Good Weather Resistance Research Articles

Study of Epoxy Acrylic Cathodic Electrodeposition Coatings and Investigation on the Electrophoretic Coating Process

As an environment-protecting waterborne coating, the cathodic electrodeposite coating has wide applications prospects.The self-crosslinked acrylate grafted epoxy resins for cathodal electrophoretic coating were synthesized by grafting acrylic polymer onto epoxy resin . This epoxy-acrylic copolymer both have high modulus, high-strength ,excellent chemical resistance and corrosion resistance of epoxy resin, and both have the light-acrylic resin fullness, good weather resistance and other characteristics of acrylic resin,which are widely used in the automotive, building materials, home appliances and other fields.The electrophoretic coating is an extremely complex process. The effects of the parameters of electrophoretic technology on the properties of paint films were studied systemically.The results show that the electrophoretic paint with better appearance and propeties can be made when voltage was about 90V,the solid share was 16%,pH was 5.8and electrophoresis time was 2-3min.

Property modification and process parameter optimization design of polylactic acid composite materials. Part I: polylactic acid toughening and photo-degradation modification and optimized parameter design

The aims of this series of studies were to improve the characteristics of polylactic acid (PLA) composites, including toughness modification and photo-degradability suppression. For toughness modification, polybutylene succinate (PBS) was used to modify the toughness of PLA material, and for photo-degradability suppression, ultraviolet (UV) absorbers and hindered amine light stabilizers (HALS) were used to restrain the photo-degradability of PLA material. The composite granules were produced by twin-screw extrusion followed by film extrusion, and the Taguchi method and principal component analysis are used to optimize processing parameters for toughening modification analysis. Through differential scanning calorimetry testing and melt flow index analysis it was determined that this combination of PLA-based composite material had good compatibility, processing flowability and weather resistance. Compared with pure PLA, it was found that the bending strength was decreased by 27.49%, the tensile strength was increased by 13.47% and impact strength was increased by 22.95%, when the processing parameter of the PBS blending ratio was 10 wt% and the mixing of UV absorbers and HALS blending ratio was 0.5 wt%. The screw speed of the twin-screw mixer extruder was 200 rpm, and the die head temperature was 220℃. After 480 hours of UV accelerated aging testing, the retention rate of tensile strength was 94.86%, which is higher than that of pure PLA by 44%. The retention rate of breaking elongation was 85.17%, which was higher than that of pure PLA by 35.17%.

Design and experimental analysis of a cylindrical compound Fresnel solar concentrator

This study presents the design of a cylinder shaped solar concentrator which is comprised of an arched Fresnel lens and a Fresnel mirror and a secondary reflector. An evacuated-tube or a concentrating photovoltaic cell can be used as the receiver being placed at the focus of the concentrator. This cylindrical compound Fresnel solar concentrator may have the advantages of good weather resistance, low driving force during tracking, good appearance and easy modularization. The dimensions of the Fresnel lens and the Fresnel reflector are calculated on the basis of optical principle. An optical simulation tool is used to obtain the optical efficiency of the concentrator for different incidence angles and therefore determine the allowable tracking error. It has been found that about 90% of the incident sunlight can still be gathered by the absorber when the tracking error is within 1.5°. Discussion is also made about the influence of the solar azimuth angle on the optical efficiency. A preliminary measurement of the optical efficiency of a prototype cylindrical concentrator is introduced. The experimental data generally agrees with the simulation result.

An Experimental Study on Anti-Corrosion Coating of Ground Oil and Gas Equipment

This common ground for today's oil and gas equipment corrosion paint, accelerated through the neutral salt spray corrosion test, Indoor UV / Condensation accelerated weathering test, Water permeability test and Resistance to chloride ion permeability test on the ground pipelines and oil and gas equipment commonly used Preservative fluorocarbon paint, silicone and acrylic polyurethane coating research laboratory tests carried out by these kinds of High-performance anti-corrosion paint used for comparison, the three coatings have good weather resistance, Fluorocarbon coating seepage rate lower than the other two coatings, anti-UV aging better than the other two coating, Fluorocarbon coating chloride ion penetration lower than the acrylic polyurethane coating.

Design approach for epoxy modified bitumen to be used in antiskid surfaces on asphalt pavement

Antiskid surfaces are thin surface layers, are often applied to provide enough surface friction. They are optimally designed to meet specific mechanical requirements. These specific requirements mainly include surface friction, resistance to raveling and resistance to chemicals such as de-icing and fuel. To prevent aggregates from raveling, a suitable binder is needed for antiskid surfaces. The binder should have a good weather and ageing resistance, as well as a good adhesion to the asphalt mixture layer.This paper describes in detail a design approach that was developed to investigate potential binders for antiskid applications. A two-component Epoxy Modified Bitumen (EMB) was used as binder in this research. Dynamic Shear Rheometer tests (DSR) and relaxation tests were conducted on original binders, weatherometer aged and oxygen aged binders. Pull tests and shear tests were used to investigate the bonding strength between the newly designed antiskid layer and the underlying asphalt mixture layer.The test results show that the EMB has good high temperature resistance. Ageing can decrease its relaxation property. The complex shear modulus of the binder can increase due to oxygen ageing, while it decreases after long term weatherometer ageing at the high frequency range. The adhesion property at the interface is much higher than the adhesion in the asphalt mixture.

Synthetic control of cage/network ratio of poly(methylsilsesquioxane)s for storage stability, hardness, and weather resistance of coating films

AbstractPoly(methylsilsesquioxane) (PMSQ) was synthesized using a two‐step process consisting of hydrolysis of methyl trimethoxysilane (MTMS) with aluminum chelate catalyst and successive condensation reactions conducted at elevated temperatures. Results of nuclear magnetic resonance and Fourier transform infrared measurements show that all terminal functional groups were SiOH in PMSQ. Results show further that PMSQ has both a cage structure and a network structure, and a cage/network ratio is represented by a height ratio of −64.5/−66.6 ppm. PMSQ of different molecular weight but the same SiOH concentration is obtainable by varying the condensation reaction conditions such as the concentration, temperature, amount of aluminum chelate catalyst, and the solvent solubility parameter. A difference of the cage/network ratio occurs. A different cage/network ratio is dependent on the different reactivities of the intramolecular and intermolecular reactions. The relations of molecular structure of the obtained PMSQ molecular structure were characterized along with functions of storage stability, film hardness, and weather resistance. PMSQ designed with a larger cage/network ratio is necessary to obtain PMSQ with good storage stability and a coating film having good weather resistance. PMSQ designed with a smaller cage/network ratio should be prepared to obtain a coating film with high hardness. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

Ageing mechanism and mechanical degradation behaviour of polychloroprene rubber in a marine environment: Comparison of accelerated ageing and long term exposure

Polymers are widely used in marine environments due to their excellent properties and good weathering resistance. Despite this extensive use, their long term behaviour in such an aggressive environment is still not well known. To assess the polymer durability within reasonable durations, it is essential to perform accelerated ageing tests to accelerate the degradation kinetics but without any modification of the degradation process. This study therefore proposes and validates accelerated ageing tests to study marine ageing of a silica-filled chloroprene rubber (CR) used for offshore applications. Several accelerated ageing protocols are investigated for temperatures ranging from 20 to 80 °C in renewed natural seawater. The ageing consequences are characterized using physical measurements (FTIR, solid state NMR) and mechanical testing based on monotonic tension tests. Instrumented micro-indentation tests are also employed, in order to describe accurately the ageing gradients through sample thickness. The measurements obtained on the samples cut from accelerated specimens are compared to those obtained from the topcoat of an offshore flowline aged under service conditions for 23 years. For both kinds of specimens, polychloroprene develops rapid material changes most clearly represented by a considerable increase in stiffness, which allows the accelerated ageing protocols to be validated.

Evaluation of the Stability of Emulsified Ethylene-Propylene-Diene-Monomer Using Novel Technique

The good weathering resistance of ethylene-propylene-diene-monomer (EPDM) as well as its good mechanical properties makes it the preferred elastomer for different commercial applications (as binder for a variety of materials). Emulsified EPDM was prepared by direct emulsifying techniques where the solution of the rubber in hydrocarbon solvent added to different aqueous solution of emulsifiers with vigorous agitation. A larger volume of polymer was reduced into smaller subunits using the mechanical energy of comminuting techniques. After that, the hydrocarbon solvent was removed by distillation. This work studied the influence of different emulsifying systems: ionic such as (dresinate, D, sodium lauryl sulphate, SLS, and sodium dodecyl benzene sulfonate, SDBS) and nonionic such as (cetyl alcohol, CA, and triton, 15-S) on the stability of the latices. The optimum emulsifying systems were investigated by using surface tension, turbidity measurements, sedimentation rate and transmission electron microscope (TEM). It was found that the systems consist of 0.5% dresinate/0.2% cetyl alcohol and 0.5% dresinate/0.2% triton 15-S gave the good storage stability with uniformed particle size ranged between 130–180 nm. These results were confirmed by surface tension which had the lowest values while turbidity had the highest values.

Limestones in Germany used as building stones: an overview

Abstract Germany has an enormous number of different carbonate rock units, which vary widely in their geological age and sedimentary depositional environment. Limestones quarried from these exposures have a wide range of usages and applications, such as dimension and ornamental stones, floor tiles and panelling, and for use as paving stones and massive stones. Since antiquity, limestones were used as building materials in areas where they were naturally available and abundant. Limestones exhibit a relatively good weathering resistance, which is mainly controlled by the mineralogical composition and the rock structure. The susceptibility of limestones to weathering and alteration is only secondarily related to the stone's contact with rainwater and its exposure to frost. In this situation the pore space is the main controlling factor. Industrialization and the subsequent increase in air pollutants, which started at the end of the nineteenth century, led to the formation of dark and unsightly crust deposits on the limestones surfaces. These crusts, being the result of man-made activities, are the main weathering problem for carbonate dimension stones.

Photocatalytic properties of silicone polyesters using calcium phosphate/titanium dioxide

AbstractThis study uses titanium dioxide treated with calcium phosphate to prepare multilayer structure composites. These products are regarded as photocatalysts. Utilizing polyethylene glycol (PEG)–silicone polyester as an adhesive spread on matrix surfaces, this can provide these products with antifouling properties, good weather resistance, and antibacterial property. It has been observed that UV irradiation has caused changes in the film molecular structure of PEG–silicone polyesters, as well as changes in the surface morphology. These changes in molecular structure have been observed by FTIR and Raman analysis. PEG–silicone polyesters contain silicon atoms with both organic and inorganic characteristics. This makes fixation of photocatalysts possible and retards oxidation of organic materials in the polyesters. The results of FTIR and Raman spectrum analyses indicate films made of these polyesters effectively cover calcium phosphate–titanium dioxide photocatalysts, retard surface cracks, and slow down decomposition, caused by UV light. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

To coat or not to coat? The maintenance of Cor‐Ten® sculptures

AbstractSince the mid sixties Cor‐Ten® steel became one of the most famous materials for outdoor sculptures until today. This material was used by many artists because of its good weather resistance. Due to not always suitable ranges of application many significant problems in the field of conservation appeared.These were surveyed in a project of the study programme ‘Object Conservation’ at the State Academy of Art and Design Stuttgart with special focus on the material and its protective rust layers, the premises for its protection, different cases of significant damage and their causes, the potential of preventive conservation and practised interventive methods.Although it seems to be in some way a contradiction in itself to coat a weathering steel, this has often been done in hands‐on conservation to overcome corrosion problems. Therefore different coating materials already in use for outdoor metal sculptures were tested on Cor‐Ten coupons in the framework of the CONSIST project in the Deutsches Bergbau‐Museum Bochum (DBM). Cor‐Ten B samples were covered with different coating materials such as: microcrystalline waxes, waxes used in technical corrosion protection, an acrylic resin and a polyurethane resin. The sheets were then weathered for 2 months in a climate chamber with a relative high humidity (but also drying cycles) and a climate chamber with a periodic changing relative high rate of SO2 gas and humidity using standard protocols developed at DBM in earlier projects. The effectiveness of the protective function of each coating materials is compared, consequences for practical applications discussed.

All-polymer composites from recycled woven polypropylene fabrics and polyethylene film

Woven polypropylene fabrics are widely used, for example, in sacks for transportation of bulk materials in agriculture and construction. There are several important end-of-life issues with these and at present the majority of these sacks are landfilled in the UK. A new process has been developed to convert these into fully recycled all-polymer composites by incorporating waste polyethylene film as the “matrix” material. The effects of lay-up arrangement, fibre orientation, extent of cleaning and drying, processing temperature, pressure, and time were all investigated. Mechanical properties of the samples were determined using a combination of flexural, tensile, and impact testing, coupled with optical and electron microscopy. The recovery of orientation of the polypropylene tapes during heating was investigated as was the bonding between the materials. It was found that there was a balance between good bonding of the materials (at higher temperatures) versus loss of stiffness because of recovery of orientation. The properties were found to be relatively insensitive to the extent of cleaning and drying that was used. It is expected that these composites will possess good outdoor weathering resistance, and a further advantage is that they will be further recyclable at the end of their lifetime. POLYM. ENG. SCI., 46:1523–1529, 2006. © 2006 Society of Plastics Engineers

Solution Properties of 1,3-Cyclohexadiene Polymers by Laser Light Scattering and Small-Angle Neutron Scattering

1,3-Cyclohexdiene polymers (PCHD) and their derivatives are of interest due to the six-member rings in the main chain, which are expected to impart higher mechanical strength and better thermal and chemical stability, as compared to common vinyl polymers. For example, hydrogenated PCHD has the highest glass transition temperature (T{sub g} {approx} 231 C) of all hydrocarbon polymers, and it also shows good heat, weather, impact, abrasion, and chemical resistance as well as low water absorption. In addition, PCHD has unique photochemical properties, such as excellent transparency, due to the isolated double bonds in the main chain. Also, block copolymers containing PCHD show unusual phase separation behavior. For example, a styrene/1,3-CHD block copolymer (PS-b-PCHD) with 50 vol % CHD (1,4/1,2 {approx} 95/5) exhibits a core-shell or hollow cylinder morphology, while a typical styrene/acyclic diene (isoprene or butadiene) block copolymer with similar composition exhibits a lamellar structure. Such phase behavior and many other properties strongly depend on the conformation of the polymer in solution or bulk. However, almost no data have been reported on the conformation of PCHD, probably because of the lack of well-defined and well-characterized samples. Here we report solution properties of PCHD in tetrahydrofuran (THF) and chloroform by multianglemore » laser light scattering, viscometry, and small-angle neutron scattering (SANS).« less

Effects of Wood Particle Size and Mixing Ratios of HDPE on the Properties of the Composites

The main goal of this research is to innovate wood-plastic composites by using various wood particle sizes and different mixture ratios (weight ratio) of HDPE (High Density Polyethylene). After mixing the wood particles (recycled wood waste) and the plastic powder, we use a molding and pressing process to make composites with a thickness of 12 mm. By doing so, the wood particle content can be increased to 75%. This kind of composite provides excellent dimensional stability, its moisture content is under 2.5%, and the thickness swelling rate after 24 hr water absorption is under 7.5%. The maximum static bending strength of this composite reaches 20.7 N/mm2, and is better than that of general commercial particleboards. The composite made of larger sized wood particles has better strength properties. In addition, when the plastic content ratio increases, the dimensional stability of the composite will increase as well. After the soaking process in boiling water, the static bending strength of wet composite remained at 50%; this shows the good weather resistance of the composite. The surface veneer overlaid peeling strength of the composite showed 1.02–1.63 N/mm. After the evaluation of processing, cost of material and strength properties of the composite, we would suggest that the use of 70% of wood particles and 30% of plastic powder is practical to produce proper sized composites.

Accelerated exposure of pigmented anti-corrosion coating systems

Two coating systems were investigated under QUV-340®/Prohesion (ultraviolet/salt fog) alternating exposure. One coating was a conventional primer high-gloss (HG) polyurethane topcoat, and the other was a single ‘self-priming’ (SP) polyurethane coating. Both coating surfaces oxidised from the exposure, but the coating bulk remained intact. Cracks developed in the ‘self-priming’ coating surface, but it remained adhering. The other topcoat showed good weathering resistance, but its primer lost adhesion after exposure. Both coatings initially developed nanoblisters, then increasing surface roughness. Electrochemical impedance spectroscopy (EIS) showed similar corrosion-protective properties during much of the exposure. Evidently, electrochemical measurements alone are not sufficient to monitor deterioration in corrosion-protective coatings.

Photooxidation and stabilization of photooxidized polyethylene and of its monopolymer blends

AbstractThe increasing use of products from recycled polymers, or from blends with recycled polymers exposed to the outdoors, implies the need for good weathering resistance. This is particularly important when the recycled material comes, in turn, from products exposed during their lifetime to the sun. In this case the presence of CO groups in the macromolecular chains strongly increases the photooxidative degradation kinetics of these secondary materials. In this work the change of the photooxidative degradation of blends of virgin and photooxidized polyethylene was evaluated as a function of the CO content present in the material. As expected, the presence of the CO groups strongly increases the photooxidation kinetics, as revealed by the increase of the carbonyl compounds, and by the decrease of the elongation at break. It was confirmed that the increase of CO groups is dependent on the content of the same groups, whereas this is not true for the mechanical properties. The use of UV stabilizer strongly improves the weathering resistance of these materials, which become almost insensitive to the initial amount of CO groups. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2244–2255, 2004

Formation of anatase nanocrystals-precipitated silica coatings on plastic substrates by the sol-gel process with hot water treatment

Anatase nanocrystals-precipitated silica coatings were formed on plastic substrates such as poly(ethylene terephtalate) (PET), acrylic resin (AC) and polycarbonate (PC) from silica-titania gel coatings with and without addition of poly(ethylene glycol) (PEG) by hot water treatment. The maximum thickness of the coatings which can be formed without cracking or peeling-off was 100 to 200 nm for PET and PC substrates, whereas it was less than 50 nm for AC substrates. After a hot water treatment at 90°C for 120 min, the size of the anatase nanocrystals increased to be 30 and 50 nm for the coatings obtained with and without PEG, respectively. Anatase nanocrystals were formed throughout the whole of the coatings obtained with PEG and were formed only on the surface of the coatings obtained without PEG. Both coatings obtained with and without PEG were highly transparent. The plastic substrates with coatings obtained without PEG showed good weathering resistance owing to the protective effects of the residual silica under-layer. The coatings obtained with PEG showed higher photocatalytic activities than those obtained without PEG due to smaller size and higher dispersion of anatase nanocrystals in the coatings.

Depositional environment and diagenesis as controlling factors for petro-physical properties and weathering resistance of siliciclastic dimension stones: integrative case study on the ‘Wesersandstein’ (northern Germany, Middle Buntsandstein)

Abstract A case study on the ‘Wesersandstein’ (Middle Buntsandstein) indicates that weathering resistance and quality of dimension stones are functions of depositional environment, and of diagenetic alterations (eogenetic as well as mesogenetic) during geological history. Two types of dimension stones, one deposited in a braided and the other in a meandering river system, were compared with respect to the fluvial architecture, the diagenetic modifications, the raw block prospectivity, and the petro-physical properties. The integrative synthesis of all these approaches indicates that depositional environment (type of fluvial architecture) and diagenesis (quartz cement and clay matrix contents) are the key processes which generally control the petro-physical properties and the weathering resistance of siliciclastic dimension stones. The highly quartz cemented ‘Grauer Wesersandstein’ with low clay matrix content, deposited as channel fill (braided river system), is characterized in general as a high quality dimension stone with very good petro-physical properties (e.g. high compressive strength, tensional strength, abrasion resistance, and freeze-thaw resistance) and high weathering resistance. In contrast to this, the ‘Roter Wesersandstein’, deposited as point bar and floodplain deposits of meandering rivers with low quartz cement and high clay matrix contents shows minor quality petro-physical properties (e.g. minor compressive strength, tensional strength, abrasion resistance, and freeze-thaw resistance) and weathering resistance. This new integrative approach combines hitherto isolated studies on dimension stone quality. It shows the complex interrelations between the geological background on the one hand and specific dimension stone properties on the other hand.

Pultruded fiber‐reinforced poly(methyl methacrylate) composites. II. Static and dynamic mechanical properties, environmental effect, and postformability

AbstractThis paper presents a novel process developed to manufacture poly(methyl methacrylate) (PMMA) pultruded composite. The mechanical, thermal, and dynamic mechanical properties, environmental effect, postformability of various fiber (glass, carbon, and Kevlar 49 aramid fiber) reinforced pultruded PMMA composites have been studied. Results show mechanical properties (i.e., tensile strength, specific tensile strength, tensile modulus, and specific flexural strength) and thermal properties (HDT) increase with fiber content. Kevlar fiber/PMMA composites possess the highest specific tensile strength and HDT, carbon fiber/PMMA composites show the highest tensile strength and tensile modulus, and glass fiber/PMMA composites show the highest specific flexural strength. Pultruded glass‐fiber‐reinforced PMMA composites exhibit good weather resistance. These composite materials can be postformed by thermoforming under pressure, and mechanical properties of postformed products can be improved. The dynamic shear storage and loss modulus (G′, G″) of pultruded glass‐fiber‐reinforced PMMA composites increased with decreasing pulling rate, and their shear storage moduli are higher than those of pultruded Nylon 6 and polyester composites.

Pultruded fiber reinforced thermoplastic poly(methyl methacrylate) composites. Part II: Mechanical and thermal properties

AbstractA novel process has been developed to manufacture poly(methyl methacrylate) (PMMA) pultruded parts. The mechanical and dynamic mechanical properties, environmental effects, postformability of pultruded composites and properties of various fiber (glass, carbon and Kevlar 49 aramid fiber) reinforced PMMA composites have been studied. Results show that the mechanical and thermal properties (i.e. tensile strength, flexural strength and modulus, impact strength and HDT) increase with fiber content. Kevlar fiber/PMMA composites possess the highest impact strength and HDT, while carbon fiber/PMMA composites show the highest tensile strength, tensile and flexural modulus, and glass fiber/PMMA composites show the highest flexural strength. Experimental tensile strengths of all composites except carbon fiber/PMMA composites follow the rule of mixtures. The deviation of carbon fiber/PMMA composite is due to the fiber breakage during processing. Pultruded glass fiber reinforced PMMA composites exhibit good weather resistance. They can be postformed by thermoforming, and mechanical properties can be improved by postforming. The dynamic shear storage modulus (G′) of pultruded glass fiber reinforced PMMA composites increased with decreasing pulling rate, and G′ was higher than that of pultruded Nylon 6 and polyester composites.