Thermoplastic Materials for Injection Molding

PharoPLAST takes a design-first approach to plastic injection molding that focuses on getting your parts right before tooling is made and production begins. Material guidance plays a critical role in delivering 100% quality, 100% of the time.

Our team brings extensive plastics-specific design and manufacturability expertise to every project. We mold parts with a wide range of thermoplastic materials, offering the range of options and in-depth knowledge required to serve both low- and high-volume programs.
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Commodity Thermoplastics

Workhorse materials that offer an excellent balance of cost and performance for general-purpose applications.

 

Polypropylene (PP)

Common trade names: Pro-fax®, Borealis®, Moplen®
Structure: Semi-crystalline

Best for:

  • Chemical-resistant housings
  • Living hinges
  • Flexible components
  • Containers
  • Automotive interior parts

Key properties:

  • Excellent chemical resistance
  • Low density
  • Good fatigue resistance
  • Low cost
  • Outstanding flex-life for living hinges

Common industries:

  • Automotive (interior trim, battery cases, bumpers)
  • Consumer products (living hinges, containers)
  • Packaging
  • Medical devices (syringes, containers)
  • Appliances

Processing notes:

  • Requires controlled mold temperature for consistent crystallinity
  • Higher shrinkage (1.5-2.5%)

Polyethylene (HDPE, LDPE)

Structure: Semi-crystalline

Best for:

  • Containers
  • Caps
  • Chemical-resistant housings
  • Packaging components

Key properties:

  • Good impact and chemical resistance
  • Moisture barrier
  • Low cost
  • Excellent toughness at low temperatures

Common industries:

  • Packaging (bottles, caps, closures)
  • Consumer products (toys, containers)
  • Chemical processing (tanks, fittings)
  • Agriculture (irrigation components)

Processing notes:

  • HDPE has higher crystallinity and stiffness
  • LDPE is more flexible
  • Both exhibit 2.0-4.0% shrinkage

Polystyrene (PS, HIPS)

Structure: Amorphous

Best for:

  • Disposable components
  • Low-cost housings
  • Packaging
  • Consumer products where high impact strength is not critical

Key properties:

  • Rigid
  • Easy to mold
  • Good dimensional stability
  • Low cost

Common industries:

  • Packaging (food containers, cups)
  • Consumer products (disposable cutlery, CD cases)
  • Toys, electronics housings (HIPS)

Processing notes:

  • HIPS (High-Impact Polystyrene) includes rubber modification for improved toughness
  • Lower shrinkage (0.4-0.7%)

Polyvinyl Chloride (PVC)

Structure: Amorphous

Best for:

  • Chemical-resistant housings
  • Electrical insulation
  • Plumbing components

Key properties:

  • Good chemical resistance
  • Flame retardant
  • Rigid or flexible depending on formulation

Common industries:

  • Construction (pipe fittings, window profiles)
  • Medical devices (tubing, blood bags)
  • Electrical (wire insulation, conduit)
  • Electrical (wire insulation, conduit)

Processing notes:

  • May require corrosion-resistant tooling and special venting
  • Plasticizers added for flexible grades

Engineering Thermoplastics

Higher-performance materials for demanding mechanical, thermal, or chemical requirements

 

Acrylonitrile Butadiene Styrene (ABS)

Common trade names: Cycolac®, Magnum®, Terluran®
Structure: Amorphous

Best for:

  • Durable housings
  • Automotive interior components
  • Electrical enclosures
  • Structural parts
  • Automotive interior parts

Key properties:

  • Excellent toughness and impact resistance
  • Good surface finish
  • Easily colored and decorated
  • Moderate heat resistance

Common industries:

  • Automotive (interior trim, instrument panels)
  • Consumer electronics (computer housings, phone cases)
  • Appliances (refrigerator liners)
  • Toys (LEGO blocks)
  • Power tools

Processing notes:

  • Hygroscopic (requires drying)
  • Low shrinkage (0.5-0.7%)
  • Excellent dimensional stability

Modified PPO (PPE) / Polyphenylene Oxide Blends

Common trade names: Noryl® (PPO/PS blend)
Structure: Amorphous

Best for:

  • Electrical housings
  • Automotive body panels
  • Large structural components
  • Water handling equipment

Key properties:

  • Excellent dimensional stability
  • Low water absorption
  • Good electrical properties
  • High heat resistance
  • Good chemical resistance

Common industries:

  • Automotive (fender extensions, wheel covers, body panels)
  • Electrical/electronics (circuit breakers, meter housings)
  • Water management (pump housings, fittings)
  • Telecommunications

Processing notes:

  • Often blended with PS or PA for improved processability
  • Low shrinkage (0.5-0.7%)

Polycarbonate (PC)

Common trade names: Lexan®, Makrolon®
Structure: Amorphous

Best for:

  • High-impact applications
  • Transparent components
  • Safety equipment
  • Electrical housings
  • Optical lenses

Key properties:

  • Outstanding impact strength
  • High heat resistance (up to 130°C continuous)
  • Excellent optical clarity
  • Good dimensional stability

Common industries:

  • Automotive (headlight lenses, interior lighting)
  • Electronics (phone cases, laptop housings)
  • Safety equipment (face shields, safety glasses)
  • Medical devices (surgical instruments, IV components)
  • Lighting

Processing notes:

  • Highly hygroscopic (requires thorough drying)
  • Low shrinkage (0.5-0.7%)
  • PC/ABS blends available for improved processability

Nylon (Polyamide: PA 6, PA 6/6)

Common trade names: Zytel® (PA 6/6), Ultramid® (PA 6 & PA 6/6), Grilon® (PA 6 & PA 6/6)
Structure: Semi-crystalline

Best for:

  • Gears
  • Bearings
  • Bushings
  • Wear surfaces
  • Structural components
  • Under-hood automotive parts

Key properties:

  • High strength and stiffness
  • Excellent wear and abrasion resistance
  • Good heat resistance
  • Low friction

Common industries:

  • Automotive (under-hood components, gears, fuel system parts)
  • Industrial equipment (bearings, bushings, wear plates)
  • Electrical (connectors, wire ties)
  • Consumer products (power tool housings, sporting goods)

Processing notes:

  • Highly hygroscopic (moisture sensitive; requires drying and proper storage)
  • Glass-filled grades significantly increase stiffness and reduce shrinkage
  • Shrinkage 1.0-2.0%

Acetal (Polyoxymethylene: POM)

Common trade names: Delrin® (homopolymer), Celcon® (copolymer)
Structure: Semi-crystalline

Best for:

  • Precision gears
  • Latches
  • Fasteners
  • Bearings
  • Moving parts requiring dimensional stability

Key properties:

  • Excellent dimensional stability
  • Low friction and wear
  • High stiffness and strength
  • Good fatigue resistance

Common industries:

  • Automotive (fuel system components, door handles, seatbelt components)
  • Consumer products (aerosol valves, zippers)
  • Industrial equipment (conveyor components, gears)
  • Medical devices (insulin pen parts, inhalers)

Processing notes:

  • Tight processing window
  • Requires controlled mold temperature
  • Homopolymer (POM-H) offers slightly better mechanical properties than copolymer (POM-C)

Polyethylene Terephthalate / Polybutylene Terephthalate (PET / PBT)

Common trade names: Rynite® (PET), Valox® (PBT), Crastin® (PBT)
Structure: Semi-crystalline

Best for:

  • Electrical connectors
  • Automotive components
  • Electrical insulation
  • Structural parts with dimensional stability

Key properties:

  • Good electrical insulation
  • Chemical resistance
  • Dimensional stability
  • Moderate heat resistance

Common industries:

  • Electrical/electronics (connectors, relay housings, switches)
  • Automotive (sensor housings, ignition components)
  • Appliances (heating element supports)
  • Industrial controls

Processing notes:

  • Requires drying
  • Glass-filled grades common for enhanced stiffness and heat deflection

Elastomers and Soft-Touch Materials

Flexible materials ideal for overmolding, grips, seals, and impact-dampening components.

 

Thermoplastic Elastomer (TPE)

Common trade names: : Santoprene® (TPV - thermoplastic vulcanizate), Kraton® (styrenic TPE), Hytrel® (polyester TPE)
Structure: Varies by type (styrenic TPEs are typically amorphous; polyolefin TPEs are semi-crystalline)

Best for:

  • Overmolded grips
  • Seals
  • Gaskets
  • Soft-touch surfaces
  • Flexible tubing

Key properties:

  • Rubber-like flexibility without vulcanization
  • Wide hardness range (Shore A 20-95)
  • Good colorability
  • Recyclable

Common industries:

  • Automotive (weatherstripping, seals)
  • Consumer products (tool handles, grips)
  • Medical devices (soft-touch components)
  • Appliances (gaskets, seals)

Processing notes:

  • Can be overmolded onto rigid substrates (PP, PC, ABS)
  • Bond strength depends on substrate compatibility

Thermoplastic Polyurethane (TPU)

Structure: Can be amorphous or semi-crystalline depending on formulation

Best for:

  • Demanding elastomer applications requiring higher abrasion resistance
  • Tear strength
  • Load-bearing capability

Key properties:

  • Excellent abrasion and tear resistance
  • High elasticity
  • Good oil and grease resistance
  • Wide hardness range

Common industries:

  • Automotive (air ducts, seals, interior skin)
  • Footwear (shoe soles, athletic wear)
  • Electronics (phone cases, cable jacketing)
  • Medical devices (tubing, catheters)
  • Sporting goods

Processing notes:

  • Hygroscopic (requires drying)
  • Higher processing temperatures than standard TPE

Understanding Amorphous vs. Semi-Crystalline Thermoplastics

The structure of your desired material directly impacts part and tooling design. Understanding these key differences allows PharoPLAST to match the ideal polymer and process to your parts to properly optimize them for full-scale production.

 

Key Structure Qualities

Amorphous thermoplastics

  • Have randomly entangled molecular chains with no organized structure.
  • They soften gradually over a temperature range (glass transition)
  • Exhibit lower and more uniform shrinkage (typically 0.3-0.8%)
  • Generally provide tighter tolerances and better dimensional stability

Semi-crystalline thermoplastics

  • Contain both amorphous regions and ordered crystalline structures
  • They have sharp melting points
  • Higher shrinkage rates (typically 1.0-4.0%)
  • Superior chemical resistance and fatigue performance
  • Processing requires tighter thermal control due to crystallization behavior during cooling

Processing Considerations

Amorphous materials generally offer:

  • Wider processing temperature windows
  • Lower, more uniform shrinkage
  • Better dimensional accuracy and tighter tolerances
  • Easier mold filling due to gradual softening behavior

Semi-crystalline materials require:

  • More precise mold temperature control to manage crystallinity
  • Consideration of higher shrinkage rates in tool design
  • Longer cooling times due to latent heat of crystallization
  • Directional shrinkage considerations in part and gate design

Recommended Materials Based on Need

There is no simple answer to which polymer is best suited for your parts. There are several criteria that impact which material is ideal for your design. The information below offers general direction for parts based on application criteria that can guide you toward an ideal material leading into a more comprehensive review.
Application NeedStructureTypical ShrinkageRecommended Materials
Tight tolerances, dimensional stabilityAmorphous0.3-0.8%ABS, PC, PS
Chemical resistanceSemi-crystalline1.0-4.0%PP, HDPE, PBT
High impact strengthAmorphous0.5-0.7%PC, ABS, PC/ABS blend
Wear resistanceSemi-crystalline1.0-2.5%Nylon, Acetal (POM)
Living hinges, fatigue resistanceSemi-crystalline1.5-2.5%PP
Transparent or optical clarityAmorphous0.3-0.8%PC, PMMA (acrylic), COC
High temperature (>150°C)EitherVariesPPS
Low cost, general purposeEitherVariesPP, PE, PS, ABS

Real Plastics Expertise, More Effective Injection Molding

PharoPLAST isn’t here to simply produce parts. We use extensive materials expertise and an engineering-first approach to support long-term outcomes and reduce risk with every design.
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