Polycarbonate is a highly durable, transparent thermoplastic polymer, containing carbonate groups to connect organic functional groups (-O-(C=O)-O). Polycarbonate, a thermoplastic, may be obtained almost anywhere. It is used in eyewear, medical gadgets, protective gear, automobile parts, DVDs, lighting fixtures, and Blu-Ray discs.
Polycarbonate, a naturally transparent amorphous thermoplastic, is important because it can transmit light internally almost as effectively as glass and resist greater impacts than many other regularly used polymers.
Polycarbonate (PC) is a popular engineering thermoplastic due to its transparency, high toughness, thermal stability, and dimensional stability. PC is commonly used in compact discs, riot shields, vandal-proof glazing, baby feeding bottles, electrical components, safety helmets, and headlight lenses.
PCs are classed as aliphatic or aromatic based on the structure of their R groups. Aromatic PCs are those that have a carbonate group directly linked to an aromatic carbon. Others are classified as aliphatic PCs. PC’s high glass transition temperature (Tg = 145ºC) is due to limited molecular rotation around its bonds.
Interesting Science Videos
Preparation of polycarbonate
PC is typically made from Bisphenol A and phosgene using a step-growth polymerization process that eliminates Cl- ions as the monomers react. This type of step-growth polymerization is generally referred to as a condensation process.
Bisphenol A (BPA) and phosgene COCl react to generate the principal polycarbonate substance. The initial step in the synthesis is to interact bisphenol A with sodium hydroxide, which deprotonates its hydroxyl groups. The diphenoxide combines with phosgene, forming a chloroformate that is then attacked by another diphenolate to give polycarbonate.
Manufacture process
Polycarbonate pellets are melted and pressed into a mold or die to achieve desired shapes for specific applications. The technique is done thousands of times.
Extrusion
Molten PC is passed through a die to form its final shape. Following this, the melt is rapidly cooled. This method creates long pipes and sheets.
Molding
The PC melt is pushed into a mold with the desired shape for the finished product. The melt is then cooled within the mold. This method is suitable for certain parts, including automotive and computer parts.
Physical properties of PC
- It maintains good mechanical characteristics from -400F to 2800F.
- It has high strength, which makes it resistant to impact and fracture.
- This material is non-toxic, colorable, and completely transparent up to 2 inches wide.
- PC also has good electrical and heat resistance.
- It is physiologically inactive.
- It is easily recyclable and cost-effective.
- It is naturally UV resistant, making it appropriate for outdoor applications without considerable degradation or yellowing over time.
- It is resistant to a wide range of chemicals, including acids, bases, and alcohols, making it appropriate for use in a variety of industrial and chemical applications.
- It is a great electrical insulator, making it ideal for electrical and electronic applications.
- It is a lightweight material, making it ideal for applications that require weight reduction, such as the automotive and aerospace sectors.
Types of Pc
- Clear PC
Transparent polycarbonate sheeting is nearly as good at transmitting light as glass. This makes it perfect for applications requiring optical clarity. Clear polycarbonate sheets can withstand impacts that would break the glass. It’s also more durable than acrylic, another popular transparent thermoplastic.
- Bulletproof PC
Some varieties of polycarbonate are bullet-resistant, however, the degree of protection varies based on various factors. The level of protection is determined by the type of polycarbonate utilized, the lamination procedure, and the total thickness of the polycarbonate sheet.
- Anti-static PC
Specific polycarbonate variations have outstanding anti-static capabilities, commonly known as electro-static dissipative. This unusual feature prevents static charge from accumulating on the material’s surfaces. As a result, anti-static polycarbonate is a good choice for components that come into touch with sensitive electronic equipment that can be damaged by static discharge. Anti-static polycarbonate has a specialized coating that prevents static charges from accumulating. Its numerous applications include assembly surfaces for electronic components as well as electronic enclosures, making it a dependable alternative for static-sensitive settings.
- Mirrored PC
Mirrored polycarbonate sheets have a reflective layer that can operate as both a standard mirror and a two-way mirror. These mirrors use polycarbonate’s superior durability to provide a lightweight and sturdy alternative to fragile glass mirrors. Polycarbonate mirrors are commonly found in the toilets of commercial aircraft and campervans.
- Abrasion resistance PC
While conventional polycarbonate sheeting is easily scratched, there are specialized polycarbonate varieties that provide exceptional abrasion resistance. These abrasion-resistant polycarbonate sheets have a protective coating on both sides, increasing their resistance to scratches. Abrasion-resistant Polycarbonate is commonly utilized in applications like optical discs, where scratches might degrade product performance.
- Colored/ Tinted PC
A large variety of sheet colors are available for different types of polycarbonate. Polycarbonate, like other thermoplastics, can be colored or tinted. While coloration is largely intended to meet aesthetic preferences, it also provides functional objectives. Polycarbonate panels with specialized tints incorporated into them to reflect solar radiation can effectively keep rooms cooler in certain applications.
- Optical grade PC
This amorphous thermoplastic is extremely transparent to visible light, ranking first among transparent, stiff thermoplastics, and has greater light transmission properties than several types of glass. This thermoplastic’s optical grade is unusual in that it gives high clarity with low distortion. These properties make it an excellent choice for a variety of industrial applications, including challenging conditions that require minimum distortion and high visual quality. Its applications include machinery guards, clear tubes, glass, electronics, and sound barriers.
- Twin-wall PC
Twin-wall polycarbonate panels provide high thermal insulation due to the ribbed design of the multi-walled sheets, which trap air within the sheet. Twin-wall polycarbonate panels provide high thermal insulation due to the ribbed design of the multi-walled sheets, which trap air within the sheet. Twin-wall polycarbonate sheets are perfect for situations where precise light transmission is required.
- Machine grade PC
Although polycarbonate and polymethyl methacrylate (PMMA; acrylic) share many characteristics, polycarbonate is one of the most commonly utilized engineering thermoplastics in applications requiring high-performance qualities due to its transparency, excellent toughness, thermal stability, and very good dimensional stability. polycarbonate has high impact rigidity and strength across a wide range of service temperatures and is commonly used in structural applications that require transparency and impact strength. Machine-grade polycarbonate is stress-relieved, making it perfect for precision machined parts.
- Glass filled PC
Glass-reinforced polycarbonate is widely employed in industrial applications where metals, notably die-cast aluminum, and zinc, are regularly used. The addition of glass fibers to polycarbonate in various proportions (10%, 20%, 30%, and 40%) improves tensile strength, stiffness, compressive strength, and reduces thermal expansion. The amount of glass fiber added to the polycarbonate has a stronger impact on each property.
- Carbon-filled polycarbonate
Carbon fibers or carbon nanotubes are added to polycarbonate to improve electrical conductivity and mechanical qualities. Carbon-filled polycarbonate is used for electrostatic discharge (ESD) protection and electromagnetic shielding.
Comaparison between acrylic and polycarbonate
Acrylic is nearly 17 times as impact-resistant as polycarbonate. Polycarbonate, on the other hand, has a 250-fold increase in impact resistance over conventional glass.
Polycarbonate is substantially more resilient than acrylic, making it perfect for high-demand applications such as bullet-resistant windows. In contrast, acrylic has a high gloss finish and is more transparent, making it ideal for exhibition cabinets. Polycarbonate is more easily scratched, while acrylic is also more easily fractured.
Acrylic is also less expensive than polycarbonate, and unlike polycarbonate, acrylics can be heated and molded to shape before being heated again without losing their quality appearance.
Applications of PC
Appliances
Polycarbonates and their mixtures are found in a variety of appliances, including refrigerators, air conditioners, coffee makers, food mixers, washing machines, hair dryers, steam iron water tanks, and more. The usage of a PC offers diverse mechanical qualities, as well as increasing a product’s robustness and cosmetic attractiveness.
Safety Glasses
Polycarbonate polymers are not only impact-resistant, but also heat, chemical, and flame retardants. As a result, this material is highly recommended for creating high-performance safety goggles and glasses with a wide range.
Niche applications
Polycarbonate, a flexible material with appealing manufacturing and physical qualities, has attracted various small-scale applications. Injection molding is commonly used for drinking bottles, glasses, and food containers.
Consumer Products
PC has low birefringence, internal stress, and great dimensional accuracy, making it ideal for the production of CDs and DVDs. Furthermore, its great transparency enables the development of unique goods for everyday usage, such as safety goggles, ophthalmic lenses, large-volume water bottles, and others. It is also optically clear, making it suitable for a variety of applications such as shatterproof eyewear, face shields, protective glasses, and even bulletproof windows.
Food Contact
Polycarbonate is employed in applications that come into direct contact with meals and beverages because it is heat and shatter-resistant. Food storage containers made of PC are reusable, assist in keeping freshness, protect foods from infection, and may be easily used in a refrigerator or microwave.
Cash dispenser
Cash dispensers are made of polycarbonate grades appropriate for structural foam injection molding. This processing approach allows for a cost savings of up to 300% when switching from cast aluminum to plastic molding.
Automotive, aircraft, and security components
When it comes to sputter deposition or evaporation deposition of aluminum in the automobile industry, injection-molded polycarbonate can yield incredibly smooth surfaces, negating the requirement for a base coat. Decorative bezels and optical reflectors are frequently made of polycarbonate. Polycarbonate is the most commonly used material for vehicle headlamp lenses due to its lightweight and great impact resistance.
Laboratory safety goggles
Polycarbonate is frequently used in eye protection and other projectile-resistant viewing and illumination applications that would typically call for glass but require significantly greater impact resistance. Polycarbonate lenses also protect the eyes from ultraviolet rays.
Polycarbonate lenses are used in a variety of applications, including vehicle headlamps, lighting lenses, sunglasses/eyeglass lenses, and swimming goggles.
Polycarbonate is lighter than glass, which has led to the creation of electronic display displays made of polycarbonate instead of glass for use in portable and mobile devices. These displays include some LCD panels and the more recent e-ink technology; however, glass is still typically needed for CRT, plasma screens, and other LCD technologies because of its higher melting temperature and ability to be etched in finer detail.
Building and Construction
The polycarbonate material is 200 times tougher and more impact-resistant than glass of equal thickness. It is also more versatile and cost-effective than glass and can be shaped and modified to meet specific needs. As a result, many construction applications and buildings now use polycarbonate plastic instead of glass.
PC is a popular glazing material for agricultural, industrial, and public buildings due to its high impact strength, transparency, UV light resistance, and weatherability.
Fencing and Protection Barrier
They are not only incredibly durable and flexible, but they also provide great impact-resistance heating. Because of their exceptional strength, they are also utilized in building a wide range of fencing, protective barriers, and partitions. They are frequently used as bulletproof barriers in banks, supermarkets, and other businesses.
Advantages of PC
Transparency: The PC is extremely transparent, allowing for good light transmission. It is widely utilized in applications requiring optical clarity, such as eyeglass lenses and clear protective shields.
Vandalism resistance: Polycarbonate is extremely indestructible and vandal-proof, making it the best material for safety glazing. Shelters, bicycle sheds, machinery, technical equipment, illuminated signage, and marine glazing are among the examples.
High strength: Polycarbonate is lightweight yet exceptionally strong. It is half the weight of glass and has 200 times the impact resistance. This amazing combination has resulted in polycarbonate being utilized for various applications, including optical wear, bullet-resistant windows, police shields, and so on.
Fire resistance: Unlike acrylic sheets, polycarbonate is fire resistant and has a fire grade of B1, indicating that it will not burn with an open flame. Polycarbonate is self-extinguishing.
Flexible nature: Polycarbonate, which is malleable and durable, can be easily molded into a variety of shapes. Glass can only be used to create flat surfaces or slanted roofs. However, polycarbonate can be utilized to create domes, barrel roofs, ogee roofs, arched roofs, and other circular-shaped roofs.
Lightweight: Despite its strength, the material is quite light. As a result, it is widely used to reduce weight in industries such as aerospace and automotive.
UV resistance: PC is resistant to ultraviolet (UV) radiation, making it suitable for applications such as greenhouse panels and protective covers for outdoor equipment.
Sustainability: Polycarbonate is also considered sustainable. It has a long service life and is completely recyclable. Polycarbonate plastics are also UV resistant, making them useful as sheet materials for outdoor applications.
Vandalism resistance: Polycarbonate is extremely indestructible and vandal-proof, making it the best material for safety glazing. Shelters, bicycle sheds, machinery, technical equipment, illuminated signs, and marine glazing are among the examples.
Simple to process: Polycarbonate is prepared in the same manner as acrylic sheets. Polycarbonate, unlike acrylic, does not melt if machined at high speeds. This material is stronger, so there is a smaller danger of breakage than with molded acrylic sheets. Polycarbonate can be sawn, machined, engraved, drilled, bent (hot), glued, and polished as an acrylic sheet.
Disadvantages of PC
- Flammability: The substance is not intrinsically flame retardant and is only partially resistant to high temperatures. Additives can be utilized to meet certain fire safety requirements.
- Chemical sensitivity: PC can be affected by some chemicals, solvents, and cleaning agents. It is critical to use appropriate cleaning materials and avoid incompatible substances.
- Sensitive to scratches: The biggest disadvantage of polycarbonate is that it is not scratch-resistant. For example, if a branch falls on a polycarbonate patio canopy, it may cause scratches. This issue can be resolved by polishing the polycarbonate.
- Cost: PC can be more expensive than other polymers.
- Not suitable for food contact: Some varieties of PA may be unsuitable for direct food contact because of concerns about the potential leaching of bisphenol A.
References
- https://www.sciencedirect.com/topics/materials-science/polycarbonate
- https://www.vedantu.com/chemistry/polycarbonate
- https://wwwcourses.sens.buffalo.edu/ce435/PC_CB.pdf
- https://pslc.ws/macrog/pc.htm
- https://www.britannica.com/science/polycarbonate
- https://www.emcoplastics.com/polycarbonate/
- https://omnexus.specialchem.com/selection-guide/polycarbonate-pc-plastic/key-applications.
- https://omnexus.specialchem.com/selection-guide/polycarbonate-pc-plastic
