Trichloroisocyanuric Acid Solutions Research Articles

DIFFERENT APPROACH TO THE MECHANISM OF ADHESION OF SURFACE TREATED WITH TRICHLOROISOCYANURIC ACID SOLUTION RUBBER AND POLYURETHANE ADHESIVE JOINTS

ABSTRACT Although the effects produced by the surface treatment of rubber with organic solvent solutions of trichloroisocyanuric acid (TCI) leading to improved adhesion to polyurethane (PU) adhesive have been established, the mechanism of adhesion involved is still unclear. In this study, the reaction of TCI species on the rubber surface with the PU adhesive leading to the formation of chemical bonds was proposed as the relevant mechanism of adhesion. As a model, TCI was added to polyurethane adhesive (PU + TCI), and a polyurethane film was immersed in TCI solution (PU − TCI), their surface, structural, and viscoelastic properties were monitored for different times. The formation of chemical bonds between the polyurethane chains and TCI species derived from the solid TCI crystals on the rubber surface during bonding formation, and the crosslinking/hardening of the PU surface were evidenced. The reaction with TCI species increased the surface energy on the PU, mainly the polar component, similar surface energies were obtained in both PU + TCI and PU − TCI after 7 days. The enhanced surface energies on the PU that reacted with TCI were ascribed to the creation of new C–Cl and C=O species, their percentages were higher on PU + TCI than on PU − TCI surface. On the other hand, new N–H stretching and carbonyl species were produced; this indicated that TCI species interacted with the hard segments. Furthermore, the crystallization peaks in PU + TCI and PU − TCI at higher temperatures and lower enthalpies than in PU indicated the disruption of the interactions between the soft segments. Therefore, the structural changes in the PU caused by reaction with TCI species affected their degree of phase separation and viscoelastic properties. The addition of solid TCI to the PU caused a noticeable degradation and hardening, the extent of degradation was more marked by increasing the time, this led to lower mechanical properties.

Fabrication of cellulose-based composite membranes for organic solvent nanofiltration

In this paper, the methods for obtaining delamination-resistant composite cellulose membranes were considered. Different approaches to improve the adhesion of the cellulose layer to the polyester non-woven support were analyzed. The first approach, consisting in etching the PET support with solutions of trichloroisocyanuric acid in acetone, had a negative effect on the formed membranes. The negative effect was to increase the hydrophobicity of the support, resulting in peeling off of the cellulose layer. Suppression of delamination was achieved by reduction of cellulose shrinkage: by its plasticization with glycerol or sequential treatment by liquids with gradually decrease of their affinity to cellulose. Nevertheless, treatment of the membrane with an aqueous solution of glycerol resulted in a decrease of the dye rejection. The optimal technique is sequential post-processing of composite membranes with ethanol and hexane, which makes it possible to obtain strong composite cellulose membranes with high values of the rejection of the nanosized anionic dye.

Mise Au Point D’un Protocole De Sterilisation D’explants Nodaux D’alchornea Cordifolia Avec De L’acide Triclororoisocyanurique

Trichloroisocyanuric acid is a swimming pool disinfectant and is readily accessible. As a result, there is the need to use it as a substitute for conventional disinfectants in in vitro culture. Nodal explants of Alchornea cordifolia, harvested in a natural environment, have been rinsed abundantly with Dettol under running water. Then it was soaked in Talo Plus (550 g/l carbendazim and 100 g/l Chlorothalonil) at 5 ml/liter, which is a broad spectrum fungicide. After then, it was immersed in 70% alcohol for 10 minutes before being soaked in different solutions of trichloroisocyanuric acid to: 6, 4, 3, 2, 1, 0.3, 0.1, and 0.08%. The explants were disinfected completely of all contaminating bacterial and fungal exogenous. This was after a treatment in solutions of acidic trichloroisocyanurique of 6 to 0.08%. The results showed that the losses of active chlorine remained low during storage at temperatures of 4 to 18 ± 2°C. They reach only 5.29% after 72 hours. At room temperature of 27 ± 2 ° C, these losses are more than 30% after three days. Concentrations of 0.1 to 0.3% are effective for the disinfection of explants. This protocol of explants disinfection in vitro culture could therefore be advantageously substituted using the hypochlorite of calcium or the chloride of mercury.

Surface modification of vulcanized styrene–butadiene rubber with trichloroisocyanuric acid solutions of different active chlorine contents

Two solutions in ethyl acetate (EA) containing 3 wt% trichloroisocyanuric acid (TCI) from two different suppliers having different active chlorine contents were used as chemical surface treatment of a vulcanized styrene–butadiene (SBR) rubber. The amount of active chlorine in the TCI solutions was evaluated by iodine titration. The changes produced in the SBR rubber were monitored by using ATR-IR spectroscopy, scanning electron microscopy and contact angle measurements. The adhesive strength variation in SBR rubber/polyurethane adhesive joints was consistent with the variation in surface chemistry, wettability, and topography of the treated SBR rubber. The increase in time between TCI solutions preparation and SBR treatment allowed an increase in adhesive strength, the highest value corresponded to the joint produced with the SBR rubber treated with TCI solution prepared for 60 days. On the other hand, the active chlorine concentration in the TCI solutions was not the only parameter determining the adhesion of SBR rubber, as the highest adhesive strength was not achieved by treating the rubber with the TCI solution with higher active chlorine content. Therefore, the effectiveness of the halogenation treatment of rubber was not always higher by using a halogenating solution with higher active chlorine content. Furthermore, the chlorine concentration in the TCI solutions was not stable in the course of time, 60 days after preparation of solutions was the most efficient chlorinating solution for SBR rubber surface modification.

Interactions at the interface between thermoplastic rubber and polychloroprene adhesive

AbstractThe interface produced between a chlorinated thermoplastic styrene‐butadiene‐styrene rubber and a polychloroprene (PCP) adhesive has been studied and compared to the interface produced using a polyurethane (PU) adhesive. Chlorination of the rubber was produced by spin coating solutions of trichloroisocyanuric acid in methyl ethyl ketone. The adhesive solution was spin coated on to the chlorinated rubber and the interface between the chlorinated rubber and the adhesive was analyzed by infrared spectroscopy.Chlorination of the rubber produces cross‐linking of the outermost chlorinated and oxidized rubber surface, which becomes insoluble in toluene. The chlorinated rubber chains are able to migrate through the chlorinated rubber/adhesive interface and produce a cross‐linked interface. Similar interfaces are obtained with PU or PCP adhesive. However it is the addition of a thermoreactive phenolic tackifier resin to the PCP adhesive, which imparts appropriate rheological properties to the PCP adhesive, responsible for the increased adhesion properties. Copyright © 2008 John Wiley & Sons, Ltd.

Environmental Friendly Surface Treatment of SBS Rubber with Acidified Chloramine T Aqueous Solutions

Abstract As environmental friendly alternative to the halogenation treatment with trichloro isocyanuric acid solutions in organic solvents (TCI/MEK), in this study a water-based surface treatment for rubber materials based in chloramine T aqueous solutions has been proposed. It was found that the effectiveness of chloramine T (CT) (N-chloro-sodium-p-toluenesulphenamide) as chlorinating agent for rubber depends on the pH of the chlorinating solution. The surface modifications and adhesion in one SBS rubber treated with aqueous solutions of CT has been studied. Acidification of CT aqueous solutions produced the formation of dichloramine T (DCT) and hypochlorous acid (HClO), species which reacted with C = C bonds of the butadiene units. A decrease in the pH of the CT aqueous solutions produced more extended surface modifications and improved adhesion properties in the joints produced with chlorinated SBS rubber and waterborne polyurethane adhesive. T-peel strength values obtained were slightly lower than those obtained for the SBS rubber surface treated with the organic solvent chlorinating system (TCI/MEK). The solvent effect leading to local swelling and therefore to deeper modifications in the rubber near surface properties was not present with water based solutions, and then, the modifications were much more superficial. On the other hand, acidification with hydrochloric acid produces deposition of NaCl crystals on the SBS rubber surface. Thus, acidification of the chloramines T solution with sulfuric acid was preferable.

Elimination of the reactivation process in the adhesion of chlorinated SBS rubber with polychloroprene adhesives

Chlorination treatment of a thermoplastic styrene-butadiene-styrene rubber (SBS) with a 3 wt% solution of trichloroisocyanuric acid (TCI) in methyl ethyl ketone (MEK) introduces chlorinated and oxidized moieties on the rubber surface which increase its surface energy and produces surface microroughness. Consequently adhesion properties, evalu- ated by T-peel strength measurements in chlorinated SBS/solvent based-polyurethane adhesive/leather joints, are enhanced. In this study, two solvent-based polychloroprene adhesives (PCP0 and PCP30R) have been considered as an alternative to the commonly used solvent-based polyurethane adhesive (PU). A thermoreactive phenolic resin was added to one of the polychloroprene adhesive formulations (PCP30R). This tackifier resin favors chlorination of the adhesive and reinforces the interface between the chlorinated adhesive and the chlorinated rubber surface. Besides, PCP30R adhesive does not need adhesive reactivation and considerable high T-peel strength value (5.7±0.3 kN/m) was obtained. Elimination of the reactivation process implies a considerable improvement of the manufacturing process in the footwear industry.

Influence of calcium carbonate added to the SBS rubber formulation on the surface modifications produced by halogenation

To improve the adhesion properties of styrene–butadiene–styrene (SBS) rubber sole to polyurethane adhesive, surface treatments are required, of which halogenation with trichloroisocyanuric acid (TCI) solutions in organic solvents is the most commonly used treatment in the footwear industry. Calcium carbonate filler is commonly added to improve the mechanical properties and to reduce shining of SBS rubber formulations. The influence of the filler on the effectiveness of surface chlorination of SBS rubber had not been considered in the existing literature. Therefore, 10 wt% calcium carbonate filler was added to the SBS rubber formulation and the surface modifications and adhesion properties produced by treatment with TCI solutions were investigated. The resulting surface modifications and adhesion were compared to those obtained in unfilled SBS rubber. It is shown that the treatment with TCI solutions was less effective in the calcium-carbonate-filled SBS rubber and a lower peel strength to polyurethane adhesive was obtained; however, a cohesive failure in the rubber was always obtained.

A Simple and Efficient Method for the Preparation of Heterocyclic N‐Oxide.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A Simple and Efficient Method for the Preparation of Heterocyclic N-Oxide

Pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2,4-dimethylpyridine, 2,6-dimethylpyridine, quinoline, isoquinoline and 2-chloropyridine are readily oxidized to their N-oxides with a solution of trichloroisocyanuric acid, acetic acid, sodium acetate and water in acetonitrile and methylene dichloride in 78%–90% yields.

Effects of overhalogenation of a synthetic vulcanized styrene–butadiene rubber sole on its adhesion behavior

The effects of halogenating the same synthetic vulcanized styrene–butadiene rubber (R2) (used as a sole material in the shoe industry) twice (double halogenation) using solutions of trichloroisocyanuric acid (TCI) in MEK were studied. The R2 rubber was treated with 0.5 and 2 wt% TCI/MEK solutions and after 1 h re-treated with additional 0.5 (0.5 + 0.5 wt% TCI/MEK) and 2 wt% TCI/MEK (2 + 2 wt% TCI/MEK) solutions. The results obtained were compared with those obtained by treating the R2 rubber once with 1 and 4 wt% TCI/MEK solutions. The surface modifications produced by the double halogenation of the R2 rubber were analyzed using advancing and receding contact angles (variations in wettability), XPS and ATR-IR spectroscopy (characterization of chemical modifications) and SEM (morphological modifications). T-peel tests on doubly halogenated R2 rubber/polyurethane adhesive joints were carried out to quantify the adhesion properties of the treated R2 rubber. The degree of chlorination was higher with increasing amount of chlorinating agent. Furthermore, the most efficient removal of hydrocarbon substances from the R2 rubber surface was obtained by double halogenation and by increasing the TCI concentration. Similar trends in surface chemistry of the R2 rubber were obtained using 0.5–2 wt% TCI/MEK, with or without double halogenation. On the other hand, by comparing the effects of treatments with 0.5 + 0.5 wt% TCI/MEK and 1 wt% TCI/MEK or with 2 + 2 wt% TCI/MEK and 4 wt% TCI/MEK, less effective removal of zinc stearate and less degree of chlorination were obtained by double halogenation although similar outermost surface modifications were produced. The second application of the TCI/MEK solution on the already halogenated R2 rubber dissolved the unreacted TCI and/or the isocyanuric acid crystals on its surface. The mechanical properties of the treated R2 rubber decreased because it became stiffer. Higher and relatively similar peel strength values were obtained in all adhesive joints prepared using treated R2 rubber. A cohesive failure in the rubber close to the chlorinated layer was always obtained.

The Oxidation of Primary Alcohols to Methyl Esters and Diols to Lactones Using Trichloroisocyanuric Acid.

AbstractFor Abstract see ChemInform Abstract in Full Text.

The Oxidation of Primary Alcohols to Methyl Esters and Diols to Lactones Using Trichloroisocyanuric Acid

Primary alcohols and diols are easily oxidized to methyl esters by a solution of trichloroisocyanuric acid with methyl alcohol in dichloromethane. In addition, α,ω-diols are also readily oxidized into lactones by refluxing with trichloroisocyanuric acid and pyridine in dichloromethane.

Treatment of thermoplastic rubberwith chlorine bleach as an alternative halogenation treatment in the footwear industry

Avoidance of solvents in bonding operations is a current demand in the footwear industry. Halogenation of rubber soles with solutions of trichloroisocyanuric acid (TCI) in different solvents has been successfully used to improve bonding to the leather uppers. In this study, the use of chlorine bleach as an alternative water surface treatment for a rubber has been tested. A thermoplastic block styrene thermoplastic (TR) was treated with bleach to improve its adhesion to a water-based polyurethane dispersion adhesive (PUD). T-peel testing, scanning electron microscopy (SEM), contact angle measurements (ethanediol, 25°C), and infrared spectroscopy (ATR-IR) were used to analyze the modifications produced on the rubber surface. Adhesion values were obtained from T-peel testing of joints produced with similarly treated TR rubber test pieces. Different experimental variables were considered in this study, namely the immersion time (0.5-2 min) in bleach, the active chlorine content (43.9- 55.6 g/l) in the bleach, the addition of a wetting agent (1-octyl-2-pyrrolidone) to the bleach, and the application of the surface treatment using an ultrasonic bath. The treatment with bleach produced the chlorination of the hydrocarbon chains on the TR rubber surface and slightly changed the surface roughness. Chlorination of the TR rubber with bleach (free active chlorine=55.6 g/l) was fast and needed only 30 sec immersion in the reagent mixture to produce high adhesion. Furthermore, the active chlorine content in the bleach was critical to assure an adequate T-peel strength value. The addition of 1-octyl-2-pyrrolidone to the bleach increased the wettability of the rubber surface, although it was necessary to carry out the surface treatment in the ultrasonic bath to obtain adequate adhesion to the PUD adhesive. Thermoplastic styrene-butadiene rubber Water-based polyurethane adhesive Bleach Halogenation Water-based surface treatment Contact angle ATR-IR spectroscopy SEM T-peel strength

Improved adhesion between polyurethane and SBR rubber treated with trichloroisocyanuric acid solutions containing different concentrations of chlorine

The chlorine concentration in trichloroisocyanuric acid (TCI) solutions depended on the solvent used to apply the chlorination agent on the rubber surface and on the time after preparation of the solutions. In this study, methyl ethyl ketone (MEK) and ethyl acetate (EA) have been used as solvents for 2 wt% TCI in the treatment of a difficult-to-bond synthetic vulcanized styrene-butadiene rubber (R2 rubber). Chlorination produced improved wettability of the R2 rubber and also the removal of paraffin wax from the surface. Furthermore, several C Cl and C O moieties are produced, and some microroughness was created. The concentration of chlorine in the 2 wt% TCI/MEK solution decreased by increasing the time after preparation, and the effects due to chlorination became less marked by increasing the time. However, the concentration of chlorine in the 2 wt% TCI/EA solution was higher and was not noticeably decreased by increasing the time after preparation, and noticeable surface modifications were produced on the R2 rubber treated with the chlorinating solution 6 weeks after preparation. The improved surface modifications of R2 rubber allowed an increase in adhesion to polyurethane adhesive, and the failure was cohesive in the chlorinated layer. A relationship between the chlorine concentration in the TCI solution and the peel strength value in treated R2 rubber/polyurethane adhesive joint was obtained.

A new water-based chemical treatment based on sodium dichloroisocyanurate (DCI) for rubber soles in the footwear industry

A new water-based chemical treatment based on sodium dichloroisocyanurate (DCI) solutions for rubber soles of different natures is reported in this study. Different concentrations (1-5 wt%) of DCI and two rubber formulations (vulcanized styrene-butadiene rubber, R2; thermoplastic rubber, TR) were considered. The effects produced by treatment of the rubber soles with DCI were compared with the standard halogenation method using trichloroisocyanuric acid (TCI) solutions in an organic solvent (ethyl acetate). The effects of chlorination on the rubber surfaces were studied using contact angle measurements, ATR-IR spectroscopy, and scanning electron microscopy. The adhesion strength was obtained from T-peel strength tests on canvas/PUD adhesive/treated rubber joints. The adhesive used throughout this study was a water-based polyurethane dispersion (PUD). The surface treatment with aqueous DCI solutions modified the surface chemistry of both the TR and R2 rubbers, creating C—Cl moieties on the surface and removing the zinc stearate from the R2 rubber surface. The use of a low DCI concentration in water was less effective in modifying the TR rubber, but was sufficient to obtain good T-peel strength values for the R2 rubber joints. On the other hand, heterogeneities and cracks were created on the rubber surface (mainly on the R2 rubber surface), which may contribute to an increase in the mechanical interlocking with the adhesive. A noticeable increase in the T-peel strength and a cohesive failure in the rubber for the joints produced with TR rubber were obtained when the rubber was treated with aqueous DCI solutions. For the canvas/PUD adhesive/chlorinated R2 rubber joint, the failure was located in a thin surface layer on the canvas. Finally, the surface treatment with TCI in ethyl acetate produced a more significant surface modification on both the TR and the R2 rubber, creating deeper roughness on the R2 rubber surface. Consequently, higher peel strength values were obtained using TCI solutions in ethyl acetate. Furthermore, the T-peel strength values were high in all joints produced with TR rubber treated with either TCI solution in ethyl acetate or aqueous DCI solution.

Improved peel strength in vulcanized sbr rubber roughened before chlorination with trichloroisocyanuric acid

The effectiveness of chlorination as surface treatment to improve the adhesion of synthetic vulcanized styrene-butadiene rubber (SBR) depends on several experimental variables. Solutions of trichloroisocyanuric acid (TCI) in methyl ethyl ketone (MEK) have been used as effective chlorination agents for several rubbers. In this study, the influence of roughening prior to chlorination treatment of a SBR rubber (R2) and the durability of the modifications produced as the time after chlorination increased have been considered. Two concentrations of the chlorination agent (0.5 and 2 wt% TCI/MEK) have been used and the chlorination treatment was applied on the R2 rubber surface using a brush. Characterization of the treated surfaces was carried out using contact angle measurements, ATR-IR spectroscopy and Scanning Electron Microscopy (SEM). T-peel tests of treated R2 rubber/polyurethane adhesive joints have been carried out to determine the adhesion properties. Roughening was an effective treatment to remove paraffin waxes (antiadherent moieties) from the R2 rubber surface. When the chlorination is produced on the roughened R2 rubber, more noticeable chemical and morphological modifications were produced, and higher adhesion was obtained. On the other hand, TCI particles appeared on the roughened and unroughened chlorinated R2 rubber surface, and the size of these TCI particles were decreased by increasing the time after treatment. Furthermore, similar peel strength values were obtained for time after halogenation higher than 2 hours; for shorter time, a decrease in peel strength was found by increasing the time, due to the migration of paraffin wax to the rubber surface.

Chlorination of vulcanized SBR rubber by immersion or brushing in TCI solutions

The effectiveness of the chlorination treatment of synthetic vulcanized styrene-butadiene rubbers is determined by several experimental variables. In this study, trichloroisocyanuric acid (TCI) solutions in butanone have been used as chlorinating agents for a difficult-to-bond vulcanized styrene-butadiene rubber (R2). The influence of the TCI concentration (0.5 and 2 wt% TCI/MEK) was studied and a comparison between the immersion and brushing procedures to apply the chlorinating agent has been carried out. Characterization of the chlorinated surfaces was carried out using contact angle measurements (water, 25°C), ATR-IR spectroscopy, and scanning electron microscopy (SEM). T-peel tests on similarly treated R2 rubber/polyurethane adhesive joints were carried out to quantify adhesion. The chlorination by immersion of R2 rubber with TCI/MEK solutions was less effective than using a brush. The effects of the chlorination were similar using both procedures (creation of roughness, improved wettability, C Cl moieties formation and deposition of TCI particles), but the extent of the modifications was more marked when using a brush. The higher concentration of chlorinating agent allows a higher degree of chlorination. Peel strength values were lower for brush-chlorinated R2 rubber because the migration of wax (which created a weak layer on the rubber surface) from the bulk to the R2 rubber surface was favoured. However, the presence of waxes on the R2 rubber surface still allowed a reasonable level of adhesion due to the predominance of polar moieties.

Characterization of polyurethanes containing different silicas

Four silicas, two fumed (one hydrophilic and one hydrophobic) and two precipitated silicas (one hydrophilic and one hydrophobic), were added to a thermoplastic polyurethane (PU). The rheological, mechanical and adhesion properties of the PU–silica composites were considered in this study. In general, the addition of silica increased the viscosity, the storage and loss moduli of the PU–silica composites in solution but only the hydrophilic fumed silica imparted pseudoplasticity and thixotropy. The rheological and mechanical properties imparted by adding fumed silicas to PU were always more important than for precipitated silicas. Interactions between the hydrophilic fumed silica, the polyurethane and/or the solvent seemed to be responsible for the improved rheological properties of the composites. Addition of silica did not modify the glass transition temperature but increased the softening temperature of PU composites. On the other hand, the immediate (green) T-peel strength of roughened or (roughened + chlorinated with 2 wt% trichloroisocyanuric acid solutions in 2-butanone) styrene–butadiene rubber/PU composite joints was greatly improved if the PU contained silica, mainly fumed silicas irrespective of their hydrophilic or hydrophobic nature. Similar T-peel strength, 72 h after bond formation was found in the joints produced with PU composites with and without silica.

Adhesion improvement of SBR rubber by treatment with trichloroisocyanuric acid solutions in different esters

Ethyl, propyl and butyl acetates (EA, PA, BA, respectively) were used as solvents for trichloroisocyanuric acid (TCI) to chlorinate styrene–butadiene rubber (SBR). Characterization of the treated surfaces was carried out using ATR-IR spectroscopy, scanning electron microscopy (SEM), and contact angle measurements. Stress-strain measurements were also carried out to determine the mechanical properties of the treated rubber. Adhesion properties were studied using a polyurethane adhesive and the failed surfaces obtained after performing T-peel tests were analyzed in order to precisely locate the joint failure. The results showed that the solvent is a key factor in the effectiveness of the chlorination of R2 rubber. The solvents with slower evaporation rate led to more pronounced modifications on the R2 rubber surface. But these solvents could favour the migration of wax from the bulk rubber to the surface creating a weak antiadherent layer that prevented adhesion. The increase in TCI percentage in the chlorinating solution produced more marked modifications on the R2 rubber surface, avoiding the migration of wax. The solvent in the chlorinating solution also affects the effectiveness of the zinc stearate elimination from the R1 rubber surface; however, good adhesion was obtained even though this compound was not completely removed, indicating that the presence of zinc stearate in the rubber formulation did not produce a detrimental effect in the adhesion of SBRs.