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Aromatic-Alicyclic Polyimides: From Basic Aspects Toward High Technologies
Published in Andreea Irina Barzic, Neha Kanwar Rawat, A. K. Haghi, Imidic Polymers and Green Polymer Chemistry, 2021
Camelia Hulubei, Elena Hamciuc, Corneliu Hamciuc
Foams are generally products derived from the PIs.34 The powder resulting from drying the sprayed polyamide solution is heated in a microwave oven and thus foamed in blocks. Water or alcohol are being removed during cyclization and thus they act as blowing agents. There are also syntactic foams, which are a category of materials produced via pre-formed hollow spheres. For instance, such foams can be accomplished by mixing equal amounts of PI and silica microballoon which are further processed by heating at temperatures around 300°C and moderate pressure.
Chemistry of the Interfaces/Interphases in Composites and Nanocomposites
Published in Omari V. Mukbaniani, Tamara N. Tatrishvili, Marc J. M. Abadie, Science and Technology of Polymers and Advanced Materials, 2019
Hollow glass microspheres K15 and H50 from 3M Scotchlite, of density 0.15 and 0.5 g/cm3, respectively, have been used for making syntactic foam. Without treatment of the hollow microspheres by (3-glycidyloxypropyl) trimethoxysilane there is still discontinuity between the matrix and the hollow glass (Figure 1.6a), whereas once bonded to the coupling agent (Figure 1.6b), better mechanical properties are observed (Table 1.2).
Introduction
Published in Bankim Chandra Ray, Rajesh Kumar Prusty, Dinesh Kumar Rathore, Fibrous Polymeric Composites, 2018
Bankim Chandra Ray, Rajesh Kumar Prusty, Dinesh Kumar Rathore
There are many cases where there are both the change in mechanical properties and water absorption kinetics of materials, they are studied like: The properties of composite tubes made up of glass/epoxy used for cooling water applications are evaluated. At different temperatures and internal pressures, the long term ageing of tubes and different resin hardeners and the influence of liners were studied. After analyzing the results, we conclude that the mechanical properties of material such as flexural strength and interlaminar shear strength are significantly affected by the hydrolysis.Syntactic foam is used in underwater applications. In specific applications, there is a need of materials with properties, as these properties can be attained by the application of composites. Hence, it offers a wide range of use for composites. Syntactic foams are used as a core of composite sandwich structures and are attractive due to the properties like thermal insulation and buoyancy [35].
Machining of novel AA7075 foams containing thin-walled ceramic bubbles
Published in Materials and Manufacturing Processes, 2020
S. Kannan, H. A. Kishawy, S. Pervaiz, K. Thomas, R. Karthikeyan, Ramanathan Arunachalam
In order to validate the developed analytical force model or metal syntactic foams, machining experimentation was performed on aluminum alloy (AA7075) reinforced with hollow ceramic alumina bubbles. Two different volume fractions (10% and 20%) and ceramic bubble sizes (avg sizes: 0.3 mm and 0.6 mm) were used in the experiments. The coated carbide tool (Kennametal™ KC5025) was used in the test with rake and clearance angles of 0 ͦ and 7 ͦ respectively. The orthogonal experiments were conducted using a three axis CNC lathe. All tests were conducted in a dry environment at different cutting parameters of uncut chip thickness (0.02,0.07,0.15,0.2 mm), cutting speed (25, 50, 100 m/min) and reinforcement volume fraction (10% and 20%) and average bubble sizes (0.3 and 0.6 mm). A KISTLER™ 9129AA three-channel dynamometer was used along with a multichannel charge amplifier type 5080 to measure the machining forces. Chips were collected after each test to measure shear angle. Tests were conducted twice to ensure repeatability and average measurement of values noted. Compression tests of casted syntactic foams were conducted using a temperature-controlled Instron machine. The samples were prepared using 15 mm diameter and 15 mm height and polished prior to testing. The force and displacement were recorded during testing from which the stress-strain graph was generated (Fig. 2). The cutting conditions and Johnson-Cook parameters for this material are listed in Tables 2 and 3 respectively.
The Effect of Carbon Nanofiber on the Dynamic and Mechanical Properties of Epoxy/Glass Microballoon Syntactic Foam
Published in Advanced Composite Materials, 2019
Mehmet Fatih Şansveren, Mustafa Yaman
Syntactic foam is lightweight and porous materials produced by mixing hollow particles (microballoons) in a matrix material [1]. These materials are closed cell foams, and this property makes syntactic foams less moisture absorbing [2]. They are used in many applications in the marine, aerospace and automobile sectors [3].
Process parameter effects on cellular structured materials using hollow glass spheres
Published in Materials and Manufacturing Processes, 2019
Jungjin Park, John M. Howard, Avi Edery, Matthew DeMay, Norman Wereley
Cellular solids are structures that are composed of a network of solid struts forming the edges and faces of cells. Cellular solids have many applications, including packaging, thermal insulation, and buoyancy.[1–3] While some applications such as aircraft require large stiffness with minimized weight, cellular solids for energy-absorbing application such as armor and protective gear should be as light as possible and require maximum energy absorbing capacity at a given plateau stress (a large strain deformation at a large constant stress).[1,4–9] Therefore, the properties of the cellular solids should be designed properly for the specific applications. There are various types of cellular solids with different properties.[9,10] Pd- and Pt-based metallic glass foams, aluminum foams, titanium foams and steel alloy cellular structures are widely used metallic foams. A metal matrix with embedded blowing agents is heated above the melting temperature. The blowing agent decompose and release gas that forces the melting precursor to expand, creating a highly porous structure. These systems are difficult to engineer since there are several factors such as impurities, distribution of blowing agents, temperature and timing that could affect the product. Temperature selection and control is critical to produce between solidification of metallic matrix and decomposition of blowing agents. One issue is difficulty in mixing metallic powders and blowing agents. It is hard to achieve good mixing quality due to particle agglomeration from interparticle interactions.[11] These processes are also often costly, and may only be used with a limited number of materials.[2,3,12] Syntactic foams are another material with high energy absorption capacity. Syntactic foam is a composite material consisting of a metal, polymer, or ceramic matrix with hollow microballoons.[13–16] It is often produced using hollow glass spheres with a binding agent such as an epoxy.[17–19] The binding agent is known to have good water and chemical resistance, but heat resistance lies only in the range of 150–320 °C.[18–20] Therefore, the binding agent can be a limiting factor for applications requiring high heat resistance.