Effect of intermolecular interactions on the viscoelastic behavior of unentangled polyamide melts

Martins, António; Bocahut, Anthony; Michon, Marie-Laure; Sotta, Paul

doi:10.1122/1.5060713

Cited by 3 publications

(4 citation statements)

References 47 publications

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“…M n is around 10000 g mol À1 for Polyamide A and B and around 6000 g mol À1 for Polyamide C whereas PPA whereas M w is around 30000 g mol À1 for Polyamide A, B and C. M n and M w were used to calculate the polydispersity index I p (see Table 1). As explained by Martins et al [16], secondary reactions may occur during polymer synthesis. These secondary reactions lead to branched chains in small proportions and, possibly, may explain why the polydispersity index varies from 3.0 to 5.1 [16].…”

Section: Methodsmentioning

confidence: 96%

“…As explained by Martins et al [16], secondary reactions may occur during polymer synthesis. These secondary reactions lead to branched chains in small proportions and, possibly, may explain why the polydispersity index varies from 3.0 to 5.1 [16]. As observed in Table 1, the values of polydispersity are larger than 2, which is the value expected by Flory's theory for linear polycondensation [16,17].…”

Section: Methodsmentioning

confidence: 96%

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Mechanical properties of amorphous and semi-crystalline semi-aromatic polyamides

Djukic

Bocahut

Bikard

et al. 2020

Heliyon

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We investigate the mechanical properties of amorphous and semi-crystalline semi-aromatic polyamides, polyphthalamides (PPA). Three relaxation processes have been identified by DMTA which is consistent with literature for polyamide. PPA exhibit a brittle-to-ductile transition from a low impact strength to a high impact strength. At room temperature, all the studied PPA are brittle. During both tensile and compression experiments, a strain hardening behavior is observed for all the studied samples and is more pronounced in compression. The testing temperature has an influence on the strain hardening modulus, contrary to the crystallinity. Strain hardening gives properties of stability and resistance to damage.

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Section: Methodsmentioning

confidence: 96%

Section: Methodsmentioning

confidence: 96%

Mechanical properties of amorphous and semi-crystalline semi-aromatic polyamides

Djukic

Bocahut

Bikard

et al. 2020

Heliyon

Self Cite

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“…In the last decade, the interest in experimental studies of end-functionalized linear polymer systems has increased considerably, − especially inasmuch as they provide well-characterized examples of much larger class materials of “self-assembled polymers”. The terminology of self-assembling applies to any flexible and cylindrical polymeric superstructure or polymer-like materials, which are obtained by the aggregation of one or more type of molecules in solution or in melt or reversible linear polymerization.…”

Section: Introductionmentioning

confidence: 99%

Microstructural Capture of Living Ultrathin Polymer Brush Evolution via Kinetic Simulation Studies

et al. 2020

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Performing dynamic off-lattice multicanonical Monte Carlo simulations, we study the statics, dynamics, and scission–recombination kinetics of a self-assembled in situ-polymerized polydisperse living polymer brush (LPB), designed by surface-initiated living polymerization. The living brush is initially grown from a two-dimensional substrate by end-monomer polymerization–depolymerization reactions through seeding of initiator arrays on the grafting plane which come in contact with a solution of nonbonded monomers under good solvent conditions. The polydispersity is shown to significantly deviate from the Flory–Schulz type for low temperatures because of pronounced diffusion limitation effects on the rate of the equilibration reaction. The self-avoiding chains take up fairly compact structures of typical size R g(N) ∼ N ν in rigorously two-dimensional (d = 2) melt, with ν being the inverse fractal dimension (ν = 1/d). The Kratky description of the intramolecular structure factor F(q), in keeping with the concept of generalized Porod scattering from compact particles with fractal contour, discloses a robust nonmonotonic fashion with q d F(q) ∼ (qR g)−3/4 in the intermediate-q regime. It is found that the kinetics of LPB growth, given by the variation of the mean chain length, follows a power law ⟨N(t)⟩ ∝ t 1/3 with elapsed time after the onset of polymerization, whereby the instantaneous molecular weight distribution (MWD) of the chains c(N) retains its functional form. The variation of ⟨N(t)⟩ during quenches of the LPB to different temperatures T can be described by a single master curve in units of dimensionless time t/τ∞, where τ∞ is the typical (final temperature T ∞-dependent) relaxation time which is found to scale as τ∞ ∝ ⟨N(t = ∞)⟩5 with the ultimate average length of the chains. The equilibrium monomer density profile ϕ(z) of the LPB varies as ϕ(z) ∝ ϕ–α with the concentration of segments ϕ in the system and the probability distribution c(N) of chain lengths N in the brush layer scales as c(N) ∝ N –τ. The computed exponents α ≈ 0.64 and τ ≈ 1.70 are in good agreement with those predicted within the context of the Diffusion-Limited Aggregation theory, α = 2/3 and τ = 7/4.

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“…Blends of PA with rubbers have been extensively studied in order to obtain new materials with good impact properties (thermoplastic elastomers). [1][2][3][4][5] An appropriate range of rubber particle size and uniform distribution of rubber particles in PA phases are requirements to reinforce PA/rubber blends.…”

Section: Introductionmentioning

confidence: 99%

In Situ Compatibilization of Polyamide 6/Carboxylated Acrylonitrile Butadiene Rubber Blends with Polyhedral Oligomeric Silsesquioxane

Alcântara

Sirqueira

Santos

et al. 2020

Macromolecular Symposia

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The aim of the study is to prepare thermoplastic elastomer composites of polyamide (PA6) with carboxylated acrylonitrile butadiene rubber (XNBR), compatibilized with polyhedral oligomeric silsesquioxane with epoxy groups (POSS‐epoxy). The addition of POSS‐epoxy, particularly 3.5 phr, improved the specialty characteristics of the PA/XNBR thermoplastic‐elastomer blend. The PA/POSS/XNBR mainly showed a considerable improvement in the elastic torque. The in situ compatibilization is confirmed by density and oil swelling analyses. The structural property relationships of the vulcanized thermoplastic, measured by XRD, DSC and Raman spectroscopy, revealed there are changes in the chemical structure induced by the molecular interactions of PA‐POSS‐XNBR. The Raman spectra confirmed the presence of silane in the PA/XNBR blend. The crystallinity results obtained from the XRD spectra of the PA/XNBR blend are modified by the POSS‐epoxy, corroborating the oil swelling results.

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Effect of intermolecular interactions on the viscoelastic behavior of unentangled polyamide melts

Cited by 3 publications

References 47 publications

Mechanical properties of amorphous and semi-crystalline semi-aromatic polyamides

Mechanical properties of amorphous and semi-crystalline semi-aromatic polyamides

Microstructural Capture of Living Ultrathin Polymer Brush Evolution via Kinetic Simulation Studies

In Situ Compatibilization of Polyamide 6/Carboxylated Acrylonitrile Butadiene Rubber Blends with Polyhedral Oligomeric Silsesquioxane

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