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PCTG vs PETG - Which Is A Better 3D Printing Filament?
Pro PCTG is 20-50% More Impact Resistant Than PETG
Key Reasons for Better Impact Toughness:
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Molecular Structure:
- PCTG contains cyclohexane dimethanol (CHDM), which gives it increased flexibility and toughness compared to PETG’s ethylene glycol structure.
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Flexibility vs. Brittleness:
- PCTG is more ductile, allowing it to absorb and dissipate energy during impact without cracking or shattering.
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Layer Adhesion:
- PCTG has better inter-layer bonding when 3D printed, reducing weak points in the structure where impact forces might cause failure.
Real-World Implications:
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Drop Resistance:
- PCTG parts are less likely to crack, chip, or break when dropped, making it ideal for high-impact applications like enclosures or wearable devices.
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Repeated Stress:
- PCTG can endure repeated bending or sudden forces better than PETG, making it more suitable for hinges, clips, and flexible parts.
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Durability in Extreme Conditions:
- PCTG resists embrittlement under low temperatures, maintaining its toughness in environments where PETG may fail.
Example Use Cases Benefiting from PCTG's Toughness:
- Protective housings for electronics or tools.
- Drone parts and propeller guards.
- Flexible clips, snap-fits, and living hinges.
- Impact-resistant containers or enclosures.
Chemical Resistance
| Chemical Type | Examples | PCTG Advantage | PETG Limitation | Comparison (CRR) |
|---|---|---|---|---|
| Alcohols | Isopropyl alcohol (IPA), ethanol, methanol | Resists prolonged exposure without degrading or cracking. | Degrades or stress cracks with high alcohol concentrations over time. | 1.8 |
| Hydrocarbons | Hexane, heptane, gasoline, mineral spirits | Better resistance to hydrocarbon-based solvents. | Softens or weakens when exposed to hydrocarbons. | 2.0 |
| Acids | Acetic acid, citric acid, phosphoric acid | Maintains structural integrity in mild to moderately concentrated acids. | Degrades faster in acidic environments at higher concentrations. | 1.4 |
| Bases (Alkalis) | Sodium hydroxide, potassium hydroxide, ammonium hydroxide | Better resistance to strong alkalis. | May crack or degrade when exposed to strong bases. | 1.33 |
| Cleaning Agents | Bleach (sodium hypochlorite), industrial degreasers, detergent solutions | Withstands harsh cleaning agents without discoloration or damage. | Discolors, cracks, or loses properties with harsh cleaning agents over time. | 1.5 |
| Oils and Lubricants | Engine oils, hydraulic fluids, cutting oils | Resists degradation from prolonged exposure to oils. | Absorbs oils over time, potentially leading to swelling or weakening. | 1.6 |
| Ketones | Acetone, methyl ethyl ketone (MEK) | Performs slightly better in low-concentration ketones. | Softens or dissolves more readily in ketone-rich environments. | 1.2 |
Pro PCTG Has Lower Moisture Absorption Than PETG
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PETG:
- Hygroscopic: PETG absorbs moisture from the air, but at a relatively low rate compared to more hygroscopic materials like nylon or TPU.
- Moisture Absorption Rate: Approximately 0.2–0.3% by weight after prolonged exposure to humid environments.
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Effects of Moisture:
- During printing, moisture in PETG can lead to stringing, bubbling, and surface defects due to water vaporizing in the hotend.
- Mechanical properties (like impact strength) can slightly degrade over time with prolonged exposure to high humidity.
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PCTG:
- Slightly Lower Moisture Absorption: PCTG absorbs less moisture than PETG, typically around 0.1–0.2% by weight.
- Improved Resistance: Due to its cyclohexane dimethanol (CHDM) component, PCTG’s molecular structure makes it less hygroscopic and more resistant to moisture-induced degradation.
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Effects of Moisture:
- PCTG generally performs better than PETG in humid conditions, retaining clarity, toughness, and dimensional stability for longer periods.
Why the Difference?
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Molecular Structure:
- PETG’s glycol modification increases flexibility but leaves the material slightly more hygroscopic.
- PCTG’s modified structure with CHDM reduces the polar sites available for moisture interaction, resulting in less absorption.
Practical Implications:
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3D Printing:
- PETG: Requires drying more frequently, especially if exposed to humid environments, as even slight moisture absorption can lead to print defects (bubbling, stringing, poor adhesion).
- PCTG: Requires less frequent drying, making it easier to handle in environments with higher humidity. It is also more forgiving if printed without drying.
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Storage:
- Both materials benefit from being stored in airtight containers with desiccant.
- PCTG will be less prone to degradation if exposed to moisture for extended periods compared to PETG.
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Long-Term Use in Humid Environments:
- PCTG is more stable and less likely to lose mechanical properties over time in high-humidity settings.
Drying
For both materials, drying before printing and proper storage is recommended for optimal performance, but PCTG is less maintenance-intensive in this regard.
When you need to dry Pro PCTG, use a temperature of 60-70C for 4-8 hours.
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