Claudio Javier Pérez

Fracture behavior of a commercial starch/polycaprolactone blend reinforced with different layered silicates

In the present work, composites based on a commercial starch/PCL blend (MaterBi-Z) reinforced with three different nanoclays: natural montmorillonite (Cloisite Na(+) (MMT)) and two modified montmorillonites (Cloisite 30B (C30B) and Cloisite 10A (C10A)) were prepared in an intensive mixer. The aim of this investigation was to determine the effect of the different nanoclays on the quasi-static fracture behavior of MaterBi-Z nanocomposites. An improvement in the fracture behavior for the composite with low contents of C30B was obtained, probably due to the easy debonding of clay achieved from a relatively weak filler-matrix interaction. On the other hand, a strong interaction had a detrimental effect on the material fracture toughness for the MaterBi-Z/C10A composites as a result of the higher compatibility of this organo-modified clay with the hydrophobic matrix. Intermediate values of fracture toughness, determined using the J-integral approach (Jc), were found for the composites with MMT due to its intermediate interaction with the matrix. The different filler-matrix interactions observed were also confirmed from the application of Pukánszky and Maurer model. In addition, multifractal analysis was applied to describe the topography of fracture surfaces. Thus, the complex fracture process could be successfully described by both experimental and theoretical tools. The obtained results suggest that it is possible to tailor the mechanical properties of the studied composites taking into account their further application.

Non-isothermal crystallization of biodegradable polymer (MaterBi)/polyolefin (PP)/hemp fibres ternary composites

The non-isothermal crystallization of biodegradable thermoplastic matrix (Mater-Bi®, MB) and traditional thermoplastic (polypropylene, PP) blends was studied using differential scanning calorimetry (DSC). Hemp fibres were used as filler, and maleic anhydride functionalized polypropylene (PP*) was employed as compatibilizer. MB forms immiscible blends with PP. Both, molten MB act as nucleating agent enhancing the crystallization rate of PP and the solidified PP act as nucleating agent to enhance the crystallization of MB. The values of half-time of crystallization (t1/2) and the parameter Zc, from Avrami’s method which characterize the kinetics of non-isothermal crystallization, showed that the crystallization rate, at the same cooling rate, decreased with the fibres and increased with the PP*; showing the retarding and accelerating effects, respectively. Some models, such as the Liu-Mo and Avrami, were found to provide a fairly satisfactory description of the crystallization kinetics of the studied blends. These results are further supported by the effective activation energy calculations by iso-conversional method of Friedman.

Preparation and characterization of micro and nanocomposites based on poly(vinyl alcohol) for packaging applications

In the present work, micro and nano composites based on poly(vinyl alcohol) matrix reinforced with cellulose (micro) and bentonite (nano) were obtained by film casting. The resulting composite materials were characterized by means of differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction, FTIR spectroscopy, water absorption, permeability, and mechanical tests. The effect of the micro and nano fillers on the thermal, mechanical, and water absorption properties of the matrix was determined. The effects of polymer molecular weight and processing steps were also studied. Based on the results of the work, the potential biodegradability and the low cost of the starting materials, it can be concluded that the produced materials may be promising for packaging applications.

Ternary composites based on HDPE and Mater-Bi reinforced with hemp fibres

The non-isothermal crystallization process of biodegradable thermoplastic matrix (Mater-Bi®, MB) and traditional thermoplastic (high-density polyethylene, polyethylene, PE) blends was studied using differential scanning calorimetry (DSC). Hemp fibres were used as filler, and maleic anhydride-functionalized high-density polyethylene

Creep behaviour of layered silicate/starch–polycaprolactone blends nanocomposites

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A comparative study of the effect of different rigid fillers on the fracture and failure behavior of polypropylene based composites

(PE∗) was employed as compatibilizer. SEM micrographs but also DSC studies show that MB forms immiscible blend with PE. The dispersed phase of molten MB acts as nucleating agent of PE enhancing the crystallization rate of PE, and also the solidified PE acts as nucleating agent by fastening the crystallization of MB. The values of half-time of crystallization (t1/2) and the Zc parameter from Avrami’s method showed that for a fixed cooling rate, the crystallization rate decreased with the incorporation of hemp fibres and with the addition of the compatibilizer,

Correction of optical distortions in dry depth profiling with confocal Raman microspectroscopy

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