Views: 0 Author: Site Editor Publish Time: 2021-07-01 Origin: Site
Among the objects that can be made from glass, jars and windows, made from soda lime glass, and kitchenware, made from borosilicate glass, are the older siblings of the family—the stalwarts. Fiber-optic cables, used to transmit nearly all our communications today, are the attention-grabbing youngest child. And fiberglass? It’s the middle child, of course—equally important yet often lost in the shuffle.
“Many people may not realize that glass is made and used in fiber form because the applications are mostly hidden,” says Michelle Korwin-Edson, a senior scientist at Owens Corning, a leading fiberglass manufacturer. Fiberglass is widely used as house and building insulation, she points out, but it may go unnoticed because it’s usually covered by drywall or tucked away in an attic.
Fiberglass may not be a flashy material, but it’s ubiquitous. It’s also big business. Today there are over 40,000 applications just for reinforcement glass fiber. Worldwide, manufacturers make some 5 million metric tons of the stuff annually, mainly for insulation and composites. Market analysts estimate that the amount produced in 2017 was worth nearly $14 billion. By 2025, they predict, that figure will climb to more than $21 billion.
Fiberglass makers have been producing the wispy material commercially since the 1930s, when it started gaining ground as a thermal insulation material for buildings. Much has changed since that time, as manufacturers have learned to tweak the glass fibers’ composition to impart properties that better suit one application or another.
To form fibers in the 5-to-20-µm-diameter range, manufacturers deliver molten glass to an extrusion device that drives the hot liquid through a nozzle that has thousands of tiny holes. The setup and processing steps differ according to the type of fiber being produced. For example, making glass-wool fibers for insulation is initially similar to making cotton candy, Korwin-Edson says. Fine streams of glass emerge horizontally through holes in a rotating spinner and quickly solidify. Afterward, they are chopped by blasts of air that blow them down to a moving conveyor belt, where they are collected and formed into insulation products, including wools, mats, and boards.
Glassmakers typically use a vertical extrusion process to make so-called continuous fibers for reinforcing plastics. According to Hong Li, a senior scientist at Nippon Electric Glass, individual fibers are gathered in bundles of 200–6,000 filaments and woven into fabrics, treated with polymers (resins) to hold them together, or processed in other ways, depending on the application.