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Polycarbonate (PC)

Polycarbonate Overview

Polycarbonate (PC) is a high-performance engineering thermoplastic known for exceptional impact resistance, optical clarity, and heat resistance. First commercialized in the 1950s, PC polymer has become essential for applications requiring transparent, durable materials.  

As a polycarbonate resin supplier, Formerra provides access to multiple PC grades optimized for medical, automotive, electronics, and safety applications. 

PC is produced through the polycondensation of bisphenol A (BPA) and phosgene or by transesterification with diphenyl carbonate. The resulting polymer features carbonate groups in the backbone chain, delivering an exceptional balance of transparency, toughness, and thermal stability.  

Polycarbonate pellets are available in various grades including medical-grade, flame-retardant, UV-stabilized, and glass-filled formulations. 

PC demonstrates outstanding impact resistance across a wide temperature range. The material maintains toughness from -40 °C to 130 °C, far exceeding other transparent polymers like polymethyl methacrylate (PMMA) or polystyrene (PS). This property makes polycarbonate resin ideal for safety applications including face shields, protective equipment, and bullet-resistant glazing. 

Optical clarity is another key strength. PC transmits up to 89% of visible light, approaching the performance of glass while delivering far superior impact resistance. The material maintains clarity over extended exposure to heat and UV radiation when properly stabilized. This combination supports applications in automotive lighting, optical media, and electronic displays. 

Heat resistance distinguishes PC from commodity thermoplastics. The material maintains dimensional stability and mechanical properties at temperatures where polyethylene and polypropylene would soften or deform.  

Heat deflection temperatures reach 132-145 °C depending on grade and stress level. This thermal performance enables use in automotive under-hood components, appliance housings, and medical device sterilization. 

PC offers good chemical resistance to dilute acids, aliphatic hydrocarbons, and alcohol solutions at room temperature. The material resists mineral acids, oxidizing agents, and reducing agents under typical operating conditions. This resistance supports applications in laboratory equipment, chemical processing, and medical devices. 

Sterilization compatibility is critical for medical applications. Polycarbonate resin withstands gamma radiation, ethylene oxide (EtO), and steam autoclaving with appropriate grade selection. Medical-grade polycarbonate resin meets USP Class VI and ISO 10993 biocompatibility requirements for surgical instruments, drug delivery devices, and diagnostic equipment. 

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Performance Characteristics

Mechanical Properties

Mechanical Properties

Tensile strength

55-72 MPa (unfilled), 90-140 MPa (glass-filled)

Tensile modulus

2,000-2,400 MPa (unfilled), 6,000-10,000 MPa (glass-filled)

Flexural strength

90-100 MPa (unfilled), 150-220 MPa (glass-filled)

Flexural modulus

2,200-2,400 MPa (unfilled), 7,000-9,500 MPa (glass-filled)

Elongation at break

80-150% (unfilled), 3-5% (glass-filled)

Notched Izod impact

600-850 J/m (unfilled, no break), 80-160 J/m (glass-filled)

Hardness (Rockwell)

R118-125 (M-scale M70-75)

Thermal Properties

Thermal Properties

Continuous use temperature

115-130 °C (unfilled)

Heat deflection temperature

132-145 °C at 0.46 MPa (unfilled), 140-155 °C at 1.8 MPa

Glass transition temperature (Tg)

145-150 °C

Melting temperature

None (amorphous polymer)

Processing temperature range

280-320 °C

Coefficient of linear thermal expansion

65-70 x 10⁻⁶/°C (unfilled), 20-30 x 10⁻⁶/°C (glass-filled)

Thermal conductivity

0.19-0.22 W/(m·K)

Flammability rating

UL94 HB (standard), V-2 to V-0 (flame-retardant grades)

Operating Environment

Operating Environment

Water absorption

0.12-0.35% in 24 h at 23 °C. Moisture absorption at saturation reaches 0.30-0.40%. Hygroscopic nature requires pre-drying of polycarbonate pellets before processing and causes minor dimensional changes in high-humidity environments.

UV/weatherability rating

Poor without stabilizers. Unprotected polycarbonate polymer yellows, loses transparency, and suffers mechanical property degradation under prolonged UV exposure. UV stabilizers are mandatory for outdoor applications.

Hydrolysis resistance

Fair to good depending on conditions. Polycarbonate injection molding pellets resist hydrolysis at room temperature in neutral pH environments. Hot water above 60 °C and strong alkalis cause hydrolytic degradation of carbonate linkages, leading to molecular weight reduction and property loss. Steam autoclaving at 121 °C requires specially stabilized medical grade polycarbonate resin to withstand repeated cycles without significant degradation. 

Stress cracking sensitivity

High susceptibility to environmental stress cracking (ESC) when exposed to organic solvents under load. Aromatic hydrocarbons, ketones, esters, and chlorinated solvents cause rapid stress cracking even at low stress levels. PC polymer requires careful material selection and stress analysis for applications involving solvent exposure or sustained mechanical loading. Glass-filled grades show reduced stress cracking tendency but lower ultimate elongation.

Electrical Properties

Electrical Properties

Dielectric constant (1 MHz)

2.9-3.0

Dielectric strength

15-20 kV/mm

Volume resistivity

10¹⁴-10¹⁶ ohm·cm

Dissipation factor (1 MHz)

0.008-0.010

Optical Properties

Optical Properties

Light transmission

87-89% (clear grades, 3mm thickness)

Refractive index

1.584-1.586

Haze

<1% (clear grades)

Yellowing index

Low (<2) with UV stabilization

Physical Properties

Physical Properties

Specific gravity

1.20 (unfilled), 1.35-1.52 (glass-filled)

Water absorption

0.12-0.35% (24 hours at 23 °C)

Moisture absorption at saturation

0.30-0.40%

Chemical Resistance

Chemical Resistance

Excellent resistance

Dilute acids, aliphatic hydrocarbons, alcohols, mineral oils, greases, detergents, aqueous salt solutions at room temperature.

Good resistance

Vegetable oils and fats.

Limited resistance

Aromatic hydrocarbons, esters, ketones, halogenated solvents, hot water (>60 °C).

Poor resistance

Strong alkalis, concentrated acids, aromatic and chlorinated solvents, amines.

PC resin from polycarbonate suppliers shows superior chemical resistance compared to acrylic but inferior to fluoropolymers.

Strengths, Weaknesses & Operating Limits

Key Strengths

  • Impact Resistance: Exceptional toughness from -40 °C to 130 °C exceeds all other transparent polymers. PC polymer delivers impact strength 200-250 times higher than glass and 20-30 times greater than acrylic, making polycarbonate resin essential for safety equipment, protective glazing, and automotive applications where breakage could cause injury. 
  • Optical Clarity: Light transmission of 87-89% approaches glass performance while maintaining superior impact resistance. Polycarbonate pellets process into transparent parts for automotive lighting, medical visualization devices, and electronic displays where optical quality is critical. 
  • Heat Resistance: Heat deflection temperatures of 132-145 °C (unfilled) and continuous use temperatures of 115-130 °C far exceed commodity thermoplastics. This thermal stability supports automotive under-hood components, appliance housings, and medical device sterilization applications. 
  • Sterilization Compatibility: Medical grade polycarbonate resin withstands gamma radiation, ethylene oxide, and steam autoclaving without significant property loss. This capability enables repeated sterilization cycles for reusable surgical instruments and diagnostic equipment. 
  • Dimensional Stability: Amorphous structure delivers uniform, predictable shrinkage (0.5-0.7% unfilled) and tight tolerance capability. Lower and more isotropic shrinkage compared to semi-crystalline polymers simplifies mold design and improves part consistency. 
  • Design Versatility: PC resin supports complex geometries, thin walls, and integrated features through injection molding. The material enables part consolidation and weight reduction in automotive, electronics, and consumer product applications. 

Known Weaknesses

  • Solvent Sensitivity: Limited resistance to aromatic hydrocarbons, ketones, esters, and chlorinated solvents causes stress cracking and environmental stress cracking (ESC) under load. Strong alkalis attack carbonate linkages, leading to rapid property degradation. Material selection must consider chemical exposure in the application environment. 
  • Scratch Susceptibility: Moderate scratch resistance requires hard-coat treatments for glazing and optical applications. Surface abrasion from handling, cleaning, and environmental exposure reduces optical clarity over time without protective coatings. 
  • UV Degradation: Unprotected polycarbonate yellows and loses mechanical properties under prolonged UV exposure. UV stabilizers are mandatory for outdoor applications to maintain appearance and performance. Even stabilized grades show gradual degradation over multi-year outdoor exposure. 
  • Moisture Absorption: Hygroscopic nature requires drying before processing. Water absorption of 0.3-0.4% at saturation causes dimensional changes in high-humidity environments and hydrolytic degradation during processing if moisture exceeds 0.02%. 
  • Notch Sensitivity: Sharp corners, notches, and stress concentrations reduce impact strength significantly. Design must avoid sharp transitions and incorporate generous radii to maintain toughness in load-bearing applications. 
  • Cost Premium: Polycarbonate resin costs significantly more than commodity thermoplastics including polyethylene, polypropylene, and polystyrene. Higher material and processing costs limit use to applications where performance justifies the premium.

Operating Limits

  • Operating temperature envelope: Continuous use temperature 115-130 °C for unfilled grades, 125-140 °C for glass-filled formulations. Short-term exposure to 150 °C acceptable for most grades. Low-temperature performance extends to -40 °C without brittle failure. Elevated temperatures above 130 °C cause creep, stress relaxation, and property degradation over time. 
  • Load/time limits: Design stresses should remain below 30-40% of ultimate tensile strength for long-term static loading due to creep. Stress relaxation is significant at elevated temperatures and under constant strain. Glass-filled grades offer improved creep resistance but reduced ductility. 
  • Processing constraints: Polycarbonate injection molding pellets require drying to <0.02% moisture before processing at 280-320 °C. High melt viscosity demands injection pressures of 70-140 MPa. Residence time must be minimized to prevent thermal degradation and molecular weight loss. Mold temperatures of 80-120 °C are required for acceptable surface finish and stress control.

Applications

Typical Applications

  • Medical device housings
  • Surgical instrument components
  • IV connectors
  • Drug delivery housings
  • Automotive lighting lenses
  • Automotive lighting components
  • Automotive interior trim
  • Automotive console components
  • Protective eyewear
  • Face shields
  • Electronic device housings
  • Appliance components
  • Food processor bowls
  • Reusable water bottles
  • Reusable food containers
  • Electrical connectors
  • Switch housings
  • Lighting diffusers
  • LED covers

Niche Applications

  • Bullet-resistant glazing
  • Security barriers for high-threat environments
  • Architectural glazing panels
  • Skylight panels
  • Greenhouse panels
  • Agricultural protective covers
  • Medical implant packaging
  • Sterile barrier systems
  • Aircraft interior components
  • Cockpit instrument panels
  • Ballistic protection visors
  • Riot shields
  • Machine guards
  • Industrial safety barriers
  • Optical media substrates
  • Telecommunications equipment housings

Key Industries

Healthcare

Mobility

Packaging

Industrial

Consumer

Building & Construction

Electrical & Electronics

Design, Assembly & Aesthetics

Surface finish capability: Excellent high-gloss finish achievable. Transparent to opaque depending on formulation. Replicates fine textures and patterns. Flow lines and weld lines visible on transparent parts. 

Sink/warpage/visible defects tendency: Minimal sink marks due to amorphous structure. Moderate warpage risk with uneven wall thickness. Internal stress from rapid cooling causes optical distortion in transparent parts. Gate location and cooling design critical for optical clarity. 

Colorability: Excellent color range via masterbatch. Deep, vibrant colors achievable. Transparent, translucent, and opaque formulations available. UV stabilizers required to prevent yellowing in outdoor applications. 

Color stability: Good with UV stabilization. Prolonged UV exposure without stabilizers causes yellowing. Heat-stable pigments required to prevent discoloration during processing at 280-320 °C. 

Optical properties: Exceptional clarity with 87-89% light transmission. Refractive index 1.584-1.586. Low haze (<1%). Internal stress causes birefringence visible under polarized light. Optical-grade formulations available for demanding applications. 

Scratch/chemical mar resistance notes: Moderate scratch resistance. Hard-coat treatments improve surface durability. Good resistance to dilute acids and aliphatic hydrocarbons. Attacked by aromatic solvents, strong bases, and hot water. Stress cracking occurs with organic solvents under load. 

Marking methods: Pad printing, hot stamping, and inkjet printing good with surface treatment. Laser marking produces permanent marks without surface preparation. Embossing and debossing produce clean features. 

Coating/painting/plating suitability: Paintable with surface pretreatment (flame, plasma, corona). Hard-coat treatments enhance scratch resistance for glazing applications. Chrome plating possible with specialized adhesion promoters. 

Joining methods: Ultrasonic welding excellent for PC-to-PC joints. Solvent bonding with methylene chloride produces strong, transparent bonds. Adhesive bonding requires surface treatment. Mechanical fastening works well with proper boss and rib design.

Polycarbonate plastic injection molding process with transparent pellets and formed parts, highlighting high-impact thermoplastic used in engineering and medical applications

Practical & Commercial Considerations

Processing equipment fit

Standard injection molding equipment suitable with proper barrel capacity and injection pressure capability (70-140 MPa). Polycarbonate pellets suppliers recommend general-purpose screws with compression ratio of 2.5:1 to 3.0:1 and L/D ratio of 20:1 to 24:1. Hot runner systems reduce waste and maintain consistent melt temperature in high-volume production. Desiccant dryers or dehumidifying hopper dryers are mandatory to achieve <0.02% moisture content before processing.

Cycle time / productivity notes

Moderate cycle times due to elevated processing temperatures (280-320 °C) and mold temperatures (80-120 °C). Cooling takes longer than commodity thermoplastics but faster than high-temperature engineering polymers like polyetherimide or polysulfone. Hot runner systems improve productivity by eliminating sprue and runner regrind. Thin-wall applications benefit from rapid heat transfer and shorter cooling times.

Drying requirements

PC polymer is hygroscopic and requires drying before processing. Dry at 120 °C for 3-4 hours in a desiccant dryer or 80-100 °C for 4-6 hours in a dehumidifying hopper dryer to reach moisture content below 0.02%. Regrind requires similar drying. Material exposed to ambient conditions absorbs moisture rapidly and must be redried. Failure to dry adequately causes hydrolytic degradation, splay marks, bubbles, and reduced molecular weight.

Melt and mold temperature guidance

Processing temperatures range from 280-320 °C depending on grade and part geometry. Thin-wall parts and complex geometries require higher temperatures (300-320 °C) for proper flow. Thick sections process at lower temperatures (280-300 °C) to minimize residence time and thermal degradation. Mold temperatures of 80-120 °C produce optimal surface finish and minimize internal stress. Higher mold temperatures (100-120 °C) improve surface gloss and reduce molded-in stress but extend cycle times.

Shrinkage

0.5-0.7% for unfilled polycarbonate resin, 0.1-0.4% for glass-filled grades. Relatively uniform shrinkage due to amorphous structure with minimal flow versus transverse direction differences. Less anisotropic than semi-crystalline polymers like polyethylene or polypropylene, simplifying mold design and improving dimensional consistency.

Dimensional stability / tolerance capability

Good dimensional stability with tight tolerances achievable (±0.1-0.2% with proper mold design and process control). Glass-filled grades offer superior precision for applications requiring close tolerances. Water absorption causes minor dimensional changes (0.1-0.2%) over time in high-humidity environments. Post-mold shrinkage stabilizes within 24-48 hours at room temperature.

Regrind and scrap utilization

Polycarbonate pellets suppliers typically recommend regrind ratios of 10-30% mixed with virgin material depending on application requirements. Higher regrind percentages cause property degradation due to molecular weight reduction from repeated heat exposure. Optical applications limit regrind to 10-15% to maintain clarity. Regrind must be dried thoroughly and free from contamination. Multiple reprocessing cycles accelerate yellowing and reduce impact strength.

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Frequently Asked Questions

What makes polycarbonate different from other transparent plastics?

Polycarbonate combines optical clarity with exceptional impact resistance far exceeding other transparent polymers. PC maintains 87-89% light transmission while delivering impact strength 200-250 times greater than glass and 20-30 times higher than acrylic (PMMA).

The material remains tough from -40 °C to 130 °C, while acrylic becomes brittle below 0 °C and polystyrene fractures easily at room temperature. PC offers superior heat resistance with continuous use temperatures of 115-130 °C compared to 70-90 °C for acrylic and 65-75 °C for polystyrene.

This combination of transparency, toughness, and thermal stability makes PC polymer essential for applications requiring durable, clear materials including automotive lighting, safety equipment, and electronic displays.

Is polycarbonate suitable for medical device applications?

Medical-grade polycarbonate resin meets USP Class VI and ISO 10993 biocompatibility requirements for direct and indirect patient contact. PC withstands multiple sterilization cycles including gamma radiation (25-50 kGy), ethylene oxide (EtO), and steam autoclaving at 121 °C with appropriate grade selection. The material provides exceptional transparency for diagnostic equipment and visualization devices while maintaining mechanical integrity after repeated sterilization. Medical applications include surgical instrument housings, IV connectors, drug delivery components, dialysis filter housings, and anesthesia equipment. PC offers chemical resistance to common disinfectants and cleaning agents used in healthcare settings. Material selection must consider application-specific requirements including contact duration, sterilization method, and regulatory compliance. 

Does polycarbonate yellow over time?

Polycarbonate without UV stabilization yellows and loses transparency when exposed to prolonged UV radiation from sunlight or fluorescent lighting. The degradation results from photooxidation of the polymer backbone, which creates chromophores that absorb visible light and cause yellowing. UV-stabilized PC grades incorporate UV absorbers and stabilizers that maintain optical properties and mechanical strength during outdoor exposure. Properly stabilized formulations demonstrate minimal yellowing after years of outdoor weathering. Indoor applications with limited UV exposure show excellent color stability without special stabilization. Material selection should consider anticipated UV exposure, required service life, and acceptable appearance changes. Coatings can further enhance UV resistance for demanding outdoor applications.

What are the main limitations of polycarbonate?

PC demonstrates limited resistance to aromatic hydrocarbons, esters, ketones, and halogenated solvents, which cause stress cracking and environmental stress cracking (ESC) under load. Strong alkalis attack the carbonate linkages, leading to hydrolysis and loss of mechanical properties. Hot water above 60 °C causes dimensional changes and property degradation over extended exposure. The material exhibits moderate scratch resistance requiring hard-coat treatments for glazing and optical applications. PC absorbs moisture (0.3-0.4% at saturation), necessitating pre-drying before processing and potentially affecting dimensional stability in humid environments. Processing temperatures of 280-320 °C are higher than commodity thermoplastics, increasing energy costs and limiting compatible colorants and additives. Material costs exceed polyethylene, polypropylene, and acrylic, though the performance benefits often justify the premium for demanding applications.

Is polycarbonate recyclable?

Polycarbonate carries recycling code 7 (other plastics) and is recyclable through mechanical and chemical recycling processes. Post-industrial scrap from injection molding pellets and extruded sheet can be reground and reprocessed with virgin material at typical ratios of 10-30% regrind. Recycled PC maintains acceptable mechanical properties for many applications though repeated processing cycles cause molecular weight reduction and property degradation. Post-consumer PC recycling is limited by collection infrastructure and contamination with other plastics, food residues, and additives. Chemical recycling breaks down PC into bisphenol A and other monomers for repolymerization into virgin-quality resin. Some manufacturers offer recycled-content PC grades and bio-based alternatives using renewable feedstocks. Material selection should consider end-of-life requirements and regional recycling capabilities. 

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Source

Polycarbonate (PC) Plastic: Properties, Uses & Application. SpecialChem. 2025. https://www.specialchem.com/plastics/guide/polycarbonate-plastic 

Understanding Polycarbonate Material Properties. Trinseo. 2024. https://www.trinseo.com/products/polycarbonate 

Makrolon Polycarbonate Product Guide. Covestro. 2025. https://solutions.covestro.com/en/products/makrolon 

Lexan Polycarbonate Resin Design Guide. SABIC. 2024. https://www.sabic.com/en/products/polymers/polycarbonate-pc