Composites and nanocomposites
Linda Gouissem
Abstract
This study explores the development of high-density polyethylene (HDPE) composites reinforced with stearic acid-treated expanded perlite (TEP) to examine their thermal, mechanical, and processing properties. The composites were fabricated using a plastograph at 200°C, incorporating perlite concentrations ...
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This study explores the development of high-density polyethylene (HDPE) composites reinforced with stearic acid-treated expanded perlite (TEP) to examine their thermal, mechanical, and processing properties. The composites were fabricated using a plastograph at 200°C, incorporating perlite concentrations from 5% to 20% by volume. The effects of stearic acid (SA) treatment and perlite content were analyzed through SEM, melt flow index (MFI), tensile and impact testing, and thermal analysis (DSC, TGA, and Vicat softening temperature). SEM analysis revealed that untreated perlite exhibited a highly porous structure, while HCl treatment induced fragmentation. At 5% SA, perlite particles were well dispersed with a thin coating, whereas at 10% SA, the coating was more pronounced, leading to agglomeration. The MFI increased with perlite loading, reaching 12.3 g/10 min at 20% perlite, compared to 8.88 g/10 min for neat HDPE. Mechanical testing showed that the elastic modulus increased by 36% (786 MPa) at 5% perlite, dropped to 460.8 MPa at 15%, and rose again to 707.7 MPa at 20%, suggesting structural reinforcement. Moderate perlite content (5-10%) preserved ductility, while higher concentrations (15-20%), especially with 10% SA, increased brittleness due to reduced interfacial adhesion. Thermal analysis showed a slight decrease in melting temperature and a slight increase in crystallization temperature with the addition of treated perlite, while thermal stability improved and the Vicat softening temperature remained unchanged. These results highlight the potential of SA-treated expanded perlite as a viable alternative to conventional fillers, offering a balance between stiffness, ductility, and thermal resistance. The developed composites are promising for lightweight and cost-effective applications in energy management and construction.
Rabiaa El Kori; Amal Lamarti; Houda Salmi; Abdelilah Hachim; Khalid El Had
Abstract
This work focuses on the damage of two thermoplastic materials; high density polyethylene "(HDPE)" and high impact polystyrene "(HIPS)". The contribution of this work is to determine the lifetime of these polymers by proposing a new static method, including different notches with different opening lengths ...
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This work focuses on the damage of two thermoplastic materials; high density polyethylene "(HDPE)" and high impact polystyrene "(HIPS)". The contribution of this work is to determine the lifetime of these polymers by proposing a new static method, including different notches with different opening lengths instead of depth change, to predict the damage behavior of HDPE and HIPS. Three damage models were used to predict the lifetime of these polymers by a proposed simple method compared to the old complex methods. Chemical and microscopic analyses including Fourier transform infrared spectrometry (FTIR) and scanning electron microscopy (SEM) were performed. The results indicated that the shape of the notch and the morphological nature of the polymer influence the mechanical behavior of these polymers. The proposed experimental factors (life fraction as a function of notches) are in very good agreement with the experimental results.
Structure and property relationship
Ali Yadegari; Jalil Morshedian; Hossein-Ali Khonakdar; Udo Wagenknecht
Abstract
High density polyethylene (HDPE) films were produced using cast film extrusion process with different draw ratios, ranging from 16.9 to 148.8. Morphology, crystallinty and orientation state of crystalline and amorphous phases of the cast films were investigated using scanning electron microscopy (SEM), ...
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High density polyethylene (HDPE) films were produced using cast film extrusion process with different draw ratios, ranging from 16.9 to 148.8. Morphology, crystallinty and orientation state of crystalline and amorphous phases of the cast films were investigated using scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and polarized Fourier transform infrared spectroscopy (FTIR) analyses, respectively. The anisotropic crystalline structures of row-nucleated lamellar morphology were observed for the films produced with high draw ratios. The crystalline phase axes orientation functions were found to be significantly dependent on the applied draw ratios. As expected, annealing increased the crystallinity and melting point temperature (Tm) of the cast films and on the other hand, it also enhanced the crystalline phase orientation. However, the results revealed that annealing also promoted non-twisted lamellar structures, since it increased fc values (c-axis orientation function) and decreased fa values (a-axis orientation function) simultaneously. Additionally, it was found that the annealing induced enhancement in c-axis orientation function was more significant for the cast films with lower draw ratios, therefore, it was dependent on the draw ratio.
