Improvement of jute fiber through ultraviolet-cured films of urethane acrylate

Formulations were developed with urethane acrylate in combination with different monomers. The role of plasticizers used as coadditives in the formulations was investigated. Physical and mechanical properties of the UV-cured films were studied. Hessian cloths made with jute fibers were coated with these formulated solutions and cured under UV radiation. Though plasticizers decrease the tensile properties of the UV-cured films, but they substantially enhance both tensile strength by 80% and elongation of the coated hessian cloths by more than 300%. Uptake of water and moisture at different relative humidity conditions decreases significantly by the hessian cloths when coated with these formulations. © 1994 John Wiley & Sons, Inc.     

Reactive diluents and properties of ultraviolet-cured polycarbonate urethane acrylates

Polymer films obtained from photocurable formulations were investigated by tensile methods and dynamic mechanical analysis. The polymer formulations contained photoinitiator, urethane diacrylate oligomer, and acrylic reactive diluent. It was found that diluent concentration may strongly affect the glass transition temperature and elastic modulus of the cured coating. When the diluent homopolymer glass transition temperature is larger than that of oligomer homopolymer, the glass transition temperature and elastic modulus of the coating film increase with the increase of the diluent concentration. When the diluent homopolymer has lower glass transition temperature than the homopolymer of the oligomer, the increase in diluent concentration leads to a decrease in glass transition temperature and elastic modulus of the UV-cured coating film. The effect of the testing temperature on tensile storage modulus of the films containing different concentrations of reactive diluents was studied as well. The data indicated that a variety of coatings with wide ranging but predictable properties can be formulated from previously examined starting materials but used at different concentrations. © 1995 John Wiley & Sons, Inc.     

Organically modified montmorillonites in UV curable urethane acrylate films

UV curable films were reinforced with an organically modified montmorillonite (MMT). The organically modified MMTs were prepared by an ion exchange process, in which sodium ions were replaced by alkyl ammonium ions. Cetyltrimethylammonium bromide (CTMA) modified clays gave rise to better intercalated clay morphology. The microstructures were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Physical properties were examined by real time infrared spectroscopy (RTIR), differential scanning calorimetry (DSC), photo-DSC, dynamic mechanical thermal analysis (DMTA). Some tensile properties were also reported. Thermal and mechanical properties were generally improved with nanoclay reinforcements. The effects of nanoclays on the properties of UV curable films are critically evaluated in this paper.     

聚氨酯丙烯酸酯/环氧丙烯酸酯分散体系的制备

用水性聚氨酯丙烯酸酯改性环氧丙烯酸酯,制备了聚氨酯丙烯酸酯/环氧丙烯酸酯分散体系。随着分散体中聚氨酯丙烯酸酯浓度的增加,体系稳定性增加,当其浓度达到30%时,可制得稳定的分散体系。这种分散体系可作为一种紫外光固化水性涂料,其涂膜的耐磨性、柔韧性都比环氧丙烯酸酯涂膜增强,而硬度变化不大。     

Synthesis of new pH-sensitive polyurethane gels using polyethylene glycol modified urethane acrylate and urethane acrylate anionomer

New type of amphiphilic pH-sensitive polyurethane networks, derived from the mixture of polyethylene glycol-modified urethane acrylates (PMUA) and urethane acrylate anionomer (UAA), were prepared and their swelling behaviors were evaluated. Three kinds of polymerization methods were employed in the synthesis of polyurethane networks. Polyurethane networks prepared by a process similar to that of soap-free emulsion polymerization (UAHG) showed the highest swelling ratio and pH-sensitivity. Additionally, four kinds of UAHG gels were prepared at different composition of UAA. As the composition ratio of UAA to PMUA increased, swelling of UAHG gels in alkali pH buffer solution and their pH-sensitivity greatly increased. Additionally, swelling of UAHG gels changed reversibly with the change of pH. Received: 18 November 1996/Revised: 10 January 1997/Accepted: 14 January 1997     

Creep recovery of acrylate urethane oligomer/acrylate networks

Creep recovery of acrylate urethane/acrylate networks was investigated as a function of time and temperature. An important outcome was the capacity for superimposition of experimental data obtained at various temperatures. Arrhenius type temperature dependence of the creep recovery was also observed. The master curve obtained did not significantly depend on the measuring mode of creep recovery or the crosslink density, and the response could be approximated by the Bueche theory. The dynamic mechanical properties of the systems were also investigated. Retardation spectrum L obtained from the dynamic mechanical data overlapped with that obtained from the creep recovery data. The activation energy obtained from the temperature dependence of the shift factor a_T also agreed with that obtained from the temperature dependence of the creep recovery. © 1996 John Wiley & Sons, Inc.     

Synthesis of CdS nanoparticles dispersed within solutions and polymer films using amphiphilic urethane acrylate chains

In this study, a new process for preparation of CdS/polymer nanocomposite films using a new amphiphilic oligomer chain (Urethane Acrylate Nonionomer: UAN) is presented. UAN chains have hydrophilic polyethylene oxide segments and polypropylene oxide-based hydrophobic segments as part of the same backbone. In addition, these chains also have reactive vinyl groups at their hydrophobic segments. For the preparation of CdS nano-colloid solutions, UAN chains acted as a stabilizer for CdS nanoparticles dispersed in a solvent. For the fabrication of CdS/polymer nanocomposite films, UAN chains in CdS nano-colloid solutions were polymerized through reactions between their vinyl groups, resulting in the formation of CdS nanoparticle dispersed films swollen by the solvent. The nature of the solvent used strongly influenced the size of the CdS nanoparticles, which was confirmed by UV absorption spectra, PL emission spectra and TEM images. Smaller sized CdS nanoparticles were formed in higher polar solvents such as DMAc and methanol, which can be explained by the higher solubility of UAN chains and the more effective dissociation and stabilization of cadmium salts and CdS nanoparticles by UAN chains in the polar solvent.     

Preparation and properties of poly(urethane acrylate) films for ultraviolet‐curable coatings

Four different UV‐curable poly(urethane acrylate)s were prepared through the reaction of two diisocyanates [i.e., toluene‐2,4‐diisocyanate (TDI) and isophorone diisocyanate (IPDI)] and two polyols [i.e., polycaprolactone triol (PCLT) and polycaprolactone diol (PCLD)], and they were characterized with Fourier transform infrared spectroscopy. The mechanical properties, thermal properties, and water sorption of the cured poly(urethane acrylate)s were also investigated with respect to the chemical structures of the polyols and diisocyanates. In comparison with linear PCLD–TDI and PCLD–IPDI, crosslinked PCLT–TDI and PCLT–IPDI with trifunctional PCLT showed relatively high thermal decomposition temperatures. The hardness and modulus of the UV‐cured poly(urethane acrylate) films, which were measured by a nanoindentation technique, were in the following increasing order: PCLD–IPDI ～ PCLD–TDI < PCLT–IPDI ～ PCLT–TDI. The pencil hardness was 3H for PCLT–IPDI and PCLT–TDI and HB for PCLD–IPDI and PCLD–TDI. Two urethane acrylates prepared from the trifunctional polyol showed better acid and alkali resistances than those made from the bifunctional polyol. These mechanical properties and chemical resistances may have been strongly dependent on the chain flexibility of the molecules and crosslinking density. Regardless of the functionality in the polyol, the change in the yellowness index showed a lower value in the poly(urethane acrylate) coating containing the aliphatic diisocyanate IPDI in comparison with the corresponding poly(urethane acrylate) with the aromatic diisocyanate TDI. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and properties of UV-curable polydimethylsiloxane urethane acrylate

A new type of a UV-curable polyurethane acrylate resin based on hydroxyterminated polydimethylsiloxane (PDMS) soft segments with molecular weight 1800 and 2,4-toluene diisocyanate (TDI)/2-hydroxyethyl methacrylate (HEMA) hard segments were synthesized. The reactivity of 2,4-TDI with the hydroxy groups of silanol and HEMA was discussed by means of IR measurements. The characteristic absorption peaks of the —NCO groups of 2,4-TDI in the para- and ortho-position should decline with increasing the reaction time. The measurements of fundamental physical properties of this type of UV-curable materials had been widely studied in addition to the effects of using various reactive diluents and some pigments. This kind of resin with good optical, electrical insulating, and adhesive properties on various matrices, could be improved in chemical properties and reduced in viscosity while promoting the coating processability by mixing with various reactive diluents. The excellent adhesive properties on glass plates can be attributed to the similar structure between the PDMS soft segments and glass which makes the application in the coating industry possible.     

氨酯丙烯酸酯树脂与氯化聚乙烯的共混

将聚酯二元醇与二苯甲院二异氰酸酯反应[n(NCO):n(OH)=2:1] 的预聚物用甲基丙烯酸-β-羟乙酯封端，得到氨酯丙烯酸酯树脂，将其与CPE共混，并对影响氨酯丙烯酸酯/氯化聚乙烯共混硫化胶的力学性能、热老化性能以及耐油性的一些因素进行了讨论。     

非离子型聚氨酯预聚体可聚合乳化剂的合成及性能

采用甲苯二异氰酸酯 (TDI) ,聚乙二醇 10 0 0 (PEG -10 0 0 ) ,丙烯酸为原料 ,通过分子设计合成了带有双键的非离子型可聚合乳化剂。并对其CMC值、流变行为及乳化力进行了表征。结果显示 :此乳化剂的CMC值在 6.0 %左右、浊点为 (54± 1)℃、HLB值为 16.1可以取代OP -10的乳化能力 ;该乳化剂可以与丙烯酸酯类单体进行乳液共聚 ,得到性能优异的共聚乳液     

Synthesis and characterization of urethane/acrylate composite latex

Polyurethane dispersion and urethane/acrylate composite latex were synthesized and characterized by using a particle size analyzer, gel permeation chromatograph (GPC), Fourier transform infrared spectroscopy coupled with attenuated total reflectance (FTIR‐ATR), dynamic mechanical analysis (DMA), and instron test machine. The amount of solvent and dimethylolpropionic acid (DMPA) used during synthesis of polyurethane resin straightway affected the average particle size and stability of aqueous polyurethane dispersion. The particle size of polyurethane dispersion had nothing to do with that of composite latex. FTIR‐ATR analyses displayed both air‐facing and substrate‐facing surfaces, containing more polyurethane component than the average composition. Some crosslinking reactions occurred in preparing urethane/acrylic composite latex, as indicated by FTIR analyses and solvent extraction. DMA demonstrated three glass transitions for the film from composite latex. Instron tests exhibited better film performance properties for the composite latex than for the corresponding blend latex. A possible particle growth mechanism for preparing urethane/acrylate composite latex was proposed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1620–1628, 2002; DOI 10.1002/app.10526     

Morphology and mechanical properties of urethane acrylate resin networks

A series of urethane acrylate resins (UARs) having various amounts of hard segment were synthesized from poly(oxypropylene) diols (PPOs) with different molecular weights and characterized. The relationship between the morphologies and mechanical properties of these UAR (UARX‐Y‐Z, in which X means the molecular weight of PPO, Y means the content of hard segment, and Z means the content of comonomer) networks was investigated in detail. It was found that the morphology of the UARX‐Y‐Z network was related to the contents of hard segment and the comonomer (methyl methyacrylate—MMA) as well as the molecular weight of PPOs. The UAR1000‐0‐34 network synthesized from PPO210(M_n = 1000) is a homogeneous system due to the good compatibility between the PPO210 and the MMA segment. TheUAR1000‐0‐60 network exhibits the morphology of partial microphase separation resulting from increasing the length of the MMA segment, so as to decrease the miscibility between the soft and hard segment. For the UAR1000‐30‐34 network having a higher content of the hard segment, the hard segments tend to form domains with the limited short‐range and long‐range order, leading to the formation of the microcrystallites, and therefore it shows higher tensile strength and elastic modulus. For UAR400‐0‐34 network with lower molecular weight PPO204 (M_n=400), a high glass transition temperature and some microcrystallites were observed. Such a network exhibits the best mechanical properties over all UAR networks studied. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1532–1537, 2000     

Synthesis and characterization of hyperbranched photosensitive polysiloxane urethane acrylate

A novel hyperbranched photosensitive polysiloxane urethane acrylate (HBPSUA) based on hyperbranched polyesters (HBP-OH) has been synthesized. HBP-OH was synthesized from N,N-diethylol-3-amine methylpropionate as AB₂ monomer and trimethylolpropane (TMP) as a core molecule. The structure of the oligomer was characterized by FTIR, GPC and ¹H NMR. The molecular weight of the oligomer is about 10,000 and the viscosity is 4446 cps at room temperature. The HBPSUA possesses good compatibility with most of acrylate monomers. The effect of photoinitiators, monomers and light intensity on the photopolymerization kinetics of the oligomer HBPSUA was investigated by real-time infrared spectroscopy (RT-IR). The results show that HBPSUA can well photopolymerize under UV-irradiation in the presence of photoinitiators. Irgacure 1700 showed the highest initiating efficiency among those tested photoinitiators. The optimal concentration of photoinitiator (Darocur 1173) is determined as 0.05 wt.%. The system of HBPSUA/TPGDA has the high conversion of double bond and polymerization rate, and they are 92.38% and 22.25 s⁻¹, respectively. Compared with linear systems (PSUA), HBPSUA has the higher photopolymerization rate and lower viscosity. The cured film of HBPSUA possesses good flexibility.     

有机硅聚氨酯丙烯酸酯预聚物的合成

以异佛尔酮二异氰酸酯（IPDI）、烷羟基硅油（SD9134）和丙烯酸β-羟乙酯（HEA）为原料,合成了一种UV固化有机硅聚氨酯丙烯酸酯预聚物（PSUA）。探讨了原料、催化剂用量、反应温度等因素对反应的影响。确定最佳反应条件为：以烷羟基硅油SD9134和IPDI为主要原料,DBTDL为催化剂,其加入量为0．05％～0．1％,反应前3步在20～40℃下反应,第4步反应温度不超过70℃,并通过IR和GPC表征了PSUA的结构。     

Preparation and properties of hydrophobic layered silicate-reinforced UV-curable poly(urethane acrylate) nanocomposite films for packaging applications

A series of poly(urethane acrylate)/Cloisite 15A (PUA/C15A) nanocomposite films were successfully prepared via a UV-curing system, and their physical and barrier properties were investigated as a function of clay content. The physical properties were strongly dependent upon the chemical and morphological structures originating from differences in Cloisite 15A content. With high clay content, the PUA/C15A nanocomposite films displayed an intercalation/exfoliation combined structure. However, no strong interfacial interactions occurred between the PUA and clay, possibly leading to poor dispersion with relatively high clay content. The thermal stability displayed some enhancement with the introduction of clay into PUA, while the gas and moisture barrier properties showed significant enhancement. The oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) decreased with increasing contents of Cloisite 15A, and varied within the range of 714.0–71.1 cm³/m² day and 29.9–13.9 g/m² day, respectively. Thus the enhanced gas and moisture barrier properties of PUA/C15A nanocomposite films make them promising candidates for food and pharmaceutical packaging applications. However, further studies will be performed to increase the compatibility and dispersion of clay particles in the PUA polymer matrix.     

Interfacial spectroscopic studies of UV cured urethane acrylate coatings

Interfacial structural changes of UV cured urethane acrylate coating films were investigated using ATR FTIR spectroscopy. These studies show that at the film–air (F–A) interface, when photo-initiator levels do not exceed 0.1% w/w, the band area ratio of H-bonding to non-H-bonding carbonyl stretching vibrations is proportional to UV energy density. However, when the initiator level is increased to 5% w/w, an increase of up to 200 mJ/cm² UV power is required in order to achieve a similar band ratio, and at higher photo-initiator levels, the amount of energy levels off. Analysis of the H-bonded to non-H-bonded band ratio near the film–substrate (F–S) interface shows that the band area ratio increases further away from the interface. At shallower depths, around 0.84 μm from the F–S interface, the magnitude of the H-bonding/non-H-bonding is smaller than that observed for the same penetration depths before UV exposure for lower photo-initiator concentration or lower energy UV exposure.     

光敏有机硅聚氨酯丙烯酸酯预聚体性能的研究

考查了光引发剂、活性单体对光敏有机硅聚氨酯丙烯酸酯预聚体（PSUA）胶膜的耐水性、拉伸强度、伸长率、硬度、柔韧性和热稳定性的影响。结果表明，胶膜具有优良的耐水性，吸水性低于4％。含单官能度单体的PSUA胶膜的接触角大于含多官能度单体的，含有IBOA的体系接触角达103．6°；当选择引发效率高的裂解型光引发剂，用量为0.5％～1％时，胶膜具有较高的接触角。含多官能度单体胶膜的拉伸强度高于含单官能度单体的体系，但伸长率较小。含TMPTA体系的胶膜的硬度最大，为0．575。胶膜具有较好的柔韧性和热稳定性，其柔韧性达到1mm级，在300℃时失重为4.61％。     

Synthesis of urethane acrylate based electromagnetic interference shielding materials

In this work, a new method, consists of synthesis of urethane acrylate (UA) followed by in situ polymerization of pyrrole using cerium (IV) as an oxidant and UV‐curing of the composites, for preparing polypyrrole–UA (PPy–UA) composite films was described. It appeared that dielectric constants of the composites increased with increasing the PPy content and decreased with increasing the frequency from 10^?2 to 10⁷, indicating an interfacial Maxwell–Wagner contribution to the permittivity. An incorporation of a small amount of PPy (15% Py) to UA matrix increased their dielectric constants more than 4 × 10⁴ (41,259) at 10^?2 Hz. So, the incorporation of PPy was very effective for enhancing the dielectric properties of UA matrix. Furthermore, the significant enhancement in dielectric properties (loss tangent and dielectric constant) contributes to the improvement in electromagnetic interference shielding efficiency. Composite films were characterized using Fourier transform infrared attenuated total reflectance (FTIR‐ATR) spectrophotometer and ¹H‐NMR. It was seen that PPy is blended with the UA matrix at the molecular level through H‐bonding interactions. A linear relationship was also observed between the characteristic groups' absorbances of PPy (from FTIR‐ATR) and dielectric constant values (from dielectric spectrometer). © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2013     

Mechanical properties of UV-cured urethane films

A series of novel photosensitive urethane oligomers was synthesized in which methacryloyl group was contained in the hard segment. The hard segment was prepared by reacting 4,4′-diphenylmethane diisocyanate with glycerine mono methacrylate, which was successively reacted with three kinds of glycols involving 1,4-poly(butadiene glycol), poly(propylene glycol), and poly(caprolactone diol). The mechanical properties of synthesized urethane oligomers after irradiating with ultraviolet light were evaluated to elucidate the effect of the molecular structure and the content of the hard segment on the mechanical property.