Properties, Use and Preparation of polyurethane
POLYURETHANE
DEFINATION-:
Polyurethane (PUR and PU) is a polymer composed of a chain of organic units joined by carbamate links. While most Polyurethane are thermosetting polymers that do not melt when heated .
POLYURETHANE notes
Polyurethane polymers are formed by reacting an isocynates and polyols .
Polyurethane products often are simply called “urethanes”.
PROPERTIES
- Good Abrasion Resistance
- Good Impact Resistance
- Good Toughness
- Low Viscosity
- High Elongation
- Good Flexibility
- Good tear Strength
- Low Shrinkage
- Hydrolytically Stable
- Resillent
- Thermal properties of polyurethanes are influenced mainly by molecular weight between the cross links , degree of segments in stiff sequence.
- Mechanical properties such as elongation break, tear strength, tensile strength are largely influenced by the presence of aromatic groups, long alkyl chain , branching and cross linking nd also degree of secondary bonding forces.
- Chemical properties of Polyurethane are greatly influenced by the types of isocyanates and polyols used to make it.
USE OF POLYURETHANES
Polyurethanes are used in
- The manufacture of flexible, high-resilience foam seating
- Rigid foam insulation panels
- Microcellular foam seals and gaskets
- Durable elastomeric wheels and tires(such as roller coaster wheels)
- Automative suspension bushings
- Electrical potting compounds
- High performance adhesives
- Surface coating and surface sealants
- Synthetic fibres
- Carpet underlay
- Hard plastic parts(e.g, for electronic instrument)
- Hoses and skateboard wheels
PREPERATION OF POLYURETHANES
- PREPERATION OF POLYURETHANE BY ELECTROSPINNING
Polyurethane nanofibres were prepared by the electrospinning method. The process parameters , including the applied voltage , feeding rate , and solution concentration were investigated carefully. The result showed that the resultant nanofibres , electrospun foam, N-dimethyl formamide solution had ultrafine diameters ranging from about 700 to 50nm. The solution concentration played a main role in influencing thetransformation of the polymer solution into ultrafine fibres, and the diameters increased with solution increased with the solution concentration increasing.
- PREPERATION OF POLYURETHANE FOAM COMPOSITES WITH ALKALI LIGNIN/Renewable PUF
The polyether polyol, RPUF, catalyst, foaming agents, foam stabilizers and alkali lignin (Alkali lignin ratio is fixed 0.5% of the total mass) were mixed according to the certain radio , then the solution was mixed with the diphenylmethane diisocyanate (MDI), and quickly poured into the mold. The polyurethane foam composites can be prepared after the solution was cured.
- Polyurethane Foams fromToluene Diisocyanate and Mixtures of Castor Oil and Polyol
Polyol/ castor oil, small amount of water, silicone oil, stannous octoate, dimethyl aminoethenol were mixed together. Afterwards toluene disocynate was added to the mixture. The mixture was stirred with an electric stirrer to ensure good dispersion of reagents and foam of desirable cell structure.stirring continued until foaming commenced when mixture was poured into a mould. The foam sample produced were left to stand for 24 hours before they were tested to ensure complete curing.
QUESTION & ANSWER
- What is Polyurethane??
ANSWER
Polyurethane is a polymer composed of a chain of organic unit joined by carbamate links. While most Polyurethane are thermosetting polymer that do not melt when heated.
2. How Polyurethane is made??
ANSWER
Polyurethane polymers are formed by reacting an isocyanates and polyols. Both isocyanates and polyols used to make polyurethanes contain on average two or more functional group per molecule.
3. What are the raw materials used to produce the Polyurethane??
ANSWER
A variety of Raw material are used to produce Polyurethanes. These includes prepolymers, stabilizers which protect the integrity of the polymer and colorants.
4. What are the use of polyurethane??
ANSWER
- The manufacture of flexible, high-resilience foam seating
- Rigid foam insulation panels
- Microcellular foam seals and gaskets
- Durable elastomeric wheels and tires(such as roller coaster wheels)
- Automotive suspension bushings
- Electrical potting compounds
- High performance adhesive
- Surface coating and surface sealents
- Synthetic fibres
- Carpet underlay
- Hard plastic parts(e.g. for electronic instrument)
- Hoses and skateboard wheels
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The post here explains about the properties and uses as well as preparation of polyurethane . These are the most essential topics of organic chemistry which could be beneficial for the students.
Polyurethane is a polymer composed of a chain of organic units joined by carbamate links. While most polyurethanes are thermosetting polymers that do not melt when heated, thermoplastic polyurethanes are also available. This is explained here with it’s uses,preparation and properties.