Engineering materials - advanced plastics 2025

Introduction to engineering materials

Engineering materials are plastics with exceptional mechanical, thermal and chemical properties that go far beyond the capabilities of traditional polymers. In an era of advanced technologies and growing industrial requirements, materials such as PEEK, PEI or carbon composites are becoming the key to innovation.

Modern injection molding industry cannot function without advanced plastics. From precision medical components, through aerospace parts, to high-frequency electronics - engineering materials find application wherever traditional plastics fail.

In this article, we will take a detailed look at engineering materials: their properties, applications, processing methods and selection criteria. You will learn why PEEK costs 100 times more than PP, but in many applications is irreplaceable.

What are engineering materials?

Engineering materials are polymers with technical parameters significantly exceeding standard plastics. They are defined by a combination of properties: mechanical strength above 50 MPa, continuous working temperature above 100°C, and resistance to aggressive chemical environments.

Classification of engineering materials:

• Structural materials - PA, POM, PC (working temperature 80-120°C)
• High-performance materials - PEEK, PEI, PPS, LCP (working temperature 150-260°C)
• Special materials - PTFE, PAI, PI (unique properties)
• Composites - materials reinforced with glass or carbon fiber

Key features of engineering materials:

• High continuous working temperature (HDT above 100°C)
• Mechanical strength (Young's modulus above 2 GPa)
• Chemical resistance to acids, bases, solvents
• Dimensional stability (low coefficient of thermal expansion)
• Special properties (conductivity, biocompatibility, radiation resistance)

Unlike standard plastics like PE or PP, engineering materials are characterized by significantly higher price (10-1000 times more expensive), but offer parameters impossible to achieve by other methods.

History of advanced materials development

The development of engineering materials began in the 1930s, when Wallace Carothers developed nylon - the first synthetic polymer with structural properties.

1935-1950: Era of pioneers

• 1935 - Nylon (PA 6.6) by DuPont
• 1938 - PTFE (Teflon) by Roy Plunkett
• 1941 - PET by Whinfield and Dickson
• Applications: fibers, coatings, containers

1950-1970: Boom of structural materials

• 1953 - POM (Delrin) by DuPont
• 1958 - Polycarbonate (PC) by Bayer
• 1962 - PPS by Phillips Petroleum
• 1965 - PEI (Ultem) by General Electric
• Revolution in industry: replacing metal with plastics

1970-1990: Era of high-performance materials

• 1978 - PEEK by ICI (now Victrex)
• 1985 - LCP by Celanese
• 1987 - Carbon fiber/polymer composites
• Aerospace and space applications

1990-2025: Specialization and nanomaterials

• Biocompatible materials (medical PEEK)
• Nanocomposites (graphene, carbon nanotubes)
• Electrically conductive materials
• Engineering biopolymers (reinforced PLA)

Today, the engineering materials market is worth over 80 billion dollars annually and is growing at a rate of 7-9% per year, driven by automotive, electronics and medical industries.

Types of engineering materials

Engineering materials are divided into several main categories, each with unique properties and applications.

High-performance materials

PEEK (Polyether Ether Ketone)

• Continuous working temperature: 260°C (short-term 315°C)
• Tensile strength: 90-100 MPa
• Young's modulus: 3.6 GPa
• Chemical resistance: excellent (only sulfuric acid)
• Price: 80-150 EUR/kg
• Applications: medical implants, aerospace industry, high-temperature bearings

PEI (Polyetherimide - Ultem)

• Working temperature: 170°C (short-term 200°C)
• Strength: 105 MPa
• Transparency in natural state
• Fire resistance class: UL94 V-0
• Price: 30-50 EUR/kg
• Applications: electronic components, anesthesia masks, aircraft housings

PPS (Polyphenylene Sulfide)

• Working temperature: 200°C
• Strength: 70-85 MPa (reinforced 180 MPa)
• Chemical resistance: exceptional
• Electrical insulation: excellent
• Price: 15-25 EUR/kg
• Applications: chemical pumps, automotive electronics, exhaust filters

LCP (Liquid Crystal Polymer)

• Melting temperature: 280-340°C
• Strength: 120-200 MPa
• Property anisotropy (molecular orientation)
• Electrical insulation up to 100 GHz
• Price: 25-45 EUR/kg
• Applications: electrical connectors, 5G antennas, minimally invasive surgery

Composites and reinforced materials

PA GF (Glass fiber reinforced polyamide)

• Fiber content: 15-50% by weight
• Strength: 150-220 MPa (vs 80 MPa unreinforced)
• Modulus: 8-12 GPa
• Shrinkage: 70% reduction
• Applications: intake manifolds, engine covers, bearings

PA CF (Carbon fiber polyamide)

• Fiber content: 10-40%
• Strength: 200-280 MPa
• Weight: 20% lighter than PA GF
• Electrical conductivity
• Price: 3-5x higher than PA GF
• Applications: drones, sports parts, EMI screens

Continuous fiber composites

• Continuous vs. chopped fiber
• Strength: up to 1000 MPa
• Technology: tape laying, pultrusion
• Applications: aerospace, F1, high-performance sports

Biopolymers and bio-based materials

PA 610 (Bio-based polyamide)

• Raw material: castor oil (60% bio-content)
• Properties: identical to PA 6.6
• Carbon footprint: 30-50% lower
• Applications: automotive industry (sustainable components)

Reinforced PLA

• 100% bio-based and biodegradable
• Reinforcement: flax, hemp fiber
• Strength: 80-120 MPa
• Temperature: limited to 60°C
• Applications: packaging, consumer electronics, disposable tableware

Bio-PET and Bio-PC

• Partially bio-based
• Properties identical to petrochemical
• Drop-in replacement (no process changes)
• Certificates: ISCC Plus, REDcert

Structure and composition of materials

The properties of engineering materials result directly from their molecular structure and morphology.

Crystalline vs. amorphous structure:

• Semi-crystalline polymers (PEEK, PA, POM): higher strength, chemical resistance, shrinkage 1.5-3%
• Amorphous polymers (PC, PEI, PSU): transparency, dimensional stability, shrinkage 0.5-0.8%
• Influencing factors: cooling rate, mold temperature, packing pressure

Molecular orientation:

• Injection direction: higher strength (+30-50%)
• Perpendicular direction: lower strength (-20-30%)
• Significance in part design
• Compensation through fiber reinforcement

Reinforcements and additives:

• Glass fiber: modulus increase (+300-500%), shrinkage reduction (-60-70%)
• Carbon fiber: highest stiffness, electrical conductivity
• Minerals (talc, mica): stiffness improvement, economy
• Functional additives: UV stabilizers, pigments, slip agents

Processing impact on structure:

• Melt temperature: impact on crystallinity (+20°C = +5-10% crystallinity)
• Mold temperature: crucial for final properties
• Injection speed: orientation vs. stresses
• Packing pressure: density and surface quality

Key technical parameters

Selection of engineering material requires analysis of a comprehensive set of technical parameters.

Mechanical properties:

• Tensile strength: 50-280 MPa (depending on material and reinforcement)
• Young's modulus: 2-15 GPa (material stiffness)
• Impact strength: 5-100 kJ/m² (Izod notched)
• Elongation at break: 2-300% (brittle vs. ductile)
• Hardness: 70-85 Shore D or 120-180 Rockwell M

Thermal properties:

• Melting temperature: 220-340°C (semi-crystalline)
• Glass transition temperature Tg: 80-220°C (amorphous)
• HDT (Heat Deflection Temperature): 100-260°C at 1.8 MPa
• Coefficient of thermal expansion: 20-80 x 10⁻⁶/K
• Thermal conductivity: 0.2-0.4 W/mK (increased in composites)

Electrical properties:

• Volume resistivity: 10¹⁴-10¹⁶ Ω·cm (insulators)
• Dielectric constant: 2.5-3.8 (LCP lowest)
• Dielectric strength: 15-40 kV/mm
• Tracking resistance: CTI 100-600V

Chemical properties:

• Acid resistance: PEEK, PPS excellent; PA limited
• Base resistance: PC weak; PPS excellent
• Solvent resistance: PEEK best
• Water absorption: 0.1% (PEEK) to 8% (PA 6) - impact on dimensions

Processing parameters (injection):

• Melt temperature: 260°C (PA) to 400°C (PEEK)
• Mold temperature: 80-180°C (critical for crystalline)
• Injection pressure: 800-2000 bar
• Cycle time: increased 30-100% vs. standard plastics

Applications of engineering materials

Engineering materials find application in industries requiring highest quality and reliability.

Automotive industry:

• Under-the-hood: intake manifolds (PA GF), turbo covers (PPS), bearings (PEEK)
• Transmission: gears (POM), clutch discs (PA CF)
• Electrical: connectors (PBT, LCP), coils (PPA), sensors (PPS)
• Trend: electrification (HV connectors from LCP, housing from PPS)
• Weight saving: 40-60% vs. metal

Aerospace and space industry:

• Structures: CF/PEEK composites (Boeing 787, Airbus A350)
• Cabin interior: PEI panels (fire resistance FAR 25.853)
• Engines: PEEK components (heat exchangers, mounts)
• Satellites: composite structures (low weight, radiation resistance)
• Certifications: AITM, Airbus AIMS, Boeing BMS

Medical industry:

• Implants: PEEK (spine, skull bone), biocompatibility ISO 10993
• Surgical instruments: PEI, PSU (sterilization 134°C, multiple)
• Pharmaceutical packaging: COP/COC (moisture barrier, transparency)
• Diagnostics: microfluidics (COC), pipettes (medical PP)
• Regulatory: FDA, MDR, USP Class VI

Electronics and telecommunications:

• 5G/6G: LCP antennas (low losses up to 100 GHz)
• SMD: LCP coils, capacitors (miniaturization)
• Housings: PC/ABS, PEI (fire resistance, EMI shielding)
• Connectors: PBT, PA 46 (temperature, reliability)

Food industry:

• Food contact: POM-C, PEEK, PPS (FDA, EU 10/2011)
• Machine components: bearings, guides (wear resistance, no lubrication)
• Sensors: PPS housings (aggressive environments, temperatures)
• Detectability: detectable plastics (metal additives or blue)

How to choose the right material?

Selection of engineering material is a multi-stage process requiring analysis of requirements, operating conditions and economic aspects.

Step 1: Functional requirements analysis

• Mechanical loads: static, dynamic, impact
• Operating temperature: continuous, short-term, thermal cycles
• Chemical environment: acids, bases, solvents, fuels
• Electrical requirements: insulation, conductivity, tracking resistance
• Regulatory: food contact, medical, aerospace

Step 2: Material preselection

• Database: Campus Plastics, MatWeb, UL Prospector
• Filters: HDT temperature, strength, chemical resistance
• Preliminary list: 3-5 candidates
• Supplier consultation: dedicated grades, modifications

Step 3: Processing analysis

• Part geometry: wall thickness, undercuts, draft angles
• Fillability: material fluidity (MFI, MVR)
• Shrinkage and warpage: dimensional tolerances
• Injection mold: temperature (up to 180°C for PEEK), strength
• Equipment: barrel temperature (up to 400°C), pressure (up to 2500 bar)

Step 4: Prototype testing

• Injection samples: filling validation, properties
• Mechanical tests: tension, bending, impact
• Environmental tests: temperature, humidity, chemicals
• Functional tests: real condition simulation
• Iteration: grade/process optimization

Step 5: Economic analysis

• Material cost: price/kg × part weight × series
• Processing cost: cycle time, energy, mold
• Quality cost: rejects, complaints
• TCO (Total Cost of Ownership): product lifecycle
• Value engineering: design/material/process optimization

Example: Component under car hood

• Requirements: 150°C continuous, engine oil, ultrasonic welding assembly
• Candidates: PA 66 GF30, PPA GF30, PPS GF40
• Analysis: PPA optimal (cost/performance)
• Grades: Grivory GV-5H (EMS), Amodel AS-4133 (Solvay)
• Validation: 2000h tests at 150°C + oil, OK

Processing and maintenance

Effective engineering material processing requires specialist knowledge, equipment and rigorous procedure compliance.

Material preparation:

• Drying: absolutely necessary for PA, PET, PC, PBT (4-8h at 80-150°C, dew point -40°C)
• Dryers: desiccant (absorption) - never use hot air dryers
• Moisture control: online moisture meter (<0.02% for PA, <0.01% for PEEK)
• Recycling: usually max 10-25% regrind (property decrease)

Injection parameters - high-performance materials:

• PEEK: melt temperature 360-400°C, mold 150-200°C, pressure 1000-2000 bar
• PEI: melt temperature 340-400°C, mold 120-160°C
• PPS: melt temperature 300-340°C, mold 120-150°C
• LCP: melt temperature 280-340°C, mold 80-140°C, low viscosity

Daily maintenance activities:

• Visual inspection of injection parts (surface defects, filling)
• Material temperature and humidity check
• Nozzle and supply channel cleanliness check
• Pressure and cycle time verification (process sheet compliance)
• Mold area cleaning from dust and contamination

Weekly maintenance activities:

• Dryer filter and vacuum system cleaning
• Screw and barrel wear check (backflow measurement)
• Mold cooling system check (temperature, flow)
• Mold inspection: cavity wear, ejectors, guides
• Temperature and pressure sensor calibration (±2°C, ±10 bar)

Monthly maintenance activities:

• Plasticizing unit inspection: screw, check ring wear
• Hot valve and mold temperature control check
• Hydraulic and pneumatic system tightness test
• Desiccant dryer regeneration (molecular sieve replacement)
• Mold cleaning: removal of deposits, sediments, rust
• Electrical measurements: heater resistance, insulation

Annual maintenance activities:

• Major injection molding machine overhaul: screw, barrel, unit replacement
• Comprehensive mold regeneration: polishing, chroming, component replacement
• Hydraulic system inspection: oil, filter, seal replacement
• Control system calibration (repeatability ±0.3%, linearity ±0.5%)
• Operator training: new materials, process optimization
• Quality audit: MSA, SPC, capability studies (Cpk > 1.67)

Common problems and solutions:

• Short shots: increase melt/mold temperature, extend injection time, check pressure
• Cracks/delamination: reduce moisture (<0.02%), lower injection speed, increase mold temp
• Warpage: optimize cooling (uniformity), increase packing time, mold temperature
• Streaks/burning: reduce injection speed, add venting, lower melt temp
• Material degradation: shorten residence time in barrel, lower temperature, purge regularly

Summary

Engineering materials are the foundation of modern injection molding industry, enabling realization of applications impossible with standard plastics.

Key conclusions from the guide:

• PEEK, PEI, PPS, LCP - high-performance materials for extreme conditions (temperature, chemistry, strength)
• Composites - fiber reinforcement increases modulus by 300-500%, but requires special anisotropy analysis
• Engineering biopolymers - PA 610, Bio-PET offer sustainability without property compromises
• Material selection - requires functional, economic and processing analysis (TCO vs. price/kg)
• Processing - temperature up to 400°C, desiccant drying, process control key to success
• Maintenance - regular moisture, mold and equipment control minimizes rejects and increases lifetime

If you are looking for a partner for engineering material processing, contact TEDESolutions experts. As an authorized partner of Tederic, we offer advanced injection molding machines adapted for processing PEEK, PEI, LCP and comprehensive technological support.

We also encourage you to familiarize yourself with our articles about industry automation, sustainable production and electric injection molding machines, which will complement your knowledge of modern plastics processing.