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Dielectric Properties of Shrinkage-Free Poly(2-Oxazoline) Networks from Renewable Resources. Polymers (Basel) 2021; 13:polym13081263. [PMID: 33924619 PMCID: PMC8070125 DOI: 10.3390/polym13081263] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/09/2021] [Accepted: 04/09/2021] [Indexed: 11/16/2022] Open
Abstract
In the course of this study, the dielectric and physicochemical properties of poly(2-oxazoline) (POx) networks from renewable resources were compared with those of fossil-based polyamide 12 (PA 12) networks. POx was synthesized by the energy-efficient, microwave-assisted copolymerization of 2-oxazoline monomers, which were derived from fatty acids of coconut and castor oil. For the preparation of composites, aluminum nitride nanoparticles n-AlN and microparticles μ-AlN as well as hexagonal boron nitride BN submicroparticles were used. Additionally, 0, 15, or 30 wt.% of a spiroorthoester (SOE) were added as an expanding monomer aiming to reduce the formation of shrinkage-related defects. For the crosslinking of the polymers and the SOE as well as the double ring-opening reaction of the SOE, a thermally triggered dual-cure system was developed. The fully-cured blends and composites containing SOEs exhibited lower densities than their fully-cured SOE-free analogues, which was indicative of a lower extent of shrinkage (or even volumetric expansion) during the curing reaction, which is referred to as relative expansion RE. The RE amounted to values in the range of 0.46 to 2.48 for PA 12-based samples and 1.39 to 7.50 vol.% for POx-based samples. At 40 Hz, the “green” POx networks show low loss factors, which are competitive to those of the fossil-based PA 12.
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Morak M, Marx P, Gschwandl M, Fuchs PF, Pfost M, Wiesbrock F. Heat Dissipation in Epoxy/Amine-Based Gradient Composites with Alumina Particles: A Critical Evaluation of Thermal Conductivity Measurements. Polymers (Basel) 2018; 10:E1131. [PMID: 30961056 PMCID: PMC6403572 DOI: 10.3390/polym10101131] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 10/02/2018] [Accepted: 10/08/2018] [Indexed: 11/17/2022] Open
Abstract
For the design of the next generation of microelectronic packages, thermal management is one of the key aspects and must be met by the development of polymers with enhanced thermal conductivity. While all polymer classes show a very low thermal conductivity, this shortcoming can be compensated for by the addition of fillers, yielding polymer-based composite materials with high thermal conductivity. The inorganic fillers, however, are often available only in submicron- and micron-scaled dimensions and, consequently, can sediment during the curing reaction of the polymer matrix. In this study, an epoxy/amine resin was filled with nano- and submicron-scaled alumina particles, yielding a gradient composite. It was found that the thermal conductivity according to laser flash analysis of a sliced specimen ranged from 0.25 to 0.45 W·m-1·K-1 at room temperature. If the thermal conductivity of an uncut specimen was measured with a guarded heat flow meter, the 'averaged' thermal conductivity was measured to be only 0.25 W·m-1·K-1. Finite element analysis revealed that the heat dissipation through a gradient composite was of intermediate speed in comparison with homogeneous composites exhibiting a non-gradient thermal conductivity of 0.25 and 0.45 W·m-1·K-1.
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Affiliation(s)
- Matthias Morak
- Polymer Competence Center Leoben GmbH, Roseggerstrasse 12, 8700 Leoben, Austria.
- Chair of Mechanics, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, 8700 Leoben, Austria.
| | - Philipp Marx
- Polymer Competence Center Leoben GmbH, Roseggerstrasse 12, 8700 Leoben, Austria.
- Chair of Chemistry of Polymeric Materials, Montanuniversitaet Leoben, Otto Gloeckel-Straße 2, 8700 Leoben, Austria.
| | - Mario Gschwandl
- Polymer Competence Center Leoben GmbH, Roseggerstrasse 12, 8700 Leoben, Austria.
- Chair of Mechanics, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, 8700 Leoben, Austria.
| | - Peter Filipp Fuchs
- Polymer Competence Center Leoben GmbH, Roseggerstrasse 12, 8700 Leoben, Austria.
- Chair of Mechanics, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, 8700 Leoben, Austria.
| | - Martin Pfost
- Chair of Energy Conversion, TU Dortmund University, Emil-Figge-Strasse 50, 44227 Dortmund, Germany.
| | - Frank Wiesbrock
- Polymer Competence Center Leoben GmbH, Roseggerstrasse 12, 8700 Leoben, Austria.
- Institute for Chemistry and Technology of Materials, Graz University of Technology, NAWI Graz, Stremayrgasse 9, 8010 Graz, Austria.
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