Skip to main content

When I saw this display case – and its contents – at the Museum of Science & Industry, Manchester, I gave something of a wry smile. It shows the basic steps in the production of acetate fibre from pine logs and indicates some of the uses for this most natural of polymers.

You see, cellulose acetate, and various products associated with it, were once a big part of my life. I spent more than 3 years in No. 2 Works Laboratory, at what was then British Celanese, Spondon, Derby. This plant lies to the south and east of the centre of the city, and, although it has shrunk somewhat in size from its peak, it is still a significant production unit for the now-named Celanese Acetate.

The process of converting cellulose to a useable polymer was developed by the Swiss brothers Camille and Henri Dreyfus in Basle, Switzerland in 1905 – they opened their first factory in 1910, which lead to a worldwide adoption of the polymer soon afterwards. Following ‘digestion’ in acetic acid and other chemicals, the cellulose in the wood is converted to cellulose diacetate (this process taking place on a different site to Spondon). When delivered to Spondon, the white acetate flake is mixed with the solvent acetone (the one used as a nail varnish remover), to form a thick, viscous white paste. This is pushed through a flat metal plate, which has been precision-drilled with hundreds of tiny holes. As these polymer ‘strings’ fall through a column of hot air, acetate filaments are formed and are drawn off by powered rollers – the textile so formed was marketed as ‘Dicel’, and used for the production of smooth, ‘drapable’ fabrics with a feel similar to that of silk. Cellulose diacetate is also used as an absorbent material in wound dressings, and as a lining material in suits, for example. You can also form thin, flexible, clear film from cellulose acetate, which can be used to make enclosures for pharmaceuticals, packaging, and other thermoplastic items.

The major problem with acetone/air mixtures is that they can be highly inflammable, even explosive, so the solvent must be recovered as quickly as possible. Fortunately, acetone is highly soluble in water, so the acetone/air mixture is ‘scrubbed’ through water, and put through a large and complex solvent recovery plant. This a) recovers the valuable solvent for re-use, and b) ensures than any water discharged to the local effluent system meets environmental standards, such as colour (in Hazen units) and the Biochemical Oxygen Demand time. The plant also produced cellulose triacetate fibre, which was dissolved in a different solvent – methylene chloride – and a different solvent recovery process, as methylene chloride is both insoluble in water and much denser than it.

The major end-use of cellulose diacetate is, however, less appealing. In the form of a crimped web of fibres – called a tow – it is used to produce billions upon billions of filter tips for cigarettes. Unfortunately, despite the fact that cellulose diacetate can be composted, the estimates for the time a cigarette ‘butt’ to bio-degrade range from 1 month (from the cigarette companies) to up to 15 years (from environmental pressure groups). Whichever estimate you choose, the remains of billions of cigarettes cause a major environmental problem.

http://peoplesmosquito.org.uk

http://shortfinals.wordpress.com

Originally posted to shortfinals on Sun Dec 23, 2012 at 05:16 PM PST.

Also republished by SciTech and Derbyshire and The Peak District.

EMAIL TO A FRIEND X
Your Email has been sent.
You must add at least one tag to this diary before publishing it.

Add keywords that describe this diary. Separate multiple keywords with commas.
Tagging tips - Search For Tags - Browse For Tags

?

More Tagging tips:

A tag is a way to search for this diary. If someone is searching for "Barack Obama," is this a diary they'd be trying to find?

Use a person's full name, without any title. Senator Obama may become President Obama, and Michelle Obama might run for office.

If your diary covers an election or elected official, use election tags, which are generally the state abbreviation followed by the office. CA-01 is the first district House seat. CA-Sen covers both senate races. NY-GOV covers the New York governor's race.

Tags do not compound: that is, "education reform" is a completely different tag from "education". A tag like "reform" alone is probably not meaningful.

Consider if one or more of these tags fits your diary: Civil Rights, Community, Congress, Culture, Economy, Education, Elections, Energy, Environment, Health Care, International, Labor, Law, Media, Meta, National Security, Science, Transportation, or White House. If your diary is specific to a state, consider adding the state (California, Texas, etc). Keep in mind, though, that there are many wonderful and important diaries that don't fit in any of these tags. Don't worry if yours doesn't.

You can add a private note to this diary when hotlisting it:
Are you sure you want to remove this diary from your hotlist?
Are you sure you want to remove your recommendation? You can only recommend a diary once, so you will not be able to re-recommend it afterwards.
Rescue this diary, and add a note:
Are you sure you want to remove this diary from Rescue?
Choose where to republish this diary. The diary will be added to the queue for that group. Publish it from the queue to make it appear.

You must be a member of a group to use this feature.

Add a quick update to your diary without changing the diary itself:
Are you sure you want to remove this diary?
(The diary will be removed from the site and returned to your drafts for further editing.)
(The diary will be removed.)
Are you sure you want to save these changes to the published diary?

Comment Preferences

Subscribe or Donate to support Daily Kos.

Click here for the mobile view of the site