Effect of conditioning on PU foam matrix materials properties

This article deals with the characterization of the thermal-induced aging of soft polyurethane (PU) foams. There are studied thermal and mechanical properties by means of thermal analysis, tensile, compression and dynamic mechanical vibration testing. It was found in this study, that the increasing relative humidity of the surrounding atmosphere leads to the initiation of the degradation processes. This is reflected in the observed decreased mechanical stiffness. It is attributed to the plasticization of the PU foams wall material. It is in agreement with the observed increase of the permanent deformation accompanied simultaneously with the decrease of Young's modulus of elasticity. The latter phenomenon is studied by the novel non-destructive forced oscillations vibration-damping testing, which is confirmed by observed lower mechanical stiffness thus indicating the loss of the elasticity induced by samples conditioning. In parallel, observed decreasing of the matrix hardness is confirming the loss of elastic mechanical performance as well. The effect of conditioning leads to the significant loss of the PU foam's thermal stability.European Regional Development Fund in Research Centre of Advanced Mechatronic Systems project within Operational Programme Research, Development and Education [CZ.02.1.01/0.0/0.0/16_019/0000867]; Internal Grant of Palacky University in Olomouc [IGA_PrF_2021_031]CZ.02.1.01/0.0/0.0/16_019/0000867; Univerzita Palackého v Olomouci: IGA_PrF_2021_03

Study of the material engineering properties of high-density poly(ethylene)/perlite nanocomposite materials

This paper was focused on application of the perlite mineral as the filler for polymer nanocomposites in technical applications. A strong effect of the perlite nano-filler on high-density poly(ethylene) (HDPE) composites' mechanical and thermal properties was found. Also found was an increase of the Young's modulus of elasticity with the increasing filler concentration. Increased stiffness from the mechanical tensile testing was confirmed by the nondestructive vibrator testing as well. This was based on displacement transmissibility measurements by means of forced oscillation single-degree-of freedom method. Fracture toughness showed a decreasing trend with increasing perlite concentration, suggesting occurrence of the brittle fracture. Furthermore, ductile fracture processes were observed as well at higher filler concentrations by means of SEM analysis. There was also found relatively strong bonding between polymer chains and the filler particles by SEM imagining. © 2020 Lubomír Lapčík et al., published by De Gruyter 2020.European Regional Development Fund in the Research Centre of Advanced Mechatronic Systems project [CZ.02.1.01/0.0/0.0/16_019/0000867]; Palacky University in Olomouc [IGA_PrF_2020_022]; Faculty of Science, Palacky University in OlomoucCZ.02.1.01/0.0/0.0/16_019/0000867; Univerzita Palackého v Olomouci: IGA_PrF_2020_02

Enhancement of the mechanical properties of HDPE mineral nanocomposites by filler particles modulation of the matrix plastic/elastic behavior

Two different nanosized mineral fillers (nano calcium carbonate and nanoclay) were used in the high density poly(ethylene) (HDPE) composites pilot plant production. Structural and mechanical properties of the prepared composites were examined in this study. The homogenous filler distribution was confirmed in the tested samples by scanning electron microscopy, transmission electron microscopy, and energy dispersive spectroscopy analyses. The fillers' fortifying effect on polymer composites' mechanical performance was confirmed as indicated by the increased elastic modulus and indentation modulus. Additionally, the possible modulation of the plastic-elastic mechanical behavior was confirmed by the type of the filler as well as its concentration used in the final composites testing articles.Palacky University in Olomouc [IGA_PrF_2021_031]; Tomas Bata University in Zlin [IGA/FT/2021/004, IGA/FT/2021/005]; Faculty of Science, Palacky University in OlomoucUniverzita Palackého v Olomouci: IGA_PrF_2021_031; Univerzita Tomáše Bati ve Zlíně: IGA/FT/2021/004, IGA/FT/2021/00

Study of mechanical properties of epoxy/graphene and epoxy/halloysite nanocomposites

This article aimed to compare various mechanical properties of epoxy/graphene and epoxy/halloysite nanocomposites. Graphene nanoplatelets (GnPs) and halloysite nanotubes (HNTs) were used as fillers at different concentrations. The studied fillers were dispersed in the epoxy resin matrices. Elastic–plastic mechanical behavior modulation was observed utilizing the fillers’ nanoparticles and carboxyl-terminated butadiene–acrylonitrile copolymer rubber-modified epoxy resin. The hypothesis of the possible preceding inter-particle gliding of the individual GnPs in the complex resin nanocomposite matrix during mechanical testings was also confirmed. Increased ductility (elongation at break increased from 0.33 mm [neat matrix] to 0.46 mm [1 wt% GnPs] [39% increase]) and plasticity of the GnP nanocomposite samples were observed. In contrast, the decreasing mechanical stiffness as reflected in the decreased Young’s modulus of elasticity (from 3.4 to 2.7 GPa [20% decrease]) was found for the epoxy/HNT nanocomposites. The obtained dynamic stiffness of the investigated nanocomposites confirmed the complexity of the mechanical response of the studied material systems as a combination of the ductile and brittle phenomena.Web of Science121art. no. 2022052

Study of mechanical properties of epoxy/graphene and epoxy/halloysite nanocomposites

This article aimed to compare various mechanical properties of epoxy/graphene and epoxy/halloysite nanocomposites. Graphene nanoplatelets (GnPs) and halloysite nanotubes (HNTs) were used as fillers at different concentrations. The studied fillers were dispersed in the epoxy resin matrices. Elastic-plastic mechanical behavior modulation was observed utilizing the fillers' nanoparticles and carboxyl-terminated butadiene-acrylonitrile copolymer rubber-modified epoxy resin. The hypothesis of the possible preceding inter-particle gliding of the individual GnPs in the complex resin nanocomposite matrix during mechanical testings was also confirmed. Increased ductility (elongation at break increased from 0.33 mm [neat matrix] to 0.46 mm [1 wt% GnPs] [39% increase]) and plasticity of the GnP nanocomposite samples were observed. In contrast, the decreasing mechanical stiffness as reflected in the decreased Young's modulus of elasticity (from 3.4 to 2.7 GPa [20% decrease]) was found for the epoxy/HNT nanocomposites. The obtained dynamic stiffness of the investigated nanocomposites confirmed the complexity of the mechanical response of the studied material systems as a combination of the ductile and brittle phenomena.CZ.02.1.01/0.0/0.0/16_019/0000867; Tomas Bata University in Zlin, TBU: IGA/FT/2022/005, IGA/FT/2023/007; Univerzita Palackého v Olomouci: IGA_PrF_2022_020, IGA_PrF_2023_024European Regional Development Fund in the Research Centre of Advanced Mechatronic Systems project [CZ.02.1.01/0.0/0.0/16_019/0000867]; Palacky University in Olomouc [IGA_PrF_2022_020, IGA_PrF_2023_024]; Tomas Bata University in Zlin [IGA/FT/2022/005, IGA/FT/2023/007]; Fischer scholarship of the Faculty of Science, Palacky University in Olomou

Application of physical-chemical approaches for encapsulation of active substances in pharmaceutical and food industries

Background: Encapsulation is a valuable method used to protect active substances and enhance their physico-chemical properties. It can also be used as protection from unpleasant scents and flavors or adverse environmental conditions. Methods: In this comprehensive review, we highlight the methods commonly utilized in the food and pharmaceutical industries, along with recent applications of these methods. Results: Through an analysis of numerous articles published in the last decade, we summarize the key methods and physico-chemical properties that are frequently considered with encapsulation techniques. Conclusion: Encapsulation has demonstrated effectiveness and versatility in multiple industries, such as food, nutraceutical, and pharmaceuticals. Moreover, the selection of appropriate encapsulation methods is critical for the effective encapsulation of specific active compounds. Therefore, constant efforts are being made to develop novel encapsulation methods and coating materials for better encapsulation efficiency and to improve properties for specific use.Univerzita Palackého v Olomouci, UPInternal Student Grant Agency of the Palacky University in Olomouc, Czech Republic [IGA_PrF_2023_024

Study of the material engineering properties of high-density poly(ethylene)/perlite nanocomposite materials

This paper was focused on application of the perlite mineral as the filler for polymer nanocomposites in technical applications. A strong effect of the perlite nano-filler on high-density poly(ethylene) (HDPE) composites' mechanical and thermal properties was found. Also found was an increase of the Young's modulus of elasticity with the increasing filler concentration. Increased stiffness from the mechanical tensile testing was confirmed by the nondestructive vibrator testing as well. This was based on displacement transmissibility measurements by means of forced oscillation single-degree-of freedom method. Fracture toughness showed a decreasing trend with increasing perlite concentration, suggesting occurrence of the brittle fracture. Furthermore, ductile fracture processes were observed as well at higher filler concentrations by means of SEM analysis. There was also found relatively strong bonding between polymer chains and the filler particles by SEM imagining.Web of Science911499149

Study of the material engineering properties of high-density poly(ethylene)/perlite nanocomposite materials

This paper was focused on application of the perlite mineral as the filler for polymer nanocomposites in technical applications. A strong effect of the perlite nano-filler on high-density poly(ethylene) (HDPE) composites’ mechanical and thermal properties was found. Also found was an increase of the Young’s modulus of elasticity with the increasing filler concentration. Increased stiffness from the mechanical tensile testing was confirmed by the nondestructive vibrator testing as well. This was based on displacement transmissibility measurements by means of forced oscillation single-degree-of freedom method. Fracture toughness showed a decreasing trend with increasing perlite concentration, suggesting occurrence of the brittle fracture. Furthermore, ductile fracture processes were observed as well at higher filler concentrations by means of SEM analysis. There was also found relatively strong bonding between polymer chains and the filler particles by SEM imagining

Intelligent high-tech coating of natural biopolymer layers

International audiencePolymeric materials play a vital role in our daily life, but the growing concern for the environment demands economical and natural biopolymers that can be cross-linked to create technologically innovative lightweight materials. Their cellular matrix with extreme flexibility makes them highly acceptable for application prospects in material science, engineering, and biomedical applications. Furthermore, their biocompatibility, mechanical properties, and structural diversity provide a gateway to research them to form technologically important materials. In the light of the same, the review covers cellulose derivatives. The first section of the study covers the general properties and applications of cellulose and its derivatives. Then, the biopolymers are characterised based on their dielectric properties, crystallinity, rheology, and mechanical properties. An in-depth analysis of the diffuse process of swelling and dissolution followed by a brief discussion on diffusion and diffusion of crosslinking has been done. The review also covers a section on swelling and swelling kinetics of carboxymethyl cellulose (CMC) and hydroxyethyl cellulose (HEC). The examination of all the aforementioned parameters gives an insight into the future aspects of the biopolymers. Lastly, the study briefly covers some preferred choices of cross-linking agents and their effect on the biopolymers

Intelligent high-tech coating of natural biopolymer layers

Polymeric materials play a vital role in our daily life, but the growing concern for the environment demands economical and natural biopolymers that can be cross-linked to create technologically innovative lightweight materials. Their cellular matrix with extreme flexibility makes them highly acceptable for application prospects in material science, engineering, and biomedical applications. Furthermore, their biocompatibility, mechanical properties, and structural diversity provide a gateway to research them to form technologically important materials. In the light of the same, the review covers cellulose derivatives. The first section of the study covers the general properties and applications of cellulose and its derivatives. Then, the biopolymers are characterised based on their dielectric properties, crystallinity, rheology, and mechanical properties. An in-depth analysis of the diffuse process of swelling and dissolution followed by a brief discussion on diffusion and diffusion of crosslinking has been done. The review also covers a section on swelling and swelling kinetics of carboxymethyl cellulose (CMC) and hydroxyethyl cellulose (HEC). The examination of all the aforementioned parameters gives an insight into the future aspects of the biopolymers. Lastly, the study briefly covers some preferred choices of cross-linking agents and their effect on the biopolymers.Tomas Bata University in Zlin, TBU: IGA/FT/2022/005; Univerzita Palackého v Olomouci: IGA_PrF_2022_020Palacky University in Olomouc [IGA_PrF_2022_020]; Tomas Bata University in Zlin [IGA/FT/2022/005]; Faculty of Science, Palacky University in Olomou