Microdeformation mechanisms in methyl methacrylate-glutarimide random copolymers

Plummer, C. J. G.; Kausch, H. H.; Tézé, L.; Halary, Jean Louis; Monnerie, L.

doi:10.1016/0032-3861(96)00231-5

Cited by 16 publications

(8 citation statements)

References 23 publications

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“…By contrast, SSA present large values when the ␣ and ␤ motions do not involve the same chain units or subunits (aged polymethylmethacrylate, maleimide copolymers, methylmethacrylate-rich glutarimide copolymers, and styrene copolymers). Similar correlations have also been established between the ␣-␤ coupling and the nature of thinfilm deformation micromechanisms: 8,9 diffuse deformation zones are favored at the expense of crazes as long as ␣-precursor motions develop. Interestingly, these findings seem to hold while considering the fracture behavior of bulk samples.…”

Section: Introductionmentioning

confidence: 52%

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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Section: Introductionmentioning

confidence: 52%

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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“…The characteristic dependence of the time t to failure on the acting stress, ΔK≈t 1/4 , and the strong effect of increasing MW on t point to the role of disentanglement as principle damage mechanism [20,108]. This conclusion [99]. The so-called mid-rib can be well distinguished in all these structures Fig.…”

Section: The 1970s: Continued Progress Through New Concepts Materialmentioning

confidence: 99%

“…These mechanisms can be observed with many glassy polymers during craze formation at different temperatures. Figure 10 shows the structure of crazes in MMA-glutarimide resulting from these mechanisms [99].…”

Section: The 1970s: Continued Progress Through New Concepts Materialmentioning

confidence: 99%

Eighty years of macromolecular science: from birth to nano-, bio- and self-assembling polymers—with slight emphasis on European contributions

Schmeling

2011

Colloid Polym Sci

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A definition of macromolecular science (as opposed to polymer science and engineering) is given, from which the year 1930 is derived as the year of its birth. The scope of treatment of this paper will be limited to solid technical polymers. Some important discoveries of polymer technology in the nineteenth century are reviewed together with the reason why the concept of macromolecules and the theory of rubber elasticity did not emerge earlier. The role of chain backbones in structure formation and mechanical loading of technical polymers has been heavily discussed ever since and has attracted this author for most of his scientific work. He offers a personal perspective of the most important achievements in three domains of macromolecular science: the synthesis of well-designed chain molecules, structural characterization and the understanding of the micro-mechanics of (nano-structured) polymer materials. Progress is generally documented by citing individual references from the discussed periods-well knowing that the development of science is due to the contributions of many more people. In conclusion, a critical outlook will be attempted on future trends in the design and application of well-adapted-and frequently complex-polymer systems towards growing human needs.

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“…Random copolymers of methylmethacrylate (MMA) also provide a convenient way to investigate the contribution of molecular parameters to the contact fatigue behaviour of glassy amorphous polymers. Extensive mechanical characterization by Halary and co-workers [87][88][89][90][91][92] showed that the incorporation of various amounts of glutarimide or N-substituted maleimide units as a co-monomer of MMA (Table 3) can result in strong changes in the plastic behaviour and deformation modes. At the molecular level, these modifications were mostly attributed to changes in the cooperative motions involved in the temperature range situated immediately above the sub-T g β relaxation, which are considered precursors of the α-relaxation [90].…”

Section: Copolymers Of Methylmethacrylatementioning

confidence: 99%

“…Addition of increas-Table 3 Formulae of the random copolymers of methylmethacrylate ing amounts of maleimide was shown to induce a decoupling of the α and β relaxation, which was associated with a marked embrittlement of the materials. Conversely, increased contents in glutarimide units tended to enhance the cooperative motions involved in yielding with some consequences on the competition between scission crazing, shear deformation and disentanglement crazing in these materials [92]. Homologous series of MMA-glutarimide (GIM) or MMA-maleimide (MIM) copolymers therefore offer the possibility of tuning the fracture properties from a ductile to a brittle behaviour, while keeping the elastic and plastic properties almost unchanged (Table 4).…”

Section: Copolymers Of Methylmethacrylatementioning

confidence: 99%

Fracture of Glassy Polymers Within Sliding Contacts

Chateauminois

Baietto

2005

Intrinsic Molecular Mobility and Toughness of Polymers II

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Cracking processes in brittle amorphous polymers within sliding contacts and their relationships with bulk fracture properties are reviewed. The focus is on the use of model single asperity contacts to mimic and characterize the failure modes which can be encountered at the microasperity level during the wear of macroscopic rough contacts between polymer surfaces and rigid counterfaces. Using the resources of in situ contact visualization, crack initiation and propagation mechanisms within epoxy substrates are detailed under contact fatigue conditions. With the prospect of understanding the fundamental mechanisms involved in particles detachment from brittle polymer surfaces, it is shown how cracks locations, orientations and depths can be predicted from a knowledge of the bulk toughness and fatigue properties of the polymer by means of a fracture mechanics analysis of the contact. In the last section, the sensitivity of contact fatigue processes to molecular parameters is addressed in the case of anti-plasticized epoxy networks and random copolymers of poly(methylmethacrylate).

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Microdeformation mechanisms in methyl methacrylate-glutarimide random copolymers

Cited by 16 publications

References 23 publications

On the viscoelastic and plastic behavior of semiaromatic polyamides

On the viscoelastic and plastic behavior of semiaromatic polyamides

Eighty years of macromolecular science: from birth to nano-, bio- and self-assembling polymers—with slight emphasis on European contributions

Fracture of Glassy Polymers Within Sliding Contacts

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