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What Is Thermoplastic?

Acrylonitrile butadiene styrene, a type of thermoplastic, is used to make LEGO® blocks.
Polycarbonate, a common type of thermoplastic, is used in eyeglass lenses.
Polyethylene, one of the most common thermoplastics, is often used in shampoo bottles.
A toy with thermoplastic parts.
Thermoplastic has been used to create bullet proof vests.
Thermoplastics are recyclable due to the the materials they are made from.
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  • Written By: Karyn Maier
  • Edited By: Bronwyn Harris
  • Last Modified Date: 03 August 2014
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A thermoplastic (sometimes written as thermo plastic) is a type of plastic made from polymer resins that becomes a homogenized liquid when heated and hard when cooled. When frozen, however, a thermoplastic becomes glass-like and subject to fracture. These characteristics, which lend the material its name, are reversible. That is, it can be reheated, reshaped, and frozen repeatedly. This quality also makes thermoplastics recyclable.

There are dozens of kinds of thermoplastics, with each type varying in crystalline organization and density. Some types that are commonly produced today are polyurethane, polypropylene, polycarbonate, and acrylic. Celluloid, which is considered the first thermoplastic, made its appearance in the mid-1800s and reigned in the industry for approximately 100 years. During its peak production, it was used as a substitute for ivory. Today, it is used to make guitar picks.

Sometimes, thermoplastics are confused with thermosetting plastics. Although they may sound the same, they actually possess very different properties. While thermoplastics can be melted to a liquid and cooled to a solid, thermosetting plastics chemically deteriorate when subjected to heat. Ironically, however, thermosetting plastics tend to be more durable when allowed to cool than many thermoplastics.

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Thermoplastics also differ from elastomers, even though some are considered both. While many thermoplastics can be stretched to a point, they generally tend to both resist, and stay in the shape they are stretched to. Elastomers, as the name suggests, bounce back. However, the addition of plasticizers to the melt can render a more pliable thermoplastic. In fact, this is usually the case when a thermoplastic is being used for plastic injection molding or extrusion.

The specific action of a plasticizer is to lower the material’s glass transition temperature (Tg), which is the point it becomes brittle when cooled and soft when heated. Tg varies with each type of thermoplastic and is dictated by its crystallization structure. However, Tg can also be adjusted by introducing a thermoplastic into a copolymer, such as polystyrene. Until the use of plasticizers, some molded thermoplastic parts were prone to crack in cold weather.

Thermoplastics have been around for a long time, but are a huge component of everyday life today. For example, acrylonitrile butadiene styrene (ABS) is a type of thermoplastic used to manufacture sports equipment, toys (i.e., LEGO® blocks), and various automobile parts. Polycarbonate is used to make compact discs (CDs), drinking bottles, food storage containers, and eyeglass lenses, among other things. Polyethylene is likely the most commonly encountered thermoplastic and is used to make shampoo bottles, plastic grocery bags, and even bullet proof vests.

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Discuss this Article

anon931891
Post 40

Which polymer is used to make toy aeroplanes? Also, how are they made, for example, injection moulding or compression moulding, etc.

anon924839
Post 37

Is teflon thermoplastic? If yes, then what property makes it thermoplastic?

anon318555
Post 29

Thermoplatics are in almost everything we use on a daily basis. I work in an injection molding facility that makes plastic car parts such as wheel well liners, cowl tops, heater cases, blower cases, etc. Pretty much, if it's plastic, it's thermo plastic. Your cell phone, your computer, your laptop, your I-Pad, drink bottles, toys, everything!

anon250669
Post 13

Thermosetting adult toys are dangerous, as the body heat may cause them to crumble or even ignite.

anon163009
Post 10

thermoplastics are plastics that can return to their original state and thermosets are ones that cannot. abs petg acrylic all are thermoplastics. phenolic is a thermoset.

anon150891
Post 9

What are the Tg levels of different thermoplastics?

anon128518
Post 6

is Thermoplastic polyurethane the same as polyurethane? is one better than the other?

anon117523
Post 5

What polymer is best suited for traffic paint application? Thanks. -- bizmuth

Irkutsk
Post 4

Thermoplastics are encountered often in everyday life. Teflon, the non-stick coating is a thermoplastic. Thermoplastics are used for road marking. Thermoplastic road marking paint lasts longer than traditional paints, offers greater visibility, and does not use carcinogenic solvents. Thermoplastics can also be combined with other fibers for added strength, this can make recycling the plastic difficult or impossible though.

eatsjello
Post 3

Thermoplastics seem to be very common. What are some other uses of thermoplastics?

skinnylove
Post 2

The requirements of the rotational moulding industry expressly state that pulverizing services must be used. Some compounding methods for thermoplastic recycling include extrusion, blending, and pelletizing.

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