Triallyl Cyanurate Research Articles

Nonterminal units effect on the cyclopolymerization of triallyl isocyanurate

Cyclopolymerization of triallyl isocyanurate (TAIC) as compared with its isomer triallyl cyanurate (TAC) is discussed in terms of the nonterminal units effect caused by the sterically bulky isocyanurate side groups. Thus, the monomer concentration dependence of the initial residual unsaturation is not explained by considering an ordinary cyclopolymerization mechanism, although TAC polymerization obeyed the mechanism. The effect of the forced introduction of bulkier noncyclic units into the polymer chain on the cyclopolymerizability of TAIC was explored by the copolymerization with allyl dibenzyl isocyanurate, resulting in the enhanced cyclization in conformity with our expectation.

Gamma radiation-induced graft copolymerization of styrene onto poly(ethyleneterephthalate) films

Gamma radiation-induced graft copolymerization of styrene onto poly(eth- ylene terephthalate) (PET) films was studied using simultaneous irradiation technique. The effects of grafting conditions on the degree of grafting were investigated. The grafting conditions include monomer concentration, irradiation dose, dose rate, and the type of solvent. Moreover, the effect of the addition of crosslinking agents (i.e., divinyl- benzene (DVB) and triallyl cyanurate (TAC)) having various concentrations were also investigated. The degree of grafting was found to be greatly dependent on the grafting conditions. Of the three diluents employed, methylene chloride was found to drastically enhance the degree of grafting. The order of dependence of the initial rate of grafting on the monomer concentration was found to be 2.2. The grafted PET films were identified by FTIR spectroscopy and characterized by X-ray diffraction (XRD). © 2000 John Wiley &

Difference in temperature effect on the polymerizations between triallyl isocyanurate and its isomer triallyl cyanurate

The temperature effect on the polymerization of triallyl isocyanurate (TAIC) was explored in detail as compared with its isomer triallyl cyanurate (TAC), since TAIC and TAC are commercially important as crosslinking agents with comonomers, and for aftercuring preformed polymers at elevated temperatures. Thus, the relative rate R p(TAIC)/ R p(TAC) decreased with temperature, accompanied by the reversed rate feature, as the higher rate for TAIC polymerization has been reported previously at 60°C [3]. No inversion was observed for the gel point and primary chain length, although the difference between TAIC and TAC polymerizations became smaller. The initial residual unsaturation decreased obviously with raised temperature for TAC polymerization, whereas only a slight decrease was observed for TAIC. These results are discussed mechanistically in terms of allyl polymerization and the steric effect caused by the bulky side-chain groups.

SOLVENT EFFECT ON GELATION IN THE RADICAL POLYMERIZATION OF TRIALLYL ISOCYANURATE

Radical solution polymerization of triallyl isocyanurate was conducted in methyl benzoate or hexyl benzoate as good or poor solvent, respectively, using AIBN as initiator at 60°C. An increased rate of polymerization, enlarged primary chain length, and promoted gelation were observed in the poor solvent. The actual gel point was compared with the theoretical one; the discrepancy between these points was great, although no substantial solvent effect was detected. These results are discussed in comparison with the results obtained from the polymerizations of its isomer triallyl cyanurate and diallyl terephthalate, a typical diallyl ester. The swelling ratio of the gel obtained just beyond the gel point was quite high, suggesting no microgelation up to the gel point conversion even in the solution polymerization.

Proton spin–spin relaxation and n.m.r. imaging of peroxide/coagent crosslinked cis-1,4-polyisoprene

Proton T2 relaxation and n.m.r. imaging experiments were utilized to study the molecular mobility and heterogeneity of cis-1,4-polyisoprene crosslinked with dicumyl peroxide in the presence of triallyl cyanurate (TAC) and zinc diacrylate (ZDA) as coagents. It was observed that the long T2 relaxation times of the rubber protons in peroxide/TAC or peroxide/ZDA crosslinked elastomers decrease with the increase in the crosslink density resulting from the addition of peroxide or coagent. The T2 relaxation times of protic solvent in swollen rubber are also affected by the physical property changes of the networks induced by peroxide and coagent addition. It was concluded that the solvent T2 relaxation times depend on solvent-polymer interactions as well as the crosslink density of the networks.

Further discussion of steric effect on the radical polymerization of triallyl isocyanurate as compared with its isomer triallyl cyanurate: polymerization and copolymerization of corresponding trimethallyl compounds

Abstract As part of our continuing studies concerned with the radical polymerization of multiallyl compounds, the polymerization behavior of triallyl isocyanurate (TAIC) was compared in detail with those of its isomer triallyl cyanurate (TAC). It was found by chance that the primary chain length of the TAIC polymer obtained was quite high compared with TAC polymerization. This is ascribed to the reduced occurrence of monomer chain transfer characteristic of the polymerization of allyl compounds due to the steric effect on transition state formation by the bulky side-chain group, providing an interesting example of reaction control in radical polymerization. In order to discuss in more detail this kind of the specific polymerization behavior of TAIC, this work deals with the polymerization and copolymerization of corresponding trimethallyl compounds including trimethallyl isocyanurate (TMAIC) and trimethallyl cyanurate (TMAC) having additional allylic hydrogens as α -methyl group in which no steric hindrance may occur for the transition state formation of monomer chain transfer reaction. TMAIC showed almost no homopolymerizability, while only slightly reduced polymerizability was observed for TMAC as compared with TAC. Specificity of TAIC polymerization was almost lost by copolymerizing about 20 mol% of TAC or TMAC.

Influence of shear stress treatment on stress-strain properties of methyl methacrylate-crosslinked butyl acrylate core-shell polymers

The incorporation of multilayer toughness modifiers to glassy polymers proceeds frequently by kneading the polymers in a molten state. This process influences the primary structure of the modifier and the properties of the blend in dependence on a shear stress intensity. In this article, we compare the properties of polymer materials prepared from a multilayer poly(methyl methacrylate) core, butyl acrylate copolymer interlayer, and methyl methacrylate copolymer shell particles {P[MMA-(BAC-co)-(MMA-co)]} by press-molding from powder and from polymer obtained by stirring a melt of this powder in the chamber of a Brabender mixer (200°C, 60 rpm, 10 min). The powder is obtained from a latex by coagulation after polymer synthesis in emulsion. Tensile testing shows different responses of the particle polymers when crosslinked in the middle layer by diallylphthalate (DAP) or by triallylcyanurate (TAC). Although many of the properties of the samples with DAP are improved by kneading, the presence of TAC in polymer particles led mostly to less desirable properties. The maximum percent strain in the polymer with 4.2 wt % of DAP upon shearing increases from 27% to 50%. In the samples with 4.5% TAC the maximum percent strain falls from 39% to 7%. Comparison of Young's modulus E for identical samples shows an analogous effect: a shift from 429 MPa to 638 MPa and from 624 MPa to 548 MPa. The design of the polymer particles used in this work leads to the conclusion that stress during kneading induces a partial desintegration of the crosslinked cage around the particle core. Thus, the varied behaviors of polymers used in this study are connected with the BAC-co network structure and its transformations during the shear stress treatment of the initial polymer material. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 493–501, 1999

Electron beam induced structural modification of a fluorocarbon elastomer in the presence of polyfunctional monomers

The influence of polyfunctional monomers—tripropyleneglycol diacrylate (TPGDA), trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimetbacrylate (TMPTMA), tetramethylolmethane tetracrylate (TMMT) and triallyl cyanurate (TAC)—on the structural changes of fluorocarbon terpolymer (F content 68%, H 1.4%) in the presence of an electron beam has been investigated with the help of IR spectroscopy (in the ATR mode) and sol-gel analysis. The absorbances at 1397, 1021, 672 and 504 cm −1 due to the C-F group, decrease on irradiation of the mixtures of fluoroelastomer and TMPTA, indicating dehydrofluorination and scission. The concentration of the double bond decreases both in the polyfunctional monomer and its blends with the polymer as a result of grafting and crosslinking. The concentration of the carbonyl group increases with radiation dose in the fluoroelastomer due to aerial oxidation. The effect of trimethylolpropane triacrylate (TMPTA) is to lower the amount of oxidation, especially at relatively higher levels. At a particular radiation dose, the behaviours of TPGDA, TMPTMA, TMMT and TAC based systems are similar to that of the TMPTA based one. The gel content increases with radiation dose. The influence of polyfunctional monomer on gel fraction is more prominent at higher concentrations, where distinct changes are observed at lower doses. At a particular level of multifunctional monomer, the gel fraction is lower for systems based on TPGDA. The ratio of chain scission to crosslinks calculated using the Charlesby-Pinner equation indicates a much higher crosslinking efficiency with polyfunctional monomer-fluorocarbon rubber matrix as compared to the control rubber.

Polymerization of Diallyl Alkyl Isocyanurates

Polymerizations of several diallyl alkyl isocyanurates were investigated to explore in more detail the steric effect observed in the polymerization of triallyl isocyanurate [3, 5], as compared to its isomer triallyl cyanurate, by changing alkyl groups from methyl, propyl, hexyl, and octyl up to lauryl. The rate of polymerization, the gel point, the cyclization constant, and the primary chain length were evaluated. For example, the primary chain length increased with an increase in the bulkiness of the alkyl group as expected, although in the polymerization of diallyl lauryl isocyanurate it decreased as a reflection of reduced rate of propagation due to the enhanced steric effect arising from a very bulky lauryl group.

Two-Step Surface Modification of Chemically Resistant Polymers: Blend Formation and Subsequent Chemistry1

Supercritical fluid (SCF) carbon dioxide processing has been studied as a new route to polymer surface modification. Three fluoropolymer substrates were studied: poly(tetrafluoroethylene) (PTFE), poly(chlorotrifluoroethylene) (PCTFE) and poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) using a two-step modification procedure. In the first step, blends or semiinterpenetrating networks were prepared by carrying out a free radical polymerization of styrene (or styrene with divinylbenzene or triallyl cyanurate) within the SCF-swollen polymer substrate. The second step involved sulfonating the polystyrene using heterogeneous (solution-solid) sulfonation conditions. Composition of the surfaces was determined by X-ray photoelectron spectroscopy, and wettability was assessed using water contact angle measurements. Depressed advancing and receding contact angles indicate increased wettability of all of the fluoropolymer samples.

The mechanism of triallylcyanurate as a coagent in EPDM peroxide vulcanization

AbstractThe reaction mechanism of ethylene‐propylene‐diene (EPDM) peroxide vulcanization, in the presence of triallylcyanurate (TAC), as a coagent, was studied by IR spectroscopy and equilibrium swelling technique. Coagent TAC is added in EPDM polymer to prevent the scission of polymer chains during the curing process. Because of this incompatibility with polymer, TAC was supposed to reside in small domains. To establish the existence of coagent bridges, the cleavage of ether linkages in the vulcanizates was made. After that treatment, IR measurements proved incorporation of coagent in polymer network. Measurements of allyl absorbances and the s‐triazine ring indicated that crosslink efficiency is enhanced and homopolymerization and cyclization take place in the presence of the coagent. In addition, the swelling results and IR measurements confirmed that the properties of the polymer, such as molecular mass and molecular mass distribution, will determine which of these reactions will predominate during the vulcanization process.

Physical and Reactive Blending of Linear Low Density Polyethylene with Copolyamide 6/6.9

Physical and reactive LLDPE/copolyamide 6/6.9 blends have been produced and characterized. Reactive blending has been performed in the presence of various low levels of high-temperature decomposing peroxide and tri-allyl cyanurate crosslinking agent. Whereas a finer morphology in the reactive blends was noted compared with the corresponding physical blends, the tensile properties deteriorated. In fact, some of the physical blends showed interesting properties. In another publication, under similar reactive blending conditions, without gel formation, some PP/ copolyamide 6/6.9 blends showed significant improvements in tensile behavior, compared to their corresponding physical blends. The presently studied reactive LLDPE/ copolyamide 6/6.9 blends always contained some gel, which is believed to cause the inferior tensile properties characterizing these blends.

Effect of Polyfunctional Monomers on Radiation Vulcanization of Styrene-Butadiene Rubber

The efficiency of seven functional monomers toward radiation vulcanization of styrene-butadiene rubber (SBR) were following the order: Tertamethylol methane tetraacrylate (ATMMT) = Toluene diisocyanate (UA306T) > Trimethylol propane trimethacrylate (TMPT) > Diethylene glycol dimethacrylate (2G) > Dipentaerthritol hexaacrylate (DPE6A) > Hexamethylene diisocyanate (UA101H) > Triallyl cyanurate (TAC). Also, it was found that low absorption of ATMMT has been overcome at low dose. The observed clear and transparent sheets indicate that the reaction was complete.

Electron Beam Initiated Grafting and Crosslinking of Ethylene Vinyl Acetate Copolymer. Part II: Mechanical and Electrical Properties

Mechanical, dynamic mechanical and electrical properties of electron beam modified ethylene vinyl acetate (EVA) copolymer in presence of trimethylolpropane trimethylacrylate (TMPTMA) and triallyl cyanurate (TAC) as sensitizer have been described. The tensile strength of the TMPTMA modified EVA increases with increase in radiation dose up to a certain level due to the development of network structure, while it does not change significantly for the TAC based system due to poor stress transfer. The tensile strength deteriorates sharply at higher radiation doses because of the predominating effect of breakdown of the network structure. However, the tensile strength changes marginally with TMPTMA level and decreases with an increase in TAC level. DMTA studies indicate mainly two transitions (namely γ and α) in the order of increasing temperature for both TMPTMA and TAC based samples. The γ-transition temperature shifts to higher values and the α-transition shifts to lower values with an increase in radiation dose due to modification of the main chain and to a decrease in crystallinity. Dielectric analysis shows a sharp transition at around -20°C for all uncured and cured samples due to movement of the highly polar acetate groups present in EVA. The loss factor decreases sharply at high temperature with increase in radiation dose due to crosslinking.

Electron Beam Initiated Grafting and Crosslinking of Ethylene Vinyl Acetate Copolymer. Part II: Mechanical and Electrical Properties

Mechanical, dynamic mechanical and electrical properties of electron beam modified ethylene vinyl acetate (EVA) copolymer in presence of trimethylolpropane trimethylacrylate (TMPTMA) and triallyl cyanurate (TAC) as sensitizer have been described. The tensile strength of the TMPTMA modified EVA increases with increase in radiation dose up to a certain level due to the development of network structure, while it does not change significantly for the TAC based system due to poor stress transfer. The tensile strength deteriorates sharply at higher radiation doses because of the predominating effect of breakdown of the network structure. However, the tensile strength changes marginally with TMPTMA level and decreases with an increase in TAC level. DMTA studies indicate mainly two transitions (namely γ and α) in the order of increasing temperature for both TMPTMA and TAC based samples. The γ-transition temperature shifts to higher values and the α-transition shifts to lower values with an increase in radiation dose due to modification of the main chain and to a decrease in crystallinity. Dielectric analysis shows a sharp transition at around -20°C for all uncured and cured samples due to movement of the highly polar acetate groups present in EVA. The loss factor decreases sharply at high temperature with increase in radiation dose due to crosslinking.

Structure property relationship of ethylene vinyl acetate copolymer grafted with triallyl cyanurate by electron beam radiation

Electron beam (EB) initiated grafting of triallyl cyanurate (TAC) onto ethylene vinyl acetate (EVA) containing 12% vinyl acetate has been carried out over a range of irradiation doses (20–200 kGy) and concentrations of TAC (0.5–5%). The grafting level, as determined from IR spectroscopy, does not change with the radiation dose at 0.5% TAC. With increase in TAC level the grafting level increases at 50 kGy dose. The gel content increases with radiation dose in the initial stage, whereas it changes marginally with the TAC level. With the increase in radiation dose or TAC level, the crystallinity decreases. The interplanar distance or the interchain distance of the grafted polymer does not change with dose or TAC level. The tensile strength is maximum at 0.5% TAC level and at the 50 kGy dose. The dielectric loss shows a maximum at 50 kGy dose and at 0.5–1.0% TAC level due to changes of polarity and the carrier chain mobility.

Electron Beam Initiated Grafting and Crosslinking of Ethylene Vinyl Acetate Copolymer. Part-I: Structural Characterization

Abstract Electron beam irradiation of Ethylene vinyl acetate, EVA (VA content 12, 28 & 45%) copolymer was carried out in presence of trimethylolpropane trimethacrylate (TMPTMA) and triallyl cyanurate (TAC) and the structure of the modified copolymers was determined with the help of IR spectroscopy and gel content measurements. The IR absorbance peak at 1640 cm−1 disappears at lower radiation dose indicating that the grafting and crosslinking reactions take place through double bonds. Some carbonyl groups are formed during irradiation. The concentration of carbonyl group increases with the radiation dose and the level of multifunctional monomers. The grafting level of TAC onto EVA determined from IR absorbance peak at 1565 cmx−1 remains almost constant with the variation of radiation dose and increases with TAC level. The gel content increases with radiation dose, but changes marginally with TMPTMA and TAC levels. The percent gel content increases linearly with vinyl acetate content in EVA.

The Structure of Copolymers of Some Alkyl Methacrylates with Triallyl Cyanurate

Abstract Copolymers of several methacrylates (propyl, pentyl, cyclohexyl and dodecyl) with triallyl cyanurate were synthesized by free-radical polymerization using benzoyl peroxide as an initiator. The structure of copolymers was analysed by quantitative extraction and followed by IR, 1H-NMR and elemental analyses.

Performance of Differently Cross‐Linked, Partially Fluorinated Proton Exchange Membranes in Polymer Electrolyte Fuel Cells

A series of differently cross‐linked FEP‐g‐polystyrene proton exchange membranes has been synthesized by the preirradiation grafting method [FEP: poly(tetrafluoroethylene‐co‐hexafluoropropylene)]. Divinylbenzene (DVB) and/or triallyl cyanurate (TAC) were used as cross‐linkers in the membranes. It was found that the physical properties of the membranes, such as water‐uptake and specific resistance, are strongly influenced by the nature of the cross‐linker. Generally it can be stated that DVB decreases water‐uptake and increases specific resistance; on the other hand TAC increases swelling and decreases specific resistance to values as low as 5.0 Ω cm at 60°C. The membranes were tested in fuel cells for stability and performance. It was found that thick (170 μm) DVB cross‐linked membranes showed stable operation for 1400 h at temperatures up to 80°C. The highest power density in the fuel cell was found for the DVB and TAC double‐cross‐linked membrane; it exceeded the value of a cell with a Nafion® 117 membrane by more than 60%.

Copolymers of higher alkyl methacrylates with triallyl cyanurate

AbstractCopolymers of higher methacrylates (propyl, pentyl, hexyl, cyclohexyl, heptyl, octyl, and dodecyl) with triallyl cyanurate were synthesized by free‐radical polymerization using benzoyl peroxide as initiator. The properties of the copolymers such as thermal stability, Tg, Vicat softening temperature, hardness, refractive indices nD, chemical stability, density, and shrinkage on polymerization were studied. The influence of the alcohol alkyl chain length in methacrylates and the content triallyl cyanurate in copolymers on their properties is discussed. © 1995 John Wiley & Sons, Inc.