On the plastic and viscoelastic behavior of methylmethacrylate‐based random copolymers

Tordjeman, Philippe; Tézé, L.; Halary, Jean Louis; Monnerie, L.

doi:10.1002/pen.11810

Cited by 37 publications

(27 citation statements)

References 27 publications

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“…Similar tendencies were reported by Oishi et al 17 and Halary et al 20 The T g of PMMA is 105°C, 14 so adding NCMI can improve greatly the thermal resistance of Plexiglas.…”

Section: Copolymer Compositionsupporting

confidence: 73%

Kinetics for copolymerization of methyl methacrylate withN-cyclohexylmaleimide

Jiang

Tai

Xia

et al. 1999

J. Appl. Polym. Sci.

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ABSTRACT:The kinetics for the radical copolymerization of methyl methacrylate (MMA) with N-cyclohexylmaleimide (NCMI) was investigated. The initial copolymerization rate R p is proportional to the initiator concentration to the power of 0.54. The apparent activation energy of the overall copolymerization was measured to be 69.0 kJ/mol. The monomer reactivity ratios were determined to be r NCMI ϭ 0.42 and r MMA ϭ 1.63. R p reduces slightly, and the molecular weight of the resultant copolymer decreases with increasing the concentration of the chain transfer agent N-dodecanethiol (RSH). The more the transfer agent, the narrower the molecular weight distribution of the resulting copolymer. The following chain-transfer constant of RSH for the copolymerization of MMA with NCMI in benzene at 50°C was obtained: C s ϭ 0.23. The glass transition temperature (T g ) of the copolymer increases with increasing f NCMI , which indicates that adding NCMI can improve the heat resistance of Plexiglas.

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“…Similar tendencies were reported by Oishi et al 17 and Halary et al 20 The T g of PMMA is 105°C, 14 so adding NCMI can improve greatly the thermal resistance of Plexiglas.…”

Section: Copolymer Compositionsupporting

confidence: 73%

Kinetics for copolymerization of methyl methacrylate withN-cyclohexylmaleimide

Jiang

Tai

Xia

et al. 1999

J. Appl. Polym. Sci.

View full text Add to dashboard Cite

show abstract

“…The temperature increment between two consecutive measurements was 2°C, and the overall temperature range under study extended from Ϫ90°C to T g ϩ 30°C. According to the observations made in previous articles, 8,21,22 the glass transition temperature T g was supposed here to be identical to the temperature at which the EЉ goes through a maximum when the frequency is 1 Hz.…”

Section: Viscoelastic Measurementsmentioning

confidence: 98%

Relationships between thermally induced residual stresses and architecture of epoxy-amine model networks

Bauchiere

Halary

Monnerie

et al. 2000

J. Appl. Polym. Sci.

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ABSTRACT:The capability of epoxy-amine resins to develop residual stresses was studied as a function of temperature and network architecture. These residual stresses were induced while cooling epoxy-glass bilayers from temperatures higher than the network glass transition temperature, T g . This behavior was the result of the marked differences (␣ r Ϫ ␣ g ), in linear thermal expansion coefficient of the two components, as evidenced by the measurement of ␣ r for the epoxy networks under study. Various network architectures were selected, resulting from variation of (1) the chemical nature of both epoxide and curing agent, (2) the nature and relative amount of the chain-extensor agent, and (3) the stoichiometric ratio. Three ranges of cooling temperature were observed systematically: first, the range of temperatures above T g , where no stress has been detected, then an intermediate temperature range (from T g to T*), where stresses develop quite slowly, and finally, the low temperature range (T Ͻ T*), where a linear increase in stress accompanies the decrease of temperature. The two latter regimes were quantitatively characterized by the extent, T g Ϫ T*, of the first one and by the slope, SDR, of the second one. T g Ϫ T* values were shown to be governed by the T g of the network: the higher the T g , the larger the gap between T g and T*. This result was interpreted by accounting for the variation of relaxation rate at T g from one network to the other. It was also shown that a semiempirical relationship holds between SDR and T g : SDR decreases monotonically as T g increases. By inspecting the effects of network architecture in more details, it turned out that SDR is governed by the Young's moduli, E r (T Ϫ T g ), of the epoxy resins in the glassy state: the lower E r (T Ϫ T g ), the lower SDR in a series of homologous networks. As E r (T Ϫ T g ) values are known to be related to the characteristics of the secondary relaxation ␤, which depends, in turn, on crosslink density, SDR values were finally connected to the amplitude of the ␤ relaxation processes. This finding was corroborated by the measurements on an antiplasticized dense network. Finally, data relative to thermoplastic-filled networks showed that the addition of thermoplastic reduces the development of residual stresses, whatever the system, is homogeneous or biphasic.

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“…Figure 2 shows that a good agreement is found between T g and T ␣ values at sufficiently large MI content, as already reported for various amorphous systems. 6,7,22,23 On the other hand, this agreement fails at MT mol fractions larger than 0.7, because T ␣ [MTS] is unambiguously larger than T g [DSC] for I1 and I2. It is worth noticing that a broadening of the EЈ peak accompanies in these cases its reduction in amplitude, which is associated with the presence of crystalline domains in the samples.…”

Section: Glass Transition and Mechanical Relaxationsmentioning

confidence: 96%

“…Recently, a further stage was passed, thanks to the study of different series of methylmethacrylate-based random copolymers, 6,7 including either styrene units, 6 or N-substituted maleimide rings, 6,7 or N-methyl glutarimide rings 7 as the comonomer. The strain-softening amplitude, SSA (which is defined as the difference between the yield stress, y , and the plastic flow stress, pf , in compression testing) was shown to be strongly related to the possible coupling between the ␤ secondary transition and the glass transition motions.…”

Section: Introductionmentioning

confidence: 99%

On the viscoelastic and plastic behavior of semiaromatic polyamides

Choe

Brûlé

Bisconti³

et al. 1999

J. Polym. Sci. B Polym. Phys.

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Different semiaromatic polyamides (SAPA) have been synthesized by step‐growth polymerization of an aliphatic diamine, M (the 2‐methyl 1,5‐pentanediamine), and isophthalic acid, I, or terephthalic acid, T, or mixtures of these two diacids. The influence of the relative amount of randomly distributed MT units on the viscoelastic properties of the materials was investigated. It was shown that the glass transition Tg, as deduced from DSC thermograms, and the relevant mechanical relaxation Tα raise when the content of MT units increases. In contrast, the broad low‐temperature secondary relaxation, called γ, does not markedly depend on the MT content. Samples systematically studied in the absence of any moisture did not exhibit the intermediate‐temperature secondary relaxation, called β, which is characteristic of the wet polyamides. The study of the plastic behavior was focused on the samples MI and I5, which are strictly amorphous, and contain 0% and 50 mol % of MT units, respectively. Mechanical experiments were carried out in both the compression and traction modes, at temperatures ranging from −80°C to Tg. Analysis of the compression data was based on the inspection of the temperature dependence of elastic modulus, E(T), yield stress, ςy, plastic flow stress, ςpf, and strain softening ςy − ςpf. Whereas the plots of ςy as a function of temperature, T, reveal some differences between MI and I5 behavior, a unique master curve was obtained by plotting ςy/E(T) vs. T − Tg, which means that the plastic behavior of these materials is controlled by their chain packing in the glassy state. The strain softening profile of MI and I5 is similar to that already reported in the case of brittle vinyl polymers. This observation is consistent with the traction data, which give evidence for the occurrence of the tensile yielding of MI and I5 at temperatures rather close to Tg. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1131–1139, 1999

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On the plastic and viscoelastic behavior of methylmethacrylate‐based random copolymers

Cited by 37 publications

References 27 publications

Kinetics for copolymerization of methyl methacrylate withN-cyclohexylmaleimide

Kinetics for copolymerization of methyl methacrylate withN-cyclohexylmaleimide

Relationships between thermally induced residual stresses and architecture of epoxy-amine model networks

On the viscoelastic and plastic behavior of semiaromatic polyamides

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