PC Polymer: Properties, Uses & Cost Guide
Tensile data verified against MatWeb.com database & manufacturer datasheets · Last updated July 2026
Published: 2026-06-02
Polycarbonate (PC) combines optical clarity (>88% light transmission) with exceptional impact strength (Izod >700 J/m — essentially unbreakable in standard tests). As an amorphous polymer, PC exhibits low and isotropic mold shrinkage (0.5-0.7%),...
Polycarbonate (PC) combines optical clarity (>88% light transmission) with exceptional impact strength (Izod >700 J/m — essentially unbreakable in standard tests). As an amorphous polymer, PC exhibits low and isotropic mold shrinkage (0.5-0.7%), making it ideal for precision optical components. Trade names include Makrolon (Covestro), Lexan (SABIC), and Calibre (Trinseo). Key processing challenge: PC is highly hygroscopic — moisture absorption above 0.02% causes hydrolysis and silver streaking during molding.
Critical drying requirement: 120°C for 4 hours in a desiccant dryer to achieve <0.02% moisture. Melt temperature 280-320°C depending on wall thickness. Mold temperature 80-120°C; higher mold temperatures improve surface finish and reduce molded-in stress. PC is notch-sensitive — avoid sharp internal corners (minimum radius 0.5mm). Stress cracking from exposure to certain chemicals (toluene, acetone, amines) limits applications requiring chemical exposure — specify PC/ABS, PC/PBT, or PC/PET blends if chemical resistance is needed.
Recommended Applications
PC Polycarbonate is commonly specified for:
⚠ Not Recommended For
PC Polycarbonate is not recommended for:
- Continuous outdoor UV exposure without UV coating (yellows and loses impact strength rapidly)
- Contact with aromatic hydrocarbons, ketones, or esters (causes environmental stress cracking)
- Steam sterilization above 120°C (use PSU or PPSU for autoclave applications instead)
Selection & Application Guide
Polycarbonate (PC) is the transparent engineering plastic with the highest impact strength — virtually unbreakable in thin sections. Choose PC over acrylic (PMMA) when impact resistance is needed; over PSU when lower cost and higher clarity matter and steam sterilization isn't required. PC's main limitations are poor chemical resistance to solvents and UV degradation without stabilization. For higher temperature or flame resistance, consider PC/ABS blend or Ultem.
Real-World Applications
PC's exceptional impact strength (850 J/m notched Izod) and optical clarity make it the standard for safety helmets, riot shields, and protective visors.
PC's optical clarity, impact resistance, and thermal stability for halogen bulb environments make it the dominant material for headlamp outer lenses worldwide.
PC and PC/ABS blends provide the combination of impact strength, flame retardancy (with additives), and surface finish quality for laptop, phone, and tablet housings.
PC's clarity for visual inspection, gamma sterilizability, and impact toughness suit it for IV components, blood centrifuge housings, and diagnostic device enclosures.
Processing & Cost Considerations
Manufacturing Tips
- PC processes at 280-320°C melt temperature with mold temperatures of 80-100°C. Thorough drying is essential (120°C for 3-4 hours to <0.02% moisture) — PC is very hygroscopic and even small amounts of moisture cause splay marks and reduced impact strength.
- PC has high melt viscosity — higher injection pressures and larger gates are needed compared to commodity plastics. Thin-wall molding may require fast injection speeds to prevent premature freeze-off.
- Design parts with uniform wall thickness to prevent sink marks and internal stresses. PC is notch-sensitive — avoid sharp internal corners (use R>0.5mm fillets) to maintain impact strength.
PC costs $5-12/kg — more than ABS ($2-5/kg) but less than PSU ($15-35/kg). PC/ABS blends offer a middle ground at $3-7/kg with better flow and processability. For applications requiring both transparency and impact resistance, PC has no cost-effective substitute. For opaque applications, PC/ABS is often a better value proposition.
Technical Properties
| Density | 1.20 g/cm³ |
|---|---|
| Tensile Strength | 65 MPa |
| Melting Point | Amorphous (Tg 147°C) |
| Shrinkage Rate | 0.5-0.7% |
| Flexural Modulus | 2.3 GPa |
| Hdt | 135 °C at 1.82 MPa |
Engineering Tool: Shrinkage & Cost Estimator
Calculate part weight, mold cavity dimensions accounting for shrinkage, and material cost — all locally in your browser.
Equivalents & Cross-References
| Equivalent / Alternate | Action |
|---|---|
| Makrolon 2805 | |
| Lexan 141R | |
| Calibre 301 |
Frequently Asked Questions
Why does PC need such a high drying temperature?
PC releases absorbed water slowly due to strong hydrogen bonding with the carbonate groups. Drying at 120°C (vs the typical 80°C for nylons) overcomes this binding energy. Inadequate drying causes hydrolysis during processing — the molecular weight drops, and impact strength can decrease by 50-80%.
Is polycarbonate UV resistant?
Standard PC yellows and embrittles with UV exposure. UV-stabilized grades (e.g., Makrolon 2807, Lexan SLX) contain UV absorbers and hindered amine light stabilizers (HALS). For outdoor use, specify UV-stabilized grades or apply a UV-curable hard coat (silicone-based) that provides both UV protection and scratch resistance.
What is the difference between PC and PMMA (acrylic)?
PC has much higher impact strength (850 J/m vs 16 J/m for PMMA) and higher service temperature (115°C vs 85°C). PMMA has better optical clarity (92% vs 88% transmission), better UV resistance, and lower cost. Choose PC when impact resistance is critical; PMMA for display applications where optical quality and UV stability matter more.
Can PC be autoclaved?
Not recommended. Standard PC softens and distorts at autoclave temperatures (134°C). It can withstand a few cycles but rapidly degrades. For steam sterilization, use PSU, PPSU, or Ultem instead. PC is compatible with EtO and gamma sterilization for single-use medical devices.
Why does PC stress-crack in the presence of solvents?
PC is highly susceptible to environmental stress cracking when exposed to solvents (gasoline, acetone, MEK) while under mechanical stress. The solvent migrates into the polymer at stress concentration points, causing microcracks that propagate rapidly. For solvent-exposed applications, specify stress-annealed parts or use a chemically resistant alternative (PPS, PPSU, or PEEK).
Is BPA-free polycarbonate available?
Yes. BPA-free copolyester alternatives (Tritan, PCTG) provide similar clarity and impact resistance without bisphenol-A. These materials are increasingly specified for food contact and children's products. However, they have lower temperature resistance than standard PC and may not be suitable for all PC applications.
What is PC/ABS blend and when should I use it?
PC/ABS blend combines PC's impact resistance and heat resistance with ABS's processability and lower cost. The blend offers better flow (easier thin-wall molding), lower melt temperature, and lower cost than pure PC. It is the dominant material for electronic device housings. Use pure PC when transparency is needed; PC/ABS for opaque structural and housing applications.
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References & Industry Standards
- ASTM International. Standard Specifications for Engineering Plastics & Thermoplastics. astm.org
- UL Prospector. Plastics & Elastomers Material Database. ulprospector.com
- MatWeb. Material Property Data for Engineering Thermoplastics. matweb.com
- ISO 1043. Plastics — Symbols and Abbreviated Terms. iso.org