1.17 Plastics and synthetic fibers are examples of the many materials made from repeating subunits of carbon-containing molecules called polymers. Although most synthetic polymers are prepared from fossil fuel sources, many researchers are exploring ways to make polymers from renewable sources instead. One example is the synthesis of an epoxy resin polymer using a by-product from cashew nut processing, another compound isolated from corn cobs, and epichlorohydrin, shown here. Identify any polar covalent bonds in epichlorohydrin by drawing ͆+ and ͆- symbols in the appropriate locations. Epichlorohydrin.