Short Pot Life Research Articles

Using Data Science Tools to Reveal and Understand Subtle Relationships of Inhibitor Structure in Frontal Ring-Opening Metathesis Polymerization.

The rate of frontal ring-opening metathesis polymerization (FROMP) using the Grubbs generation II catalyst is impacted by both the concentration and choice of monomers and inhibitors, usually organophosphorus derivatives. Herein we report a data-science-driven workflow to evaluate how these factors impact both the rate of FROMP and how long the formulation of the mixture is stable (pot life). Using this workflow, we built a classification model using a single-node decision tree to determine how a simple phosphine structural descriptor (Vbur-near) can bin long versus short pot life. Additionally, we applied a nonlinear kernel ridge regression model to predict how the inhibitor and selection/concentration of comonomers impact the FROMP rate. The analysis provides selection criteria for material network structures that span from highly cross-linked thermosets to non-cross-linked thermoplastics as well as degradable and nondegradable materials.

Controlling the stability and adhesion performance of cold-setting phenol–resorcinol–formaldehyde resin adhesives through methanol addition

Phenol–resorcinol–formaldehyde (PRF) resin adhesives are commonly used in the manufacture of laminated timber products, and they are cold-set at room temperature rather than hot-pressed to generate a three-dimensional polymer structure in the products. However, their excellent reactivity often leads to poor storage stability and a short pot life. This study examines the influence of methanol addition on the stability and adhesion performance of PRF resins. These resins were synthesized by various levels of methanol addition (5 %, 10 %, and 15 %), and their structures were investigated using Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies. Furthermore, differential scanning calorimetry (DSC) was used to analyze their thermal behavior, and their cure kinetics were analyzed with two isoconversional analyses: Kissinger–Akahira–Sunose (KAS) and Vyazovkin (VYZ) method. The adhesion performances of PRF resins were evaluated for glue-laminated timber (GLT). The results demonstrated that the viscosity and solids content of PRF resins decreased while their gelation time increased as the methanol addition level increased. Methanol addition has also improved the resin stability over time. The chemical structure of PRF resins did not change considerably with an increase in the methanol level. However, methanol interaction with formalin in a hardener presumably hindered the reactivity of PRF resins. This was supported with an increase in the apparent activation energy of the curing process of PRF resins as the methanol level increased. In addition, decreasing the methanol levels from 15 % to 5 % enhanced the adhesion performance of GLT bonded with PRF resins. The results indicated that adding methanol to PRF resins improved its stability while simultaneously weakened its performance. However, 5 % methanol level is recommended for PRF resins.

Improving the mechanical, thermal and surface properties of polyaspartic ester bio-based polyurea coatings by incorporating silica and titania

Polyaspartic ester polyurea coatings are known for their eco-friendly properties due to the absence of VOCs and free isocyanates. While these coatings offer many advantages to the industry, achieving durability often requires the use of trimers with high NCO content. In such cases, applicators face challenges due to their notably short pot life. Furthermore, the second component used is a petroleum-based polyisocyanate, which limits its classification as a sustainable material. In this study, bio-based polyisocyanates were employed in polyaspartic coatings for the first time, thereby positioning them as sustainable alternatives without compromising their conventional properties. Fourier Transform Infrared Spectroscopy (FT-IR) and Nuclear Magnetic Resonance Spectroscopy (13C and 1H) were utilized to characterize the structure of polyaspartic ester coatings derived from biobased polyisocyanates along with solvent-free and catalyst-free PAEs. It was determined that the coating formulation had a convenient working time at room temperature. Pendulum hardness and contact angle measurements indicated that hard coatings with hydrophobicity were obtained with the addition of SiO2 and TiO2 particles without reducing the working time. The results revealed a notable 37% increase in tensile strength with the addition of 3 wt% silica compared to the base coating, and a remarkable 43 wt% increase when the coating obtained an equal proportion of titanium and silica at the same concentration. Additionally, Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) studies revealed that the composite coatings comprising titanium and silica particles exhibited higher glass transition temperatures and residual char yields compared to the base coating. The morphology and surface roughness of the coatings were characterized using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM).

Melamine–Urea–Formaldehyde Resin Adhesive Modified with Recycling Lignin: Preparation, Structures and Properties

The wettability, bonding strength and flexibility of modified melamine–urea–formaldehyde resin adhesive with hydroxymethyl lignin (LMUF) were investigated. Moreover, the curing performance, thermal properties and chemical structure of LMUF were analyzed by differential scanning calorimetry (DSC), thermogravimetry (TG), scanning electronmicroscopy (SEM), X–ray diffraction (XRD), Fourier–transform infrared spectroscopy (FTIR) and 13C nuclear magnetic resonance (13C–NMR). The synthesis mechanism of LMUF was also discussed. The results demonstrated that: (1) LMUF resin is characterized by low free formaldehyde and a short pot life. (2) With the increase in hydroxymethyl lignin, the bonding strength and flexibility of the LMUF increased first and then decreased. They reached their maximum when the hydroxymethyl lignin content was 6%–8%, which represented increases of 36% and 102%, respectively. (3) The DSC and TG analyses showed that the LMUF resin had a high hot-pressing temperature, but its thermostability was increased. (4) The XRD and SEM analyses proved that the LMUF resin was characterized by flexibility failure, especially at 6% of hydroxymethyl lignin. (5) Hydroxymethyl lignin is a type of flexible long-chain molecule, which was introduced into spaces between the rigid triazine rings through adhesion and penetration, thus improving the regular single structural form of MUF resin and increasing the compactness of the system. As a result, the resin had stronger deformability and cohesion in the molecules. The bonding strength and flexibility were improved to different degrees.

Kinetic and Chemical Effects of Clays and Other Fillers in the Preparation of Epoxy–Vinyl Ether Composites Using Radical-Induced Cationic Frontal Polymerization

Addition of fillers to formulations can generate composites with improved mechanical properties and lower the overall cost through a reduction of chemicals needed. In this study, fillers were added to resin systems consisting of epoxies and vinyl ethers that frontally polymerized through a radical-induced cationic frontal polymerization (RICFP) mechanism. Different clays, along with inert fumed silica, were added to increase the viscosity and reduce the convection, results of which did not follow many trends present in free-radical frontal polymerization. The clays were found to reduce the front velocity of RICFP systems overall compared to systems with only fumed silica. It is hypothesized that chemical effects and water content produce this reduction when clays are added to the cationic system. Mechanical and thermal properties of composites were studied, along with filler dispersion in the cured material. Drying the clays in an oven increased the front velocity. Comparing thermally insulating wood flour to thermally conducting carbon fibers, we observed that the carbon fibers resulted in an increase in front velocity, while the wood flour reduced the front velocity. Finally, it was shown that acid-treated montmorillonite K10 polymerizes RICFP systems containing vinyl ether even in the absence of an initiator, resulting in a short pot life.

Experimental and Simulative Analysis of the Pressure Development in a Closed Injection Pultrusion Process with Multiple Chamber Geometries

The use of innovative higher-performance highly reactive resin systems requires an enhancement of the established method of fiber impregnation (open bath) towards closed resin-injection pultrusion (CIP), due to the short pot life of the resin systems. The result is that the open bath is developed into a closed injection and impregnation chamber ("ii-chamber"). In this study, three parameters-resin viscosity, opening angle and opening factor at the injection point on the ii-chamber-are varied, each in three stages. For each set of parameters, a pultrusion trial is conducted and the process pressures in the ii-chamber and pultrusion die measured. This enables direct feedback via the process conditions of the as yet uncured composite. The data obtained are used to validate a newly developed simulation model. The model is based on Darcy's law, which has been extended to take fiber movement into account and thus represent the resulting pressure increase in the die. The flexible ii-chamber and die concept enhance our understanding of the processes taking place in the die system. The sensitivity of the process pressures can be shown for the three influencing variables. The experiment shows that of the three influencing variables investigated, viscosity has the greatest sensitivity to pressure development. In general, it can be said that over the length of the pultrusion die system, the pressure level increases across the three measuring points.

A Preliminary Study on a New Epoxy Resin IR-3 for High-Field Superconducting Magnet Applications

Epoxy resins are commonly used in high field superconducting magnets for electrical insulation and mechanical reinforcement. However, many of the epoxy systems for vacuum pressure impregnation (VPI) techniques show drawbacks like easy cracking at low temperatures, short pot life, and/or low glass transition temperatures <formula><tex>$(T_g)$</tex></formula>. High-field dipole magnets are under development at the Institute of High Energy Physics (IHEP) for the pre-study of future high-energy accelerators. Finding the most appropriate epoxy is critically important. Herein, a new epoxy resin (named IR-3) is developed. Its potting properties including thermal shock, viscosity, <formula><tex>$T_g$</tex></formula>, and mechanical strength before and after radiation are presented and were compared with CTD-101K which is mostly used in accelerator magnets. Additionally, the thermal and electrical characteristics of high-temperature superconductor (HTS) coils encapsulated with these epoxies were also investigated. The results show that IR-3 is a promising encapsulating material for impregnating HTS coils and has the potential application in high field accelerator magnets

3D Printing of Soft Magnetoactive Devices with Thiol‐Click Photopolymer Composites

Magnetoresponsive polymers have gained increased attention in the design of soft actuators as they can be spatially as well as temporally activated and enable an external noninvasive control of movement. By introducing the magnetoresponsive properties in photocurable resins, one can fabricate personalized and complex structures (via vat photopolymerization 3D printing), whose movement can be conveniently controlled by an external magnetic field. Advancing from acrylate‐based photopolymers, which often suffer from shrinkage stress, low monomer conversion, and oxygen inhibition, the fabrication of magnetoresponsive thiol‐click photopolymers containing Fe3O4 nanoparticles as magnetic fillers is highlighted. The addition of the thiol crosslinker yields soft and flexible polymer composites, whose cure kinetics, viscosity, thermal, and mechanical properties are studied as a function of the thiol and filler content. Although cure rate and final monomer conversion decrease with rising filler concentration, the cure kinetics is reasonably fast at 6 wt%. The short pot life, a result of thiol‐Michael reactions induced by Fe3O4 nanoparticles, and a high thiol content, are overcome by the addition of an appropriate stabilizer. As proof of concept, 3D structures are fabricated by digital light processing (DLP) 3D printing and their magnetically driven movement is demonstrated.

Comparison of the Processing of Epoxy Resins in Pultrusion with Open Bath Impregnation and Closed-Injection Pultrusion

In this study, the influence of the open bath and closed-injection pultrusion (CIP) processing methods of epoxy resins on the quality of glass fiber composites was investigated. In addition to the state-of-the-art epoxy resin system with long pot life, new resin systems with short pot life have recently been developed. These systems require processing by closed-injection pultrusion. The epoxies with long pot life allow both processing variants. The experimental work was carried out with two types of injection and impregnation chambers (ii_chamber), namely with a conical and a teardrop design. Fully impregnated composites, which were used for further analyses, could be produced by using the conical ii_chamber. The composite properties of the open bath and the conical ii_chamber impregnation methods were compared. No significant influence on the bending stress could be determined; the interlaminar shear strength was up to 10% better with open bath impregnation than with ii_chamber. For the composites investigated, it was shown that the open bath and ii_chamber impregnation methods can be used to produce parts with partially comparable properties, as demonstrated for the epoxy formulation with long pot life. These results indicate that processing of epoxy systems with a short pot life is also possible by closed-injection pultrusion. Furthermore, the influence on the composite properties of the time interval between the mixing of an epoxy resin and processing in an open bath was investigated. No significant effect on the bending stress and interlaminar shear strength could be determined.

Synthesis and properties of eco-friendly coatings using waterborne polyaspartic and blocked isocyanate

Polyaspartic coating is well known as one of popular eco-friendly coatings because of non VOC and excellent mechanical properties such as fast curing, abrasion resistance, chemical resistance, light resistance and so on. Despite of a number of advantages applying polyaspartic coatings to industries, there are limitations to replace conventional polyurea and waterborne coatings in particularly continuous processing lines because of its very short pot life and relatively high price. To improve short pot life, polyaspartic resin was dispersed in water using emulsifier and a blocked isocyanate as a curing agent was added. The curing reaction between -NH of aspartic and -NCO of blocked isocyanate and properties of coatings were analyzed by measuring viscosity, pencil hardness, FT-IR, weatherometer, yellowing, etc. The results showed that the pot life of waterborne polyaspartic coatings became much longer than that of conventional polyaspartic one without the change in light resistance.

Density predictions using a finite element/level set model of polyurethane foam expansion and polymerization

Polyurethane foams are used widely for encapsulation and structural purposes because they are inexpensive, straightforward to process, amenable to a wide range of density variations (1–50 lb/ft3), and able to fill complex molds quickly and effectively. Computational models of the filling and curing process are needed to reduce defects such as voids, out-of-specification density, density gradients, foam decomposition from high temperatures due to exotherms, and incomplete filling. This paper details the development of a computational fluid dynamics model of a moderate density PMDI structural foam, PMDI-10. PMDI is an isocyanate-based polyurethane foam, which is chemically blown with water. The polyol reacts with isocyanate to produce the polymer. PMDI-10 is catalyzed giving it a short pot life, meaning that the foam is liquid and flowable only for a short-time; it foams and polymerizes to a solid within 5 min during normal processing. To achieve a higher density, the foam is over-packed to twice or more of its free-rise density of 10 lb/ft3. The goal for modeling is to represent the expansion, filling of molds, and the polymerization of the foam. This model will be used to reduce defects, optimize the mold design, understand processing parameter sensitivities, and predict the final foam properties.A homogenized continuum model for foaming and curing was developed based on reaction kinetics, documented in a recent paper; it uses a simplified mathematical formalism that decouples these two reactions. The chemo-rheology of PMDI is measured experimentally and fit to a generalized-Newtonian viscosity model that is dependent on the extent of cure, gas volume fraction, and temperature. The conservation equations, including the equations of motion, an energy balance, and three rate equations are solved using a stabilized finite element method. The equations are combined with a level set method to determine the location of the foam-gas interface as it evolves to fill the mold. Understanding the thermal history and loads on the foam due to exothermicity and oven curing is very important to the results, since the kinetics, viscosity, and other material properties are all sensitive to temperature. Results from the model are compared to experimental flow visualization data to understand the interface evolution with time and post-test X-ray computed tomography (CT) data for the density prediction validation. Several geometries are investigated including two configurations of a mock structural part and a bar geometry to specifically test the density model. We have found that the model predicts both average density and filling profiles well. However, it under predicts density gradients, especially in the gravity direction. Further model improvements are also discussed for future work.

Kinetic Prediction of Fast Curing Polyurethane Resins by Model-Free Isoconversional Methods.

In this work, the characterisation of reaction kinetics of a methylene diphenyl diisocyanate (MDI)-based fast curing polyurethane resin (PUR) and the mathematical description of its curing process are presented. For the modelling of the reaction process isoconversional methods, which are also called model-free approaches, are used instead of model-based approaches. One of the main challenges is the characterisation of a reactive system with a short pot life, which already starts to crosslink below room temperature. The main focus is the evaluation of the applicability of isoconversional methods for predicting the reaction kinetics of fast curing polyurethane resins. In order to realise this, a repeatable methodology for the determination of time- and temperature-dependent reaction curves using differential scanning calorimetry (DSC) is defined. The cure models defined by this method serve as the basis for process simulations of PUR processing technologies such as resin transfer moulding (RTM) or reactive injection moulding (RIM) and reactive extrusion (REX). The characterisation of the reaction kinetics using DSC measurements is carried out under isothermal and non-isothermal conditions. Within this work isoconversional methods have been applied successfully to experimentally determined DSC data sets. It is shown that the reaction kinetics of fast curing polyurethane resins can be predicted using this methods. Furthermore, it is demonstrated that the time-dependent change of conversion of the considered polyurethane under isothermal curing conditions can also be predicted using isoconversional methods based on non-isothermal DSC measurements. This results in a significant reduction in the experimental effort required to characterise and model the curing process of polyurethanes.

Effect of Tetracycline in Improving Composite Propellant Pot Life

Propellant mixing and casting processes are the most complex and important operations in composite propellants manufacturing. They are affected by the rheological properties of the propellant. Casting process of composite propellants is influenced directly by its pot life. The short pot life of the propellant formulations can result in low reliability andincrease the processing cost [1]. The propellant pot life is defined as the time available for accomplishing the processing steps of mixing and casting propellant before the propellant loses its fluid nature [2]. Different methods have been proposed for improving composite propellant process by extending its pot life using some affected chemical materials. This work concentrated on using the well-known antibiotic (tetracycline) to achieve this objective. When tetracycline added to the propellant formulation, the pot life was extended by a considerable time ranged between two and four hours. This extension referred to the solution which tetracycline offered to the problem that occurs from using transition metal materials (ferrocene compounds) in the propellant slurry to improve the burning rate. This addition of ferrocene compounds results in accelerating the curing reaction and so, shorten the pot life of the slurry. Tetracycline has good possibilities for metal complex formation and its activity depends on its metal binding function [3]. Moreover, tetracycline is cheap and available which let its use easier than other materials used for the same purpose. The results obtainedfrom this work can help the manufacturer in filling big rocket motors by use of small mixers by applying the above method of extending the propellant pot life.

γ‐Butyrolactone‐processable high‐modulus poly(ester imide)s

Abstractγ‐Butyrolactone (GBL)‐processable high modulus heat‐resistant materials were developed in this work. The polyaddition of an ester‐containing tetracarboxylic dianhydride, i.e. hydroquinone bis(trimellitate anhydride) (TAHQ), and 2,2′‐bis(trifluoromethyl)benzidine (TFMB) in GBL resulted in gelation in the initial reaction stage. The incorporation of a methyl group to TAHQ (M‐TAHQ) allowed polymerization with TFMB in GBL and led to a homogeneous poly(ester imide) (PEsI) precursor solution with a short pot life of 3 days, whereas a simple copolymerization approach using bulky/flexible comonomers to TAHQ/TFMB was less effective. PEsI precursors (PEsAAs) were prepared from TFMB, M‐TAHQ and a minor fraction of 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA) or a fluorene‐containing tetracarboxylic dianhydride. These PEsAA systems showed drastically improved GBL solution stability. In particular, the M‐TAHQ(80);6FDA(20)/TFMB copolymer system provided a PEsAA film with a very high light transmittance at 365 nm (&gt;70%). A photosensitive film composed of this matrix resin and diazonaphthoquinone provided a clear positive‐tone pattern by development in a 2.38 wt% tetramethylammonium hydroxide aqueous solution at room temperature with a high dissolution contrast. The thermally cured PEsI film achieved a very high tensile modulus (&gt;5 GPa) as the present target with other desirable properties, i.e. sufficient film flexibility, a relatively low coefficient of thermal expansion, a high Tg and low water absorption. The present materials can be promising candidates as novel buffer coat films in semiconductor applications. Copyright © 2011 Society of Chemical Industry

Novel latent catalysts for 2K-PUR systems

Polyurethane chemistry is established throughout the world in many coating, adhesive, sealant, foam and elastomer applications. This results essentially from the impressive variability of properties that can be achieved through the vast diversity and possible combinations of polyurethane raw materials. Although dibutyltin dilaurate (DBTL) is the most versatile metal catalyst in polyurethane reaction catalysis, its unfavorable toxicological profile and the changes in its classification and labeling are forcing the formulators to look for alternative catalysts. On the other hand, the constant need for increased productivity, i.e. faster curing systems, can only be achieved at the expense of a very short pot-life when using standard catalysts, e.g. DBTL. In the present paper, we show that we have successfully developed a smart way of meeting the two opposite requirements through the development of photo-latent metal catalysts. Since the latter will release the active catalyst only upon exposure to UV-light, the formulation will remain stable for a long time as long as it remains in the dark. Data showing the influence of UV-light exposure on the performance of these novel latent metal catalysts in a model two-component polyurethane coating are presented in comparison to the non-latent reference catalyst.

Development of a Water- and Oil-repellent Treatment for Silk and Cotton Fabrics with Fluoroalkyl-trimethoxysilane

The application of silane adsorbents for water- and oil-repellent treatment of textile products was developed. As a fluoroalkyl-trimethoxysilane, heptadecafluoro-1,2-tetrahydrodecyl-1,1,1-trimethoxysilane was used, and tetramethoxysilane (TMOS) as a cross-linker, was used. The effects of the concentrations of the cross-linker and promoter were investigated in detail. Further, the effect of adding another silane adsorbent and a suitable solvent were examined. The treatment was found to be effective in imparting antistain properties to silk and cotton fabrics. Moreover, by adding the cross-linker to the adsorption solution, the wash durability and abrasion resistance of these fabrics were improved. In order to obtain similar water- and oil-repellent properties, the solute concentrations required with methanol as a solvent are twice of those required with a hydrocarbon solvent (ShellSol® D40). Although the use of alcohol as a solvent may be nature-friendly, its drawback was a short pot life. On the other hand, the addition of a long silane adsorbent (OPTOOL® DSX) and a promoter (Sila-Ace® S-340) was concluded to be unfavorable for imparting the oil-repellent characteristics to fabrics.

New generation of crosslinking agents based on multifunctional methylaziridines

This publication describes new generation of crosslinking agents based on methylaziridine derivates, crosslinking reaction of pressure-sensitive acrylic adhesives (PSA) and their performance after crosslinking such as tack, adhesion and cohesion. Crosslinking of PSA is an established technology used in many industrial manufacturing processes. New applications and technical specifications stimulate the continuous development of new crosslinking agents with very interesting properties. The weak point of methylaziridine crosslinker systems, which is their very short pot life, is examined.

Redox and photoinitiated crosslinking polymerization: III. Clear and pigmented acrylic coatings

The redox polymerization of acrylic resins initiated by the benzoyl peroxide (BPO)/amine system has been used, in addition to photopolymerization, to harden the shadow areas of UV-cured clearcoats as well as pigmented coatings. Both reactions (redox- and photopolymerization) were followed quantitatively by infrared spectroscopy through the decay of the characteristic infrared band of acrylate double bonds and by hardness measurements. The spontaneous redox initiation was more specifically followed by pyrometry and near-IR spectroscopy. The BPO/amine redox system was shown to greatly accelerate the hardening of the coating in the shadow areas, a hard coating being obtained after a few minutes at room temperature. Because the formulation has a short potlife, it must be used as a two-pack system. Moreover, this type of redox initiation proved to be highly sensitive to oxygen. The viscoelastic properties of the thermally cured material were characterized by dynamic mechanical analysis, and were shown to be similar to those obtained by UV-curing alone. This exothermal initiation process is also highly efficient to cure thick pigmented specimens, and it has no detrimental effect on the weathering resistance of the coating.

Multifunctional propyleneimines-new generation of crosslinkers for solvent-based pressure-sensitive adhesives

This article describes work with the goal of crosslinking pressure sensitive acrylic adhesives (PSA) and a new generation of crosslinkers based on multifunctional propyleneimine derivates. Crosslinking of PSA is an established technology used in many industrial manufacturing processes. New applications and technical specifications stimulate the continuous development of new crosslinking agents with very interesting properties. These new crosslinkers influence physico-mechanical properties of acrylic PSA such as tack, peel resistance (adhesion) and shear strength (cohesion). The weak point of propyleneimine crosslinkers is their very short potlife.

An epoxy novolac emulsion system for ambient cure protective coatings

Water-borne two-pack coatings based on a novel low particle size epoxy novolac emulsion, crosslinked with polycycloaliphatic polyamine provide a good balance of several properties. Because the films cured possess a high crosslink density of cross linkage, expectations such as rapid through film drying time, high hardness development at an early stage during cure, very good film formation at 10°C and 80% R.H., and chemical resistance can be met. However, there are also adverse aspects to consider regarding the combination of a water-insoluble hydrophobic polyamine and a modified epoxy novolac emulsion. eg no visible end of pot life, relative short pot life and a brittleness of coatings associated with a tendency to peeling when exposed to salt spray and humid conditions. The study also revealed that the quality of a cured two-component epoxy binder emulsion system depends to a great extent on the quality of the emulsion, particularly on the size and distribution of the droplets. A low particle size epoxy emulsion improves the film formation, drying time, water resistance, gloss, adhesion and hardness. For this purpose epoxy emulsions with a narrow particle size distribution and relatively low particle size (mean value ca. 0.4 µm) can be developed using a proprietary mechanical emulsion process. The aqueous coating system described may be useful for applications where conventional epoxy novolacs are already used as low temperature heat cure coatings like drill pipe coatings, oil pipelines and fuel storage tanks and in fields where their chemical, water and solvent resistance can be utilised. Further ambient cure applications may be protective coatings for indoor use, eg food factories, schools, hospitals and office buildings, industrial maintenance coatings for concrete, mortar, bricks, plaster and wood.