China 
Africa 
Explore chapters and articles related to this topic
Thermoset Polymer Matrix–Based Natural Fiber Composites
Published in Shishir Sinha, G. L. Devnani, Natural Fiber Composites, 2022
Polyimide was discovered by Bogert and Rensitshaw in 1908. However, the polyimide used for commercial purposes was made in 1950. Polyimide is a high-temperature engineered polymer that is used for temperatures up to 315°C. The curing system can either be condensation or addition. In addition to the curing system, polyimides can be made with solvents like dimethylformamide (DMF) and dimethylacetamide (DMAC). which are removed during the curing process. The condensation curing system gives water as a by-product, which results in serious volatile management issues during curing. To remove the lowering in mechanical properties of the matrix, the volatiles should be removed before resin gelation (McKeen, 2021). They are difficult to process compared to epoxy because they need high processing temperature and higher pressure. The volatile impedes the potential while processing polyimide. They have great resistance power and excellent flexural strength. PMR-15 is one of the best addition-cured polyimides, which means polymeric monomer that contains three monomers and has a molecular weight of 1,500. Another promising resin PETI-5 was developed after screening the materials. PETI stands for phenylethynyl terminated imide. NMP, which stands for N-methyl pyrrolidone, is a major retainer during curing to manage volatiles and voids. They are characterized by an exceptional combination of mechanical toughness, thermal stability, outstanding dielectric property, and chemical resistance.
Synthesis of Polyimides
Published in Malay K. Ghosh, K. L. Mittal, Polyimides Fundamentals and Applications, 2018
During the past three decades since the commercialization of Kapton polyimide, an impressive variety of polyimides has been synthesized because of both scientific and commercial interests [1–4]. Polyimides possess outstanding key properties such as thermoxidative stability, high mechanical strength, high modulus, excellent electrical properties, and superior chemical resistance. Because of these merits, general difficulty in processing polyimides and their high cost did not deter further exploration of new compositions and new processing methods aimed at value-added niche markets in high technology applications. An important consideration in the successful synthesis of polyimides is a design of proper composition and proper choice of synthesis method. The latter is ultimately determined by the physical and chemical properties of monomers and polymers as well as those of intermediates. In this chapter, the fundamental aspects and new developments in the chemistry of polyimide synthesis will be discussed, particular emphasis on reaction mechanisms.
Sensing Effects and Sensitive Polymers
Published in Gábor Harsányi, Polymer Films in Sensor Applications, 2017
Recent improvement in polymide processing for integrated circuit and interlay dielectric applications (see Section 1.4) enables humidity sensors to be fabricated on integrated circuit structures [22]. Using this technique, small, low-cost humidity sensors are available, and, most importantly, it becomes possible to integrate the humidity sensor with other sensors and signal-processing circuitry on the same substrate. The application of photosensitive polyimides (see Section 1.4) reduces the number of patterning process steps. Polyimides offer the following further advantages: an almost linear response to humidity changes, good absorption of water, resistance to chemical attack, mechanical strength, and high temperature capability. The sensitivity and response depend upon the sensor geometry, including the layer thickness and the geometry of the electrodes as well.
Effects of Gamma Irradiation on the Morphological, Physical, and Thermal Properties of B4C/CF/PI/AA6061 Hybrid Composite Laminates
Published in Nuclear Science and Engineering, 2020
Xuelong Fu, Jie Tao, Dunwen Zuo
In recent years, polyimide resin has gained increasing attention in the engineering field.1,2 As a special engineering plastic, aromatic polyimide is widely used in the aerospace and microelectronics fields, the nuclear industry, and other fields owing to its excellent heat resistance, mechanical properties, and chemical stability.3,4 Moreover, polyimide resin possesses excellent high-temperature stability and good radiation resistance5,6 up to 5 × 107 Gy when compared with polyethylene, polypropylene, and polyamide. The notable usage of polyimide resin is primarily in applications such as films,7 coatings,8 or membranes.9 Usually, the polyimide resin is always combined with other inorganic fillers such as carbon nanotubes,10 graphene,11 boron nitride,12 boron carbides13 (B4C), etc. It has been demonstrated that polymer matrix is highly affected by fillers where the specific dimension, dispersion state, and interaction between the fillers and the polymer play significant roles.14,15 On the other hand, polyimide resin contains a high content of hydrogen elements, which can effectively attenuate fast neutrons. As a result, it is good to assess the physical and chemical properties of polyimide matrix composite in nuclear engineering.
Microscopic damage behavior in carbon fiber reinforced plastic laminates for a high accuracy antenna in a satellite under cyclic thermal loading
Published in Advanced Composite Materials, 2018
Satoshi Kobayashi, Tomoaki Shimpo, Ken Goto
In the present study, we selected three types of resin as candidate materials for a high accuracy antenna in next radio astronomy satellite, such as polycyanate ester (NM31, JX Nippon Oil and Energy Co.), polyimide (PETI-340M, Ube Industry LTD.) and epoxy (#133, Toho Tenax Co.). Polycyanate ester has lower moisture absorption property which results in lower out-gas in space and higher dimension accuracy. Polyimide has higher heat resistant and lower creep deformation properties. Carbon fiber (M46J, Toray Industry Inc.) was used as a reinforcement in all specimens. Specimens with polycyanate ester, polyimide and epoxy were denoted as CM, IM and EM, respectively. Laminate configurations were decided to attain near 0 CTE as [0/30/90/-30/0]4S for CM and IM and [0/30/90/-30/0]8 for EM. Stacking direction was set as width, because near 0 axial CTE at the cross section in thickness during bending was expected in the actual usage in the antenna. Top and bottom surfaces of the specimens are polished with emery papers and finished with alumina slurry with 0.3 mm diameter. In this study, we observed specimen surface to evaluate microscopic damage behavior. Serious microscopic damage occurred in 90° plies as mentioned below. We denoted 90° plies as 1st90°, 2nd90°, 3rd90° and 4th90° from outermost to innermost to distinguish the location of the 90° plies. Summary of specimen data is shown in Table 1.
Design reviews on a multipurpose power sockets for different applications
Published in Cogent Engineering, 2018
Chin jie Wong, Umar Nirmal, Sharmeeni Murugan
Another type of plastics that is widely used is polyimide. Thermosetting polyimide is one of the highest performing engineering plastics, with superior performance in applications under severe conditions. The properties of polyimide materials include:high temperature resistance that have operating temperature of 315°C,high wear resistance,low thermal expansion,good thermal and electrical insulation,relatively easy to machine,