First-generation, simple bisphenol-based phthalonitriles had high melting points and a short processing window. The Navy scientists addressed these issues in the new second-generation, oligomeric PEEK-like phthalonitrile. With no curing additive present, the resin or composite starts to soften and melt at about 60°C to 63°C. At 125°C, 150°C, 175°C, and 250°C, viscosity values were 1,940, 230, 80, and 30 centipoise (cP), Keller told us.
Although the curing temperature of both first- and second-generation phthalonitrile is the same, newer curing additives afford the ability to cure above 150°C, with faster curing reactions at higher temperatures. This makes it easily possible to control the time to cure and the speed at which the polymerization reaction occurs as functions of the amount of curing additive used and the curing temperature.
"The new phthalonitrile resin can be cured to a shaped solid or gelation at 200°C or 250°C, with curing occurring faster at the higher temperature," said Keller. "With some catalysts or curing additives that we've especially developed for the PEEK-like phthalonitrile, we can even cure to gelation at temperatures as low as 150°C. Of course, the shaped, cured component can be post-cured at higher temperatures to complete the cure, and the postcure can be done on the cured shaped polymer or composite in a high-temperature oven and in the absence of an autoclave or pressure."
Keller said the fact that the material does not soften or exhibit a glass-transition temperature at temperatures over 400°C during continuous modulus mechanical studies is novel. "Other polymers have not previously been reported with this characteristic and with the ability to retain shape under stress at temperatures up to 350°C for aerospace, oil drilling, and other domestic applications needing such stability. Moreover, the cured phthalonitrile is oxidatively stable for applications at these temperatures."
Aside from applications for oil rigs, aircraft, and ships, others may include robotic and autonomous firefighting systems, fire-resistant textiles, automotive components, wind turbine blades, structural composites, and battery casings.
The Navy's new powerful LaWS laser weapon is great at taking out composite targets over a mile away. How much time before other countries like China and Russia design their own and burn through our composites?
Ann, while I don't have a use for this information today, it is certainly handy to have. This source of knowledge is a resource, and like most resources becomes reallyn valuable wnen you need it, and only "interesting" the rest of the time. I can see an immediate application of this material in high frequency hiher power RF electrical applications.
What was not mentioned about the new material was outgassing, which affects the usefulness of a material for satellite and space applications, and also for semiconductor fabrication applications.
ON the issue of technical writing, DN has consistently evidenced that the deeper a technical issue is, the lesser the comments. (Case in point; this article). But I think that should be expected; -- for example, there have been several other deep articles from Guest Bloggers that I couldn't begin to comment on. The interested field of commenters just naturally narrows.
ON the subject of RIM, I was [minimally] familiar with another industrial process – Reaction Injection Molding (a different RIM) which is [loosely translated as] an injection of a 2-part epoxy. A very slow processing time because 'cure' is required. Checking my old faithful resource, Wikipedia doesn't have a page for your definition of RIM but does link it to your other suggested process, Resin Transfer (RTM).
Always interesting to learn about new things – Thanks!
Artificially created metamaterials are already appearing in niche applications like electronics, communications, and defense, says a new report from Lux Research. How quickly they become mainstream depends on cost-effective manufacturing methods, which will include additive manufacturing.
SpaceX has 3D printed and successfully hot-fired a SuperDraco engine chamber made of Inconel, a high-performance superalloy, using direct metal laser sintering (DMLS). The company's first 3D-printed rocket engine part, a main oxidizer valve body for the Falcon 9 rocket, launched in January and is now qualified on all Falcon 9 flights.
Lawrence Livermore National Laboratory and MIT have 3D-printed a new class of metamaterials that are both exceptionally light and have exceptional strength and stiffness. The new metamaterials maintain a nearly constant stiffness per unit of mass density, over three orders of magnitude.
Smart composites that let the material's structural health be monitored automatically and continuously are getting closer to reality. R&D partners in an EU-sponsored project have demonstrated what they say is the first complete, miniaturized, fiber-optic sensor system entirely embedded inside a fiber-reinforced composite.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.