Effect of Filler Particle Size on the Recyclability of Fly Ash Filled HDPE Composites

Fly ash polymer composites are innovative high-performance materials that reduce the environmental worries and disposal complications of heavy industry produced fly ash. This study developed and characterized such composites of high-density polyethylene (HDPE) matrices and found that the use of small (50–90 µm) particles of fly ash could give rise to the tensile modulus (~95%) and tensile strength (~7%) of their reinforced composites when compared to neat HDPE materials. While these results themselves convey a strong message of how fly ash can be effectively utilized, this was not the key aim of the current study. The study was extended to examine the effect of fly ash particle size on the recyclability of relevant HDPE composites. The extrusion-based multiple recycling of composites gave slightly lower mechanical properties, primarily due to filler/matrix delamination when large fly ash particles were used. Compared to freshly made fly ash-filled HDPE composites, although using small (50–90 µm) fly ash particles reduced the tensile modulus and tensile strength of recycled composites, the values were still far above those from neat HDPE materials. This novel insight directs the effective utilization of fly ash and provides long-term sustainable and economical solutions for their practical applicability.

The Relationship between a Defined Microstructure within the Mold Surface and the Corresponding Roughness on the Part: A Systematic Study on Particle Size, Filler-, and Compatibilizer Content

The perception of a surface and its haptic properties are significantly influenced by roughness and microstructure, respectively, whereby non-negligible parameters include friction, contact area, temperature, and humidity between the human finger and the examined surface. In particular, for a scientific investigation on haptic influences, the production of samples with a defined surface roughness is indispensable. The aim of this study is to analyze the impact of various mold insert roughnesses combined with the influences of particle size, filler-, and compatibilizer content on impression quality. An unfilled high density polyethylene was chosen as a reference for the impression quality investigations, while fillers with significantly different particle sizes and a compatibilizer were used to produce proprietary compounds. Injection molded parts were manufactured utilizing mold inserts with three different line roughness values. To support the obtained results, a multivariate analysis of variance, a simulation of the filling phase as well as a rheological material characterization were conducted. The results revealed that (i) the impression quality can be independent of the applied insert roughness based on the filler particle size that was studied, (ii) an increasing on both filler particle size and compatibilizer content raise the sample roughness as a function of the penetration ability of the filler into the insert valleys, and (iii) with a higher insert roughness, the thermoplastic moldings generally exhibit a significantly smoother topography. An assumed correlation between part roughness and melt viscosity could not be confirmed.

The Effects of Filler Shape, Type, and Size on the Properties of Encapsulation Molding Components

Fillers are essential in the encapsulation molding compound. For three fillers of crystal, spherical, and fused silica, the effects of their size, type, and shape on the viscosity, flow spiral length, thermal conductivity, and coefficient of thermal expansion (CTE) of the compound were explored in this study. The results show that fillers with a larger particle size have a smaller viscosity and flow better; spherical fillers are better than the polygonal ones in this respect. In contrast, both thermal conductivity and CTE increase as the filler particle size increases; the values of these two properties of crystal silica are about twice those of fused silica; the thermal conductivity of polygonal silica is larger than that of spherical silica. On the other hand, the dependence of CTE on the filler shape is insignificant, but is significant to the filler type. The degree of curing of the compound with polygonal silica is also higher than that with either spherical or crystal silica. Namely, curing is affected by both filler type and shape, and can be tuned accordingly to suit specific needs.

Effects of mesoporous silica particle size and pore structure on the performance of polymer-mesoporous silica mixed matrix membranes

The effects of filler particle size and pore structure on the gas separation performance of mixed matrix membranes were comprehensively investigated via elaborate synthesis of mesoporous silicas.

Biogenic Composite Filaments Based on Polylactide and Diatomaceous Earth for 3D Printing

New composites containing a natural filler made of diatom shells (frustules), permitting the modification of polylactide matrix, were produced by Fused Deposition Modelling (3D printing) and were thoroughly examined. Two mesh fractions of the filler were used, one of <40 µm and the other of 40−63 µm, in order to check the effect of the filler particle size on the composite properties. The composites obtained contained diatom shells in the concentrations from 0% to 5% wt. (0−27.5% vol.) and were subjected to rheological analysis. The composites obtained as filaments of 1.75 mm in diameter were used for 3D printing. The printed samples were characterized as to hydrophilic–hydrophobic, thermal and mechanical properties. The functional parameters of the printed objects, e.g., mechanical characteristics, stability on contact with water and water contact angle, were measured. The results revealed differences in the processing behavior of the samples as well as the effect of secondary granulation of the filler on the parameters of the printing and mechanical properties of the composites.

Effect of Al2O3 with Different Nanostructures on the Insulating Properties of Epoxy-Based Composites

High thermal conductivity insulating dielectrics with good electrical properties have received widespread attention due to the continuous development of power systems and power electronic technologies. In this paper, the effects of differently structured nano alumina fillers on the thermal conductivity and insulating properties of polymer-based composites were studied. It was found that all three types of Al2O3 nano-fillers enhanced the thermal conductivity of the composites, and the thermal conductivity increased more dramatically with increasing filler particle size. It is worth noting that Al2O3 nanowires (NWs) exhibited the most significant improvement in thermal conductivity. The volume resistivity of the composites first increased and then decreased with increasing mass fraction of fillers, and Al2O3 nanoplates (NPLs) showed the most significant improvement in the insulation performance of the composites. The dielectric constants of the composites increased with increasing mass fraction of fillers, while the dielectric losses first decreased and then increased with the same trend, yet the mass fractions of fillers for the three materials were different when the dielectric loss reached a minimum. In addition, all three types of filler increased the AC breakdown strength of the composites, but Al2O3-NPLs showed the most significant improvement on the breakdown performance of the composites.