Analysis of diterpenoic compounds in natural resins applied as binders in museum objects by capillary electrophoresis

The exudates of conifers consist mainly of diterpenoic acids of the abietane and pimarane type (abietic, neoabietic, dehydroabietic, palustric, pimaric, isopimaric, levopimaric and sandaracopimaric acid) and larixol acetate. These natural resins were used as adhesives, coatings, varnishes or plasticizers in artistic and historic works since ancient times. For the purpose of conservation and restoration and for art historic examination of such museum objects the identification of the binding media used is undoubtedly of paramount importance. In the present paper, the characterization of these resins based on the pattern of their diterpenoid constituents is carried out by capillary electrophoresis. For separation a background electrolyte which has been initially introduced for the analysis of chlorinated and natural resin acids in waste water was modified and the experimental conditions were adjusted in terms of resolution and analysis time. Separation was carried out in borate buffer at pH 9.25 (ionic strength 20 mmol L(-1)) with methyl-beta-cyclodextrin and sulfobutylether-beta-cyclodextrin as additives to increase selectivity and enhance the solubility of the analytes. With this electrophoretic system the resin acids of interest and larixol acetate--all as anionic cyclodextrin complexes--were separated within 5 min and detected at 200, 250 and 270 nm with a diode array detector. The electrophoretic patterns served for the characterisation of the relevant diterpenoic resins, balsams and copals. Sample pre-treatment was limited to sonication in methanol at 55 degrees C for 30 min. This enables the identification of the resins in mixtures with other binders like plant gums, animal glues or drying oils, even when these media are present in excess. Colophony was identified as resinous constituent of a modelling mass for gilded frames originating from the 19th century.     

Perspective thermally stable thermoset binders for polymer composite materials

Brief review of the modern state in the field of thermally stable thermoset resins used as binders for engineering polymer composites in presented. Synthesis, processing, properties, and application of such materials are discussed. The list of binders includes polyimide PMR resins, oligoimides with reactive end groups, bismaleimides, and phthalonitrile resins.     

Tailor-made UV-curable powder clear coatings for metal applications

UV-curable powder coatings combine most of the benefits of conventional powder coatings together with the advantages of radiation-curable liquid coatings. This new coating process is not only environmentally friendly. It can also be used to coat substrates like wood, plastic, glass or metal at low temperatures within a short curing time. Several coatings based on binders like urethane vinylethers/unsaturated polyesters or methacrylates are developed for metals, wood or pvc flooring. This paper describes urethane acrylates as a new resin system for UV-curable powder clear coatings. The binders can be amorphous or (semi)crystalline. By combining both types it is possible to get tailor-made binders which exhibit an unique coating performance of excellent adhesion, good flexibility and high hardness on metal substrates. The appearance of the clear coatings can be varied from high to low translucent. In addition, the coatings show a good weatherability.     

Current state of projects in field of epoxy resins and curing agents for adhesives: Production and quality

The article discusses the current state of the production of epoxy resins and curing agents. It is noted that, in recent years, the rate of increase in production and the variety of epoxy binders, in addition to those made by well-known worldwide producers, such as Dow Chemical and Hexion, the leading positions are occupied by companies of Southeast Asia and China. There is analysis of the reasons for the Russian epoxy production being of track. The aspects of the epoxy resins and curing agents quality estimation are discussed.     

Preparation and properties of wooden fiberboards with phenol cardanol formaldehyde adhesives

The results of a study of wooden fiberboards, for which phenol cardanol formaldehyde resins with different cardanol content were used as binders, are shown. The influence of technological factors on the bending strength of fiberboards and their water absorption in the case of the use of such binders is shown.     

Adhesive-Strength Evaluation via the <Emphasis Type="Italic">Pull-Out</Emphasis> Method in a Binder—Elementary-Filament System at Various Treatments of Filaments

The adhesive strength of binders with elementary filaments that have been used for the production of LUP carbon tape covered by different types of coatings is evaluated via the pull-out method. Two types of single-layer coatings are considered, one of which is based on titanium of the VT1-0 brand while the other is made of 12Kh18N10T steel, as well as a bilayer coating composed of a titanium layer coated by a stainlesssteel layer. The adhesive strength is determined for thermoreactive (epoxy with amine hardener) and thermoplastic (polyamide) types of binders. The best adhesive strength (more than 30%) of binders is achieved when the LUP carbon tape is covered with stainless steel.     

How to control dirt pick-up of exterior coatings

The composition of dirt and the tendency of coatings to pick up dirt are determined largely by the location. The factors affecting the tendency of coatings to pick up dirt are varied and complex. That is why the problem of dirt pick-up on exterior coatings can only be resolved satisfactorily by optimisation of the paint formulation as a whole (PVC, type of formulation, surface texture) and of all the raw materials (binders, pigments, fillers, additives).     

Carbon-reinforced plastics based on hybrid polyimide-organosilicon binders

Compounds based on the synthesized polyimides and organosilicon resins were developed. The compatibility of organosilicon resins with polyimide binders was studied by electron microscopy. The possibility of preparing fibrous composite materials, carbon-reinforced plastics, using such polyimide-organosilicon binders was demonstrated. The viscoelastic and strength properties of the materials obtained were studied. The optimum binder composition, ensuring 90% preservation of the elastic modulus and 70% preservation of strength of the carbon-reinforced plastic relative to the initial values after keeping in air for 50 h at 350°C, was chosen.     

The biodeterioration of synthetic resins used in conservation

Synthetic resins have been extensively employed by artists in their works of art, e.g. as paint binders, or by conservators for conservation treatments, e.g. as stone consolidants and protectives. It is generally thought that synthetic resins are less prone to chemical, physical and biological deterioration than other organic products but there are many articles in the scientific literature and some reports in the conservation of cultural heritage literature claiming that microorganisms are capable of degrading synthetic resins. This paper reviews the researches on the biodeterioration of synthetic resins used in the conservation of cultural heritage, including stone, painting and textile materials, carried out in the last fifty years.     

保形涂料的研究进展

介绍保形涂料的固化机理,比较了各类光固化保形涂料及其修复方法,综述紫外光固化保形涂料的研究进展。     

Classification and identification of organic binding media in artworks by means of Fourier transform infrared spectroscopy and principal component analysis

Fourier transform infrared spectroscopy is a powerful analytical technique to study organic materials. However, in Cultural Heritage, since the sample under analysis is always a complicated matrix of several materials, data analysis performed through peak-by-peak comparisons of sample spectra with those of standard compounds is a tedious method that does not always provide good results. To overcome this problem, a chemometric model based on principal component analysis was developed to classify and identify organic binding media in artworks. The model allows the differentiation of five families of binders: drying oils, waxes, proteins, gums, and resins, taking into account the absorption bands in two characteristic spectral windows: C–H stretching and carbonyl band. This new methodology was applied in the characterization of binders in three kinds of artworks: papers of historical, archeological, and artistic value, easel paintings, and polychromed stone-based sculptures.     

Stress development during drying of calcium carbonate suspensions containing carboxymethylcellulose and latex particles

Stress development during drying of coatings produced from aqueous dispersions of calcium carbonate particles in the presence and absence of organic binders was studied using a controlled-environment stress apparatus that simultaneously monitored drying stress, weight loss, and relative humidity. Specifically, the influence of two organic binders on drying stress evolution was investigated: (1) carboxymethylcellulose, a water-soluble viscosifying aid, and (2) a styrene-butadiene latex emulsion of varying glass transition temperature. The stress histories exhibited three distinct regions. First, a period of stress rise was observed, which reflected the capillary tension exerted by the liquid on the particle network. Second, a maximum stress was observed. Third, it was followed by a period of either stress decay or rise depending on the organic species present. Significant differences in stress histories were observed between coatings containing soluble and nonsoluble binders. Maximum drying stresses (sigmamax) of 0.2-0.5 MPa were observed for coatings produced from pure calcium carbonate or calcium carbonate-latex suspensions, whereas coatings with carboxymethylcellulose exhibited substantially higher sigmamax values of 1-2 MPa. Upon drying, these coatings were quite hygroscopic, such that cyclic variations in relative humidity induced large cyclic changes in residual stress.     

The effect of fluoropolymer architecture on the exterior weathering of coatings

Fluoropolymers of several different types (poly(vinylidene fluoride), alternating copolymers, perfluorinated ether polyols) are commercially available as coatings resins. While all these resins share certain chemical properties (e.g. hydrophobicity), the performance in the area of weathering depends crucially on details of the molecular structure. A number of recent studies have examined the mechanisms by which different fluorinated coatings weather, and have highlighted some ways in which the molecular structure affords photochemical protection that is not possible with conventional polyester or polyurethane coatings. The most weatherable fluoropolymer systems not only meet the most stringent worldwide industry specifications for high performance architectural and protective topcoats, but have demonstrated over thirty years chalk and fade resistance in south-facing Florida exposures.     

粉末涂料的改性研究

简述了粉末涂料改性的研究进展。重点介绍了环氧树脂在丙烯酸树脂 /环氧树脂混合型粉末涂料中的作用 ;无封端剂的聚氨酯粉末涂料交联和 1 ,4-环己烷二甲醇酯二苯甲酸酯作为粉末涂料改性剂的研究进展     

Electron beam curable branched chain polyurethane acrylates for magnetic media coatings

Electron beam curable binder resins have been studied to realize the high quality magnetic coatings. It was supposed that resibs with a higher crosslink density could lead to magnetic coatings with higher abrasion resistance. Branched chain polyurethane acrylates show a higher degree of cure by irradiation with an electron beam in comparison with linear polyurethane acrylates.This paper describes the potential wear resistance between properties of magnetic coatings and the physical properties of the cured unpigmented branched chain polyurethane acrylates that were used as the binder resins.     

Binders for exterior coatings exhibiting low soiling tendency

Elastomeric coatings protect building facades and flat roofs from moisture and weather exposure. As a drawback, these coatings are prone to dirt-pickup due to the low glass transition temperature of the used polymeric binders. Strategies to overcome this enhanced soiling tendency are discussed, and the results of laboratory and outdoor soiling tests are compared. A novel method for the assessment of wet soiling tendency is presented.     

Investigations of the effect of viscosity of resin on the diffusion of pyrene in silicone polymer coatings using steady state fluorescence technique

The diffusion phenomenon of pyrene in silicone coatings prepared from various commercial silicone resins with different viscosities was investigated using steady state excimer fluorescence technique. The amount of pyrene lost from the coatings by diffusion at different temperatures ranging from 25 to 70 °C was estimated from the excimer emission intensity. The diffusion coefficients (D) and activation energy of diffusion of pyrene in silicone coatings were determined. It was found that the kinetic parameters of pyrene were comparable in all the four silicone coatings and independent of the viscosity of the resin. The D values were lower than those expected for pyrene in PDMS resins in the corresponding viscosity range. This may be attributed to restricted mobility of pyrene due to cross-linking of polymer chains in the cured silicone coatings.     

Modified coatings based on chlorosulfonated polyethylene

The results of investigations of the effect of solid petroleum resins, epoxide oligomers, and type of curing agent upon the properties of varnishes and coatings based on chlorosulfonated polyethylene are given. It is shown that the use of cycloaliphatic isocyanates and amine-containing organic silicon compounds allows one to obtain coatings with a complex of high processing and operating characteristics.     

Tunable poly(hydroxyl urethane) from CO2‐Based intermediates using thiol‐ene chemistry

CO₂‐based, crosslinked poly(hydroxyl urethane)s (PHUs) are accessed via a set of efficient reactions based on the addition chemistry of thiol‐ene and amines‐cyclic carbonates. This strategy to utilize 5‐membered cyclic carbonates produced from CO₂ is robust, facile, modular, and atomically efficient in nature. The thiol‐ene reaction was utilized to access bis(cyclic carbonate), tris(cyclic carbonate), and tetrakis(cyclic carbonate) in quantitative yield from 4‐vinyl‐1,3‐dioxolan‐2‐one and thiols. Multi‐functional cyclic carbonates were simply mixed with diethylenetriamine and/or 1,6‐diaminohexane to generate crosslinked PHUs from 25 to 80 °C. These materials are easy to scale‐up and are potential candidates in many applications such as coatings, binders, and resins. The resulting polymers have glass transition temperatures between ?1 and 16 °C and thermal decomposition temperatures from 190 to 230 °C. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Characterization of Paint by Fourier-Transform Infrared Spectroscopy,Raman Microscopy,and Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy

The identification of automotive coatings has become important for forensic scientists to trace suspects. Popular automotive coatings include acrylic, amino, alkyd, nitro, and polyurethane paints. Various pigments and additives are added to the coatings, which may create difficulty in characterization of paint evidence. In this study, Fourier-transform infrared spectroscopy, Raman spectroscopy and scanning electron microscopy-energy dispersive X-ray spectroscopy were used to characterize an eleven-layer paint sample. Most layers were only a few micrometers thick. Infrared spectroscopy has several advantages in identifying resins and additives, while Raman is more effective in characterizing additives and inorganic pigments. Scanning electron microscopy-energy dispersive X-ray spectroscopy provides elemental analysis information. The results reveal that the combination of these techniques provides more accurate paint identification than using them separately.