PP and ABS are two of the most widely used thermoplastics, each with distinct advantages. This guide provides a detailed comparison to help you choose the right material for your application.
1. Mechanical Properties
Tensile Strength - PP: 25-40 MPa - ABS: 40-55 MPa - Winner: ABS (37% higher on average)
Impact Strength (Notched Izod) - PP: 2-5 kJ/m² (brittle at low temperature) - ABS: 10-30 kJ/m² (good at low temperature) - Winner: ABS (significantly better)
Flexural Modulus - PP: 1.0-1.5 GPa - ABS: 2.0-2.5 GPa - Winner: ABS (stiffer)
Elongation at Break - PP: 100-600% (very flexible) - ABS: 10-50% (rigid) - Winner: PP (more ductile)
Heat Deflection Temperature - PP: 90-110°C (at 0.45 MPa) - ABS: 85-100°C (at 0.45 MPa) - Winner: PP (slightly better)
2. Chemical & Environmental Resistance
Chemical Resistance - PP: Excellent resistance to acids, bases, solvents. Only attacked by strong oxidizers and chlorinated solvents - ABS: Good resistance to acids, bases. Attacked by ketones, esters, and some hydrocarbons
Moisture Absorption - PP: < 0.01% (essentially zero) - ABS: 0.2-0.5% (requires drying before processing)
UV Resistance - PP: Poor (requires stabilizers for outdoor use) - ABS: Poor (requires stabilizers or paint for outdoor use)
Food Contact - PP: FDA compliant grades widely available - ABS: FDA compliant grades available but less common
Winner by Environment: - Wet/humid: PP (no moisture absorption) - Chemical exposure: PP (broader resistance) - Indoor dry: Either (no significant difference) - Outdoor: Neither (both need stabilization)
3. Processing Comparison
Melt Temperature - PP: 200-250°C - ABS: 210-250°C
Mold Temperature - PP: 20-60°C (fast cooling) - ABS: 50-80°C (better surface finish)
Drying Required - PP: No (hydrophobic) - ABS: Yes, 80°C for 2-4 hours
Shrinkage - PP: 1.0-2.5% (isotropic, high) - ABS: 0.4-0.7% (lower, better dimensional control)
Cycle Time - PP: Shorter (fast crystallization) - ABS: Moderate
Surface Finish - PP: Good but can have flow marks - ABS: Excellent (high gloss possible)
Processing Winner: - Speed: PP (faster cycles) - Dimensional precision: ABS (lower shrinkage) - Surface quality: ABS (better gloss) - Simplicity: PP (no drying needed)
4. Decision Framework
Choose PP When: - Low cost is the primary driver - Chemical resistance is critical - Moisture resistance is needed - Living hinges are required - High flexibility is desired - Food contact compliance is needed
Choose ABS When: - High impact strength is required - Good surface finish/appearance matters - Dimensional precision is critical - Low shrinkage needed for tight tolerances - Electroplating is required (ABS plateable) - Appliance housing application
When to Substitute: - ABS → PP: Acceptable if impact requirements are low and cost savings are significant - PP → ABS: Necessary when appearance, impact, or plating requirements demand it
Cost Comparison (typical, per kg): - PP: $1.00-1.50 - ABS: $1.80-2.50 - PP saves 30-40% on material cost