Composites and nanocomposites
Raid Banat; Malek Aljnaid; Manal Al-Rawashdeh
Abstract
Mechanical and physical properties of various weigh percentages (0% - 40%) of olive pomace flour (OPF)-loaded linear low density polyethylene (LLDPE) in the presence of 0%, 5% and 10% coupling agent (C) were formulated and studied. Extrusion and hot press processing techniques were used to fabricate ...
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Mechanical and physical properties of various weigh percentages (0% - 40%) of olive pomace flour (OPF)-loaded linear low density polyethylene (LLDPE) in the presence of 0%, 5% and 10% coupling agent (C) were formulated and studied. Extrusion and hot press processing techniques were used to fabricate OPF/LLDPE composites. Tensile stress at yield increased by 20% with the increasing of the filler loading up to 20%; and marginally increased in the presence of the C. Whereas, the decline in the tensile strain at yield of the polymer composite improved with the increase in the C content. The modulus increased from 631 MPa for the neat LLDPE to 680, 808 and 700 MPa for the composites filled by 5%, 10% and 20% filler content, respectively. Whereas, a decrease in the given modulus (550 MPa) was observed at 40% filler loading. The modulus has shown a successive improvement upon the addition of the C with values not less than 800 MPa. The impact strength decreased with the increase in filler loading from 119 kJ/m2 for the neat LLDPE to 81, 43, 27 and 16 kJ/m2 for the 5%, 10%, 20% and 40% OPF/LLDPE samples, respectively. On the contrary, 10% C addition improved the impact strength of the composite by two folds in the case of 10 - 40% filler inclusion. The scanning electron microscopy (SEM) illustrations proved the mechanical performance of various bio-composite formulations. Water absorption of the bio-composite increased with the OPF loading, from 0.73% for the neat LLDPE to 2.6% for 40% OPF-filled polymer composite, and decreased upon increasing the C content with an average of 1.4% for all composites. Formulated by mixing cellulosic-based material OPF and LLDPE, the bio-composite demonstrated compatible physical properties and can be used as an already available cellulosic filler for the bio-composite materials.
Polymer processing
Shirin Shokoohi; Ghasem Naderi
Abstract
Elastomer vulcanizates based on natural rubber (NR), NR reclaim (NRR) and layered silicates were compounded in an internal mixer and cured on a two-roll mill. Cure characteristics and mechanical properties of samples based on 50NR/50NRR reinforced with Cloisite 20A, Cloisite 30B and Nanolin DK1 were ...
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Elastomer vulcanizates based on natural rubber (NR), NR reclaim (NRR) and layered silicates were compounded in an internal mixer and cured on a two-roll mill. Cure characteristics and mechanical properties of samples based on 50NR/50NRR reinforced with Cloisite 20A, Cloisite 30B and Nanolin DK1 were compared to those of conventional NR/NRR/kaolin microcomposites. Due to the light/soft nature of organoclays suppressing the friction forces, the minimum torque values decreased in the presence of organoclays, whereas the crosslink density, evidenced by the difference between the maximum and minimum torque values, increased in all samples and scorch times shortened by 37% to a minimum in the presence of Nanolin alkaline/catalytic role in the cure reaction. Fatigue resistance improved by about 10% benefiting the crack tips blunting/energy consuming hysteresis mechanisms motivated by the organoclays among which Nanolin DK1 provides the most efficient dispersion/distribution of nanolayers by faster intragallery crosslinking reactions that pushes the stacks apart. Higher states of dispersion in this sample would also promote strain-induced crystallization under deformation responsible for the improvements seen in the modulus and elongation-at-break. Two-step mixing sequence further improved the compound performance due to the dispersion state progress confirmed by X-ray diffraction and transmission electron microscopy (20% in fatigue resistance and 53% in tensile modulus). In-situ compatibilization through bis(triethoxysilylpropyl)tetrasulfide bi-functional silane coupling agent also promoted modulus and fatigue resistance. However, a prolonged scorch time was observed due tothe blinded NR cure-reactive sites as well as steric hindrance of large functional groups in the presence of this coupling agent.
