What is cellulose, and what is cellulose ether? Production and use in construction
How the cellulose in plant fibre becomes the additive that holds water in mortar: how cellulose ether is made and what it does on site.
What is cellulose?
Cellulose is the natural polymer that makes up plant cell walls. It is abundant in fibrous plants such as wood, cotton and flax. Glucose molecules link end to end to form long chains, and that structure is what gives a plant its strength and rigidity.
What is cellulose ether?
Attach ether groups to the cellulose chain chemically and you get cellulose ether. Raw cellulose doesn't dissolve in water; cellulose ether does, thickens the water and can form a film. Those properties put it to work in many sectors, from textiles and food to pharmaceuticals and cosmetics. Our interest here is construction.
How is cellulose ether made?
- Raw material. Pure cellulose is obtained from cellulose-rich sources such as wood pulp or cotton linters.
- Alkali activation. The cellulose is treated, usually with sodium hydroxide (NaOH) solution. This swells the fibres and makes the cellulose ready to react.
- Etherification. The activated cellulose is reacted with alkyl halides such as methyl chloride or ethyl chloride; for hydroxyethyl and hydroxypropyl grades, ethylene oxide or propylene oxide is also used. This is the step where ether groups attach to the chain.
- Washing and purification. The product is washed to remove by-products and unreacted chemicals.
- Drying and grinding. The dried cellulose ether is turned into powder or granules and packed.
Where is it used in construction?
- Renders and mortars. This is the main use. Cellulose ether holds water in the mortar and regulates its consistency. The mortar doesn't dry out early on the wall and stays workable for longer.
- Concrete. Raises the viscosity of the mix and reduces segregation and bleeding. It is useful where the mix must not wash out, such as underwater concrete.
- ETICS mortars. Holds water in adhesive and base-coat mortars and helps the mortar bond well to the insulation board.
- Paints and coatings. Thickens paint and helps it spread evenly. Because it slows drying, it gives the applicator more time.
- Other construction chemicals. Also used in waterproofing products, joint fillers and render additives.
- Precast elements. In products such as extruded fibre cement boards, it lets the mortar leave the die cleanly without breaking apart.
In most of this list, cellulose ether does the same job: it holds water, sets the consistency and buys the applicator time.
Let's pick the right product together.
Tell us what you make and we will suggest the product that fits.