Tensile properties and stress relaxation of polypropylene at elevated temperatures

Ariyama, Takashi; Yasunari, Mori; Kaneko, Kenji

doi:10.1002/pen.11647

Cited by 55 publications

(29 citation statements)

References 16 publications

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“…The activation energies calculated from the slope of the regression curve were found to be 348 and 307 kJ·mol -1 for UD and CP lay-ups, respectively. Note that they are of the same order as previously reported in the literature [38][39][40][41]. The activation energy for shifting the master curve for UD is …”

Section: Time-temperature Superposition (Tts)supporting

confidence: 76%

All-PP composites (PURE®) with unidirectional and cross-ply lay-ups: dynamic mechanical thermal analysis

Abraham¹,

Banik²,

Karger‐Kocsis

2007

Express Polym. Lett.

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The original concept of self-reinforced composite, a composite with matrix and reinforcement from the same polymer, was presented by Capiati and Porter [1] three decades ago for high density polyethylene. Later this concept was adopted to polypropylene (PP) [2][3][4][5] [20,21]. Particularly, in a series of recent papers, Alcock and coworkers [22][23][24] described composite materials in which both the reinforcement and the matrix were based on PP. The related composites under the trade name of PURE ® are produced from highly oriented co-extruded tapes having a skin-core-skin (A:B:A) morphology. The skin layer (A) contains a PP random copolymer, whereas the core layer (B) is composed of PP homopolymer.Since the copolymer skin layer has a melting temperature below that of the homopolymer core, selfreinforced (also termed as homocomposites or all-PP composites) PP systems can be produced using a suitable processing window. Note that during consolidation the PP copolymer forms the matrix, while the highly oriented PP homopolymer fraction acts as continuous reinforcement. This approach (i. e. copolymer for the matrix and homopolymer for the reinforcement) can be used to produce all-PP composites using the film stacking technique, as well [25]. The most recent development with all-PP composites is to exploit the polymorphism-related difference in the melting range between the beta-(giving the matrix) and alpha-phases (serving as reinforcement) PPs [26,27]. All-PP composites are characterized by their outstanding mechanical properties at very low density. Their main advantage over conventional glass fiber reinforced ver-519 * Corresponding author, e-mail: karger@ivw.uni-kl.de © BME-PT and GTE Abstract. All polypropylene (all-PP) composite laminates with unidirectional (UD) and cross-ply (CP) lay-ups were produced by hot consolidation from oriented coextruded PP tapes (PURE ® ). The consolidation of the tapes, wound on a steel plate, occurred in autoclave vacuum bag molding. The set processing conditions resulted in all-PP laminates of high rigidity as the PP copolymer surface layers of the tapes were molten and thus forming the matrix, while their PP homopolymer core remained unaffected and thus fulfilled its role as reinforcement. Specimens cut off from the laminates were subjected to dynamic mechanical thermal analysis (DMTA) in a broad temperature range (T = -50…120°C) at various frequencies (f = 10 -2 …10 1 ). For the DMTA results the time-temperature superposition principle was adopted and master curves in the form of storage modulus vs. frequency (f = 10 -9 …10 20 ) and loss factor vs. frequency were created. All-PP composites (PURE

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Section: Time-temperature Superposition (Tts)supporting

confidence: 76%

All-PP composites (PURE®) with unidirectional and cross-ply lay-ups: dynamic mechanical thermal analysis

Abraham¹,

Banik²,

Karger‐Kocsis

2007

Express Polym. Lett.

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“…The nonlinear viscoelastic response of polypropylene was studied by Ward and Wolfe 30 and Smart and Williams, 31 and, more recently, by Ariyama, [32][33][34][35] Wortmann and Schulz, 36,37 Dutta and Edward, 38 and Read and Tomlins. 39,40 In the past couple of years, the linear viscoelastic behavior of isotactic polypropylene was analyzed by Fricova et al, 41 Andreassen, 42 LopezManchado and Arroyo, 43 Gallego Ferrer et al, 44 and Souza and Demarquette, 45 to mention a few.…”

Section: Introductionmentioning

confidence: 97%

Model for the viscoelastic and viscoplastic responses of semicrystalline polymers

Drozdov

Christiansen

2003

J of Applied Polymer Sci

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Constitutive equations are derived for the time-dependent behavior of semicrystalline polymers at isothermal loading with small strains. A semicrystalline polymer at temperatures above the glass-transition point for its amorphous phase is thought of as a network of macromolecules bridged by junctions (physical crosslinks, entanglements, and crystalline lamellae) that can slide with respect to their reference positions in the bulk material under straining. The network is assumed to be highly inhomogeneous, and it is modeled as an ensemble of mesoregions (MRs) with various strengths of interchain interaction. Two types of MRs are distinguished: passive, where these interactions prevent detachment of strands from junctions; and active, where active strands separate from junctions and dangling strands merge with the network at random times as they are thermally agitated. The viscoelastic response of a semicrystalline polymer reflects reformation of strands in active MRs, whereas its viscoplastic behavior is associated with sliding of junctions. Stress-strain relations for uniaxial deformation are developed by using the laws of thermodynamics. Adjustable parameters in the constitutive equations are found by fitting experimental data for isotactic polypropylene in a tensile test with a constant strain rate and in tensile relaxation tests at various strains. Fair agreement is demonstrated between the observations and the results of numerical simulation. It is revealed that the viscoplastic flow of junctions strongly affects the rearrangement process in active MRs, whose rate reaches a threshold value in the vicinity of the apparent yield point.

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“…[3][4][5] Effects of prior strains, 6 as well as the application of different strain rates, have also been studied. 7 Long-term viscoelastic properties have been investigated by using the time-temperature superposition principle. [7][8][9][10][11][12][13] It is well known that these properties significantly govern the applicability of PE and polypropylene (PP).…”

Section: Introductionmentioning

confidence: 99%

“…7 Long-term viscoelastic properties have been investigated by using the time-temperature superposition principle. [7][8][9][10][11][12][13] It is well known that these properties significantly govern the applicability of PE and polypropylene (PP). Nevertheless, in the case of semicrystalline polymers, it is sometimes difficult to obtain satisfactory prediction of a longterm viscoelastic behavior.…”

Section: Introductionmentioning

confidence: 99%

Viscoelastic behavior of semicrystalline polymers at elevated temperatures on the basis of a two-process model for stress relaxation

Djoković

Kostoski

Dramićanin

2000

J. Polym. Sci. B Polym. Phys.

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Tensile properties and stress relaxation of polypropylene at elevated temperatures

Cited by 55 publications

References 16 publications

All-PP composites (PURE®) with unidirectional and cross-ply lay-ups: dynamic mechanical thermal analysis

All-PP composites (PURE®) with unidirectional and cross-ply lay-ups: dynamic mechanical thermal analysis

Model for the viscoelastic and viscoplastic responses of semicrystalline polymers

Viscoelastic behavior of semicrystalline polymers at elevated temperatures on the basis of a two-process model for stress relaxation

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