Styrene‐maleic anhydride copolymers: Synthesis, characterization, and thermal properties

Polyurethane prepolymers are widely used in reactive hot melt adhesives and moisture-cured coatings. The segmented moisture-cured formulations, based on polytetramethylene glycol (PTMG-1000)/trimethylol propane (TMP)/isophorone diisocyanate (IPDI) and PTMG/TMP/ toluene diisocyanate (TDI), were prepared with NCO/OH ratio of 1.6 : 1.0. The excess isocyanate groups of the prepolymers were chain extended in the ratio of 2 : 1 (NCO/ OH) with different aliphatic diols and 4 : 1 with different aromatic diamines. The surplus isocyanate groups of the formulations were completely reacted with atmospheric moisture, and the thermal stability of the postcured materials obtained as cast films were evaluated by thermogravimetric (TG) analysis. It was observed that initial degradation temperatures were above 270°C, with two-or three-step degradation profiles. The degradation parameters were evaluated using the Broido and Coats-Redfern methods.The thermal resistance of moisture-cured formulations using diisocyanates with the cycloaliphatic structures (IPDI) and the aromatic TDI, at the same NCO/OH ratio (1.6), and TMP content were compared from the isothermal TG experiments at different temperatures and dynamic TG experiments at different heating rates in nitrogen and oxygen environments. The observation suggests that polyurethane-containing sulfone groups and straight-chain diol chain extenders were more stable. It was also observed that at lower temperature polyurethane, prepared from aliphatic diisocyanates (IPDI), was more stable than the aromatic diisocyanate (TDI) containing polyurethanes. At high temperature, the stability order follows the reverse trend.

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“…The integral form of the rate equation in a dynamic heating expression experiment may be expressed as where p ( x ) = ∫

_{∞}^{italicx}

[exp(− x )/ x 2 ] dx , and x = E / RT ; g (α) is the integral form of the conversion dependency function 22, 23…”

Section: Methodsmentioning

confidence: 99%

Thermal stability of chemically crosslinked moisture‐cured polyurethane coatings

Chattopadhyay

Sreedhar

Raju

2005

J of Applied Polymer Sci

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“…The copolymerization between ST and MAH have a strong tendency to form alternating copolymer. [15][16][17][18][19][20][21][22] The propagation step between ST and MAH can be modeled in terms of a penultimate group effect, [15][16][17]19,20] complex-participation model [15][16][17][18][19][20] (donor-acceptor complexes between ST-MAH), and the terminal model (Mayo-Lewis). [21,22] The terminal Mayo-Lewis model is the simplest one and was used to model the propagation step between ST and MAH.…”

Section: Model Descriptionmentioning

confidence: 99%

“…In the binary terminal copolymerization model, the propagation step includes four reactions between ST (M 1 ) and MAH (M 2 ). However, MAH does not homopolymerize, [15][16][17][18][19][20][21][22] thus the final terminal mechanism comprises three reactions. The reactivity ratios for the monomers (r 1 and r 2 ) are The distribution of species between the polymer and continuous phase is obtained through relations for thermodynamic equilibrium and material balances.…”

Section: Model Equationsmentioning

confidence: 99%

Mathematical Modeling of the Stabilizer‐Free Dispersion Copolymerization of Styrene and Maleic Anhydride: Particle Growth

Giudici

2020

Macro Reaction Engineering

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almost constant after nucleation, the particle growth is intrinsically related with the kinetics of the reaction. Due to the complexity of dispersion polymerization, mathematical models have been developed to understand this phenomenon. Nucleation, [9-11] mass transfer between the polymer phase and the continuous phase [7,8] and particle growth [8,10-13] have been studied in the literature for the traditional dispersion polymerization. To the best of our knowledge no model exists to simulate the nucleation and growth steps of a stabilizer-free dispersion copolymerization. In this work a mathematical model to predict the global conversion, copolymer composition and the polymer particle diameter during time is proposed for stabilizer-free dispersion polymerization. The model is an application of the model proposed by Sáenz and Asua, [8] that considered only the growth of the particles, with a fixed number of particles during the entire process. The main contribution of this work is the validation of a particle growth model to stabilizer-free dispersion polymerization using the terminal model (Mayo-Lewis) to the propagation step for the copolymerization between styrene (ST) and maleic anhydride (MAH) and adjustment of the gel effect constants. The validation data were obtained experimentally by stabilizer-free dispersion copolymerization between ST and MAH in the organic solvents isopentyl and isobutyl acetate (IPA and IBA). 2. Experimental Section 2.1. Materials Styrene (Merck Millipore, 99%), maleic anhydride (Caal Reagentes Analíticos), azobisisobutyronitrile (AIBN) (MIG Quimica Ltda EPP), isopentyl acetate (Sigma-Aldrich, >97%), isobutyl acetate (Sigma-Aldrich, >97%), and acetone (Sigma-Aldrich, 99.5%) were used as received, without further purification. 2.2. Polymerization Procedure Experiments of the stabilizer-free dispersion copolymerization of ST/MAH in IBA or IPA were carried out in glass A model is proposed for particle growth in the stabilizer-free dispersion copolymerization of styrene (ST) and maleic anhydride (MAH). The model is based on the assumptions that 1) polymerization occurs in both the continuous phase and the polymer particles, 2) the nucleation step is fast, and the number of polymer particles is fixed during the process, 3) the particle population is monodisperse, 4) the propagation step between ST and MAH follows the terminal model, and 5) the termination step is diffusion-controlled, causing an autoacceleration effect in the process. The model predicts the global conversion, copolymer composition and the polymer particle diameter during time. The validation data are obtained experimentally by stabilizer-free dispersion copolymerization and the model predictions are in good agreement with the experimental data.

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“…The steady decline is likely due the decrease in polarization as the sample approaches the paraelectric-ferroelectric transition temperature. In addition, PSMA undergoes a glass transition at 63.9°C, 28 which would complicate the interpretation of these measurements.…”

Section: -3mentioning

confidence: 99%

Switching kinetics of ferroelectric polymer nanomesas

Othon

Kim

Ducharme

et al. 2008

Journal of Applied Physics

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The switching dynamics and switching time of ferroelectric nanomesas grown from the paraelectric phase of ultrathin Langmuir-Blodgett vinylidene fluoride and trifluoroethylene copolymer films are investigated. Ferroelectric nanomesas are created through heat treatment and self-organization and have an average height of 10 nm and an average diameter of 100 nm. Ferroelectric nanomesas are highly crystalline and are in the ferroelectric phase and switch faster than 50 s. The dependence of switching time on applied voltage implies an extrinsic switching nature.

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Styrene‐maleic anhydride copolymers: Synthesis, characterization, and thermal properties

Cited by 13 publications

References 0 publications

Thermal stability of chemically crosslinked moisture‐cured polyurethane coatings

Thermal stability of chemically crosslinked moisture‐cured polyurethane coatings

Mathematical Modeling of the Stabilizer‐Free Dispersion Copolymerization of Styrene and Maleic Anhydride: Particle Growth

Switching kinetics of ferroelectric polymer nanomesas

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