What is the difference between thermoplastics and thermosets?

Among many types of plastics divided into several families, we can divide them into two categories: thermoplastics and thermosets. Since some plastics belong to the two categories depending on the modifications made in the initial chemical structure.

Thermosets

They are curing resins, much used in crafts such as polyester resin, or in small maintenance in civil construction such as epoxy resin.

After polymerization and rigid, this resin does not return to its original state, that is, it does not soften even with the heat - it is the so-called "cure", an attempt to heat the thermoset in order to fuse it fatally will lead to degradation. The cure is an irreversible chemical reaction called reticulating, also known by the term crosslinking; and occurs more easily and quickly in the presence of heat and may occur at room temperature. It is noteworthy that this type of reaction is exothermic (releases heat), so even at room temperature the heating of the plastic material occurs naturally.

The crosslinking that occurs during the reaction is caused by the bonding of atoms between / through two linear polymers, resulting in a rigid three-dimensional chemical structure. In the figure below it is possible to see an example of a polymerization reaction of styrene-polyester copolymer, used in craftwork.

The thermosets as well as the thermoplastics can be fiber reinforced and loaded with other fillers. They are quite rigid even without the addition of reinforcements, however, it is that story of glass: the harder the more fragile; making them to be used in more specific applications such as where thermoplastics do not withstand heat and in exclusively manual work applications. In addition, the fact that the thermoset cannot be reprocessed adds a further disadvantage, with waste destined for the production of loads in the form of powder.

Thermoplastics

Unlike thermosets, thermoplastics do not cure and can be easily melted with heat (between 135° C and 250°C [275°F and 482°F] depending on the polymer) and cured again with cooling at room temperature. They can be reprocessed several times, but obviously, they lose properties at each recycling and can also degrade due to the high number of re-cycles.

Compared to thermosets, they have much lower thermal and dimensional stability, but have a much easier and economical processability.

Below is a table with examples of the main families of polymers, thermoplastics and thermosets, their best-known trade names and manufacturing companies.

THERMOSETS
Family	Commercial name	Manufacturer
Alkyds	Uradil	DSM
Epoxies	D.E.R.	Dow
	Araldite	Huntsman Advanced Materials
Phenolic	Bakelite	Union Carbide
Diallyl Phthalate (DAP)	Daiso DAP	Daiso
Melanins	Cymel	Allnex
Polybutadienes	Ricon	Total Cray Valley
Polyesters	Laminac	Island Pyrochemical Industries
	Paraplex	Rohm and Haas
Silicones	Xiameter	Dow Corning
Ureas	Urecoll	Basf
THERMOPLASTICS
Family/Polymer	Commercial name	Manufacturer
ABS	Terluran	Styrolution
Acetalics	Delrin	DuPont
Acrylics	Plexiglas	Evonik
Aramids	Nomex	DuPont
Cellulosics	Tenite	Eastman Chemical
	Ethocel	Dow
Ionomers	Surlyn	DuPont
Polyamides (Nylons)	Zytel	DuPont
	Technyl	Solvay
Polycarbonates	Lexan	Sabic
Polyesters (PBT)	Valox	Sabic
	Celanex	Celanese

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