CO2 Recycling: Trees to Plastics

The Process of Making Trees into Plastic Eastman Chemical Company Website 13may01

 

We've documented, in our posts to the WV Coal Association R&D Blog, that, not only can coal be converted in economical and responsible ways into the variety of liquid fuels and plastics manufacturing raw materials that we, as a modern industrial nation, need, the primary by-product of coal use, Carbon Dioxide, can itself be directly captured and recycled into those same fuels and plastics.

 

We've also documented that botanical materials, such as cellulose, can also be converted into liquid fuels using the same technologies as are used for coal liquefaction, and even as a co-feed raw material with coal in the same, appropriately-specified, process stream.

 

Such botanically-derived cellulose-to-fuel technology represents an inherent route of Carbon Dioxide recycling, and it avoids capital expense that might be required for direct CO2 capture and processing.

 

We have, as noted, shown that coal can be converted into plastics manufacturing raw materials, as is being done by Eastman Chemical in Kingsport, Tennessee.

 

Cellulose has the same potential, as well. And, as with direct Carbon Dioxide recycling, into methanol that would be used for the manufacture of plastics as opposed to liquid fuel, such practice of converting cellulose into plastic would represent an essentially permanent, and profitably productive, route of "sequestration" for atmospheric Carbon Dioxide.

 

Eastman Chemical, as per the article linked above, has developed such technology. An extended excerpt from their site follows. Keep in mind, as you read it, that the cellulose they use to make these valuable, lasting products, is a material that recycles, in a very "Green", ecologically-responsible fashion, the primary by-product of our coal use industries, and "sequesters" it in a way that should be more than satisfactory to all but the Big Oil lackeys, who hope to coerce our coal industries into pumping, at all our expense, CO2 deep into the earth - to force out more petroleum they can further extort us, and enrich themselves, with.

 

The excerpt has been edited somewhat to improve length and clarity. As always, we urge our readers to access the site through the link for more information.

 

The Process of Making Trees into Plastic

Eastman Chemical Company 

From Trees to Plastic
Trees to Cellulose 4.78 lb of wood chips = 1 lb of cellulose
Cellulose to Ester 0.59 lb of cellulose = 1 lb of ester
Ester to Plastic 0.92 lb of ester = 1 lb of plastic
Trees to Plastic2.60 lb of wood chips = 1 lb of plastic

From Trees to Cellulose

In the process of converting trees to cellulose, little is wasted. The bark is removed before pulping and is used as fuel for the conversion process itself. The tree is chipped and then cooked in a digester to separate cellulose fibers. Lignins and resins produced at this stage can also be used for other chemical products or as fuel.

The resulting pulp of alpha cellulose and hemicellulose is treated with various bleaching chemicals to reduce the hemicellulose content and remove the last traces of lignins and resins. At this stage, the pulp is clean and white. It is pressed to remove water, then dried and wound onto rolls. This is the high-quality, high-alpha cellulose used to manufacture cellulose esters for plastics. Only the highest-quality pulps are used for Tenite cellulosics

From Cellulose to Ester

Cellulose esters are made by reacting high-purity cellulose with selected acids and anhydrides in a multistage process. The choice of acids and anhydrides determines the chemical composition and properties of the final Tenite cellulosic plastic; the cellulosic plastics—acetate, butyrate, and propionate—are chemically different.

In esterification and hydrolysis, the cellulose, acids, and anhydrides are reacted under controlled catalyst concentrations and temperatures to determine the chemical make-up and viscosity of the cellulose ester. A viscous solution—the cellulose ester dissolved in acid—is formed at this stage. The solution then undergoes ultrafine filtration to remove traces of unreacted cellulose fibers and by-products. This ultrafine filtration is critical in making high-quality material required for injection molding and extrusion applications. Then, in a process known as precipitation, the cellulose esters are separated from the viscous solution of water and acids as a solid powder. Following precipitation, the cellulose esters are washed to remove residual acids, then dried.

From Ester to Plastic

Cellulose ester, plasticizer, and additives are compounded in the final manufacturing step to produce the finished cellulosic plastic.

Tenite cellulosic plastics, the first of the modern thermoplastics, have been used for more than 60 years because they:

• Have an excellent balance of properties, including toughness, hardness, strength, surface gloss, clarity, chemical resistance, and a warm feel.
• Are available in a variety of formulas, plasticizer levels, and additives.
• Are easily molded, extruded, and fabricated.
• Are resistant to attack or change by a wide variety of common household, industrial, and medical chemicals.

Properties

Tenite cellulosic plastics, noted for their excellent balance of properties, are available in a variety of formulas and plasticizer levels and can be tailored to the requirements of the user.

Mechanical
Tenite acetate, butyrate, and propionate are specified by the percentage of plasticizer.

The mechanical properties of Tenite cellulosic plastics differ with plasticizer level. The type and amount of plasticizer affects the mechanical properties of the plastic. Lower plasticizer content yields a harder surface, higher heat resistance, greater rigidity, higher tensile strength, and better dimensional stability; higher plasticizer content increases impact strength.

Electrical

Electrical properties of Tenite acetate, butyrate, and propionate are similar. All have a high dielectric constant, good dielectric strength and volume resistivity, and a high dissipation factor.

Chemical Resistance

Tenite cellulosic plastics are characterized by exceptional resistance to chemically induced stress cracking. Tenite cellulosics are resistant to attack or change by a wide variety of common household, industrial, and medical chemicals such as toothpaste, aliphatic hydrocarbons, bleach, detergents/soaps, ethylene glycol, salt solutions, vegetable and mineral oils, alcohols, and lipids.

Cellulosics are frequently chosen not only for their good balance of properties and ease of processing but also for their extraordinary appearance characteristics.

Special formulations of Tenite butyrate and propionate for outdoor applications or formulations that meet FDA regulations are available.