Chapter 6-2

Chapter 6-2 - Chapter 6 Manufactured Cellulosic Fibers:...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Chapter 6 Manufactured Cellulosic Fibers: Rayon: 1 st regenerated fiber (regenerated cellulose) a manufactured fiber composed of regenerated cellulose unmodified cellulosic fiber artificial silk First produced in US First manufactured fiber Unmodified cellulosic fibers viscose rayon regular rayon high-wet-modulus Rayon (HWM) high-tenacity rayon Cuprammonium rayon Lyocell Modified cellulosic fibers acetate triacetate Viscose Rayon: wood pulp (major source) cotton fibers linters bamboo (goes through the same processes as viscose rayon) Viscose Rayon Processing: timber harvested eucalyptus tree spruce tree southern pine chips treated to remove lignin & resin dissolving pulp 95% cellulose pressed into blotter-like sheets (95% cellulosic) Manufacturing Steps of Viscose Rayon: 1. slurrying ( steeping ) soaked in sodium hydroxide (soak blotter-like sheets) swells polymer chains (easier to break and dissolve prepares for step 2) alkali cellulose shredded into white crumbs (shred those sheets) 2. Ageing polymer chains broken easier to dissolve 3. xanthation carbon disulfide polymers pushed apart 4. dissolving & ripening in sodium hydroxide viscous like honey 5. filtration insoluble particles removed delustering agent, pigment added PLACE TO PUT ADDITIVES 6. extrusion wet spun dilute sulfuric acid bath *RAYON HAS SO MANY STEPS WITH CHEMICALS IT IS NOT GREEN TO MAKE ILLEGAL TO MAKE IN U.S. NOW PRODUCED IN ASIA* Modifications: high-wet-modulus rayon (HWM) modal , polynosic rayon = HWM Better than regular Rayon resistance to deformation when wet not aged, xanthate dissolved in water, lower acid concentration, stretched more high-tenacity rayon tire cords Molecular Structure: cellulosic like cotton regular viscose rayon short chains much lower dp lower orientation smaller crystalline/higher amorphous areas HWM rayon (a step up from regular viscose rayon still less than cotton!) longer chains more crystalline more tenacity than regular viscose rayon low dp Physical Properties: color & luster white bright or dull (dulled u would see dots) shape regular rayon serrated/striations HWM less crenulated (more like perfect circles) specific gravity moderate weight (like cotton, linen) Mechanical Properties: strength lower than cotton, linen decreased wet strength...
View Full Document

This note was uploaded on 01/19/2012 for the course HUEC 2040 taught by Professor Staff during the Fall '08 term at LSU.

Page1 / 15

Chapter 6-2 - Chapter 6 Manufactured Cellulosic Fibers:...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online