Mechanical loss peaks of polypropylene/EPDM blends in relation to their fracture toughness and impact strength

Karger‐Kocsis, J.; Kiss, L. F.; Кулезнев, В. Н.

doi:10.1002/actp.1982.010330103

Cited by 35 publications

(25 citation statements)

References 18 publications

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“…These results clearly indicate, in the viscosity ratio range used in this work, that the dispersed EPDM phase in EPDM/PP blends forms nano-scale fibers and challenges the current view of EPDM being dispersed as spherical particles in PP [18][19][20][51][52][53][54].…”

Section: Epdm Minor Phasementioning

confidence: 77%

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Continuity development in polymer blends of very low interfacial tension

Bhadane

Champagne

Huneault

et al. 2006

Polymer

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Continuity development in polymer blends of very low interfacial tension AbstractPhase continuity development and co-continuous morphologies are highly influenced by the nature of the interface in immiscible polymer blends. Blends of ethylene-propylene-diene terpolymer (EPDM) and polypropylene (PP) possess an interfacial tension of about 0.3 mN/m and provide an interesting model system to study the detailed morphology development in a very low interfacial tension binary system. A variety of blends with viscosity ratios of 0.2-5.0 and shear stresses of 11.7-231.4 kPa were considered. Using a variety of sophisticated morphology protocols it is shown that at low blend compositions, the dispersed phase actually exists as stable fibers of extremely small diameter of 50-200 nm and the continuity develops by fiber-fiber coalescence. An analysis using break-up times from Tomotika theory also supports the notion of highly stable dispersed fiber formation. These results challenge the current view of the dispersed phase as small spherical droplets. It is shown, under these conditions, that a seven-fold variation in the viscosity ratio has virtually no influence on % continuity or morphology, while a large change in the matrix shear stress from 11.7 to 90.9 kPa has an important effect on pore diameter. Both sides of the continuity diagram are studied and highly symmetrical continuity behavior is observed with composition. In fact a single master continuity curve is observed for these blends varying in viscosity ratio from 0.7-5.0 and with shear stresses from 11.7-90.9 kPa. Although the glass transition temperatures indicate that these materials are completely immiscible after melt mixing and cooling, it is shown that the blends demonstrate the morphological features of a partially miscible system. These results support a concept that the blend was partially miscible during melt blending, at which time the gross morphological features of the blend were developed, but becomes fully phase separated upon cooling. It appears that the quenching of the EPDM/PP blend from the melt is rapid enough to preserve the imprint of that partial miscibility on the gross blend morphology. q

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Section: Epdm Minor Phasementioning

confidence: 77%

“…Typically in the literature, low concentrations of dispersed EPDM in PP blends are considered to be composed of spherical droplets dispersed in a PP matrix [18][19][20][51][52][53][54]. However, it is very difficult to infer the shape of the minor phase from 2-dimensional micrographs.…”

Section: Epdm Minor Phasementioning

confidence: 99%

Continuity development in polymer blends of very low interfacial tension

Bhadane

Champagne

Huneault

et al. 2006

Polymer

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“…Figure 5 shows a pronounced local maximum at 10 8C in the temperature dependence of the fracture toughness K Ic measured at quasi-static loading, which is clearly correlated with the glass transition, that is, the a relaxation. This maximum, which has also been found for PP/ethylene propylene diene monomer rubber (EPDM) blends, [51] is load-determined because it exists as a function of temperature in the relation K I ¼ f(T) but not in the crack-tip-opening displacement. (In the relation G Id ¼ f(T) for PP/EPDM, such a maximum occurs at room temperature.)…”

Section: Pp Materialsmentioning

confidence: 99%

Time‐ and Temperature‐Dependent Fracture Mechanics of Polymers: General Aspects at Monotonic Quasi‐Static and Impact Loading Conditions

Lach

Grellmann

2008

Macro Materials & Eng

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Well‐defined correlations exist between the maxima in mechanical loss factor and the local maxima in temperature‐ or loading‐speed‐dependent fracture toughness. The non‐linear viscoelastic fracture processes and small‐strain deformations are characterised by the same Arrhenius‐type activation enthalpies. The local increase in toughness is linearly correlated with the relaxation strength of molecular relaxation processes. Stable crack propagation can be understood as a three‐phase process resulting in steady‐state stable crack growth. The normalised steady‐state crack‐tip‐opening displacement is independent of matrix material, temperature and loading speed.magnified image

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“…Recording of dynamic mechanical analysis (DMA) spectra followed the known techniques 23 under the following conditions. • Thickness of compression molded plate specimen was 2.5 mm.…”

Section: Dynamic Mechanical Analysismentioning

confidence: 99%

Structure and properties of impact copolymer polypropylene. II. Phase structure and crystalline morphology

Hongjun

Luο

Xiangxu

et al. 1999

J. Appl. Polym. Sci.

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In this work, an impact copolymer polypropylene (ICPP) was separated into 4 fractions, A, B, C, and D. The phase structure, thermal behavior, and crystalline morphology of the ICPP and its 4 fractions were studied thoroughly using scanning electron microscopy (SEM). Dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and polarized light microscopy (PLM). Results of SEM and DMA show that ethylene-propylene rubber (EPR) and part of the ethylene-propylene segmented copolymer disperse as toughening particles in the ICPP. The size and size distribution of these particles are determined by chain structure of the fractions of ICPP. From fraction A to fraction D, the morphology changes from noncrystalline to semicrystalline gradually, as shown by DSC. DSC results also indicate that thermal behavior of the ICPP agrees greatly with its chain structure. PLM demonstrates that it is difficult for the ICPP to grow perfect spherulites, that is, partially, because the matrix of ICPP, fraction D, has defects in its macromolecular chain. Another cause is that there is a good compatible structure in the ICPP and so the noncrystalline component (including all fractions) hinders the growth of the spherulite.

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Mechanical loss peaks of polypropylene/EPDM blends in relation to their fracture toughness and impact strength

Cited by 35 publications

References 18 publications

Continuity development in polymer blends of very low interfacial tension

Continuity development in polymer blends of very low interfacial tension

Time‐ and Temperature‐Dependent Fracture Mechanics of Polymers: General Aspects at Monotonic Quasi‐Static and Impact Loading Conditions

Structure and properties of impact copolymer polypropylene. II. Phase structure and crystalline morphology

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