Ultra-violet degradation of polypropylene: 2. Residual strength and failure mode in relation to the degraded surface layer

Schoolenberg, G.E.; Meijer, HA

doi:10.1016/0032-3861(91)90447-q

Cited by 43 publications

(16 citation statements)

References 3 publications

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“…on the chains in the amorphous phase induces the formation of tensile residual stresses [37,38] . In addition, the presence of surface cracks, as seen previously on SEM micrographs (Figure 5), can be considered as one of the reasons for the embrittlement of the material, causing a serious deterioration in the mechanical properties of the products even after short term exposures [19] . Consequently, the presence of these cracks facilitates the failure.…”

Section: Effect Of Uv-irradiation On the Mechanical Properties Of Tramentioning

confidence: 68%

“…Therefore, the damage caused by UV irradiation is the formation of surface cracks inducing thereafter the embrittlement of the material [19,36] . Figure 5 compares the surface topography of the UV-BMU133 and UV-BMU133-T3-0.1 traced blend respectively.…”

Section: Morphological Propertiesmentioning

confidence: 99%

“…The most important practical consequence of chemi-crystallization is the formation of cracks caused by contraction of the surface layers [18] . The presence of surface cracks is indeed one of the main reasons for the embrittlement of ductile semi-crystalline polymers such as PP, causing serious deterioration in the mechanical properties of the polymer after short-term exposures [16,19] . In order to decrease the UV degradation and extend the lifetime of PP polymer, there is a growing interest in adding UV screeners to bulk polymers during processing.…”

Section: Introductionmentioning

confidence: 99%

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Photodegradation of a polypropylene filled with lanthanide complexes

Massardier

Louizi

2015

Polímeros

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SbstractThis research aims at studying the photodegradation of a polypropylene formulation filled with lanthanide complexes. These complexes can be used as tracers for the identification of polymer materials in order to facilitate an high speed automatic sorting of plastic wastes for an economically efficient recycling. By paying attention to the evolution of carbonyl absorption bands in FTIR spectra, it is observed that the addition of lanthanide complexes into our formulation improves UV stability of polypropylene by reducing the extent of photo-degradation. Furthermore, TG analyses show that the traced blends can maintain better thermal properties, after irradiation. A significant increase of the crystallinity degree and a decrease of the melting temperature are more pronounced for the unfilled UV-irradiated PP. This might result from chemi-crystallization that can occur when chain entanglements are broken as a result of chain scissions. From SEM analyses, it is observed that the severity of surface cracks induced by photo degradation is reduced for filled PP. The mechanical tests are in agreement with this result and show a fundamental change in the behavior of the as-exposed blends from a ductile to a brittle material.

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Section: Effect Of Uv-irradiation On the Mechanical Properties Of Tramentioning

confidence: 68%

Section: Morphological Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Photodegradation of a polypropylene filled with lanthanide complexes

Massardier

Louizi

2015

Polímeros

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“…Thus, this additive can be reused after further purification if necessary, increasing its added-value. of chain scission [15,54,55] and the effect of chemi-crystallisation, which is responsible of the surface cracking by contraction of surface layers, causing grave weakening in different properties of the samples after short-term exposures [54,55].…”

Section: Thermal Stabilitymentioning

confidence: 99%

Novel silicon microparticles to improve sunlight stability of raw polypropylene

Cháfer

Badía

Teruel-Juanes

et al. 2015

European Polymer Journal

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a b s t r a c tOxidation of polyolefins by ultraviolet/visible irradiation is a significant limitation for their use in several technological applications. The use of high-tech additives such as silicon microparticles becomes a compositing strategy that can improve the performance of these materials at long-term service conditions. Silicon particles were added to non-additivated raw polypropylene (PP) prepared by hot melt extrusion and subjected to accelerated sunlight irradiation tests. The stability of thermal properties, mechanical performance and thermal decomposition behaviour of composites was evaluated by differential scanning calorimetry, dynamic mechanical-thermal analysis and thermogravimetry. This paper shows the potential of silicon microparticles to protect PP from degradation during both processing and accelerated sunlight irradiation. The addition of polydisperse silicon microparticles to the raw polypropylene preserved the appearance and improved the thermal behaviour, mechanical properties and thermal stability. It was found that silicon particles at 5 wt% provided a suitable protection of raw non-additivated PP against sunlight irradiation.

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“…when the surface material is modified by environmental ageing or by shear in injection moulding. In the first case, a brittle layer forms at the surface due to oxidation, ultraviolet radiation, exposure to elevated temperature, or stress cracking agents (Schoolenberg and Meijer (1991)). Injection moulding may form skin layers which are more rigid and tougher in the flow direction than the core material.…”

Section: Introductionmentioning

confidence: 99%

Effect of skin fracture on failure of a bilayer polymer structure

Godart

Leevers

2007

Int J Fract

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A thin skin of low tensile failure strain, if bonded to the tensile surface of an unnotched impact bend specimen of much tougher material, can change the global failure mode from ductile to brittle. A novel model of this well-known effect is developed and applied to results from impact tests on a tough core of polyamidepolyethylene blend, with a single skin of brittle EVOH. At a fixed crosshead speed, notched specimens of the blend become brittle at a relatively low temperature T bt . Un-notched bilayer specimens continue to show skin fracture up to a considerably higher temperature T fs ; above this temperature they do not fail at all but below T bt they too fail in a brittle manner. Within the temperature range from T fs down to T bt there is a transition from crack arrest, either at the skin/core interface or further into the core where a crack would not normally propagate, to brittle fracture. This brittle fracture temperature is predicted by modelling the process as a three-phase impact event. In the first phase, the striker bends the bilayer quasi-statically. The second phase begins with instantaneous fracture of the skin at its failure strain. The skin ends retract at finite speed, and a craze grows in the adjacent core material to accommodate the local strain singularity. The last phase is a striker-driven impact event similar to that in a notched bend specimen of the core material, except that the crack-tip craze already bears the adiabatic temperature distribution generated while it was driven open by skin retraction. The criterion for craze decohesion, and hence for a crack jump, is the same adiabatic decohesion criterion which accounts for the speed-dependence of impact fracture in notched monolayer specimens. Applied computationally, this model predicts whether a bilayer structure fails in a brittle way or whether cracks initiated in the skin are arrested, either temporarily or permanently, at the skin/core interface.

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Ultra-violet degradation of polypropylene: 2. Residual strength and failure mode in relation to the degraded surface layer

Cited by 43 publications

References 3 publications

Photodegradation of a polypropylene filled with lanthanide complexes

Photodegradation of a polypropylene filled with lanthanide complexes

Novel silicon microparticles to improve sunlight stability of raw polypropylene

Effect of skin fracture on failure of a bilayer polymer structure

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