PC Polycarbonate (Makrolon/Lexan): Optical Clarity & Impact Strength
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.
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.
Related Diagnostics & Materials
PEEK Polyetheretherketone: High-Performance Polymer...
Polyetheretherketone (PEEK) is a colorless organic thermoplastic polymer in the polyaryletherketone (PAEK) family,...
Ultem PEI (Polyetherimide): High-Temperature Amorphous...
Polyetherimide (PEI), best known by Sabic's trade name Ultem, is an amorphous high-performance thermoplastic...
PTFE Teflon: Ultimate Chemical Resistance & Low-Friction...
Polytetrafluoroethylene (PTFE), widely known by the trade name Teflon, is a fluoropolymer with the lowest...
PPS Ryton: Polyphenylene Sulfide High-Temp...
Polyphenylene sulfide (PPS), best known by Solvay's trade name Ryton, is a semicrystalline high-performance...
LCP Vectra: Liquid Crystal Polymer for Micro-Molding &...
Liquid Crystal Polymer (LCP), best known by Celanese's trade name Vectra, is a unique class of thermotropic...
Vespel Polyimide: Extreme-Temperature Polymer for...
Polyimide (PI), commercially known as DuPont Vespel, is the highest-temperature-rated polymer commercially...
PAI Torlon: Polyamide-Imide Extreme-Performance Polymer...
Polyamide-imide (PAI), commercially known as Solvay Torlon, occupies the performance space between PEEK and...
PES Veradel: Polyethersulfone Transparent High-Temp...
Polyethersulfone (PES), commercially known as Solvay Veradel or BASF Ultrason E, is an amorphous high-temperature...
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