Sidra Siraj

In this study, silica in the form of raw local natural sand was added to high-density-polyethylene (HDPE) in order to develop a composite material in the form of sheets that could have potential applications in thin film industries, such as packaging, or recycling industries, such as in 3D printing. The silica/HDPE composite sheets were developed using a melt extruder followed by using a hot press for compression molding. The impact of two different particle sizes (25 µm and 5 µm) of the silica particles on selected properties such as toughness, elastic modulus, ductility, and composite density were analyzed. A considerable increase in the toughness and elastic modulus was observed from 0 wt% to 20 wt% with a 25 µm filler size. However, a general decreasing trend was observed in the material’s toughness and elastic modulus with decreasing particle size. A similar trend was observed for the ductility and the tensile strength of the sheets prepared from both filler particle sizes. In terms of the composite density, as the filler was increased from 20 wt% to 50 wt%, an increase in the composite densities was noticed for both particle sizes. Additionally, the sheets developed with 25 µm particle size had a slightly higher density than the 5 µm particle size, which is expected as the size can account for the higher weight. Results from this work aim to analyze the use of local sand as a filler material that can contribute towards maximizing the potential of such composite materials developed in extrusion industries.

Polymer composite sheets using a low-cost filler (local natural sand) and polymer (high-density polyethylene, HDPE) as a replacement of the traditionally used wood-fiber-based sheets for paper-based applications were developed. The sand/polymer composite sheets were prepared by melt extrusion in a melt blender followed by compression molding. The effects of varying particle size, concentration, and the use of a compatibilizer (polyethylene-grafted maleic anhydride) was studied on the mechano-chemical performance properties of the composite sheets such as morphology, thermal and mechanical properties, and wettability characteristics used in the printing industry. In terms of thermal stability, filler (sand) or compatibilizer addition did not alter the crystallization, melting, or degradation temperatures significantly, thereby promoting good thermal stability of the prepared sheets. Compatibilization improved anti-wetting property with water. Additionally, for the compatibilized sheets prepared from 25 µm sand particles, at 35 wt%, the contact angle with printing ink decreased from 44° to 38.30°, suggesting improved ink-wetting performance. A decrease in the elastic modulus was also observed with the addition of the compatibilizer, with comparable results to commercial stone paper. Results from this study will be considered as a first step towards understanding compatibility of local natural sand and polymers for paper-based application.

Silica exhibits properties such that its addition into polymeric materials can result in an enhanced overall quality and improved characteristics and as a result silica has been widely used as a filler material for improving the rheological properties of polymeric materials. The usage of polymers in three-dimensional printing technology has grown exponentially, which has increased the amount of waste produced during this process. Several polymers, such as polypropylene (PP), polyvinyl alcohol (PVA), polylactic acid (PLA), and nylon, are applied in this emerging technology. In this study, the effect of the addition of silica as a filler on the mechanical, thermal, and bulk density properties of the composites prepared from the aforementioned polymeric waste was studied. In addition, the morphology of the composite materials was characterized via scanning electron microscopy. The composite samples were prepared with various silica concentrations using a twin extruder followed by hot compression. Generally, the addition of silica increased the tensile strength of the polymers. For instance, the tensile strength of PVA with 5 wt% filler increased by 76 MPa, whereas those of PP and PLA with 10 wt% filler increased by 7.15 and 121.03 MPa, respectively. The crystallinity of the prepared composite samples ranged from 14% to 35%, which is expected in a composite system. Morphological analysis revealed the random dispersion of silica particles and agglomerate formation at high silica concentrations. The bulk density of the samples decreased with increased amount of filler addition. The addition of silica influenced the changes in the characteristics of the polymeric materials. Furthermore, the properties presented in this study can be used to further study the engineering design, transportation, and production processes, promoting the recycling and reuse of such waste in the same technology with the desired properties.

Antimicrobial materials produced by 3D Printing technology are very beneficial, especially for biomedical applications. Antimicrobial surfaces specifically with enhanced antibacterial property have been prepared using several quaternary salt-based agents, such as quaternary ammonium salts and metallic nanoparticles (NPs), such as copper and zinc, which are incorporated into a polymeric matrix mainly through copolymerization grafting and ionic exchange. This review compared different materials for their effectiveness in providing antimicrobial properties on surfaces. This study will help researchers choose the most suitable method of developing antimicrobial surfaces with the highest efficiency, which can be applied to develop products compatible with 3D Printing Technology.

Polymer/composite sheets were developed using sand as the filler, and high-density polyethylene (HDPE), by melting extrusion in a melt blender followed by compression molding. The effects of addition of filler, and the addition of polyethylene grafted maleic anhydride (PE-g-MA) as the compatibilizing agent were investigated by observing the morphology, the mechanical performance as well as the wettability characteristic via contact angle measurements. A decreasing trend was observed with filler addition, both for the Young’s modulus and yield stress values of each of the samples, from 1200.81 MPa and 35.15 MPa at 0 wt% to 1182.33 MPa and 23.11 MPa for the non-compatibilized sheet at 35 wt%, to 629.95 MPa and 9.56 MPa in the case of the compatibilized sheet respectively. However, addition of filler did not significantly affect the surface wetting in any case, thereby promoting good anti-wetting performance for both sets of sheets. As a result, the potential use of such synthetic composite sheets could be considered as a good alternative for applications which require reduced ductility or increased anti-wetting performance.

Due to the significant properties of silica, thermostatics can be enhanced using silica-additives to maximize the quality of polymer compounds and transform plastics into tailored properties. The silica additives can enhance the handling and quality performance of composites and thermoplastic polymers due to their diverse potential. Besides, using silica as an additive in different characteristics can allow granulates and powders to flow easily, minimize caking, and control rheology. On the other hand, the eruption of 3D printing technology has led to a massive new waste source of plastics, especially the polylactic acid (PLA) that is associated with the fused deposition modeling (FDM) process. In this paper, the impact on the mechanical properties when silica is mixed with waste PLA from 3D printing was studied. The PLA/silica mixtures were prepared using different blends through twin extruders and a Universal Testing Machine was used for the mechanical characterization. The result indicated that increasing silica composition resulted in the increase of the tensile strength to 121.03 MPa at 10 wt%. Similar trends were also observed for the toughness, ductility, and the yield stress values of the PLA/silica blends at 10 wt%, which corresponds to the increased mechanical property of the composite material reinforced by the silica particles. Improvement in the mechanical properties of the developed composite material promotes the effective recycling of PLA from applications such as 3D printing and the potential of reusing it in the same application.

The impact of ionic liquid (IL) solution on the recycling process of polyethylene terephthalate (PET) waste containers used to store drinking water, with a focus on optimizing the added percentage and processing conditions of IL was studied. Characterization using differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA), Fourier transform infrared spectroscopy (FTIR) and nano-indentation tests were performed. Generally, an increase in the degradation temperatures was observed with increasing IL%. Since they were quite comparable, their good thermal stability could be considered. An increase in the hardness was noticed from 0.41 at 0% to 0.45 at a 2% IL solution. A rise in the modulus of elasticity was also observed from 5.5 GPa at 0% to 8 GPa at 2% IL solution. Although there has been some improvement in the properties of the IL blends, limitations such as IL cost and their effective recycling remains a challenge and needs more efforts to fully explore their potential.