Adhesion and micromechanical deformation processes in PLA/CaSO4 composites

Imre, Balázs; Keledi, Gergely; Renner, Karl; Móczó, János; Murariu, Marius; Dubois, Philippe; Pukánszky, Béla

doi:10.1016/j.carbpol.2012.04.005

Cited by 29 publications

(24 citation statements)

References 44 publications

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“…The fiber might influence also interphase formation and 6 the mobility of the polymer molecules. We investigated these questions in previous studies in detail (Dora et al 2012;Imre et al 2012;Molnár et al 2009). We found that crystallinity is negligible in PLA, while in PP/wood composites limited aggregation resulted from the mere physical contact of the particles due to geometrical reasons (Dányádi et al 2007).…”

Section: Resultsmentioning

confidence: 99%

“…Biodegradable polymers can be applied in packaging and agriculture, but the application range of compostable materials, including PLA, is even wider, it extends from the electronic to the automotive industry, but it can be used also in construction (Ogawa & Obuchi 2010). Often large stiffness and strength is required from structural materials, thus PLA is often modified with inorganic fillers (Chang et al 2003;Fukushima et al 2010;Fukushima et al 2009;Huda et al 2007;Imre et al 2012;Jiang et al 2007;Kasuga et al 2003;Kim et al 2010;Li et al 2009;Li et al 2008;Lin et al 2007;Luo et al 2009;Marras et al 2007;Molnár et al 2009;3 Murariu et al 2008;Nakayama & Hayashi 2007;Rhim et al 2009;Russias et al 2006;Wang et al 2010;Yuzay et al 2010) and with fibers (Ahmed et al 2011;Chen et al 2010;Haque et al 2010;Huda et al 2006b;Liu et al 2012;Shen et al 2009;Wan et al 2001). The combination of PLA with natural fibers is a convenient way to produce compostable material thus the study of the structure and properties of such composites is of large scientific and practical interest (Bax & Müssig 2008;Bledzki et al 2009;Huda et al 2006a;Huda et al 2008;Huda et al 2005;Mathew et al 2005;Oksman et al 2003;Petersson et al 2007;Petinakis et al 2009;…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Biocomposite from polylactic acid and lignocellulosic fibers: Structure–property correlations

Faludi

Dora

Renner

et al. 2013

Carbohydrate Polymers

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PLA biocomposites were prepared using three corncob fractions and a wood fiber as reference. The composites were characterized by tensile testing, scanning electron (SEM) and polarization optical (POM) microscopy. Micromechanical deformation processes were followed by acoustic emission measurements. The different strength of the components was proved by direct measurements. Two consecutive micromechanical deformation processes were detected in composites containing the heavy fraction of corncob, which were assigned to the fracture of soft and hard particles, respectively.The fracture of soft particles does not result in the failure of the composites that is initiated either by the fracture of hard particles or by matrix cracking. Very large particles debond easily from the matrix resulting in catastrophic failure at very low stresses. At sufficiently large shear stresses large particles break easily during compounding, thus reinforcement depending on interfacial adhesion was practically the same in all composites irrespectively of initial fiber characteristics.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Biocomposite from polylactic acid and lignocellulosic fibers: Structure–property correlations

Faludi

Dora

Renner

et al. 2013

Carbohydrate Polymers

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“…the separation of the interface between the matrix and the reinforcement, several other processes including matrix yielding, the pull-out or fracture of the fibers, cavitation, etc. may also take place during the deformation of the composites (Dányádi et al 2007;Faludi et al 2013a;Imre et al 2012;Renner et al 2007;Renner et al 2010b). Some of these are burst-like processes emitting elastic waves, which can be picked up by appropriate sensors.…”

Section: Interfacial Adhesionmentioning

confidence: 99%

Thermoplastic starch/wood composites: Interfacial interactions and functional properties

Müller

Renner

Móczó

et al. 2014

Carbohydrate Polymers

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Thermoplastic starch (TPS)/wood composites were prepared from starch plasticized with 36 wt% glycerol. The components were homogenized by dry-blending, extruded and injection molded to tensile bars. Tensile properties, structure, deformation, water adsorption and shrinkage were determined as a function of wood content, which changed between 0 and 40 vol% in 7 steps. The modification of TPS with wood particles improves several properties considerably. Stiffness and strength increases, and the effect is stronger for fibers with larger aspect ratio. Wood fibers reinforce TPS considerably due to poor matrix properties and strong interfacial interactions, the latter resulting in the decreased mobility of starch molecules and in the fracture of large wood particles during deformation.Strong interfacial adhesion leads to smaller water absorption than predicted from additivity, but water uptake remains relatively large even in the presence of wood particles. The shrinkage of injection molded TPS parts is very large, around 10 %, and dimensional changes occur on a very long timescale of several hundred hours. Shrinkage decreases to a low level already at 15-20 vol% wood content rendering the composites good dimensional stability.

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“…2. The material was a PLA/CaSO4 model composite, in which only a single micromechanical deformation, debonding occurs [37]. Individual acoustic events are indicated by small circles in the figure.…”

Section: Deformation Mechanismsmentioning

confidence: 99%

Factors determining the performance of thermoplastic polymer/wood composites; the limiting role of fiber fracture

et al. 2014

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Thermoplastic polymer/lignocellulosic fiber composites were prepared with a considerable range matrices and fibers in an internal mixer. Tensile properties were determined on bars cut from compression molded plates. Local deformation processes initiated around the fibers were followed by acoustic emission testing supported by electron and polarization optical microscopy. The analysis of results proved that micromechanical deformation processes initiated by the fibers determine the performance of the composites.Debonding usually leads to the decrease of composite strength, but decreasing strength is not always associated with poor adhesion and debonding. The direction of property change with increasing wood content depends on component properties and interfacial adhesion.Good interfacial adhesion often results in the fracture of the fibers. Depending on their size and aspect ratio fibers may fracture parallel or perpendicular to their axis. At good adhesion the maximum strength achieved for a particular polymer/wood pair depends on the inherent strength of the fibers, which is larger for perpendicular than parallel fracture. Inherent fiber strength effective in a composite depends also on particle size, larger particles fail at smaller stress, because of the larger number of possible flaws in them. A very close correlation exists between the initiation stress of the dominating local deformation process and composite strength proving that these processes lead to the failure of the composite and determine its performance. HIGHLIGHTS-Good interfacial adhesion of components often results in the fracture of fibers.-Inherent strength of wood flour influences strength and performance of composites.-Close correlation between initiation of deformation process and composite strength.

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Adhesion and micromechanical deformation processes in PLA/CaSO4 composites

Cited by 29 publications

References 44 publications

Biocomposite from polylactic acid and lignocellulosic fibers: Structure–property correlations

Biocomposite from polylactic acid and lignocellulosic fibers: Structure–property correlations

Thermoplastic starch/wood composites: Interfacial interactions and functional properties

Factors determining the performance of thermoplastic polymer/wood composites; the limiting role of fiber fracture

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