We have previously discussed the highly versatile member of the polyester family,　polybutylene terephthalate (PBT), so now it’s time to examine why PBT is used.
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How PBT is made

You may recall that PBT material is created by combining liquid 1 1,4-butanediol (BDO) and solid terephthalic acid (TPA). It is commonly represented in a repeating unit as　C4H8O2C6H4CO2 but can also be written in the expanded form as (O−C6H4−CO−O　(CH2)4)n.
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Polybutylene terephthalate’s key properties

PBT material has an abundance of attractive features. From low water absorption and easy processability to high breakdown voltage and friction resistance, PBT is known for its strength.
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⁠The ease of using additives to boost PBTs properties contributes to the durability. Non-reinforced PBT has a density range from 1.30 to 1.38 grams per cubic centimeter (g/cm³) and can withstand continuous heat from 130 to 150°C. However, both ranges increase when additives are included. For example, mixing glass fibers into PBT increases its continuous use temperature to 120 and 140°C.
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⁠It is not only the ability to tolerate temperature that increases when PBT is reinforced; the following also improves:

• Tensile strength: Grows from 50-60 MPa to 90-150 MPa, depending on the level of r　translucent einforcement.
• Flexural yield: Increases from 70-90 MPa to 120-200 MPa
• Flexural Modulus: Significantly increases when glass is added, moving from 2.5-3.0 GPa to 6.0-10.0 GPa
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In its natural state, PBT appears off-white, but fillers can be used to precisely match existing shades. Additionally, it retains color over time. Plus, when a flame retardant is included, PBT becomes a self-extinguishing plastic with long-term resistance to organic solvents and gasoline.
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What are the different types of PBT?

PBT resin is well known as an engineering plastic with more than a dozen variants, each tailored to the final product's needs. A few versions are more commonly used.
⁠PBT-GF30 is PBT reinforced with 30% glass fibers to increase strength, stiffness and dimensional stability. PBT-GF30 is used for automotive and industrial parts along with high-stress electrical components. Also popular is PC-PBT, a blend of polycarbonate (PC) and polybutylene terephthalate (PBT) with high impact, chemical and heat resistance. PC-PBT is easy to process and is typically found in consumer goods and electronics.
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The polybutylene terephthalate market

PBT resin uses, and applications are vast. You will find PBT in things like:

• Machinery: Thanks to significant friction resistance, PBT is frequently found in gears, bearings, rollers and pump parts.
• Electronics: High thermal stability and insulation properties make PBT useful for switches, circuit breakers and coil formers.
• Textiles: Known for its elasticity and stretch, PBT fabric (i.e., a type of polyester) is chlorine-resistant, durable, quick-drying and comfortable.
• Medical: Due to its capacity to handle complex shapes, PBT medical uses are common, including surgical instruments, diagnostic equipment and inhalers.
• Packaging: Strong barrier properties and dimensional stability make PBT food grade, which is convenient for use in takeaway containers, bottles and closures.
• Automotive: Because of its light weight and excellent mechanical and thermal properties, PBT is used for exhaust valves, airbag control parts, various switches and relays.⁠

Makeup brushes are another surprisingly recent addition to the PBT market. These brushes have traditionally used animal hair, which has cuticles that allow powder to blend well with the skin. However, the demand for alternative materials that protect animal welfare has led to brushes made with a special filament processing method. The bristles are thin, with artificial cuticles and an antibacterial agent mixed in.
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What are the pros and cons of PBT?

We have listed quite a few PBT material pros above, but that does not mean there aren’t any constraints. In comparison to some other engineered plastics, PBT is somewhat vulnerable to acids and alkalis and when immersed in hot water for long periods of time it undergoes hydrolysis which decreases its strength.
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⁠That aside, one of the main challenges to using PBT is its high cost. So, why is PBT expensive? In addition to market demand allowing for a higher price tag, raw material and additive costs, plus the state-of-the-art equipment to conduct complex chemical processing, must be considered. Plus, PBT needs a lot of quality control during processing and is not as easily recyclable as some other plastics.
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PBT: Precise and Practical 

With its ease of processing, dimensional stability and attractive finish, it’s no wonder that PBT is a top choice for industries worldwide.