Mechanical, thermal, electrical characteristics and emi absorption shielding effectiveness of rubber composites based on ferrite and carbon fillers

In this work, rubber composites were fabricated by incorporation of manganese-zinc ferrite alone and in combination with carbon-based fillers into acrylonitrile-butadiene rubber. Electromagnetic parameters and electromagnetic interference (EMI) absorption shielding effectiveness of composite materials were examined in the frequency range 1 MHz–3 GHz. The influence of ferrite and fillers combination on thermal characteristics and mechanical properties of composites was investigated as well. The results revealed that ferrite imparts absorption shielding efficiency to the composites in tested frequency range. The absorption shielding effectiveness and absorption maxima of ferrite filled composites shifted to lower frequencies with increasing content of magnetic filler. The combination of carbon black and ferrite also resulted in the fabrication of efficient EMI shields. However, the EMI absorption shielding effectiveness was lower, which can be ascribed to higher electrical conductivity and higher permittivity of those materials. The highest conductivity and permittivity of composites filled with combination of carbon nanotubes and ferrite was responsible for the lowest absorption shielding effectiveness within the examined frequency range. The results also demonstrated that combination of ferrite with carbon-based fillers resulted in the enhancement of thermal conductivity and improvement of mechanical properties. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Slovak Research and Development AgencySlovak Research and Development Agency [APVV-16-0136, APVV-19-0091]Agentúra na Podporu Výskumu a Vývoja, APVV: APVV-16-0136, APVV-19-009

Evaluation of the Properties of PHB Composite Filled with Kaolin Particles for 3D Printing Applications Using the Design of Experiment

In the presented work, poly(3-hydroxybutyrate)-PHB-based composites for 3D printing as bio-sourced and biodegradable alternatives to synthetic plastics are characterized. The PHB matrix was modified by polylactide (PLA) and plasticized by tributyl citrate. Kaolin particles were used as a filler. The mathematical method “Design of Experiment” (DoE) was used to create a matrix of samples for further evaluation. Firstly, the optimal printing temperature of the first and upper layers was determined. Secondly, the 3D printed samples were tested with regards to the warping during the 3D printing. Testing specimens were prepared using the determined optimal printing conditions to measure the tensile properties, impact strength, and heat deflection temperature (HDT) of the samples. The results describe the effect of adding individual components (PHB, PLA, plasticizer, and filler) in the prepared composite sample on the resulting material properties. Two composite samples were prepared based on the theoretical results of DoE (one with the maximum printability and one with the maximum HDT) to compare them with the real data measured. The tests of these two composite samples showed 25% lower warping and 8.9% higher HDT than was expected by the theory

In Vitro Characterization of Poly(Lactic Acid)/ Poly(Hydroxybutyrate)/ Thermoplastic Starch Blends for Tissue Engineering Application

Complex in vitro characterization of a blended material based on Poly(Lactic Acid), Poly(Hydroxybutyrate), and Thermoplastic Starch (PLA/PHB/TPS) was performed in order to evaluate its potential for application in the field of tissue engineering. We focused on the biological behavior of the material as well as its mechanical and morphological properties. We also focused on the potential of the blend to be processed by the 3D printer which would allow the fabrication of the custom-made scaffold. Several blends recipes were prepared and characterized. This material was then studied in the context of scaffold fabrication. Scaffold porosity, wettability, and cell-scaffold interaction were evaluated as well. MTT test and the direct contact cytotoxicity test were applied in order to evaluate the toxic potential of the blended material. Biocompatibility studies were performed on the human chondrocytes. According to our results, we assume that material had no toxic effect on the cell culture and therefore could be considered as biocompatible. Moreover, PLA/PHB/TPS blend is applicable for 3D printing. Printed scaffolds had highly porous morphology and were able to absorb water as well. In addition, cells could adhere and proliferate on the scaffold surface. We conclude that this blend has potential for scaffold engineering

The possibility of using the regranulate of a biodegradable polymer blend based on polylactic acid and polyhydroxybutyrate in FDM 3D printing technology

The study's main objective is the possible application of regranulate based on PLA and PHB bioplastics in the FDM 3D printing technique. The idea of using regranulate in the tested PLA/PHB biodegradable polymer blend can help to reduce the amount of plastic waste produced after defective or unwanted 3D printing from these types of materials suitable for 3D printing or after the industrial production of filaments with inadequate geometric parameters, which may help to economize raw material resources and, ultimately, lower the cost of studied polymer materials producing. The regranulate was added to the non-recycled biodegradable polymer blend with the same chemical composition in two different processes for making the filament for 3D printing. Based on testing the processing and utility properties of the processed regranulate materials, it was found that the regranulate partially degrades during multiple processing and thereby reduces the average molar mass and viscosity of the tested material during its processing. However, it was proven that despite the reduction of molecular characteristics after regranulate additions, it was possible to prepare the filaments by both investigated technologies of the regranulate addition and subsequently, it was possible to print such filaments using FDM 3D printing technology, even when the polymer blend contained a high content of regranulate. It was also proven that PLA/PHB materials containing regranulate exhibit comparable thermophysical and strength characteristics to the virgin PLA/PHB polymer blend

Influence of Multiple Thermomechanical Processing of 3D Filaments Based on Polylactic Acid and Polyhydroxybutyrate on Their Rheological and Utility Properties

This study focused on material recycling of a biodegradable blend based on PLA and PHB for multiple applications of biodegradable polymeric material under real conditions. In this study, we investigated the effect of multiple processing of a biodegradable polymer blend under the trade name NONOILEN®, which was processed under laboratory as well as industrial conditions. In this article, we report on testing the effect of blending and multiple processing on thermomechanical stability, molecular characteristics, as well as thermophysical and mechanical properties of experimental- and industrial-type tested material suitable for FDM 3D technology. The results showed that the studied material degraded during blending and subsequently during multiple processing. Even after partial degradation, which was demonstrated by a decrease in average molecular weight and a decrease in complex viscosity in the process of multiple reprocessing, there was no significant change in the material’s thermophysical properties, either in laboratory or industrial conditions. There was also no negative impact on the strength characteristics of multiple processed samples. The results of this work show that a biodegradable polymer blend based on PLA and PHB is a suitable candidate for material recycling even in industrial processing conditions. In addition, the results suggest that the biodegradable polymeric material NONOILEN® 3D 3056-2 is suitable for multiple uses in FDM technology

PLA/PHB-Based Materials Fully Biodegradable under Both Industrial and Home-Composting Conditions

In order to make bioplastics accessible for a wider spectrum of applications, ready-to-use plastic material formulations should be available with tailored properties. Ideally, these kinds of materials should also be "home-compostable" to simplify their organic recycling. Therefore, materials based on PLA (polylactid acid) and PHB (polyhydroxybutyrate) blends are presented which contain suitable additives, and some of them contain also thermoplastic starch as a filler, which decreases the price of the final compound. They are intended for various applications, as documented by products made out of them. The produced materials are fully biodegradable under industrial composting conditions. Surprisingly, some of the materials, even those which contain more PLA than PHB, are also fully biodegradable under home-composting conditions within a period of about six months. Experiments made under laboratory conditions were supported with data obtained from a kitchen waste pilot composter and from municipal composting plant experiments. Material properties, environmental conditions, and microbiology data were recorded during some of these experiments to document the biodegradation process and changes on the surface and inside the materials on a molecular level

PLA/PHB-based materials fully biodegradable under both industrial and home-composting conditions

In order to make bioplastics accessible for a wider spectrum of applications, ready-to-use plastic material formulations should be available with tailored properties. Ideally, these kinds of materials should also be "home-compostable" to simplify their organic recycling. Therefore, materials based on PLA (polylactid acid) and PHB (polyhydroxybutyrate) blends are presented which contain suitable additives, and some of them contain also thermoplastic starch as a filler, which decreases the price of the final compound. They are intended for various applications, as documented by products made out of them. The produced materials are fully biodegradable under industrial composting conditions. Surprisingly, some of the materials, even those which contain more PLA than PHB, are also fully biodegradable under home-composting conditions within a period of about six months. Experiments made under laboratory conditions were supported with data obtained from a kitchen waste pilot composter and from municipal composting plant experiments. Material properties, environmental conditions, and microbiology data were recorded during some of these experiments to document the biodegradation process and changes on the surface and inside the materials on a molecular level.IGA/FT/2022/006; Agentúra na Podporu Výskumu a Vývoja, APVV: 313011V336, APVV-20-0193, APVV-20-0256; European Regional Development Fund, ERDF: FCH-S-21-7553Internal Grant Agency [IGA/FT/2022/006]; Slovak Research and Development Agency [APVV-20-0256, APVV-20-0193]; European Regional Development Fund [313011V336]; Specific University Research Grant [FCH-S-21-7553