by batch process were formed. Koenig hardnesses decreased with increasing acrylic/polyurethane ratio. Properties of emulsions synthesized by semibatch processes were compared with the results reported for a different polyurethane dispersion. Copyright © 2003 Society of Chemical Industry     

丙烯酸酯改性聚酯聚氨酯水分散体的合成及结构表征

用甲基丙烯酸羟乙酯封端的水性聚氨酯预聚体与丙烯酸酯发生聚合，制备丙烯酸酯改性水性聚氨酯分散体。考察了工艺条件对分散体稳定性及成膜物性能的影响。同时用红外光谱和扫描电镜讨论了丙烯酸酯改性聚氨酯成膜物的结构特征，用热分析仪分析了膜的热稳定性能。     

Synthesis and photopolymerization of hyperbranched polyurethane acrylates applied to UV curable flame retardant coatings

A series of hyperbranched polyurethane acrylates containing phosphorus were prepared by reaction of a phosphorus‐containing triol with toluene‐2,4‐diisocyanate and hydroxylethyl acrylate at given ratios. The resins obtained were found to polymerize rapidly in the presence of a photofragmenting initiator under UV irradiation, and the maximum polymerization rate increased with temperature up to 125 °C, then decreased quickly. The UV cured films have flame retardancy with a limiting oxygen index of 27.0. © 2002 Society of Chemical Industry     

Effect of Quasi‐nanometer zirconium carbide on the physical characterization of zirconium carbide/polyurethane composite films irradiated under ultraviolet light

We used quasi‐nanometer zirconium carbide (ZrC) and a polyurethane (PU) resin under roller pressure to form a composite film and found that the tensile strength at break, elongation at break, and modulus gradually decreased with increasing ultraviolet (UV)‐irradiation time for films of both PU and the PU/ZrC composite. However, this phenomenon was significantly higher for the PU film than for the ZrC/PU composite film. The construction of the PU film changed after UV irradiation, but that of the PU/ZrC composite film was almost unchanged. The degradation of PU molecules occurred in the absence of ZrC particles after irradiation with UV light but almost did not occur in the presence of ZrC particles. This was confirmed with Fourier transform infrared spectroscopy and gel permeation chromatography analyses. It was suggested that polymer radicals which formed through the photooxidation of UV irradiation and free radicals which formed through the photoreduction of nanometer ZrC/UV irradiation interacted to form a dead polymer to stop the degradation; simultaneously, the chemical bonding between polymer molecules could be re‐formed from free radicals created by photooxidation and photoreduction and thus reduce the mobility of PU molecules, thereby raising the glass‐transition and melting temperatures of the soft segment. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4842–4849, 2006     

Rheological studies of ultraviolet curing with an oscillating plate rheometer

The dynamic viscoelastic behavior during UV curing was studied for thin liquid films of epoxy acrylate prepolymer by the use of an oscillating plate rheometer. The dynamic viscosity rapidly increases after a certain period of irradiation, so that the UV curing process has the minimum exposure energy required to start polymerization. The minimum exposure energy markedly increases with increasing sample thickness; this results from the inconsistency of degree of curing in the direction perpendicular to the shearing surface. Since free radicals which initiate polymerization are formed by photochemical decomposition of initiator, the ability to cure a film depends on the light intensity at a given depth of the film. the attenuation of light in the film is primarily responsible for this inconsistency. When UV light is applied through a UV filter, the curing behavior is analyzed by a single exponential decay of light with depth because the curing is induced by absorption of a monochromatic light of 365 nm. On the other hand, when UV light from a UV lamp whose output spectrum is a continuum is directly applied, the curing behavior is explained by a combination of energy absorption at different wavelengths. In both cases, the theoretical curves of dynamic viscosity predicted in relation to spectral sensitivity show a good agreement with the experimental results.     

Control of polymerization processes of 10,12-pentacosadiynoic acid LB films

Studies have been carried out on KrF excimer laser light (EX), X-ray or electron beam (EB) induced polymerization of 10,12-pentacosadiynoic acid (PDA) Langmuir-Blodgett (LB) films in relation to molecular density or molecular arrangement of the films using X-ray diffraction analysis, infrared (IR) spectroscopy and Raman spectroscopy. The molecular arrangement or density of the PDA LB films was controlled by subphase conditions when the films were built up, such as pH, temperature of a subphase or salt concentration in the subphase. Polymerization sensitivity of the PDA LB film was affected by the arrangement or molecular density. On low density (A type) films the polymerization occurred by irradiation with EX, X-ray or EB, but on high density (B type) films the polymerization occurred only when the irradiation was carried out by high energy beams such as X-ray or EB. Decomposition of polymerized films was observed further by excessive irradiation of EX or X-ray, but not on the B type films. It was revealed by X-ray diffraction analysis that in the A type film, the PDA molecules bent to a larger extent than those in the B type film and the polymerization proceeded topochemically, that is, the thickness decreased little after EB irradiation in a helium atmosphere. On the other hand, in the B type film, the thickness decreased by about 10% as a result of EB irradiation. By IR reflection-absorption (RA) and Raman measurements, it was confirmed that conjugated diacetylenic bonds disappeared and conjugated double and new conjugated triple bonds appeared after high energy beam irradiations. These results support the supposition that 1,4-polymerization, i.e. polydiacetylene type polymerization, occurs easily in the A type film and 1,2- or 3,4-polymerization, i.e. polyacetylene type polymerization, occurs in the B type film, and that the polymerized A type film was decomposed at the polydiacetylenic bond when the irradiation continued further. It was also shown that the polyacetylene type polymer was obtained only when the B type film was irradiated with the high energy beam.     

分子结构中碳碳双键对水性UV聚氨酯分散体的影响

采用异佛尔酮二异氰酸酯(IPDI)、聚酯二元醇(聚己二酸-1,4丁二醇酯)(PBA)为主要原料合成了环氧改性的、固体分约为50%的水性紫外光固化聚氨酯分散体(PUD)。通过预聚物中聚氨酯分子末端的—NCO基团与丙烯酸羟丙酯(HPA)和季戊四醇三丙烯酸酯(PETA)上的羟基发生反应,从而引入碳碳双键,使PUD具备紫外光固化的性能。研究了水性UV分散体的碳碳双键对水性聚氨酯的拉伸强度、硬度、粒径等性能方面的影响,同时对涂膜进行动态力学性能测试(DMA)和断面结构表征(SEM)。结果表明:双键含量增加,UV涂料的拉伸强度和硬度增大,分散体和涂料的其他性能基本不变;DMA测试表明随着双键含量的减小,软段的T_g(s)移向低温,硬段的T_g(h)移向高温,相分离趋于完全;SEM测试表明树脂的交联程度越大,抵抗断裂的程度也越大。     

Surface photografting polymerization of vinyl acetate (VAc), maleic anhydride (MAH), and their charge transfer complex (CTC). III. VAc(3)

Vinyl acetate (VAc) was grafted onto low‐density polyethylene (LDPE) substrates by UV irradiation with benzophenone (BP) as the photoinitiator. BP preabsorbed film samples and BP precoated film samples were prepared in advance and applied as the substrates onto which VAc was photografted, together with the method in which BP was dissolved in VAc directly. In addition, the efficiency of the polymerizations applying the preirradiation technology was examined. The conversion percent, grafting percent, and grafting efficiency were determined by a gravimetric method. The contact angles of the grafted films against water were also measured. The results show that BP preabsorbing and precoating were favorable to grafting polymerization, especially the BP precoating method, which was due to its simple operation and the ease of controlling the amount of BP. The diffusion of BP and VAc through the substrates proved to be an important factor for grafting polymerization. Through UV irradiation, dormant groups can be introduced onto LDPE film, which may be activated again by UV irradiation or by heating, leading to the formation of free radicals. Grafting polymerization can be initiated during the activation process in the presence of monomer. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1426–1433, 2001     

Synthesis,Characterization, and Application Studies of Polyurethane Acrylate Thermoset Coatings: Effect of Hard Segment

The waterborne polyurethane acrylate coatings are smart option to reduce the environmental hazards. To evaluate the structure–property relationship, polyurethane acrylate coating dispersions were synthesized with aromatic and aliphatic hard segments. Furthermore, to evaluate the performance, dispersions were used to finish the cotton fabric. The dispersions were prepared by prepolymer method followed by emulsion polymerization in aqueous medium. The characterization of dispersions was performed by Fourier transform infrared, dynamic light scattering, atomic force microscopy, differential scanning calorimetry, and thermogravimetric analysis. In general, aliphatic hard segment has shown more appreciable results. But, thermal stability of aromatic polyurethane acrylate was more pronounced as inherent rigidity of aromatic diisocyanate dominates.     

UV-Radiation curing of waterborne acrylate coatings

A kinetic study of the ultrafast curing of water-based acrylate resins upon UV irradiation was conducted by means of infrared spectroscopy. Under intense illumination, the crosslinking polymerization was found to occur in the dried film within less than one second to generate a totally insoluble polymer. The influence of a number of critical factors on the polymerization rate and cure extent has been investigated, namely the type of photoinitiator, the chemical structure of the acrylate functionalized oligomer, and the sample temperature. Coating obtained from emulsions undergo a faster and more extensive polymerization than coatings obtained from dispersions, because of a greater molecular mobility in the soft low-modulus polymer formed. Very hard coatings were produced by the UV curing of dispersion-type acrylate resins, especially when the UV irradiation was performed at 80°C on the sample emerging from the drying oven. T_g values up to 120°C were reached when such resins were UV-cured at ambient temperature as 1-mm thick plates, because of the large amount of heat released during such ultrafast polymerization. UV-cured coatings made of aliphatic polyurethane-acrylates proved to be very resistant to accelerated weathering in the presence of adequate light stabilizers. Presented in part at the RadTech Europe Conference in Berlin, November 3–5, 2003.