烷基烯酮二聚体施胶体系对挂面再生纸表面不良施胶的成因剖析

针对某造纸厂再生纸抄造工程实际中,烷基烯酮二聚体（AKD）表面施胶挂面再生纸耐水性能提高不明显的质量问题,采用接触角、红外光谱（FTIR）、热重（TG）、X射线光电子能谱技术（XPS）、扫描电镜（SEM）、能谱（EDS）等研究方法,对纸厂生产的AKD施胶挂面再生纸纸样进行表征研究。结果表明,纸样接触角变化表现两面性差异,施胶纸样正面初期接触角为114.5°,反面初期接触角为118.5°,正面临界润湿接触角（≥90°）时间不足9min,反面临界润湿接触角为9min,纸样不具备长效耐水性,AKD施胶体系对纸张长效耐水性的贡献不明显;施胶后AKD特征官能团β-乙烯基丙内酯消失,施胶纸样和施胶萃取纸样在不同氛围下的失重行为不同,原子组成和原子价态化学环境不同,施胶纸样中含有可被四氢呋喃（THF）抽出的可溶物（AKD水解产物酮）,水解产物酮相对含量高于99.0%。AKD不良施胶的主要原因在于施胶体系配伍不当,导致AKD与纤维素酯化接枝反应的具有长效耐水产物的量不足。     

两种碳纤维上浆剂的比较

测试并比较了某国产上浆剂和进口上浆剂的黏度、表面张力、粒径等性能,研究了两种碳纤维上浆剂对聚丙烯腈基碳纤维表面形貌、耐磨性、水接触角、表面能、拉伸强度等性能的影响。结果表明,国产上浆剂固含量高、黏度高、粒径小,进口上浆剂黏度低、表面张力小、粒径分布窄。采用国产上浆剂上浆后的碳纤维,接触角为56.701°,毛丝量为0.15 mg/m,表面能为41.32 mJ/m²,耐磨次数为447次,拉伸强度为2.86 GPa;采用进口上浆剂上浆后的碳纤维表面光滑,接触角为51.063°,毛丝量为0.08 mg/m,表面能为47.26 mJ/m²,耐磨次数为461次,拉伸强度为2.95 GPa。     

基于二苯乙烯荧光增白型返黄抑制剂的合成及应用

以4,4'-二氨基二苯乙烯-2,2'-二磺酸(简称DSD酸)为原料,用三聚氯氰为交联单体,将紫外线吸收剂2,4-二羟基-二苯甲酮与二苯乙烯型荧光增白剂引入同一分子中,再引入牛磺酸,经过亲核取代等设计出既含有荧光增白基团又具备紫外光吸收功能的双三嗪氨基二苯乙烯荧光增白型返黄抑制剂。采用红外光谱和核磁共振波谱、紫外光谱、荧光光谱分析方法对其结构及光学性质进行了初步研究,并通过紫外光加速老化实验考察了目标产物对化机浆纸张的返黄抑制效果。实验结果表明,合成的目标产物在涂布中的最佳用量为1.0%(质量分数,下同),经过72 h光老化处理后,合成的产物光抑制效果更好,更适合作光诱导返黄抑制剂,与单独使用荧光增白剂和紫外光吸收剂相比,老化后纸张的白度分别少下降了4.74% ISO和4.15% ISO。     

国产碳纤维上浆剂的比较

探索了不同类型国产上浆剂对碳纤维接触角、表面能、耐磨性、表面微观形态等物理特性的影响。结果表明:使用YJ上浆剂的碳纤维的硬挺度、耐磨性比使用FD、HIT的好,使用HIT上浆剂的碳纤维的外观、丝束幅宽比YJ的好。     

大豆分离蛋白纸张表面施胶剂的制备及性能

以大豆分离蛋白(SPI)为原料、烯基琥珀酸酐(ASA)为疏水改性剂，控制ASA与SPI伯氨基的摩尔比合成四种不同酰化度的疏水大豆分离蛋白ASAn-SPI (下标n表示摩尔比，n=0.5，1，1.5和2)。通过伯氨基含量、FT-IR、UV-vis、荧光光谱、疏水指数等测定方法对ASAn-SPI的结构和性能进行表征。结果表明：长链疏水基团成功引入到SPI骨架上，ASAn-SPI的酰化度和疏水指数随着n的增加而增大，当n达到1.5后趋于稳定。ASA1.5-SPI的施胶量为0.77 g/m2时，施胶纸的初始水接触角可达132?，水滴保留时间可达53 min。XPS和SEM分析证实ASA1.5-SPI在纸纤维表面形成一层粗糙的疏水薄膜。此外，纸张力学性能测试表明，ASA1.5-SPI施胶纸的抗张强度由未施胶纸的0.6 kN/m提升至0.67 kN/m。     

Application of the surface free energy concept in polymer processing

The surface characteristics of variously treated carbon and glass fibres have been determined by contact angle measurements (using a capillary rise technique), inverse gas chromatography, and zeta potential measurements. The contact angles of water and methylene iodide were used to calculate the dispersive and non-dispersive components of the fibre surface free energy by applying the geometric mean approach, and the approach by Fowkes to estimate the acid-base term of the thermodynamic work of adhesion. The results obtained correlate with those of inverse gas chromatographic and zeta potential measurements. The non-polar surface character of the carbon fibre can be altered by oxidizing, or finishing the fibres with an epoxy resin. The acid-base term of the thermodynamic work of adhesion, W^ab _a, and the non-dispersive component of the surface free energy, γ^p _s, are increased drastically by these treatments. Treatment of the 'high-energy' glass fibre surface with an aminosilane results in a relatively low surface free energy with basic surface groups. When epoxy dispersions were used for sizing the glass fibres, the surface free energy increased without changing the basic surface character. A direct correlation between the surface-energetic properties of the fibres and the mechanical behaviour of the fibre-reinforced polyamide composites was not generally found.     

Effect of pigmentation on the surface chemistry and surface free energy of paper coating binders

The effect of the addition of clay and TiO₂ pigments on the surface energy and surface chemistry of films made from polymers used in paper coating formulations was evaluated. The polymers were carboxymethyl cellulose, polyvinyl alcohol and a protein-based polymer - all water-soluble - and two styrene-butadiene latexes of different carboxylation levels. The morphology of the surfaces was characterized by SEM examination, gloss measurement and stylus profilometry. Chemical composition was determined by EDS and XPS techniques. Surface energy and its Lifshitz-van der Waals and acid-base components were obtained from contact angle measurements using the van Oss et al. approach. Even though the addition of pigment increasingly upset the planar surface of the films, their surface chemistry and surface energy were only slightly affected over the pigmentation range studied (up to 40% by volume) and were dominated by the characteristics of the binder polymer.     

Interfacial microstructure and properties of carbon fiber-reinforced unsaturated polyester composites modified with carbon nanotubes

To improve the interfacial properties in carbon fiber (CF)-reinforced unsaturated polyester (UP) composites, we directly introduced functionalized carbon nanotubes dispersed in the fiber sizing onto the fiber surface. For comparing the influence of polymer type on sizing effect, two different polymers (UP MR13006 and water-soluble epoxy (EP)) were used to prepare sizing agent. Morphology and surface energy of CFs were examined by scanning electron microscopy and dynamic contact angle analysis test. Tensile strength was investigated in accordance with ASTM standards. Mechanical properties of the composites were investigated by interlaminar shear strength (ILSS) and impact toughness. Test results indicate that TS, ILSS, and impact toughness were enhanced simultaneously. For UP matrix, the sizing agent containing UP has better reinforcing and toughening effect than the sizing agent containing water-soluble EP.     

Comparison of the surface energetics data of eucalypt fibers and some polymers obtained by contact angle and inverse gas chromatography methods

This study compares two approaches to determine the surface energy of solids, and its acid-base components in particular: inverse gas chromatography (IGC) and analysis of contact angle data using the Good-van Oss theory. The comparison is made in the context of wood fibers from Eucalyptus globulus and Eucalyptus regnans pulped by the kraft and neutral sulfite semi-chemical (NSSC) processes, and of selected polymers. Contact angles on wood fibers were measured using the Wilhelmy method and on polymer samples using the sessile drop technique. For the dispersive component of the surface energy, the level of agreement between the two approaches was reasonable, using alkanes for the IGC measurements and diiodomethane for the Wilhelmy and sessile drop techniques. However, agreement was poor for the acid and base characteristics when monopolar probes were used for IGC and water, formamide, and diiodomethane for contact angle measurements. The Good-van Oss approach suggested that all fibers and polymers are monopolarly basic, whereas IGC measurements suggested that they are bipolar. When new values were used for the acid and base components of the surface energy of the liquid probes based on the values for water proposed by Della Volpe and Siboni, all samples still appeared strongly basic. This is inconsistent with the chemical nature of the lignocellulosic fibers. Thus, the Good-van Oss approach provides a poor indication of acid-base properties of the surfaces of solids in suggesting that lignocellulosic fibers and polymers are strongly basic. The above issues as well as potential problems in measuring the surface energy of lignocellulosic fibers using the three-liquid procedure and the Good-van Oss approach are discussed.     

Paper sizing agents from micelle‐like aggregates of polystyrene‐based cationic copolymers

A series of polystyrene‐based cationic copolymers (PSCC) were synthesized by copolymerization of styrene and the cationic comonomer vinylbenzyl trimethylammonium chloride. These copolymers can be used as internal paper sizing agents in a broad pH range. The effect of the charge density on the PSCC colloid properties was investigated. It was found that at room temperature the PSCC could change from water insoluble to colloidally dispersible and finally to fully water soluble as the charge density was increased. Based on the understanding of their colloid behavior, PSCCs were applied as internal sizing agents for paper. The results showed that the hydrophobicity of handsheets could be significantly improved by PSCCs and the sizing performance was a function of copolymer addition, charge density, particle size, drying temperature, and pH conditions. The present study indicated some potential advantages of PSCC copolymers as internal sizes. PSCC can be self‐retained on the fiber surface, no hydrolysis occurs during the storage and application, and no sizing reversion occurs. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2067–2073, 2000     

Characterization of epoxy resin surface energetics

This study has characterized the energetics of both the liquid state and the solid state of two commercially available epoxy resins: a DGEBA- and a TGMDA-based epoxy system. The surface properties of the liquid epoxies were evaluated by wetting measurements using a dynamic contact angle analysis (DCA). The Lifshitz-van der Waals components of the surface tension were found to be similar for both epoxy systems, while the acid-base components were found to be slightly different. Two different techniques were used to characterize the cured epoxy surface properties: wetting measurements and vapor adsorption measurements by means of inverse gas chromatography (IGC). The Lifshitz-van der Waals components of the surface energy were observed to be nearly the same for both epoxies, confirming that both resins have the same potential for non-specific interactions, in both liquid and solid states. Evaluations of the acid-base components of the work of adhesion by DCA and the Gibbs free energy change by IGC suggest that both cured epoxies show non-negligible specific interactions with both acidic and basic probes. However, computations of the accepticity and donicity parameters showed that both cured epoxies are predominantly basic, but also possess non-negligible acidity. It is likely that the presence of water on the solid surface contributes to the acidic character of the cured epoxies. The temperature dependence of the liquid surface tension for both epoxy systems was investigated. The same temperature dependence was observed: the surface tension decreased with temperature, following a linear regression. Corrections for viscous-drag effects on the liquid surface tension measurements were also made.     

Fluorinated segmented polyurethane anionomers for water–oil repellent surface treatments of cellulosic substrates

Three model structures of linear segmented anionomeric polyurethanes based on perfluoropolyether dimethylol‐terminated oligomers, isophorone diisocyanate, and dimethylol propionic acid were synthesized and obtained in the form of aqueous dispersions. The structures differed from each other in the chemical nature of the chain extender (diol or diamine) and in the content of carboxylic acid. Dispersions and polymer films were characterized by dynamic light scattering, dynamic mechanical analysis, differential scanning calorimetry, and contact angle measurements. Diluted aqueous dispersions were also evaluated as protective sizing agents in paper treatment, both as bulk modifiers and as surface treatments. Paper sheets characterized by high water and oil repellence were obtained. The results showed that performance is mainly related to the ionic group content of the polymer and to its molecular architecture. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1364–1372, 2005     

Surface and Interfacial Structure of Release Coatings for Pressure Sensitive Adhesives I. Polyvinyl N-Alkyl Carbamates

Polyvinyl N-alkyl carbamates belong to the general class of long alkyl side chain polymers. Such polymers are commonly used as release coatings for pressure sensitive adhesive tapes. In this paper the bulk, surface, and interfacial structures of polyvinyl N-alkyl carbamates having either decyl or octadecyl side chains are examined. The bulk structures and thermal transitions were characterized using X-ray scattering and differential scanning calorimetry. Dynamic mechanical thermal analysis was used to investigate thermal transitions and rheology (i.e., segmental mobility) of the polyvinyl N-alkyl carbamates. The surface energies of polyvinyl N-alkyl carbamate coatings were determined using contact angle methods, while X-ray photoelectron spectroscopy and static secondary ion mass spectrometry were employed to characterize the near-surface compositional profiles of the coatings. The peel force provided by the polyvinyl N-alkyl carbamate coatings, as a function of aging time and temperature, was measured for a tape having an acrylic acid containing alkyl acrylate based pressure sensitive adhesive. The changes in peel force with aging time and temperature were related to the ability to maintain a stable interfacial structure between the PSA and polyvinyl N-alkyl carbamate coatings. Changes in the interfacial composition upon aging were characterized by comparing the surface compositions of the PSA and polyvinyl N-alkyl carbamate coatings initially, prior to contact, as well as after aging and peeling them apart. The increase in peel force upon aging can be attributed, in large part, to a restructuring at the PSA/polyvinyl alkyl carbamate interface. Energetically favorable acid-base interactions between the basic urethane and acetate groups in the polyvinyl alkyl carbamates and the acrylic acid groups in the PSA provide a driving force for the restructuring. If the segmental mobility within the polyvinyl alkyl carbamate is sufficient, restructuring can occur, leading to increased concentrations of these groups at the PSA/polyvinyl alkyl carbamate interface, resulting in higher attractive forces and greater adhesion. The propensity for the polyvinyl N-alkyl carbamate coatings to restructure upon contact with a polar medium was also characterized by monitoring the receding contact angle of water, as a function of water contact time and temperature. A good correlation is seen between the ability of the polyvinyl alkyl carbamate coatings to provide a low peel force for the acrylate PSA tape and the ability of the coatings to maintain a high water receding contact angle.     

Effect of sizing on interfacial adhesion of commercial high strength carbon fiber‐reinforced resin composites

The influence of sizing agent on interfacial shear strength (IFSS) of carbon fiber/epoxy (CF/EP) and carbon fiber/bismaleimide (CF/BMI) was investigated. Since sizing agent can alter physicochemical properties of CF surface, possible affecting factors, including sizing reactivity, chemical reactions between sizing and resin, wettability of fiber with resin, fiber surface roughness, and chemical composition of fiber surface, were discussed. It is found that contact angle of fiber with resin and sufficient chemical reactions between sizing and resin reveal strong correlation with the interfacial adhesion of CF/EP and CF/BMI, while the effect of surface roughness and the amount of oxygen on the fiber surface are relatively weak. Due to EP type of the composition, the sizing agent tends to improve the wettability of CF with EP, while goes against for the fiber with BMI. POLYM. COMPOS., 254–261, 2016. © 2014 Society of Plastics Engineers     

Acid–base interactions and covalent bonding at a fiber–matrix interface: contribution to the work of adhesion and measured adhesion strength

The work of adhesion, W _A, and the practical adhesion in terms of the interfacial shear strength, τ, in some polymer-fiber systems were determined to establish a correlation between these quantities. An attempt was made to analyze the contributions of various interfacial interactions (van der Waals forces, acid-base interaction, covalent bonding) to the 'fundamental' and 'practical' adhesion. The surface free energies of the fibers were altered using different coupling agents. To characterize the strength of an adhesion contact, the ultimate adhesion strength, τ_ult, was determined for the onset of contact failure. The adhesion of non-polar polymers occurs through van der Waals interaction only; therefore, fiber sizing does not affect the adhesion strength. For polar polymers, such as poly(acrylonitrile butadiene styrene) and polystyrene, adhesion is sensitive to fiber treatments: suppression of the acid-base interaction by using an electron-donor sizing agent γ-aminopropyltriethoxysilane results in a decrease of both 'fundamental' and 'practical' adhesion. In the case of epoxy resins, the main contribution to the work of adhesion is made by covalent bonds. Since the process of their formation is irreversible, the work of adhesion determined from micromechanical tests seems to be more reliable than indirect estimations, such as from wetting and inverse gas chromatography techniques. Fiber treatment by sizing agents results in considerable changes in the intensity of adhesional interaction with the epoxy matrix. A correlation between the work of adhesion, the ultimate interfacial shear strength, and the strength of macro-composites has been found.     

Preparation and characterization of superhydrophobic surfaces based on hexamethyldisilazane-modified nanoporous alumina

Superhydrophobic nanoporous anodic aluminum oxide (alumina) surfaces were prepared using treatment with vapor-phase hexamethyldisilazane (HMDS). Nanoporous alumina substrates were first made using a two-step anodization process. Subsequently, a repeated modification procedure was employed for efficient incorporation of the terminal methyl groups of HMDS to the alumina surface. Morphology of the surfaces was characterized by scanning electron microscopy, showing hexagonally ordered circular nanopores with approximately 250 nm in diameter and 300 nm of interpore distances. Fourier transform infrared spectroscopy-attenuated total reflectance analysis showed the presence of chemically bound methyl groups on the HMDS-modified nanoporous alumina surfaces. Wetting properties of these surfaces were characterized by measurements of the water contact angle which was found to reach 153.2 ± 2°. The contact angle values on HMDS-modified nanoporous alumina surfaces were found to be significantly larger than the average water contact angle of 82.9 ± 3° on smooth thin film alumina surfaces that underwent the same HMDS modification steps. The difference between the two cases was explained by the Cassie-Baxter theory of rough surface wetting.     

Surface Characterization of Chlorinated Synthetic Vulcanized Styrene-Butadiene Rubber Using Contact Angle Measurements,Infra-Red Spectroscopy and XPS

The surface of a sulfur-vulcanized synthetic styrene-butadiene rubber (SBR) was treated with ethyl acetate solutions containing different amounts of trichloroisocyanuric acid (TCI). The chlorinated SBR surfaces were characterized using contact angle measurements (water, ethane diol, n-hexadecane), infra-red (IR) spectroscopy and XPS. Chlorination produced an increase of surface free energy which was mainly due to the enhancement of the acid-base component of the surface free energy, which remained almost unchanged when the amount of TCI was increased. Depending on the amount of chlorination agent, several chemical species were present on the SBR surface: i) For low amounts of TCI (up to 2 wt%), mainly chlorinated hydrocarbon and C – O species were present on the surface; ii) For medium amounts of TCI (between 2 and 5 wt%), an excess of unreacted TCI remained on the surface and a relatively small amount of isocyanuric acid was deposited; iii) For high amounts of TCI (larger than 5 wt%), a weak boundary layer (mainly composed of isocyanuric acid) was formed on the surface and thus the effects due to chlorination were decreased. There was good agreement between the experimental results obtained with contact angle measurements and XPS because both provided information on a surface region close to 100 Å, whereas IR spectroscopy results showed deeper penetration of the chlorinating agent into the SBR surface. The estimated thickness of the chlorinated layer was near 5000 Å as estimated from XPS measurements of SBR surfaces modified by argon ion bombardment.     

SiO_2气凝胶的制备及性能表征

以正硅酸乙酯(TEOS)为硅源,采用酸碱两步法来制备SiO_2气凝胶,从溶胶-凝胶反应原理出发,分别研究用水量、乙醇用量以及反应温度对凝胶时间的影响,从而确定溶胶-凝胶反应的基础配比。在此基础上,研究干燥化学控制剂用量对凝胶时间和开裂程度的影响,并采用多种材料分析手段对SiO_2气凝胶进行测试分析。结果表明,制备得到SiO_2气凝胶具有三维纳米多孔结构且无裂纹,比表面积576.64 m~2/g,接触角145°。     

磷-硼杂化预聚物嵌段水性聚氨酯纸张施胶剂的制备和性能

以甲苯二异氰酸酯（TDI）、聚乙二醇（PEG）为单体,二羟甲基丙酸（DMPA）和磷-硼杂化预聚物PBHP为扩链剂,通过逐步加聚制备不同组分的含磷、硼元素的阻燃水性聚氨酯（FRWPU）。FRWPU与聚磷酸铵（APP）、季戊四醇（PER）、三聚氰胺（MEL）膨胀阻燃体系复配制备阻燃纸张施胶剂。采用红外光谱（FTIR）、核磁共振波谱（NMR）、热重分析（TGA）、扫描电镜（SEM）、接触角测定、X射线光电子能谱（XPS）和垂直燃烧测试对FRWPU分散体、FRWPU薄膜、未施胶纸样和施胶纸样进行了表征。研究表明,随着PBHP加入量的提高,薄膜的疏水性增强,FRWPU40的接触角为85.4°,较FRWPU0提高了35.3%;同时,薄膜的最大热分解速率下降,800℃的残留质量从0上升到7.80%;施胶纸样的最大热分解速率下降,残留质量提高,平均炭化长度减小。当PBHP含量为50%时,残炭量为27.84%,较FPU0/IFR提高了30.6%;平均炭化长度为5.9cm,较FPU0/IFR降低了30%。SEM结果表明,施胶纸样燃烧后表面生成更加致密的炭层,阻燃性能提高。     

On the interpretation of contact angle hysteresis

The determination of solid surface free energy is still an open problem. The method proposed by van Oss and coworkers gives scattered values for apolar Lifshitz-van der Waals and polar (Lewis acid-base) electron-donor and electron-acceptor components for the investigated solid. The values of the components depend on the kind of three probe liquids used for their determination. In this paper a new alternative approach employing contact angle hysteresis is offered. It is based on three measurable parameters: advancing and receding contact angles (hysteresis of the contact angle) and the liquid surface tension. The equation obtained allows calculation of total surface free energy for the investigated solid. The equation is tested using some literature values, as well as advancing and receding contact angles measured for six probe liquids on microscope glass slides and poly(methyl methacrylate) PMMA, plates. It was found that for the tested solids thus calculated total surface free energy depended, to some extent, on the liquid used. Also, the surface free energy components of these solids determined by van Oss and coworkers' method and then the total surface free energy calculated from them varied depending on for which liquid-set the advancing contact angles were used for the calculations. However, the average values of the surface free energy, both for glass and PMMA, determined from these two approaches were in an excellent agreement. Therefore, it was concluded that using other condensed phase (liquid), thus determined value of solid surface free energy is an apparent one, because it seemingly depends not only on the kind but also on the strength of interactions operating across the solid/liquid interface, which are different for different liquids.