RESUMO
A solution casting approach is used to create hollow glass microsphere (HGM)-filled epoxy-syntactic foam composites (e-SFCs) by varying the concentrations of HGM in epoxy according to different particle sizes. Density analysis is used to investigate the impact of concentration and particle size regularity on the microstructure of e-SFCs. It was observed that e-SFCs filled with an HGM of uniform particle sizes exhibit a reduction in density with increasing HGM concentration, whereas e-SFCs filled with heterogeneous sizes of HGM exhibit closeness in density values regardless of HGM concentration. The variation in e-SFC density can be related to HGM packing efficiency within e-SFCs in terms of concentration and particle size regularity. The particle size with lowest true density of 0.5529 g/cm3, experimental density of 0.949 g/cm3 and tensile strength of 55.74 MPa resulted in e-SFCs with highest specific properties of 100.81 (MPa·g/cm3), with a 35.1% increase from the lowest value of 74.64 (MPa·g/cm3) at a true density of 0.7286 g/cm3, experimental density of 0.928 g/cm3 and tensile strength of 54.38 MPa. The e-SFCs' theoretical density values were obtained. The variance in theoretical and experimental density values provides a thorough grasp of packing efficiency and inter-particle features.
RESUMO
Packaging materials are used to protect consumer goods, such as food, drinks, cosmetics, healthcare items, and more, from harmful gases and physical and chemical damage during storage, distribution, and handling. Synthetic plastics are commonly used because they exhibit sufficient characteristics for packaging requirements, but their end lives result in environmental pollution, the depletion of landfill space, rising sea pollution, and more. These exist because of their poor biodegradability, limited recyclability, etc. There has been an increasing demand for replacing these polymers with bio-based biodegradable materials for a sustainable environment. Cellulosic nanomaterials have been proposed as a potential substitute in the preparation of packaging films. Nevertheless, their application is limited due to their poor properties, such as their barrier, thermal, and mechanical properties, to name a few. The barrier properties of materials play a pivotal role in extending and determining the shelf lives of packaged foods. Nanofillers have been used to enhance the barrier properties. This article reviews the literature on the barrier properties of cellulose/clay nanocomposite polymers. Cellulose extraction stages such as pretreatment, bleaching, and nanoparticle isolation are outlined, followed by cellulose modification methods. Finally, a brief discussion on nanofillers is provided, followed by an extensive literature review on the barrier properties of cellulose/clay nanocomposite polymers. Although similar reviews have been presented, the use of modification processes applied to cellulose, clay, and final nanocomposites to enhance the barrier properties has not been reviewed. Therefore, this article focuses on this scope.
RESUMO
Syntactic foam made from hollow glass microspheres (HGM) in an epoxy matrix has proven to be a good material with a strong structural strength. Understanding filler particle size variation is important in composite material formation, especially in syntactic foam, because of its numerous applications such as aerospace, marine, and structural purposes. In this present work, the effects of particle variation in different sizes (20-24 µm, 25-44 µm, 45-49 µm, and 50-60 µm) on the mechanical properties of the syntactic foam composites with a focus on flexural strength, modulus, and fracture surfaces are investigated. The particle sizes are varied into five volume fractions (5, 10, 15, 20, and 25 vol%). The results show that the highest flexural strength is 89 MPa at a 5 vol% fraction of 50-60 µm particle size variation with a 69% increase over the neat epoxy. This implies that the incorporation of HGM filler volume fraction and size variation has a strong effect on the flexural strength and bending modulus of syntactic foam. The highest particle size distribution is 31.02 at 25-44 µm. The storage modulus E' increased at 30 °C, 50 °C, and 60 °C by 3.2%, 47%, and 96%, respectively. The effects of wall thickness and aspect ratio on the size of the microstructure, the fracture surfaces, and the viscoelastic properties are determined and reported accordingly.