Surface treatment of fluorinated rubber with triazine thiols and their properties

Fluorinated (FKM) vulcanizates were treated by immersing in an aqueous solution of triazine thiols, NaOH, and onium salts for 15–60 min at 50–95°C (W-Method). Treated FKM vulcanizates further were postcured in an air oven for 20 h at 200°C to complete the reaction. The onium salt of triazine thiols were found to be formed by a reaction among the triazine thiols, NaOH, and onium salts and to act as cross-linking agents to the surface of FKM vulcanizates. In the acetone solution of onium salts of triazine thiols, FKM vulcanizates were also treated by immersing for a few minutes at 20°C and then by heating in an air oven for 20 min at 200°C (A-Method). Triazine thiols were introduced as crosslinks onto the FKM backbone. The degree of cross-linking in the surface increased by these treatments and the depth of cross-linking reached up to about 40 μm thickness by control of treating conditions. The coefficient of friction in FKM vulcanizates decreased as a result of the surface treatment up to about 0.5 from 2.6. FKM vulcanizates decreased the tensile strength by these surface treatments because of the generation of cracks on the surface at 50% or 100% elongation. The surface treatment of FKM vulcanizates suppressed markedly the fixing between FKM vulcanizates and stainless steel at 150°C. Especially, the A-Method was very effective treating for retarding the fixing between FKM vulcanizates and metals. © 1994 John Wiley & Sons, Inc.     

Curing reaction of elastomers with triazine thiols and sulfen amides

Curing reaction of elastomers with triazine thiols and sulfen amides in the presence of ZnO and stearic acid was investigated for curing parameters and curing mechanism. The curing parameters such as curing rate, induction period, and curing efficiency were influenced by the pKa of thiol groups in triazine thiols and amines corresponding in sulfen amides, by the steric hinderance of 6-substituted groups in triazine thiols and on amino groups in sulfen amides, by the molar ratio of sulfen amides to triazine thiols, and by the reacting positions and the properties of elastomers. Triazine thiols acted as curing agents. Sulfen amides played two important roles in curing elastomers with triazine thiols. They gave poly(triazinyl disulfide) which is a curing precursor. Curing activators are formed in the reaction of the precursors, sulfen amides, and ZnO. The activators react with elastomers to give crosslinks, pendants and triazine dithiols or triazinyl disulfide oligomers. The pendants react with sulfen amides to give the crosslinks. The triazine thiols or triazinyl disulfide oligomers react with sulfen amides to reproduce the curing precursors. The structure of crosslinks is estimated to be      

Crosslinking of PVC and NBR blends

The purpose of our work is to control the interfacial bonds between PVC and NBR using the ammonium salts of triazine thiols and dithiodimorpholine (DTDM) and thereby reveal the relation between the interfacial bonds and the final mechanical properties of products. In the experimental work a two-stage process was used. At first, an NBR/PVC blend was mixed with a mono-tetra-n-butylammonium salt of triazine trithiol at a temperature of 100°C on a two-roll mill to give the branching structure of triazine thiols into PVC. In the second stage branched NBR/PVC reacted with DTDM to afford the branched PVC containing trithiomorphonyl groups. In the presence of ZnO at 160°C trithiomorphonyl groups react with NBR to form a crosslinking structure between NBR and PVC. The mechanical properties of cured NBR/PVC blends were markedly improved by the treatment process and after addition of tetramethylthiuram monosulphide also. The mechanical properties were not improved by increasing the concentration of TT-TBA (tetrabutylammonium salt of 1,3,5-triazine-2,4,6-trithiol) over 4.2 phr.     

Polyimides containing s‐triazine rings

A series of new polyimides containing s‐triazine rings have been synthesized via Diels–Alder intermolecular polymerization of 2,6‐bis(2‐furanylmethylimino)‐4‐isopropoxy‐1,3,5‐triazine with various bis(maleimide)s. All the poly(imino‐s‐triazine imide)s were characterized by elemental analyses, FTIR spectral studies, number average molecular weight ( M _n) by non‐aqueous conductometric titration and thermogravimetry. Glass‐fibre reinforced composites were prepared via an in situ Diels–Alder intermolecular reaction between 2,6‐bis(2‐furanylmethylimino)‐4‐isopropoxy‐1,3,5‐triazine and various bis(maleimide)s. The composites were characterized for chemical resistivity and mechanical properties. © 2003 Society of Chemical Industry     

Effect of various triazine derivatives on the thermal oxidative degradation of isotactic polypropylene

A number of triazine derivatives, mostly aryloxy-s-triazines, were prepared, and the effects of these compounds on the thermal oxidative degradation of isotactic polypropylene were examined by conventional oxygen uptake. Almost all triazine derivatives prepared showed a more or less inhibitive effect on the degradation of the polymer. Among them, α- and β-napthyloxy-s-triazines were found to be excellent inhibitors. On the basis of the results obtained, the relationship between inhibitive effect and the structure of the triazine derivatives is discussed.     

Oxidation of thiols in gas-liquid systems. II. Reaction in the presence of added metal catalysts

Comparisons have been made of some kinetic features of the oxidation in alkaline solution of a series of simple aliphatic and aromatic thiols in the presence of added metal catalysts. With ethanethiol as the reactant, the catalytic activity of a wide variety of metals, added to the solution as simple salts, has been determined. Furthermore, using three typical metal catalysts, the oxidation of a series of thiols has been investigated and an attempt has been made to correlate rates of oxidation with the geometric structure and electron-directing properties of the organic groups present. The size of such groups has been found to be one of the most important factors controlling the overall rate of oxidation.     

Cytocompatible and regenerable antimicrobial cellulose modified by N‐halamine triazine ring

This study reports the formation of cyanuric chloride hydrolysate and its attachment onto cellulose fibers though covalent bonding. The hydrolysis product, 2,4‐dichloro‐6‐hydroxy‐1,3,5‐triazine, is prepared in water solution at ambient temperature, and directly used as a treatment solution for the treatment of cotton fabrics without any prior work‐up. The triazine treated fabrics are rendered antimicrobial through exposure to chlorine bleach. The oxidative chlorine bonded to the triazine‐treated cotton is very stable and regenerable to standard washing tests and UVA irradiation test. The N‐halamine modified cotton fabrics demonstrate excellent antimicrobial efficacy against Staphylococcus aureus ATCC 6538 and Escherichia coli O157:H7 ATCC 43895 with 7‐logs reductions within the contact time of 10 and 5 min, respectively. In addition, the results of in vitro cell viability test suggested that the N‐halamine modified fabrics have excellent cytocompatibility to mammalian cells. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40627.     

Solvent effects in the oxidation of sulphur compounds. Anionic oxidation of high molecular weight thiols and disulphides to sulphonate salts

The base-catalysed oxidation of high molecular-weight aliphatic thiols and disulphides to sulphonate salts by molecular oxygen has been studied from 23.5° to 80°. The preferred solvent was hexamethylphosphoramide. Generally, yields and selectivities of the sulphonate salts varied from 95 to 99% at 80°. Potassium and sodium hydroxides were equally effective as the base catalysts. Other solvents and bases were explored and factors which control selectivity to the final product determined. The reactions are believed to involve sulphenate ions produced by attack of hydroxide ion on the disulphide linkage. Such species are unstable and may be oxidised directly by oxygen or disproportionate to sulphonate ions and disulphides.     

Evaluation of new 3‐mercaptopropionate thiols for thiol‐ene photopolymerization coatings using experimental design

Three 3‐mercaptopropionate thiols, 1,6‐Hexane bis(3‐mercaptopropionate) (HD‐SH), trans‐1,4‐Cyclohexanedimethyl bis(3‐mercaptopropionate) (CHDM‐SH), and 4,4′‐Isopropylidenedicyclohexane bis(3‐mercaptopropionate) (HBPA‐SH) were formulated with 1,3,5‐triallyl‐1,3,5‐triazine‐2,4,6(1H,3H,5H)‐trione (TATATO) and photoinitiator. The formulations were photopolymerized via thiol‐ene photopolymerization. A ternary experimental design was employed to elucidate the influence the three thiols on the thermomechanical and coatings properties of thiol‐ene photopolymerizable materials. Tensile strength, tensile modulus, elongation‐to‐break, glass transition temperature (T_g), and crosslink density (XLD) were investigated. Coating properties including pencil hardness, pull‐off adhesion, MEK double rubs, and gloss were also investigated. Relative reaction conversion was determined by photo differential scanning calorimeter (PDSC). Thiol‐ene photopolymerizable materials containing HBPA‐SH resulted in improving tensile strength, tensile modulus, T_g, and pencil hardness but lowering of crosslink density and relative conversion. This was attributed to steric and rigidity of the double cycloaliphatic structure. The inclusion of CHDM‐SH into the systems resulted in the synergistic effect on elongation‐to‐break and pull‐off adhesion. The HD‐SH generally resulted in a diminution of thermomechanical and coating properties, but improved the crosslink density. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Thiourethane thermoset coatings from bio‐based thiols

Three bio‐based thiols were synthesized via the thermal thiol‐ene reactions between sucrose soya ester (SSE) and multifunctional thiols; then, thiourethane coatings were produced from these thiols and their coating properties were studied. A series of high bio‐renewable content thiol oligomers were synthesized according to the previously reported thermal thiol‐ene reaction. Fourier transform infrared spectra (FTIR) confirmed the complete consumption of the double bonds in SSE, and gel permeation chromatography confirmed the formation of high‐molecular‐weight oligomers. The viscosity of these oligomers remained low due to their compact and branched structures. Thermoset thiourethane coatings were prepared from these thiol oligomers and polyisocyanate trimer resins with dibutyltin diacetate as the catalyst. FTIR spectra confirmed the formation of the thiourethane group. However, coatings based on isophorone diisocyanate (IPDI) polyisocyanate resin showed a lower degree of cure because of the decreased resin mobility due to the rigid cyclohexane ring. Generally, all the coatings showed good adhesion to aluminum panels, and had high gloss. However, they exhibited low tensile strength, modulus and chemical resistance due to the flexibility of the fatty acid chain. Coatings based on more rigid IPDI‐based polyisocyanate showed higher T_g, hardness and direct impact resistance compared with the hexamethylene‐diisocyanate (HDI) based polyisocyanate counterparts. Thermogravimetric analysis results showed that coatings based on mercaptanized soybean oil have better thermal stability than those from di‐pentene dimercaptan or glycol di‐3‐mercaptopropionate. Two T_g values were found by both differential scanning calorimetry and dynamic mechanical thermal analysis of thiourethanes from HDI‐based polyisocyanate and di‐pentene dimercaptan or glycol di‐3‐mercaptopropionate based oligomers due to phase separation resulting from the poor compatibility between HDI‐based polyisocyanate and the respective oligomers. Copyright © 2011 Society of Chemical Industry     

Synthesis and characterization of aromatic polyamides containing an s‐triazine ring with thiophenoxy linkages

A series of aromatic polyamides containing an s‐triazine ring with thiophenoxy linkages was synthesized from two new diacids, namely 2,4‐bis‐(4‐carboxyphenoxy)‐6‐thiophenoxy‐s‐triazine and 2,4‐bis‐(3‐carboxyphenoxy)‐6‐thiophenoxy‐s‐triazine, and commercially available aromatic diamines by using Yamazaki's phosphorylation reaction. The polyamides were obtained in good yields and were characterized by solubility tests, viscosity measurements, FTIR, ¹H and ¹³C NMR spectroscopy, X‐ray diffraction studies and thermogravimetric analysis. The polyamides were found to have inherent viscosities in the range of 0.35 to 0.56 dl g^?1 in N,N‐dimethylacetamide (DMAc) at 30 ± 0.1 °C. All the polyamides were readily soluble in solvents such as DMAc, N‐methyl‐2‐pyrrolidone (NMP), N,N‐dimethylformamide (DMF) and m‐cresol. Thermogravimetric analysis of the polyamides indicated no weight loss below 345 °C under a nitrogen atmosphere. Copyright © 2004 Society of Chemical Industry     

Rheological cure characterization of phosphazene–triazine polymers

Cyclomatrix phosphazene–triazine network polymers were synthesized by co‐curing a blend of tris(2‐allylphenoxy), triphenoxy cyclotriphosphazene (TAP), and tris(2‐allylphenoxy) s‐triazine (TAT) with bis(4‐maleimido phenyl) methane (BMM). The co‐curing of the three‐component resin was investigated by dynamic mechanical analysis using rheometry. The cure kinetics of the Diels–Alder step was studied by examining the evolution of the rheological parameters, such as storage modulus (G′), loss modulus (G″), and complex viscosity (η*), for resins of varying compositions at different temperatures. The curing conformed to an overall second‐order phenomenological equation, taking into account a self‐acceleration effect. The kinetic parameters were evaluated by multiple‐regression analysis. The absence of a definite trend in the cure process with blend composition ratio was attributed to the occurrence of a multitude of competitive reactions whose relative rates depend on the reactant ratio and the concentration of the products formed from the initial phase of reaction. The cure was accelerated by temperature for a given composition, whereas the self‐acceleration became less prominent at higher temperature. Gelation was accelerated by temperature. The gel conversion decreased with increase in maleimide concentration and, for a given composition, it was independent of the cure temperature. The activation energy for the initial reaction and the crosslinking process were estimated for a composition with a maleimide‐to‐allyl ratio of 2 : 1. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 908–914, 2003     

Revisiting aromatic thiols effects on radical photopolymerization

Influence of thiols on kinetics of acrylate radical photopolymerization in the presence and absence of photoinitiators was studied. The kinetics was monitored by infrared absorption and photo-differential scanning calorimetry. It was found that aromatic thiols at concentrations, <0.5% (∼0.05 M), can accelerate radical photopolymerization. Initiation of radical photopolymerization by some aromatic thiols in the absence of conventional photoinitiators was observed. As well as expected inhibition of photopolymerization at higher concentration of aromatic thiols due to chain transfer was detected. A ground state charge-transfer complex formation between thiols and benzoin based photoinitiators was detected.Mechanism of thiols participation in photopolymerization involving reduction of oxygen inhibition and dissociation of charge-transfer complexes is discussed.     

Reaction of 6-bromo-6-deoxycellulose with thiols in lithium bromide-N,N-dimethylacetamide

Nucleophilic substitution reactions of 6-bromo-6-deoxycelluloses of high degrees of substitution with eight thiols having functional groups such as carboxyl and amino groups were studied under homogeneous conditions in LiBr-N, N-dimethylacetamide in the presence of triethylamine. The reactions under the homogeneous conditions proceeded more extensively than those run under heterogeneous conditions in aqueous alkaline solutions. The reactivity of thiols was found to increase with increasing acidity of the mercapto groups of the thiols. Reaction products with 2-mercaptobutanedioic acid and with 2-mercaptobenzoic acid were soluble in alkaline and neutral water but not in 1 N HCl, while the reaction products with 2-aminoethanethiol did not dissolve even in 1 N HCl. The reaction products with cysteine showed amphoteric behavior. © 1996 John Wiley & Sons, Inc.     

Thermal behavior and properties of naphthalene containing bismaleimide–triazine resins

A series of bismaleimid·triazine (BT) resins were prepared from various dicyanate esters and 2,7-bis(4-maleimidophenoxy)naphthalene (BMPN), which contains a naphthalene group and an aryl ether linkage in the backbone. Their curing behaviors were characterized by differential scanning calorimetry. The exotherm temperature and polymerization reactivity were strongly affected by the chemical structure of the various dicyanate ester monomer. Thermal behaviors were investigated by thermogravimetric analyses and dynamic mechanical analyses. The glass transition temperatures (T_g) of these cured resins with bismaleimide/dicyanate ester at the 1/2 molar ratio were in the range of 250–322°C, and exhibited excellent thermal stability up to 400°C in nitrogen. These results provided a structure–properties relationship for the cured bismaleimid·triazine resins. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1199–1207, 1998     

Ultraviolet photopolymerization induced by a triazine derivative

2‐(3,4‐Methdioxyphenyl)‐4,6‐bis(trichloromethyl)‐ 1,3,5‐triazine (MBTTR) was used as a photoinitiator for the polymerization of acrylate monomer. Ultraviolet–visible absorption spectroscopy was used to investigate the photochemical behavior during the photophysical process. The photopolymerization kinetics were monitored by real‐time Fourier transform infrared spectroscopy. The polymerization rates of the acrylates were significantly higher than those of the methacrylates. When MBTTR induced the polymerization of trimethylolpropane triacrylate, there was an optimum polymerization rate and the final conversion was obtained at 0.1 wt % MBTTR. MBTTR was an inefficient photoinitiator for ethyl vinyl. The final conversions of tripropylene glycol diacrylate induced by MBTTR and triazine/1,3‐benzodioxole were similar. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Surface-enhanced Raman scattering of carbazole-based covalent triazine framework

A kind of carbazole-based covalent triazine framework (CTF-Cz) has been synthesized from a carbazole derivative. The porous polymer can efficiently adsorb probe molecules due to the strong intermolecular interactions caused by the polar triazine moiety. CTF-Cz directly serves as the surface-enhanced Raman scattering substrate without any post proceeding techniques. The enhancement factor of CTF-Cz is ~10⁵ for detecting rhodamine 6G (R6G). The lowest unoccupied molecular orbital energy level of CTF-Cz (−3.93 eV) is much lower than that of R6G, which is in favor of the charge transfer from R6G to CTF-Cz for illumination under a 532 nm laser, which is proved by time resolved photoluminescence spectra. The efficient charge transfer induced by the strong intermolecular π–π interactions and large molecular-orbital delocalization contribute to the enhanced Raman signals of R6G on CTF-Cz.     

Preparation and characterization of uniform molecularly imprinted polymer beads for separation of triazine herbicides

Uniform molecularly imprinted polymer beads were synthesized by precipitation polymerization for separation of triazine herbicides. A series of imprinted polymers were prepared using ametryn as template and divinylbenzene as crosslinking monomer, in combination with three different functional monomers under different solvent conditions. Under optimized reaction conditions, we obtained uniform molecularly imprinted polymer microspheres that display favorable molecular binding selectivity for triazine herbicides. The imprinted polymer beads synthesized using methacrylic acid as functional monomer in a mixture of methyl ethyl ketone and heptane showed the best results in terms of particle size distribution and molecular selectivity. Compared with nonimprinted polymer microspheres, the imprinted microspheres displayed significantly higher binding for a group of triazine herbicides including atrazine, simazine, propazine, ametryn, prometryn, and terbutryn. For the first time, precipitation polymerization has been used to produce highly uniform imprinted microspheres suitable for affinity separation of triazine herbicides. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Mechanism of stabilization of poly(vinyl chloride). I. The cleavage of organotin compounds by aqueous hydrochloric acid

A number of organotin compounds with the general formula R_nSnY_4-n where R = alkyl and aryl, Y = thiolate, carbothiolate, and carboxylate, and n = 0, 1, 2, 3 were cleaved with aqueous hydrochloric acid to give the corresponding organotin chlorides and thiols, carbothiolic acids or carboxylic acids. The organotion salts were also evaluated as thermal stabilizers for PVC, and their efficiency was compared with the nature of the aqueous acid cleavage products.¹     

Synthesis and characterization of poly(arylene ether s‐triazine)s containing alkyl‐, aryl‐ and chloro‐substituted phthalazinone moieties in the main chain

Soluble and heat‐resistant polymers have great potential for use as processable, high‐temperature polymeric materials. In this study, four types of new poly(arylene ether s‐triazine)s containing alkyl‐, aryl‐ and chloro‐substituted phthalazinone moieties in the main chain were prepared through direct solution polycondensation of 2,4‐bis(4‐fluorophenyl)‐6‐phenyl‐s‐triazine with each of methyl‐, phenyl‐ and chloro‐substituted phthalazinones. A key feature of these polymers is the incorporation of phthalazinone and side groups into the poly(arylene ether s‐triazine) backbone to endow them with good solubility while maintaining other attractive properties. The polymers were obtained in high yields, and had inherent viscosities ranging from 0.38 to 0.55 dL g^?1. Their structure was characterized using Fourier transform infrared and NMR spectra and elemental analysis. The polymers were almost amorphous, and soluble in N‐methyl‐2‐pyrrolidone, pyridine, N,N‐dimethylacetamide, hot N,N‐dimethylformamide and sulfolane. Tough and nearly transparent films obtained by direct solution casting exhibited good mechanical properties. The resulting polymers displayed glass transition temperatures ranging from 255 to 265 °C and thermal decomposition temperatures for 10% mass loss ranging from 476 to 599 °C, according to differential scanning calorimetry and thermogravimetric analysis, respectively. The reactivity of substituted phthalazinones in nucleophilic displacement reactions and the effect of the side groups on the physical properties of the polymers were also investigated. The results obtained revealed that such s‐triazine‐containing polymers possessed good solubility while maintaining acceptable thermal stability and high mechanical strength with the incorporation of alkyl‐, aryl‐ and chloro‐substituted phthalazinone moieties into their backbones, which makes them an attractive series of high‐performance structural materials. Copyright © 2010 Society of Chemical Industry