Semi-synthetic resins have gained popularity over the years. These resins are made of naturally occurring fibers obtained from cotton and wood pulp linters, and are generally referred to as cellulosic. These synthetic plastic resins exhibit a wide range of properties, which makes them a popular choice across industries. Are you intrigued to know how and where these cellulosic are used? If yes, this post discusses these resins, their properties, and more.
Know About Cellulosic, Their Composition, and Manufacturing
Cellulose is one of the most abundantly available natural polymers on earth. Cotton fibers comprise 90% cellulose, which makes it one of the common raw materials for several semi-synthetic cellulosic. Cellulosic resins are usually made of ester cellulose and ether cellulose.
- Ester Cellulose: Cellulose acetate-butyrate (CAB), cellulose Acetate (CAC), and cellulose acetate-propionate (CAP) are a few important synthetic cellulose esters. The plastic resins produced from these esters are known as butyrate, acetate, ethyl cellulose, and propionate. Of these, cellulose acetate has been widely used in several commercial applications, and is a thermoplastic by nature. So, here, we can concentrate on its composition and manufacturing.
Cellulose acetate is produced by mixing acetic anhydride and glacial acetic acid with cotton fiber and sulfuric acid. Here, sulfuric acid initiates the reaction. This composition produces cellulose triacetate, which is further hydrolyzed by adding water. Cellulose acetate is the end product of this reaction.
- Ether Cellulose: Like ester cellulose, ether cellulose is also produced from linters of cotton and wood pulp. The linters are treated with a sodium hydroxide solution and they form alkali cellulose. In the next step, the linters are treated with an epoxide or an alkyl halide or alkyl sulfate. Ethyl cellulose and methyl cellulose are two important types of cellulose ethers. Some popular ether cellulose includes carboxymethylcellulose (CMC), hydroxyethylcellulose (HEC), and hydroxylpropylcellulose (HPC). These cellulose polymers are created by treating linters of wood pulp or cotton with chloroacetate (CMC), as well as HEC or HPC epoxides.
A Fair Overview on Properties of Cellulosic
The properties of cellulosic can be altered by adding plasticizers to them. Thus, their property ranges also differ widely. The following pointers will help you understand them better.
- Cellulosic resins are available in translucent, opaque, and transparent colors.
- They can be availed in mottles and pearlescent colors, and possess brilliant surface gloss.
- Most cellulosic are available in crystal clear composition.
- Depending on plasticizers, these resins can resist inorganic and organic weak acids, vegetable oils, and hydrocarbons.
- Different plasticizers are added to improve moisture resistance, toughness, and flexibility of these resins.
- Most cellulosic possess excellent formability, which contributes to their increasing use in various applications.
- Many types such as cellulose acetate propionate may have little or no odor.
Specific Properties of Cellulosic Resins
As said before, the properties of these resins widely differ due to their composition. The following pointers will help you understand the properties of specific resins.
- Plastic parts made of ethyl cellulose can be used over a broad temperature range. They can withstand extremely low and high temperatures. Ethyl cellulose has low thermal conductivity and specific heat.
- Ethyl cellulose is resistant to black powder and nitroglycerine, which is why it is widely used for military applications.
- Methyl cellulose is used to make polymer films, and they possess low elongation and brilliant strength at regular temperatures.
- Methyl cellulose assures excellent oil, solvent, and UV resistance.
- Cellulose acetate is a flexible and most stable cellulose thermoplastic. The acetate is mixed with plasticizers to improve their physical properties.
- Ethyl cellulose assures excellent dimensional stability and can repel moisture strongly.
Common Applications of Cellulose Resins
Owing to their widely differing composition, these resins are used in various applications. The following are a few popular ones.
- Butyrates are used for creating durable parts such as tool dials, cash register keys, as well as data processor, knobs, switch covers, and so on.
- Ethyl cellulose is used for making rollers, helmets, flashlight housings, as well as various tool handles.
- Propionates are used for making fuel-filter bowls, marine steering wheels, handles for a toothbrush, cosmetic storage containers, safety goggles, and so on.
- Acetates are used for making cast films as well as sheets for packaging, pen barrels, eyeless glass frames, and so on.
As the formulation, applications, and properties of cellulosic are well introduced through this post, plastic manufacturers also understand the importance of sourcing these resins from trusted suppliers. Mid Continent Plastics is one of the popular suppliers of cellulosic resins in the US. The company has been buying and selling these resins and other popular plastic resins for several years now.