ABS vs. Polypropylene (PP): Deciding Between Two Popular Plastics

In the world of plastic manufacturing, two of the most common and versatile thermoplastics are ABS (Acrylonitrile Butadiene Styrene) and Polypropylene (PP).

Both materials are widely used in consumer products, automotive parts, packaging, and custom injection-molded components. However, each material offers a unique set of mechanical, thermal, and chemical properties that make it better suited to specific applications.

This guide will walk you through everything you need to know about ABS vs. Polypropylene, from fundamental properties to real-world applications. If you're trying to decide which plastic to choose for your custom part or product design, this comprehensive breakdown is for you.

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What Are ABS and Polypropylene?

What Is ABS?

ABS is a rigid, opaque thermoplastic made by combining three monomers: acrylonitrile, butadiene, and styrene. The resulting polymer is tough, impact-resistant¹, and performs well in a variety of environments.

Characteristics of ABS:

• Good dimensional stability²
• High impact resistance
• Smooth surface finish
• Easy to machine and finish
• Bonds well with adhesives and coatings

ABS is commonly used for:

• Automotive trim
• Electronic housings
• LEGO bricks
• Helmet shells

What Is Polypropylene (PP)?

Polypropylene is a semi-crystalline thermoplastic known for its lightweight, chemical resistance³, and flexibility. It is one of the most produced plastics worldwide and is especially common in packaging, medical products, and automotive components.

Characteristics of PP:

• Low density (lightweight)
• Excellent chemical resistance
• Tough and flexible
• High fatigue resistance (hinges and snaps)
• Naturally hydrophobic

Common applications include:

• Food containers
• Medical syringes
• Automotive battery cases
• Living hinges

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Key Differences in Material Properties

Let’s take a closer look at the mechanical, thermal, and chemical⁴ differences between ABS and PP.

Property	ABS	Polypropylene (PP)
Density	1.04 g/cm³	0.90 g/cm³
Impact Resistance	High	Moderate to high
Flexibility	Rigid	Semi-flexible
Tensile Strength	~40 MPa	~30 MPa
Heat Resistance (HDT)	Up to 100°C	~90–100°C
Chemical Resistance	Moderate	Excellent
UV Resistance	Poor (requires additives)	Poor (can degrade under UV)
Water Absorption	Slightly higher	Very low
Surface Finish Quality	Excellent	Moderate
Recyclability	Good	Excellent

Dive Deeper: Why These Differences Matter

• ABS is more dimensionally stable and gives a superior surface finish, making it ideal for parts that require tight tolerances and aesthetic appeal.
• PP, on the other hand, is better suited for parts exposed to chemicals, moisture, or repeated stress like flexing or bending.

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Which Plastic Performs Better in Your Application?

This is a function of your priorities—strength, chemical resistance, appearance, or cost?

Use Case Scenarios

Application Type	Recommended Material
Durable enclosure with high gloss	ABS
Hinged packaging or closures	PP
Fluid reservoirs or tanks	PP
Structural, load-bearing part	ABS
Food-safe, microwave containers	PP
Complex designs with detailed finish	ABS
Cost-sensitive high-volume part	PP

Dive Deeper: Environmental and Performance Considerations

• In automotive applications, both ABS and PP are used but for different reasons. ABS⁵ might be used in dashboards and interior trims for its surface finish and stiffness, while PP is used for battery casings and fluid containers due to chemical resistance.
• In consumer electronics, ABS is preferred because it is easy to color, paints well, and has an excellent look and feel.
• For applications exposed to chemicals or moisture, such as detergent containers or lab equipment, PP performs better due to its inertness.

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Cost, Processability, and Durability Comparison

Cost

In general, Polypropylene is less expensive than ABS, both in raw material costs and processing. This makes it more attractive for high-volume and cost-sensitive applications.

Machinability and Processability

Feature	ABS	PP
Injection Molding	Easy to mold with good detail	Requires higher mold temp
CNC Machining	Excellent	Poor—tends to deform or burr
Adhesive Bonding	Excellent	Difficult (needs special primers)
Painting and Coating	Easy to paint and coat	Requires surface treatment

• ABS is easier to machine and bond, which is great for prototypes and low-volume production.
• PP resists many solvents and adhesives, making post-processing more difficult.

Durability

• ABS is more rigid and holds its shape under load.
• PP is tougher when it comes to repeated stress, such as snap fits or living hinges.

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When to Choose ABS or PP for Custom Parts

Choose ABS If:

• You need sharp dimensional accuracy⁶
• The part requires a smooth surface finish
• It will be painted, plated, or coated
• You require high stiffness and rigidity
• The application is indoors and not exposed to chemicals

Choose PP If:

• The part must resist chemicals, acids, or water
• You need flexibility or living hinges
• Weight savings are critical (PP is lighter)
• It's for food-grade or medical applications
• You're working with tight budgets

Dive Deeper: Design Considerations for Each

ABS Design Tips:

• Include radii at corners to reduce stress
• Avoid overly thin walls to maintain rigidity
• Consider using venting during molding to avoid surface defects

PP Design Tips:

• Use thicker hinges for long flex life
• Allow for more shrinkage in the mold design
• Avoid paint or adhesives—use snap fits for assembly instead

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Conclusion

ABS and Polypropylene are both excellent materials for plastic manufacturing, but each has clear advantages based on the part’s purpose.

• Use ABS when visual appeal, dimensional control, and rigidity matter most.
• Use PP when chemical resistance, flexibility, or cost are your top priorities.

By understanding the differences and aligning them with your application, you can make an informed choice that ensures functionality, longevity, and cost-efficiency.