Effect of morphology on stress relaxation of polypropylene

Attalla, G.; Guanella, I.; Cohen, Robert E.

doi:10.1002/pen.760231605

Cited by 28 publications

(11 citation statements)

References 5 publications

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“…The apparent activation energies calculated from the slope of the regression curve were found to be 188 and 148 kJ · mol − 1 for UD and CP laminates, respectively. These values are comparable to that of Attalla et al (163–221 kJ · mol − 1 , depending on the experimental conditions),33 Wada (167 kJ · mol − 1 )34 and Dutta and Edward (200 kJ · mol − 1 ) 32. Our results are also in close agreement to that of Alcock et al 35 who reported that activation energies of ≈300 and ≈100 kJ · mol − 1 for their woven all‐PP composites were necessary to shift the dynamic flexural modulus and tensile strength master curves, respectively.…”

Section: Resultssupporting

confidence: 90%

Flexural Creep Behavior of Unidirectional and Cross‐Ply All‐Poly(propylene) (PURE®) Composites

Banik

Abraham

Karger‐Kocsis

2007

Macro Materials & Eng

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The long‐term viscoelastic behavior of reinforced all‐poly(propylene) composites was studied by flexural creep tests. Both unidirectional and cross‐ply laminates were prepared from PURE® coextruded tapes by vacuum bag molding in an autoclave. The specimens were subjected to isothermal creep tests at different temperatures ranging from 20 to 80 °C under an applied load. The time‐temperature superposition principle was verified for the creep data. An Arrhenius type relationship was found to better describe the shift data obtained from the creep tests. The activation energies relating to the different reinforcement architecture and different relaxation process were calculated.magnified image

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Section: Resultssupporting

confidence: 90%

Flexural Creep Behavior of Unidirectional and Cross‐Ply All‐Poly(propylene) (PURE®) Composites

Banik

Abraham

Karger‐Kocsis

2007

Macro Materials & Eng

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“…This average activa- Figure 5 are plotted against the inverse temperature in Figure 7. It appears that the data may be tion energy is comparable with that of Attalla et al 28 (163-221 kJ/mol depending on the expericrudely described in terms of an activation energy Q defined by eq. (7).…”

Section: Shift Factor and Apparent Activation Energysupporting

confidence: 72%

“…It is important to note mainly to the large response variable values, leading to a misleading nonlinear regression analysis. that Attalla et al 28 observed experimentally that the activation energies for iPP were essentially…”

Section: Shift Factor and Apparent Activation Energymentioning

confidence: 94%

“…chanical analysis has always revealed two main transitions. 28,32,41 The highest temperature peak The parameters used for the single-relaxation nonlinear regression analysis were Dh Å 1 (the (a) in iPP is said to be associated with a crystalline phase-related relaxation (inter-or intracrysrelative strength of the relaxation) and Q Å 200 kJ/mol (the activation energy calculated from lintalline motion origin). This broad relaxation (lying from 40ЊC to higher than 100ЊC) is a complex ear regression).…”

Section: Shift Factor and Apparent Activation Energymentioning

confidence: 99%

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Generic relaxation spectra of solid polymers. I. Development of spectral distribution model and its application to stress relaxation of polypropylene

Dutta

Edward

1997

J. Appl. Polym. Sci.

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An important aspect of designing polymeric articles for engineering applications and predicting their properties over their lifetime is the computation of their time-dependent viscoelastic behavior. A simplified numerical computational technique based on a Gaussian spectral distribution model was developed to describe this behavior over a wide range of time and temperature. The model was used to describe the stressrelaxation behavior of isotactic polypropylene (iPP) over a wide range of strain, time, and temperature. It appears that a spectrum with two components (one distribution for the amorphous zone and the other for the crystalline zone) is sufficient to describe the viscoelastic behavior of iPP. The parameters specifying the distributions (mean relaxation time, standard deviation, and relaxation strength) may be obtained by nonlinear regression analysis and the temperature dependence of the distributions may be evaluated experimentally. An excellent fit between experimental data and the mathematical model is observed. The method may be applied generally for any linear viscoelastic property (e.g., static and dynamic relaxation and creep in tensile or shear) and for any polymer.

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“…The activation energy values are listed in Table 1. This data are in harmony with other works [17,20,22,23].…”

Section: Resultssupporting

confidence: 90%

Effect of consolidation on the flexural creep behaviour of all-polypropylene composite

Izer

Bárány

2010

Express Polym. Lett.

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Abstract. The long-term viscoelastic behaviour of self-reinforced polypropylene composites (SRPPC) was studied by short-term flexural creep tests at different temperatures. As reinforcement a fabric, woven from highly stretched split PP yarns, whereas as matrix materials α and β crystal forms of isotactic PP homopolymer and random copolymer (with ethylene) were selected and used. The composite sheets were produced by film-stacking method and compression moulded at different processing temperatures (5, 20, 35°C above the melting temperatures of the matrices) keeping the holding time and pressure constant. The manufactured specimens were subjected to isothermal creep tests at different temperatures ranging from -20 to 80°C under an applied load. The time-temperature superposition principle was verified for the creep data. An Arrhenius type relationship described the shift data obtained from the creep tests. It was found, that with improving consolidation (increasing processing temperature) the creep compliance decreased and good correlation was found between creep compliance and density/peel strength.

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Effect of morphology on stress relaxation of polypropylene

Cited by 28 publications

References 5 publications

Flexural Creep Behavior of Unidirectional and Cross‐Ply All‐Poly(propylene) (PURE®) Composites

Flexural Creep Behavior of Unidirectional and Cross‐Ply All‐Poly(propylene) (PURE®) Composites

Generic relaxation spectra of solid polymers. I. Development of spectral distribution model and its application to stress relaxation of polypropylene

Effect of consolidation on the flexural creep behaviour of all-polypropylene composite

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