Editing Rayon (section)

== Structural modification ==
The physical properties of rayon remained unchanged until the development of high-tenacity rayon in the 1940s. Further research and development led to high-wet-modulus rayon (HWM rayon) in the 1950s.<ref name="Kadolph 2001" /> Research in the UK was centred on the government-funded [[British Rayon Research Association]].

''High-tenacity rayon'' is another modified version of viscose that has almost twice the strength of HWM. This type of rayon is typically used for industrial purposes such as tire cord.<ref name="Ohio" />

Industrial applications of rayon emerged around 1935. Substituting cotton fiber in tires and belts, industrial types of rayon developed a totally different set of properties, amongst which tensile strength and elastic modulus<!--Tensile strength and elasticity are different properties; the author is confused.--> were paramount.

'''''{{vanchor|Modal}}''''' is a [[genericized trademark]] of [[Lenzing AG]], used for (viscose) rayon which is stretched as it is made, aligning the molecules along the fibers. Two forms are available: "polynosics" and "high wet modulus" (HWM).<ref name="Undershirts">{{Cite news |url=https://www.undershirts.co.uk/blogs/research/viscose-vs-modal-vs-lyocell |title=Viscose vs. Modal vs. Lyocell – Difference? |publisher=Robert Owen Undershirts Co |access-date=2018-06-11 }}</ref><ref name="The Spruce">{{Cite web |url=https://www.thespruce.com/how-to-wash-modal-clothes-2145794 |title=How to Wash Modal Clothes |website=The Spruce |access-date=2018-06-11 }}</ref>{{better source needed|date=August 2021}} ''High-wet-modulus rayon'' is a modified version of viscose that is stronger when wet. It can be [[mercerized]] like cotton. HWM rayons are also known as "polynosic".{{contradictory inline|date=August 2021}} Polynosic fibers are dimensionally stable and do not shrink or get pulled out of shape when wet like many rayons. They are also wear-resistant and strong while maintaining a soft, silky feel. They are sometimes identified by the trade name Modal.<ref name="Ohio">{{Cite web |last=Smith |first=Joyce A. |url=http://ohioline.osu.edu/hyg-fact/5000/5538.html |title=Rayon – The Multi-Faceted Fiber. Ohio State University Rayon Fact Sheet |archive-date=2010-03-31 |archive-url=https://web.archive.org/web/20100331124255/http://ohioline.osu.edu/hyg-fact/5000/5538.html }}</ref> Modal is used alone or with other fibers (often cotton or [[spandex]]) in clothing and household items like pajamas, underwear, bathrobes, towels, and bedsheets. Modal can be [[Clothes dryer|tumble-dried]] without damage.<ref name="Undershirts" /> The fabric has been known to [[Pill (textile)|pill]] less than cotton due to fiber properties and lower surface friction.<ref name="The Spruce" /> The trademarked Modal is made by spinning beech-tree cellulose and is considered a more eco-friendly alternative to cotton, as the production process uses on average 10–20 times less water.<ref>{{Cite web |url=https://www.lavenderhillclothing.com/pages/what-is-modal |title=What is Modal fabric? Discover the eco-friendly fabric modal }}</ref>