Page 26 - Plastics News March 2019

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What are Thermoplastics? Polyamide is most commonly associated with the
production of ropes and belts.
As discussed earlier, plastics are widely recognized as
real-world applications of the use of chemistry. From Advantages and Disadvantages of Thermoplas-
plastic containers, bottles, and life-saving medical tics
devices to aerospace components, plastics are a,aterial
that is used in applications all around us. Thermoplastic The primary advantage of thermoplastics is their wide
polymers are one such type of plastic which is known for range of applications. Thermoplastics are high strength,
its versatility and recyclability. Thermoplastic polymers lightweight materials and have relatively low processing
form when repeating units called monomers link into costs. Additionally, thermoplastic components are
chains or branches. relatively easy to manufacture with high volume and
precision.
Thermoplastic pellets soften when heated and become
more fluid as more heat is administered. The curing The primary disadvantage of using thermoplastics instead
process is 100% reversible as no chemical bonding takes of materials such as metal is their relatively low melting
place. This characteristic allows thermoplastics to be point. Certain types of low-quality thermoplastics can melt
remolded and recycled without negatively affecting when they're exposed to the sun for extended periods.
the material’s physical properties. There are a variety Furthermore, thermoplastics can have poor resistance to
of thermoplastic resins that offer various performance organic solvents, hydrocarbons, and highly polar solvents.
benefits, but the majority of materials commonly used Thermoplastics are susceptible to creep, which occurs
offer high strength, shrink-resistance, and easy flexibility. when the material stretches and weakens under exposure
Depending on the resin, thermoplastics can serve low- to long-term stress loads. The susceptibility to creep is
stress applications such as plastic bags or can be used in further exacerbated by the lower melting temperature
high-stress mechanical parts. Examples of thermoplastic of the material. Other types of thermoplastics, such as
polymers include polyethylene, PVC, and nylon. 1 composites, can fracture instead of becoming deformed
Applications of Thermoplastics under high-stress conditions.
In polluted, acidic, environments such as may be found in Table 2: Pros and Cons of Thermoplastic Materials
modern cities, steel piping systems are often vulnerable to
rust or corrosion and therefore need special provisions for Thermoplastic Pros Thermoplastic Cons
corrosion protection. The cost associated with protecting Extremely adhesive to metal
steel piping systems that are exposed to these harsh High recyclable
environments can be expensive. Thermoplastics are Superb impact resistance
considered to be a favorable substitute to minimize these Can be remolded and reshaped May soften when reheated
costs. Certain properties of thermoplastics that make
them a suitable substitute material are: Excellent corrosion resistance
• Their ability to withstand corrosive materials and Slip enhancement
corrosive environments. Detergent and chemical
• Being able to carry materials of extreme temperatures resistance
(hot or cold). Flexibility and elongation of
• Their capacity to handle virtually any type of fluid the coating film Can be more expensive than
transport application. Electrical insulation thermoset
Common materials used to produce these pipes are PVC or Chip resistance
CPVC. Additional materials include polypropylene, PVDF, Aesthetically-superior finishes
ABS, nylon, and polyethylene. Polyethylene gas tanks are
used to transport natural gas for use in residential and Superb corrosion resistance
commercial applications. Image credit:
Other common applications for thermoplastics include Types of Thermoplastic Materials
high-pressure polyethylene to encapsulate rigid objects
like electrical equipment. Low-pressure polyethylene Types of thermoplastics commonly employed for
is very elastic and ideal for insulating electrical cables. manufacturing include polyethylene (PE), polyvinyl

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