Relationship between surface chemistry and surface energy of different shape pigment blend coatings

The influence of pigment shapes and pigment blends on the surface energy was investigated and compared with the surface chemistry of pigmented latex coatings. The coatings were made of different volume ratios of two pigments: plate-like kaolin clay pigment and prismatic precipitated calcium carbonate (PCC) pigment. These were mixed together with carboxylated styrene–butadiene–acrylonitrile latex (SBA), and applied over nonabsorbent substrates as well as absorbent substrates. The composition of the surface of the coatings was investigated by X-ray photoelectron spectroscopy (XPS). Two approaches were used to estimate the total surface energy and the components of the coatings: a conventional approach—“the Kaelble approach”—and a more modern approach—“the van Oss approach.” Pigment blends with different shapes and increments caused a change in the surface chemistry and the surface energy of the latex coatings. As the prismatic PCC pigment particles increased in the kaolin/SBA coating system, the SBA latex content at the coating surface increased and the total surface energy of the coating decreased. This is valid for both nonabsorbent as well as absorbent substrates. It was found that there was a strong correlation between the surface energy and the surface composition. The surface energy of the coatings estimated by the Van Oss approach was always lower than that estimated by the Kaelble approach. Colloidal interactions between pigment–pigment and/or pigment–binder were thought to play an essential role in determining the final coating surface energy and its components. Changes in the surface latex content and the surface energy due to the different pigment blends investigated were found to fit straight-line equations.     

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.     

An investigation of the effect of pigment on the degradation of a naturally weathered polyester coating

A series of coil coatings based on a polyester/melamine resin formulation, incorporating different pigment systems, were naturally weathered after being exposed to the elements in Hainan, PRC, for 2 years. The surface chemistry and morphology, before and after weathering, was investigated using both traditional (i.e., gloss retention, color change) and novel (i.e., X-ray photoelectron spectroscopy [XPS], atomic force microscopy [AFM], and scanning electron microscopy [SEM]) methods. Chemical changes occurring in the coating bulk were investigated using step-scan photoacoustic Fourier transform infrared spectroscopy (SSPA-FTIR). It was found that the coating surface morphology, surface chemistry, and bulk chemistry, both before and after weathering, were all affected by the type and concentration of the pigments included in the coating formulation. Moreover, it was found that different types of pigment catalyze different coating degradation mechanisms.     

Optimization of milling parameters on the synthesis of stearic acid coated CaCO3 nanoparticles

Surface modification of precipitated calcium carbonate particles (calcite) in a planetary ball mill using stearic acid as a modification agent for making dispersion in hydrocarbon oil was investigated. Different parameters for processing (milling) such as milling time, ball-to-sample ratio, and molar ratio of the reactant were varied and analyzed for optimization. The physical properties of the hydrophobically modified calcium carbonate particles were measured; the particle size and morphology of the resulting samples were characterized by transmission electron microscopy and X-ray diffraction. The surface coating thickness was estimated using small angle X-ray scattering.     

A study of the effect of different iron oxide pigment grades on properties of an industrial latex coating

Two red iron oxide pigments with similar properties but prepared by different chemical processes were obtained for evaluation. One process provided a pigment described as rhombohedral in shape; the other was described as spheroidal. The pigments were incorporated into an industrial latex coating formulation at the same pigment volume concentration. Properties of the liquid formulations, wet applied films, dried films, and free films were measured. Representative tests run were viscosity, gloss, adhesion, and prohesion. Differences in the degree of coalescence, accelerated corrosion testing, surface appearance, and mechanical properties were observed. Based on experimental data, conclusions were made attempting to correlate pigment morphology with coating properties. However, other inherent differences, such as particle size distribution, were found to obscure the singular effect of particle morphology.     

Time and cost effective methods for testing chemical resistance of aluminium metallic pigmented powder coatings

Polyester based powder coatings containing different types of aluminium metallic flake pigments have been investigated with respect to their chemical stability in acid environments. The metallic flakes are made chemically stable by covering them in silica. The degree of silica coverage and the silica morphology are far more important for the chemical stability of the pigments than the silica thickness. The acid resistance of the final powder coating is found to depend on the pigment embedment depth, on the chemical composition and morphology of the powder coating, and on the silica coating of the pigment. The latter being the single most important factor in our study.     

The surface energy as an indicator of miscibility of SAN/EDPM polymer blends

Surface properties of blends prepared of styrene-acrylonitrile and ethylene-propylene-diene changing the homopolymer proportions and compatibilized by high impact polystyrene have been studied by contact angle measurement. The surface free energy of interphase of homopolymers pairs, work of adhesion, and wetting coefficient were calculated using Wu’s geometric mean method and the total surface free energy and acid–base components of the blends by using van Oss, Good and Chaudhury method. Blends were also characterized by dynamic mechanical analysis and by scanning electron microscopy. The miscibility of studied blends was estimated through changes of surface free energy, energy of interface and through the shifts of glass transition temperature and changes in morphology. From the results, it can be seen that added compatibilizer reduces the interface energy and provides more homogenous system by interfacial segregation and rearrangements of molecules at the blend surface. The results of morphological observations reveal that the addition of a small percentage of compatibilizer decreases the domain size of the dispersed phase and enhances the compatibility of the blends.     

粉煤灰微珠-Ag复合颗粒的制备工艺和分析

采用化学镀的方法,以银氨溶液为镀液,甲醛为还原剂,按照一定的工艺过程对粉煤灰微珠进行表面镀银处理,得到了粉煤灰微珠-Ag复合颗粒。同时借助激光粒径分析仪、X射线衍射仪、场发射扫描电子显微镜、X射线能谱仪等检测设备对复合颗粒的粒径分布、化学成分、镀层表面形貌和结构进行了分析。对复合微珠进行保温隔热性能测试,掺镀银微珠的涂料比原微珠的涂料温度低约4℃。结果表明,按照设定的工艺过程,可以成功制备出具有保温隔热低辐射功能的粉煤灰微珠-Ag复合颗粒,作为一种功能性骨料有望用于建筑物外围护结构表面的砂浆或涂料中以降低对远红外热的辐射能力。     

彩色复合型反射隔热涂层的制备及性能

将空心微珠和二氧化钛为填料的涂层做底层,反射型颜料的涂层做表层,制备了阻隔-反射彩色复合型反射隔热涂层。采用紫外/可见/近红外分光光度计、红外发射率仪、精密色差仪和扫描电子显微镜对涂层性能进行表征,自制隔热性能测试装置考察涂层的隔热性能。结果表明,采用复合型涂层结构可显著提高涂层的太阳光反射比和隔热性能,铬绿、群青和铁铬黑颜料掺量分别为20%、20%和10%时,复合涂层的太阳光反射比较高,可达0.646 1、0.602 1和0.539 8,比相同颜料掺量的表层高40.82%、31.03%和58.67%,隔热性能比相同颜料掺量的表层高2.5、1.9和2.8℃,其主要应用性能符合相关标准。     

Mutual correlations between parameters characterizing the miscibility,structure and mechanical properties of polymer blends

Polymer blends were prepared in the whole composition range using polymers of different polarity. Mechanical properties were characterized by tensile measurements. Surface and interfacial properties were measured and calculated and parameters characterizing the miscibility were determined. A correlation was found between the yield stress and the thermodynamic quantities characterizing the degree of miscibility. Since both the degree of miscibility and morphology are influenced by the interfacial tension, it can be regarded as the best candidate to correlate polymer/polymer interaction and mechanical properties in polymer blends.     

Poly(ethylene oxide) and its blends with sodium alginate

A series of blends based on poly(ethylene oxide) (PEO) and sodium alginate (NaAlg) were prepared by solution casting method. The blends thus obtained were characterized by using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), tensile strength test, contact angle measurements and atomic force microscopy (AFM). FT-IR studies indicate that there are the hydrogen bonding interactions due to the ether oxygen of PEO and the hydroxyl groups of NaAlg. The thermal stability of the blends was slightly affected with increasing NaAlg content. DSC results showed that both melting point and crystallinity depend on the composition of the blends. Mechanical properties of the blend films were improved compared to those of homopolymers. Surface free energy components of the blend films were calculated from contact angle data of various liquids by using Van Oss-Good methodology. It was found that the surfaces both of the blends are enriched in low surface free energy component, i.e. NaAlg. This conclusion was further confirmed by the AFM images observation of the surface morphology of these blends.     

Studies of the Mechanical Properties and Practical Coating Adhesion on PP Modified by Oxidized Wax

In this study, the influences of polarity and the amount of oxidized polypropylene wax (OPPW) in blends with polypropylene (PP) were investigated by studying their surface properties. OPPW was completely miscible with PP up to 10 wt%. The adhesive strength of a acrylic-based primer coating on PP sheets, containing different wt% of OPPWs, was evaluated by using a direct 'pull off' test method. The results showed that the adhesive strength of the coating improved with an increase of the amount of OPPW in the blend. However, the degree of polarity in the OPPW did not have a significant impact on its adhesive properties. These observations were also supported by the results of ATR–FT-IR spectroscopy and surface energy measurements of the substrate. Furthermore, the results of adhesion test on the coating panels showed a significant enhancement after exposing to heat in an oven prior to the application of coating, e.g., about 230% increase for the blend containing 8 wt% of OPPW. The TGA curves showed a maximum drop of about 10% in thermal stability in comparison with that of the unblended PP. The changes in the mechanical properties of the blends were explained by considering the morphology of the blends and were supported by the changes in blend crystalinity and melting behavior. The elastic modulus remained almost unchanged while elongation and stress to breakpoint experienced a sharp reduction at concentrations of wax content higher than 6 wt%. The study showed a good balance of substrate coatability with its bulk properties at a blend concentration of about 6 wt% of OPPW.     

EPDM粘度对PP＼EPDM共混物断口形态和冲击性能的影响

用机械共混的方法制备了一系列不同ＥＰＤＭ粘度的ＰＰ／ＥＰＤＭ共混物，对其力学性能和结晶行为进行了表征，并用扫描电子显微镜（ＳＥＭ）研究了共混物冲击样条的断口形态。实验结果表明，ＥＰＤＭ粘度对共混物的冲击强度有较大影响，随着ＥＰＤＭ粘度的增大，共混物的冲击强度出现极大值，而结晶行为的变化则较小，研究共混物冲击样条的断口形态发现，共混物的冲击强度随ＥＰＤＭ粒径的变化出现极大值。     

细乳液聚合法制备PY-17/PE蜡/PS复合乳胶粒子

通过细乳液聚合法制备彩色墨粉用多组分复合乳胶粒子,即通过细乳液聚合法制备聚苯乙烯包覆有机颜料PY-17和聚乙烯蜡的三元复合乳胶粒子。通过透射电子显微镜、激光粒度仪、紫外可见分光光度计和热失重分析仪对制备的复合乳胶粒子形貌、粒度、热学和光学特性进行表征,着重研究了乳化剂种类及用量、颜料用量和聚乙烯蜡用量对复合乳胶粒子粒径和形貌的影响,并对复合乳胶粒子的热学及光学特性进行了表征。结果表明,使用复合乳化剂,颜料PY-17用量不大于单体量8%、聚乙烯蜡用量占单体量不大于10%时,制备的复合乳胶粒子粒径较小,分布窄,包覆较为完整;并且复合乳胶粒子的热学及光学特性发生了一定的改变。     

Surface nanaostructure evolution of functionalized polypropylene fibers

It is well‐known that fiber surface characteristics affect friction, wetting, conductivity, and other performance properties. This paper reports the evolution of the surface nanostructures of meltblown polypropylene (PP) fibers during the process of plasma treatment followed by copper (Cu) sputter coating. The effects of plasma treatment and Cu sputter coating on the surface morphology, chemistry, and properties of the fibers were characterized using scanning probe microscope (SPM), environmental scanning electron microscopy (ESEM), and electrical analysis. The atomic force mode (AFM) and lateral force mode (LFM) in the SPM were used to scan the fiber surface. AFM observations revealed the evolution of the surface morphology formed by surface treatment. The LFM images also indicated the change in surface nanomechanical behavior. A full energy dispersive X‐ray analysis (EDX) mounted on the ESEM was used to examine the change in the chemical compositions of the functional surfaces. The electrical properties of the functionalized materials were analyzed using electrical resistance test. The Cu sputter coating significantly altered the surface conductivity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Calcium sulphate as pigment for improved functional properties of coated paper

In the last few years, interest and demand of high bright paper have forced paper manufacturers to think new ways to improve brightness and whiteness of coated paper. Pigment coating is widely used to enhance the optical properties such as brightness, whiteness, and gloss of paper and paperboard. These optical properties are the most important for end user and also determine the final cost of coated paper. Calcium sulphate has inherent better optical properties compared to other conventional pigments for example ground calcium carbonate, precipitated calcium carbonate and kaolin clay. The present study was carried out with an aim to synthesize calcium sulphate using waste procured from phosphoric acid industry and to study its impact on the rheology of coating color as well as optical properties of coated paper. Addition of calcium sulphate improved the water retention property of coating color which can be helpful for improving the machine runnability. The results also revealed that calcium sulphate can be used as a pigment to produce coated paper of high brightness and whiteness. The brightness and whiteness of the coated paper were improved 4 and 15 points, respectively by using 50 parts of calcium sulphate as a pigment replacing clay from the coating formulation. The surface strength in terms of IGT pick value of coated sheets was found significantly comparable using calcium sulphate as pigment. The print gloss results were observed analogous with matt grade coated paper.     

Effect of vanadium additive and phosphating time on anticorrosion,morphology and surface properties of ambient temperature zinc phosphate conversion coatings on mild steel

An attempt has been made to investigate the effect of phosphating time and vanadium additive on the anticorrosion and surface properties of ambient temperature zinc phosphate coatings. Zinc phosphate coatings with different phosphating times and vanadium concentrations were applied to low carbon steel samples. A potentiostatic polarization test in 3.5 wt% NaCl solution was carried out to investigate the electrochemical properties of coated samples. Field emission scanning electron microscopy, energy-dispersive spectroscopy, and atomic force microscopy were utilized to evaluate the microstructure, chemistry and roughness of coatings. Surface properties such as wettability, surface tension, and work of adhesion were measured. Results indicate that the sample which was immersed for 30 min in the phosphating bath exhibits the lowest corrosion current density, one tenth of bare steel, due to formation of a compact coating while having a low number of microcracks. Addition of 500 ppm vanadium to the coating in a secondary bath decreases the corrosion rate of zinc phosphate coating remarkably, by almost 80%. Microstructural results reveal that vanadium-rich precipitates are formed and enhance the coating coverage on the steel substrate. Vanadium addition increases the surface roughness, surface free energy, and work of adhesion of the phosphate coating.     

Thermal-induced recovery of small deformations and degradation defects on epoxy coating surface

Surface defects, which are dependent on the surface properties, determine the appearance, toughness, and other properties of coatings; thus, changes to the morphology of a damaged epoxy coating surface were investigated on annealing. Changes in mechanically produced indentations and scratches with annealing indicate a surface transition temperature about 10 degree lower than the measured bulk glass transition temperature (T _g). Polymer molecules at a free surface, even in a crosslinked coating, may have higher mobility, and thus allow different relaxation activity from the bulk material. The eventual extent of deformation is a function of the annealing temperature and time. Results showed that the deformation profile diminished, driven by viscoelastic deformation and surface energy; the effect of structural relaxation will be further studied. When the surface features were generated by photodegradation, the roughness increased initially when temperature was increased, possibly due to phase coarsening, and then the roughness diminished during extended annealing.     

Surface properties of polyamides modified with reactive polydimethylsiloxane oligomers and copolymers

Surface modification of polyamide-6 (PA-6) was investigated by melt blending with silicone-urea copolymers or organofunctionally terminated polydimethylsiloxane oligomers. Blends were prepared in a laboratory scale high-shear melt mixer. Surface characteristics of the blends were determined by static water contact angle measurements and X-ray photoelectron spectroscopy. Effect of the type, composition, average molecular weight and amount of the silicone additive in the blends, on the surface properties were determined. Influence of the thermal history of the samples on the surface properties was also investigated. All of the blends showed formation of silicone rich surfaces. Surface modification was permanent due to either the formation of chemical bonds between additive and polyamide and/or very strong hydrogen bonding between urea and amide groups.     

Preparation and performance of waterborne UV‐curable polyurethane containing long fluorinated side chains

Novel waterborne UV‐curable polyurethane containing long fluorinated side chains (WUVFPU) was prepared and the fluorinated component was incorporated by two novel fluorinated macromolecular diols (FDO) with different chain length as chain extender. FDO was synthesized via free radical polymerization of hexafluorobutyl methacrylate (HFBMA) using 1‐thioglycerol (TG) as chain transfer agent. Extremely low dosage of FDO incorporated could change the surface property significantly. The influence of both the content and chain length of FDO on the surface energy, surface composition and morphology were investigated by contact angle measurement, XPS and AFM. Surface energy significantly decreased at extremely low concentration of FDO. The hydrophobicity was enhanced with increasing both the content and the chain length of FDO. XPS and AFM results revealed the enhancing hydrophobicity was attributed to the enrichment of F atoms and rougher surface morphology. Gel content, pencil hardness, adhesion, and optical transmittance tests were employed to investigate the coating properties of the UV‐cured films. The preparation and investigation of WUVFPU might provide better understanding of the influence of fluorinated chain length on the properties of polyurethane for theory. Moreover, it might provide a facile and effective route to prepare polyurethane materials with low surface energy for engineering and industry. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44506.