Introduction
The polymer chains can be free to slide past one another (thermoplastic) or they can be connected to each other with crosslinks (thermoset). Thermoplastics (including thermoplastic elastomers) can be reformed and recycled. This reflects the fact that above Tg they may be shaped or pressed into molds, spun or cast from melts or dissolved in suitable solvents for later fashioning. On the other hand, Thermosets which also includes cross linked elastomers aren't reworkable. They are distinguished via a high degree of cross-linking, resist deformation and solution once their final morphology is achieved. Such polymers are usually prepared in molds that yield the desired object since once formed, can't be reshaped via heating.
Thermoplastics
Polymers that flow when heated; therefore, simply reshaped and recycled. This property is due to presence of long chains through limited or no crosslinks. In a thermoplastic material the very long chain-like molecules are held together via comparatively weak Vander Waals forces. When the material is heated the intermolecular forces are weakened so that it becomes soft and flexible and eventually, at high temperatures, it is a viscous melt (it flows). When the substance is permitted to cool it solidifies once more. For example, polyethylene (PE), polypropylene (PP), poly (vinyl chloride) (PVC), polystyrene (PS), poly (ethylene terephthalate) (PET), nylon (polyamide), unvulcanized natural rubber (polyisoprene)
Thermosets
Decompose when heated; therefore, can't be reformed or reprocessed. Presence of extensive crosslinks between long chains induces decomposition upon heating and renders thermosetting polymers brittle. A thermosetting polymer is created through a chemical reaction that has 2 stages. The 1st stage consequences in the formation of long chain-like molecules similar to those present in thermoplastics, but still able of additional reaction. The second stage of the reaction (crosslinking of chains) takes place during moulding, generally under the application of heat and pressure. During the 2nd stage, the long molecular chains have been interlinked via strong covalent bonds so that the substance can't be softened again through the application of heat. If excess heat is applied to such materials they will char and degrade.
For example, epoxy, unsaturated polyesters, phenol-formaldehyde resins, vulcanized rubber.
Table: Characteristics of Thermoplastic and Thermosetting Polymers
Industrially important thermoplastic and thermosetting polymers
A number of thermoplastics with very good mechanical, electrical, thermal and chemical characteristics are usually termed to as engineering plastics. They are polycarbonates, polyacetals, polyamides, polyethylene, polystyrene, polypropylene, poly(vinyl chloride) and polytetrafluoroethylene. It doesn't mean that only these are helpful within the engineering context. Therefore there are epoxides, formaldehyde-based resins (for instance, phenol-formaldehyde, urea-formaldehyde, and melamine-formaldehyde) and unsaturated polyesters (reinforced as appropriate).
There are 5 main areas of application for polymers, namely, plastics, elastomers, fibers, surface finishes, protective coatings and adhesives. The equivalent polymer might be utilized in two or more applications. For instance, nylon, a well known textile fiber is as well utilized as a plastic molding material and as a film. Similarly epoxides are used in paints and adhesives as well as composites. The main factors determining the application of a given polymer is its mechanical behavior. If this can be appropriately altered via physical and chemical means then the polymer can be utilized in more than one application.
Table: Industrially Important Thermoplastics Polymers
HDPE (High Density Polyethylene): Linear structure, better mechanical properties but more difficult to process than LDPE.
LDPE (Low Density Polyethylene): Branched structure, easier to process than HDPE.
Table: Industrially Important Thermosetting Polymers
Tutorsglobe: A way to secure high grade in your curriculum (Online Tutoring)
Expand your confidence, grow study skills and improve your grades.
Since 2009, Tutorsglobe has proactively helped millions of students to get better grades in school, college or university and score well in competitive tests with live, one-on-one online tutoring.
Using an advanced developed tutoring system providing little or no wait time, the students are connected on-demand with an expert at www.tutorsglobe.com. Students work one-on-one, in real-time with a tutor, communicating and studying using a virtual whiteboard technology. Scientific and mathematical notation, symbols, geometric figures, graphing and freehand drawing can be rendered quickly and easily in the advanced whiteboard.
Free to know our price and packages for online chemistry tutoring. Chat with us or submit request at [email protected]
tutorsglobe.com freshwater shortages assignment help-homework help by online fresh water crisis and management tutors
tutorsglobe.com amphibious hydrophytes assignment help-homework help by online hydrophytes tutors
TutorsGlobe.com Acid-Bases and Salts-General Properties Assignment Help-Homework Help by Online Access Chemistry Tutors
Classification of Living Organisms tutorial all along with the key concepts of Hierarchy of Living Organism, Binomal Nomenclature and Kingdoms.
Introduction to Microbiology tutorial all along with the key concepts of Microorganisms, Microorganisms are Cells, Classification Systems for Microorganisms, Domain Bacteria, Domain Archaea and Domain Eucarya
Population genetics tutorial all along with the key concepts of Deriving Gene or Allelic Frequencies, Hardy-Weinberg principle, factors influencing the Hardy Weinberg principle, Modern evolutionary synthesis and Hardy-Weinberg Law
tutorsglobe.com cobb-douglas utility functions assignment help-homework help by online choice and utility maximization tutors
Optimal Costing System is dissimilar from entity to entity. It relies on an in-depth analysis of costs and advantages related with designing of an appropriate costing system.
Avail notable Geophysics Assignment Help at affordable prices and put an end to sleepless nights by scoring A++!
Here, at our Human Sexuality Assignment Help service; students are assisted by the qualified tutors for top-notch papers.
Testing-Analysis of Polymers tutorial all along with the key concepts of Simple identification tests, Sophisticated Instrumental Techniques, Direct observation
job costing method of costing is employed in job order industries in which the production is as per the needs of the customer.
Ratios can be collected into categories, with each category relating to a specific aspect of financial performance or position.
www.tutorsglobe.com offers statement of cash flow homework help, statement of cash flow assignment help, statement of cash flow projects help, accounting tutoring by qualified tutors.
tutorsglobe.com thallus organization assignment help-homework help by online algae tutors
1942142
Questions Asked
3689
Tutors
1462560
Questions Answered
Start Excelling in your courses, Ask an Expert and get answers for your homework and assignments!!