Enhancements of epoxy resin based syntactic foam by inner interface and matrix modifications

Author(s):  
A. Strauchs ◽  
A. Schnettler
2021 ◽  
Vol 10 (1) ◽  
pp. 883-903
Author(s):  
Yi Wang ◽  
Jun Wang ◽  
Jie Wang ◽  
David Hui

Abstract This study focused on experimental and numerical investigations into the low-velocity impact behavior of epoxy resin matrix syntactic composites with embedded hollow glass microspheres (HGMs) and multiwalled carbon nanotubes (MWCNTs). The synergistic effects of HGMs and MWCNTs on the mechanical properties of epoxy resin composites were improved by applying amine and acid treatments to HGMs and MWCNTs, respectively. The influence of the MWCNT content and the applied impact energy on the impact responses and compression strength after the impact of these syntactic foam panel samples were discussed. The results indicated that modifying HGMs and MWCNTs contributed to improving the energy absorption and the strength retention factor (SRF) of these panels and the SRF increased with increased MWCNT content. Moreover, multiscale finite-element (FE) models were developed to simulate panel impact behavior, and modeling results were compared with experimental data. Then, the verified FE model was used to analyze the influence of CNT types (helical CNTs vs MWCNTs) and the diameter-to-thickness ratios of HGMs. This study provided a theoretical basis and design reference for a novel lightweight composite material subjected to low-velocity impact, which could be applied as a core material for sandwich structures in aerospace, marine engineering, transportation, and civil infrastructures.


Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3185
Author(s):  
Zhongyuan Zhang ◽  
Xiaohan Dai ◽  
Le Li ◽  
Songsong Zhou ◽  
Wei Xue ◽  
...  

As a lightweight and highly insulating composite material, epoxy resin syntactic foam is increasingly widely used for insulation filling in electrical equipment. To avoid core burning and cracking, which are prone to occur during the casting process, the epoxy resin-based syntactic foam insulation materials with high thermal conductivity and low coefficient of thermal expansion are required for composite insulation equipment. The review is divided into three sections concentrating on the two main aspects of modifying the thermal properties of syntactic foam. The mechanism and models, from the aspects of thermal conductivity and coefficient of thermal expansion, are presented in the first part. The second part aims to better understand the methods for modifying the thermal properties of syntactic foam by adding functional fillers, including the addition of thermally conductive particles, hollow glass microspheres, negative thermal expansion filler and fibers, etc. The third part concludes by describing the existing challenges in this research field and expanding the applicable areas of epoxy resin-based syntactic foam insulation materials, especially cross-arm composite insulation.


2009 ◽  
Vol 66 ◽  
pp. 284-287 ◽  
Author(s):  
Zhuo Chen ◽  
Yan Qin ◽  
Zhi Xiong Huang ◽  
Qiang Shen ◽  
Lian Meng Zhang

Low density syntactic foam monolayer slices, which were made of epoxy resin matrix and plastic microballoons (MB), were fabricated by rolling process with thickness controlled at 200μm. Density of monolayer slice ranges from 0.500g/cm3 to 0.996g/cm3 and it is designed to fit power law equation. The volume percentage of plastic microballoons in the monolayer pellets varies from 16.61% to 58.06%. The slices were characterized by optical and scanning electron microscopy, and measurement of density and sound wave velocity. The density, glass transition temperature and acoustic impedance were observed to vary with the volume percentage of plastic microballoons in the composite. Graded syntactic foams were fabricated by stacking slices of different density in a sequence of density gradient and the slices were bound together with adhesive made of epoxy resin-hardener under the pressure of 5MPa.


Author(s):  
D. J. McComb ◽  
J. Beri ◽  
F. Zak ◽  
K. Kovacs

Gonadotroph cell adenomas of the pituitary are infrequent in human patients and are not invariably associated with altered gonadal function. To date, no animal model of this tumor type exists. Herein, we describe spontaneous gonadotroph cell adenomas in old male and female Sprague-Dawley rats by histology, immunocytology and electron microscopy.The material consisted of the pituitaries of 27 male and 38 female Sprague Dawley rats, all 26 months of age or older, removed at routine autopsy. Sections of formal in-fixed, paraffin-embedded tissue were stained with hematoxylin-phloxine-saffron (HPS), the PAS method and the Gordon-Sweet technique for the demonstration of reticulin fibers. For immunostaining, sections were exposed to anti-rat β-LH, anti-ratβ-TSH, anti-rat PRL, anti-rat GH and anti-rat ACTH 1-39. For electron microscopy, tissue was fixed in 2.5% glutaraldehyde, postfixed in 1% OsO4 and embedded in epoxy-resin. Tissue fixed in 10% formalin, embedded in epoxy resin without osmification, was used for immunoelectron microscopy.


Author(s):  
J. Temple Black ◽  
William G. Boldosser

Ultramicrotomy produces plastic deformation in the surfaces of microtomed TEM specimens which can not generally be observed unless special preparations are made. In this study, a typical biological composite of tissue (infundibular thoracic attachment) infiltrated in the normal manner with an embedding epoxy resin (Epon 812 in a 60/40 mixture) was microtomed with glass and diamond knives, both with 45 degree body angle. Sectioning was done in Portor Blum Mt-2 and Mt-1 microtomes. Sections were collected on formvar coated grids so that both the top side and the bottom side of the sections could be examined. Sections were then placed in a vacuum evaporator and self-shadowed with carbon. Some were chromium shadowed at a 30 degree angle. The sections were then examined in a Phillips 300 TEM at 60kv.Carbon coating (C) or carbon coating with chrom shadowing (C-Ch) makes in effect, single stage replicas of the surfaces of the sections and thus allows the damage in the surfaces to be observable in the TEM. Figure 1 (see key to figures) shows the bottom side of a diamond knife section, carbon self-shadowed and chrom shadowed perpendicular to the cutting direction. Very fine knife marks and surface damage can be observed.


Author(s):  
J. G. Adams ◽  
M. M. Campbell ◽  
H. Thomas ◽  
J. J. Ghldonl

Since the introduction of epoxy resins as embedding material for electron microscopy, the list of new formulations and variations of widely accepted mixtures has grown rapidly. Described here is a resin system utilizing Maraglas 655, Dow D.E.R. 732, DDSA, and BDMA, which is a variation of the mixtures of Lockwood and Erlandson. In the development of the mixture, the Maraglas and the Dow resins were tested in 3 different volumetric proportions, 6:4, 7:3, and 8:2. Cutting qualities and characteristics of stability in the electron beam and image contrast were evaluated for these epoxy mixtures with anhydride (DDSA) to epoxy ratios of 0.4, 0.55, and 0.7. Each mixture was polymerized overnight at 60°C with 2% and 3% BDMA.Although the differences among the test resins were slight in terms of cutting ease, general tissue preservation, and stability in the beam, the 7:3 Maraglas to D.E.R. 732 ratio at an anhydride to epoxy ratio of 0.55 polymerized with 3% BDMA proved to be most consistent. The resulting plastic is relatively hard and somewhat brittle which necessitates trimming and facing the block slowly and cautiously to avoid chipping. Sections up to about 2 microns in thickness can be cut and stained with any of several light microscope stains and excellent quality light photomicrographs can be taken of such sections (Fig. 1).


Author(s):  
C. F. Oster

Although ultra-thin sectioning techniques are widely used in the biological sciences, their applications are somewhat less popular but very useful in industrial applications. This presentation will review several specific applications where ultra-thin sectioning techniques have proven invaluable.The preparation of samples for sectioning usually involves embedding in an epoxy resin. Araldite 6005 Resin and Hardener are mixed so that the hardness of the embedding medium matches that of the sample to reduce any distortion of the sample during the sectioning process. No dehydration series are needed to prepare our usual samples for embedding, but some types require hardening and staining steps. The embedded samples are sectioned with either a prototype of a Porter-Blum Microtome or an LKB Ultrotome III. Both instruments are equipped with diamond knives.In the study of photographic film, the distribution of the developed silver particles through the layer is important to the image tone and/or scattering power. Also, the morphology of the developed silver is an important factor, and cross sections will show this structure.


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