水性油墨用室温自交联纯丙乳液的合成及应用

以甲基丙烯酸甲酯(MMA)、丙烯酸异辛酯(2-EHA)、甲基丙烯酸(MAA)、双丙酮丙烯酰胺(DAAM)为聚合单体,己二酰肼(ADH)为交联剂,采用半连续种子乳液聚合法合成软核硬壳结构的水性纯丙乳液。利用ATR-FTIR、TEM、GPC、TG、DMA表征水性纯丙乳液的结构和性能。结果表明:乳液成膜过程中DAAM中的—CO—与ADH中的—NHNH_2发生反应,交联度增加,提高了乳液膜的耐水性、热稳定性、玻璃化转变温度和油墨在双向拉伸聚丙烯(BOPP)薄膜上的附着力。当DAAM用量(以MMA和2-EHA的总质量为基准,下同)从0增加到2%,m(ADH)∶m(DAAM)=0.7∶1.0时,乳液膜的吸水率从24.2%降到7.6%,油墨的附着力从87%升至100%;当m(ADH)∶m(DAAM)从0∶1增加到0.7∶1.0,DAAM用量为2%时,乳液膜的吸水率从28.1%降至7.6%,油墨的附着力从0增至100%。当DAAM用量为2%,m(ADH)∶m(DAAM)为0.7∶1.0时,水性纯丙乳液可用作环保型水性油墨的连接料。     

TBA studies of prepreg curing behavior

The torsional braid analysis (TBA) equipment has been used as an automated torsion pendulum to characterize prepreg materials in the form of single ply strips (2-1/2 × 1/8 in.). Compared to the use of coated glass braids, the main difference was a marked weakening of the gelation mechanical damping peak in isothermal runs. However, prepreg materials consisting of epoxy resins on glass, carbon or aramid fibers were successfully run isothermally to provide gelation and vitrification times as a function of temperature, or in constant heating rate scans to reveal the T < T_g and the T_g relaxations of the uncured resins, and at higher temperatures phenomena associated with gelation, vitrification and devitrification.     

Synthesis and characterization of self-crosslinkable zinc polyacrylate latices at room temperature

The zinc ion self-crosslinkable polyacrylate latexes (PAs) cured at room temperature were synthesized by seeded semi-continuous emulsion polymerization with zinc oxide (ZnO) as crosslinker. The ZnO and methacrylic acid (MAA) mass contents, method of ZnO introduction in relation to the degree of crosslinking, and the properties of self-crosslinkable latices are examined and discussed. The characterization techniques such as Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC), transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA) have been used to determine the structure and properties of PAs. The experimental results show that in a certain range, the average particle size decreases with an increase in the content of MAA, while the latex stability is undoubtedly improved. The optimum mass content of MAA is 12?% of the total monomers. The optimum amount of ZnO needed is 25?% (mole fraction) of MAA, and the optimum temperature of ZnO introduction is 60?°C. TEM analyses show that the latex particles are coarse spherical particles with surface enriched with comprising abundant carboxyl groups, and zinc ions are dissociated as zinc ammine complex in the aqueous phase. FTIR analyses confirm that the chelate crosslinking occurs between zinc ions and carboxylic acid during the film-forming process. The DSC results indicate that the glass transition temperature (T _g) of PAs increases as a function of the formation of a coordinate structure, and the obtained film exhibits excellent initial hardness and sandability. TGA analyses demonstrate that the introduction of ZnO evidently enhances the thermal stability of self-crosslinkable PAs.     

自交联封闭性乳液的合成与性能

以双丙酮丙烯酰胺（DAAM）、甲基丙烯酸甲酯（MMA）、丙烯酸丁酯（BA）和甲基丙烯酸（MAA）为共聚单体,采用半连续种子乳液聚合工艺合成自交联封闭性聚丙烯酸酯乳液（PAE）,考察了DAAM和复合乳化剂对乳液聚合稳定性以及涂膜性能的影响。研究发现：随着DAAM含量的增加,乳液聚合稳定性下降,粒径增大,涂膜的耐介质性能和交联度提高,合适的DAAM加入量为总单体质量的3.0%,DAAM和己二酰肼(ADH)的最佳摩尔比为2∶1。采用SDBS+OP-10+OP-40为复合乳化剂体系,选用乳化剂的含量为2.35%,阴/非离子乳化剂质量比为1∶1.25;复合乳化剂在种子、核、壳比例为1.5∶1∶2,制备的乳液具有较好的聚合稳定性（乳液凝胶率低和单体转化率高）,乳液耐电解质（钙离子）稳定性好,涂膜具有优异的封闭性。傅里叶红外光谱（FTIR）表明在涂膜形成过程中DAAM的酮羰基与ADH的酰肼基反应生成腙（C=N）,TEM分析显示乳液的乳胶粒子呈核壳结构,TGA分析发现DAAM改性的PAE降低了涂膜的热稳定性。     

室温自交联水性聚丙烯酸酯乳液的合成、结构与性能

以甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)、丙烯酸(AA)和双丙酮丙烯酰胺(DAAm)为共聚单体,采用半连续种子乳液聚合工艺,合成了具有核–壳结构的室温自交联水性聚丙烯酸酯乳液。以十二烷基硫酸钠(SDS)与辛基酚聚氧乙烯醚(OP-10)为复合乳化剂,研究了其用量对聚合反应稳定性的影响,讨论了不同DAAm用量下乳胶粒的粒径分布、漆膜耐水性和力学性能,确定了较佳的用量:复合乳化剂用量为单体质量的3.0%,w(DAAm)为4%。透射电镜(TEM)分析表明,乳胶粒具有明显的核–壳结构。热分析表明,以己二酰肼(ADH)为交联剂,交联后漆膜的玻璃化转变温度明显提高,红外光谱分析证明了酮肼交联反应的发生。     

聚酯树脂粉末涂料的固化行为

用差示扫描量热法(DSC)对固态条件下聚酯/TGIC(triglycidyl isocyanurate)体系的非等温固化反应动力学进行了研究。根据DSC和热重（TG）的分析结果,对聚酯粉末的固化过程及热稳定性进行了探讨,通过温度-升温速率图外推法确定了该体系的凝胶温度、固化温度和后固化温度分别为113、146和195℃。采用Kissinger方程、Doyle-Ozawa方程和Crane方程对DSC数据进行分析,得到了固化反应的平均表观活化能65.71 kJ·mol^-1,频率因子8.50×106 min^-1、反应级数0.95,建立了该树脂体系的固化动力学模型。讨论了固化反应速率、固化度、固化温度与时间等关系的变化规律及影响因素,为优化铝型材用粉末涂料聚酯体系的固化工艺提供了理论基础。     

聚丙烯酸酯涂料的制备

以甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)、丙烯酸(AA)为单体,以十二烷基苯磺酸钠为乳化剂,当m(BA)∶m(MMA)∶m(AA)=33∶17∶1,通过乳液聚合制得丙烯酸酯类乳液,再加入填料及各种助剂,经过高速搅拌、均质而出料。并且讨论了乳化剂及引发剂用量对乳液聚合、乳液及涂料性能的影响。     

DSC and TBA studies of the curing behavior of two dicy-containing epoxy resins

The curing behavior of two commercial dicy-containing resins (I & II), both with recommended cures of 127°C/2 h, has been studied by differential scanning calorimetry (DSC), torsional braid analysis (TBA) and Fourier Transform infrared spectroscopy. Compositional analysis reveals that the two resins differ primarily in the amine/epoxy ratio and the nature of the main epoxy components. Factors contributing to the complex curing behavior observed with II are identified. Isothermal kinetic runs by DSC and TBA lead to estimates for the conversion at the gel point, and to results which suggest that the reactions of epoxy with amine and hydroxyl occur with similar activation energies and similar heats of reaction.     

Electrochemical and in situ FTIR studies of biferrocene platinum(II) complex

Electron transfer mechanism during redox process of Pt(LSB)₂, a derivative of S-benzyl-N-(ferrocenyl-1-methyl-metylidene)-dithiocarbazate (HLSB), is studied by cyclic voltammetry, differential pulse voltammetry, digitally simulation and in situ FTIR spectroelectrochemistry. Electrochemistry results indicated the redox process of Pt(LSB)₂ involves two consecutive one-electron steps. Coordination of Pt to HLSB resulted in the increase of electron-withdrawing of the dithiocarbazate group, which is demonstrated by the positive shift of redox potentials of Pt(LSB)₂ compared with those of HLSB. The peak-peak separation of 129 mV revealed a strong degree of electronic communication between the two-ferrocene moieties in Pt(LSB)₂. The results of in situ FTIR indicated that electronic communication takes place through the skeleton chain of HLSB due to the extensive electron delocalization in the whole molecule.     

Conversion and in situ FTIR studies of direct NO decomposition over Cu-ZSM5

Copper ion-exchanged zeolites ZSM5 with SiO₂:Al₂O₃ molar ratios 33 and 53 have been subjected to activity tests for direct decomposition of NO (2000 ppm, GHSV 560–5400 h⁻¹). In situ infrared measurements were used to follow the reaction and surface and gas phase compositions. IR studies were also done in excess oxygen with rapid NO₂ formation in the gas phase.

A high level of overexchange of copper in the zeolite in combination with a low concentration of acid sites, concurrent with a high SiO₂:Al₂O₃ ratio, enhances the conversion of NO. A vibrational band at 1631 cm⁻¹ is observed below the light-off temperature and interpreted as a bridged nitrato group bound to Cu²⁺–O–Cu²⁺ dimers. This band disappears above the light-off temperature but the intensity below this temperature correlates with the catalytic activity. We interpret that these bridge bound nitrato groups act as siteblockers on the active sites for NO conversion and that a tentative reaction intermediate, N₂O₃, also binds in a bridge configuration to the same Cu²⁺–O–Cu²⁺ dimers.

A second nitrato group with unidentate coordination and vibrational bands at 1598/1575 cm⁻¹ probes isolated copper ions.

A third infrared band at 2130 cm⁻¹ confirms previous observations of -ions bound to the zeolite. We conclude that these species are coordinated to deprotonated and negatively charged sites on the zeolite and that these sites for adsorption are blocked by Cu²⁺ ion-exchange. The 2130 cm⁻¹ species appear to have no role in direct NO decomposition but the adsorption sites are crucial for the stability of the zeolite and intimately related to ion mobility in the lattice.

Prolonged immersion of the zeolite in dilute solutions of copper ions improves the catalyst performance by copper hydroxylation leading to enhanced formation of the above dimers.

A high SiO₂:Al₂O₃ ratio leads to more stable catalysts, particularly in combination with a modest overexchange of copper ions. Excessive amounts of copper escalates the deactivation of the Cu-ZSM5 catalyst through the migration and sintering of cupric oxide crystallites.     

原位红外光谱法研究碱性溶液中对氯苯酚电还原反应

采用循环伏安和原位红外光谱技术,研究了对氯苯酚（4-CP）在碱性体系中的电化学还原反应。对氯苯酚在Ag电极、Pt电极和GC电极上的循环伏安行为表明,Ag电极对4-CP有较好的电还原活性,能在较正的电位下还原4-CP。通过原位红外光谱技术对4-CP在Ag电极上的电还原机理的初步探讨,结果表明4-CP首先在电极表面形成自由基负离子,随着电位的进一步负移,生成苯酚负离子,从而实现4-CP电化学脱氯降解的目标。     

In situ FTIR studies of propene adsorption over Ag- and Cu-exchanged Y zeolites

Ag- and Cu-exchanged forms of HY zeolite are prepared by the solid-state ion exchange (SSIE) technique. Samples with different metal loadings ranging from low to high exchange are obtained. Both compositional and structural investigations of the exchanged zeolites are performed by elemental analysis, powder X-ray diffraction (XRD), and nitrogen adsorption porosimetry. The acidity investigation is carried out by using the Fourier transform infrared spectroscopy (FTIR) of pyridine adsorption. Propene adsorption over the Ag- and Cu-exchanged zeolites is studied at room temperature by using in situ FTIR spectroscopy. XRD analysis shows good conservation of the zeolitic structure after ionic exchange even at high exchange degree. Porosity measurements indicate that the increase of Ag and Cu exchange degrees leads to a decrease of the porous volumes and the specific surface areas, which is more pronounced for Ag-exchanged zeolites. The acidity evaluation for both exchanged metals shows an important decrease of Brønsted acidity and a slight increase of Lewis acidity, which are more noticeable at high degree of exchange. Instantaneous oligomerization of propene on HY zeolite at room temperature is favored by the relatively high amount of Brønsted acid sites. The propene molecules interact more strongly with Cu²⁺ than with Ag⁺. The shape of the CC stretching band of the FTIR spectra involves at least two overlapping bands indicating that the propene CC bond may interact with several kinds of Ag⁺, Cu²⁺ and Cu⁺ sites of various propene bonding.     

Kinetic studies of a UV-curable powder coating using photo-DSC, real-time FTIR and rheology

The curing kinetics of UV-curable powder coatings based on commercial unsaturated polyesters were monitored using photo-DSC, Real-Time FTIR-ATR and a modified rheometer equipped with a UV source. The effect of physical and chemical factors on curing such as type of photoinitiator, photoinitiator concentration, temperature and atmosphere of curing were evaluated. Coatings containing amounts of photoinitiator from 0.5 to 10 wt% were cured at different temperatures in less than 10 s reaching conversions approximately of 60%. The increase of the temperature of curing reduces the final conversion and also the rate of polymerization due to the chain transfer process and depolymerization that dominates the photopolymerization at high temperatures. The reactivity of the photoinitiators was similar for all the studied photoinitiators apart from benzophenone that was found to be the slowest initiator.     

用FTIR研究聚氨酯弹性体的固化动力学

使用傅里叶变换红外光谱仪 ,原位跟踪了催化及未催化聚氨酯弹性体(PU)的固化反应动力学行为。结果表明 ,—NCO和—OH的本体聚合在反应初期遵循二级反应和催化动力学规律 ;未催化和催化的PU固化反应的活化能分别为48.0kJ/mol和38.86kJ/mol,频率因子分别为3.01×108 L/(mol·s)和1.14×108L/(mol·s)。     

Functionalized graphene and graphene oxide solution via polyacrylate coating

Water soluble graphene with various chemical- and biofunctionalities is essential for their different applications. However, exfoliated graphenes are insoluble in water and water soluble graphene oxide precipitate if they are chemically reduced to graphene. We have developed a polyacrylate coating method for graphene oxide and then chemically reduced it into graphene. We found that polyacrylate coating can improve the colloidal stability of both graphene and graphene oxide. The coated graphene has been characterized using XPS, FTIR, XRD and micro-Raman spectroscopy. The primary amine present on the coating backbone has been used to derive glucose functionalized water soluble graphene. Various other functional graphenes can be anticipated from the polyacrylate coated graphene.     

Dehydration and rehydration of mesolite: An in situ FTIR study

The dehydration and rehydration processes of mesolite belonging to NAT group of zeolites were investigated using in situ Fourier Transform Infrared spectroscopy (FTIR). The thermal induced variations of the water molecule bending (ν₂), the stretching (ν₃ and ν₁) modes and the corresponding second order modes in the wavenumber region 4000–8000 cm⁻¹ were followed as indicative of the dehydration process. Observed spectral variations were well correlated with thermogravimetric studies and indicate that the mesolite dehydrates in three stages (470; 510 and 650 K). Anomalous spectral variations of 4600 cm⁻¹ at first stage indicate that the dehydration is triggered by the expulsion of water coordinating AlO₄ tetrahedron. Partial rehydration (up to 85%) at second stage indicates disordering of natrolite and scolecite layers. During the third stage mesolite completely dehydrates, causing the destruction of framework.     

In situ FTIR spectroscopic studies of electrooxidation of ethanol on Pd electrode in alkaline media

Electrooxidation of ethanol on a polycrystalline Pd disk electrode in alkaline media was studied by in situ Fourier transform infrared (FTIR) reflection spectroscopy. The emphasis was put on the quantitative determination of intermediates and products involved in the oxidation. It has revealed that most of ethanol was incompletely oxidized to acetate. The selectivity for ethanol oxidation to CO₂ (existing as CO₃²⁻ in alkaline media) was determined as low as 2.5% in the potential region where Pd electrode exhibited considerable electrocatalytic activity (−0.60 to 0.0 V vs. SCE). Nevertheless, the ability of Pd for breaking C-C bond in ethanol is still slightly better than that of Pt under the same conditions. Besides, a very weak band of adsorbed intermediate, bridge-bonded CO (CO_B) was identified on the Pd electrode for the first time, suggesting that CO₂ and CO₃²⁻ species may also be generated through CO pathway (i.e., indirect pathway).     

In situ FTIR studies of methanol adsorption and dehydrogenation over Cu/SiO2 catalyst

In situ FTIR spectroscopy was used to identify the adsorbed species and the intermediates during methanol dehydrogenation over Cu/SiO₂ catalyst, and a schematic reaction network was proposed. Methoxy species on copper, which were derived from adsorbed methanol, dehydrogenated into formaldehyde. Then several competitive pathways took place. The adsorbed formaldehyde could desorb to the gas phase, or react with another adsorbed methoxy group to form methyl formate, and/or undergo further dehydrogenation to CO and H₂. Carbon monoxide formed from the decomposition first adsorbed on high-index planes of copper, and then on low-index planes as the reaction progressed. With the increase of temperature, the concentration of formaldehyde and CO in gas phase increased, and that of methyl formate decreased.     

用FTIR研究环氧树脂的固化反应

采用傅里叶变换红外光谱研究了双酚Ａ型环氧树脂／马来酸酐固化剂／咪唑类固化催化剂体系的固化反应。结果表明,固化催化剂的用量在０．２％～２．０％（质量分数）时,对环氧树脂与固化剂的反应可起到明显的催化作用;大于２．０％时反应机理发生显著变化,环氧树脂与催化剂优先反应,抵制环氧树脂与固化剂的反应。     

In situ FTIR studies on the conversion of methanol over acidic forms of various zeolites

In situ investigations of the interaction of methanol on zeolites of the faujasite, pentasil and mordenite types were performed. We suppose that CH₃)- or (CH₃)₂O… species exist on the surface of the H-ZSM-5 zeolite in the temperature range between 380 and 470 K which desorb above 470 K and form dimethyl ether (DME). The band at 1502 cm⁻¹ represents aromatics being intermediates in the aromatization of methanol. The band at 1595 cm⁻¹ is due to polymeric “coke” which cannot be removed from the zeolite up to 670 K. In the case of the H-Y zeolite no band at 1500 cm⁻¹ assigned to aromatics could be observed.