Carbon fiber reinforced polymer as epoxy, but other thermoset or thermoplastic polymers, such as polyester, vinyl ester, or nylon, are sometimes used. The composite material may contain aramid (e.g. Kevlar, Twaron), ultra-high-molecular-weight polyethylene (UHMWPE), aluminium, or glass fibers in addition to carbon fibers. The properties of the final CFRP product can also be affected by the type of additives introduced to the binding matrix (resin). The most common additive is silica, but other additives such as rubber and carbon nanotubes can be used. The material is also referred to as "graphite-reinforced polymer" or "graphite fiber-reinforced polymer" ("GFRP" is less common, as it clashes with
Answering the Question: What is Enlightenment? Answering the Question: What is Enlightenment? "Answering the Question: What Is Enlightenment?" () is a 1784 essay by the philosopher Immanuel Kant. In the December 1784 publication of the "Berlinische Monatsschrift" ("Berlin Monthly"), edited by Friedrich Gedike and Johann Erich Biester, Kant replied to the question posed a year earlier by the Reverend Johann Friedrich Zöllner, who was also an official in the Prussian government. Zöllner's question was addressed to a broad intellectual public community, in reply to Biester's essay entitled: "Proposal, not to engage the clergy any longer when marriages are conducted" (April 1783) and a number of leading