Plastic Materials (Part 3): In-depth Analysis of PP-TD
Time：2026-10-10 08:18:04 / Popularity： / Source：
For previous reading, please refer to Plastics Materials (Part Two): In-Depth Analysis of PP+EPDM-TD.
PP-TD (Talc-filled Polypropylene) is one of the most basic and widely used varieties in modified PP family. It does only one thing – adds rigidity to PP with talc, simple, direct, and inexpensive. Unlike PP+EPDM-TD, PP-TD does not contain a rubber toughening phase; it relies solely on talc flake structure to improve rigidity and heat resistance. Although its toughness is not as good as EPDM-filled PP, it has significant advantages in rigidity, hardness, heat resistance, dimensional stability, cost, making it preferred material for appliance housings, automotive structural parts, and lamp housings.
PP-TD (Talc-filled Polypropylene) is one of the most basic and widely used varieties in modified PP family. It does only one thing – adds rigidity to PP with talc, simple, direct, and inexpensive. Unlike PP+EPDM-TD, PP-TD does not contain a rubber toughening phase; it relies solely on talc flake structure to improve rigidity and heat resistance. Although its toughness is not as good as EPDM-filled PP, it has significant advantages in rigidity, hardness, heat resistance, dimensional stability, cost, making it preferred material for appliance housings, automotive structural parts, and lamp housings.
I. What is PP-TD? A Visual Guide
PP-TD = PP matrix + talc (Talc) filler, the simplest binary modification system:
| Components | Functions |
| PP | Matrix material, providing basic properties and processability |
| TD (Talc) | Talc filler, improving rigidity, heat resistance, and dimensional stability |
Number after TD = percentage of talc filler. TD10 = 10% talc, TD20 = 20%, TD40 = 40%.
Talc's Lamellar Structure – Source of Rigidity
Talc's Lamellar Structure – Source of Rigidity
Talc is a natural layered silicate mineral with a typical lamellar structure. When added to PP, these lamellar particles disperse like "scales" in matrix: Restricting molecular chain movement → Significantly increased rigidity; Impeding heat conduction → Increased heat distortion temperature; Reducing crystallization shrinkage → Improved dimensional stability.
| Performance | With Increasing TD Content | Variation Range |
| Flexural Modulus | ↑ Significantly Increases | TD40 can reach 3-4 times that of pure PP |
| Heat Deflection Temperature | ↑ Increases | TD40 has a 30-50℃ higher temperature than pure PP |
| Dimensional Stability | ↑ Improves | Shrinkage decreases from 1.5% to below 0.8% |
| Surface Hardness | ↑ Increases | Talc improves surface scratch resistance |
| Impact Toughness | ↓ Decreases | Notched impact strength decreases from 5-10 kJ/m² in pure PP to 2-4 kJ/m² |
| Density | ↑ Increases | TD40 density can reach over 1.2 g/cm² |
| Elongation at Break | ↓ Decreases | Degree decreases from >100% in pure PP to 10-20% |
Key Characteristics: PP-TD is a "specialist" – very strong in rigidity and heat resistance, but weak in toughness. Suitable for applications requiring high load-bearing capacity, heat resistance, and dimensional stability, but with low impact risk.
PP-TD vs PP+EPDM-TD: How to Choose?
PP-TD vs PP+EPDM-TD: How to Choose?
| Comparison Dimensions | PP-TD (Pure Filler) | PP+EPDM-TD (Toughened Filler) |
| Rigidity | Higher | Slightly Lower |
| Toughness | Low (Notched Impact 2~5kJ/m2) | High (Notched Impact 15~30kJ/m2) |
| Low Temperature Performance | Poor, brittle at low temperatures | Good, still tough at -30℃ |
| Heat Resistance | Better | Slightly Lower |
| Cost | Lower | Higher (EPDM is expensive) |
| Surface Hardness | Higher | Slightly Lower |
| Typical Applications | Applicable to appliance housings, lamp housings, frames, HVAC systems | Applicable to bumpers, dashboards, exterior trim |
TD10 (10% Talc): TD10 has low filler content, good flowability, excellent surface quality, suitable for applications with high appearance requirements but not extreme rigidity requirements.
TD20 (20% Talc) – Most Commonly Used Grade: TD20 is the mainstream grade of PP-TD, offering the best balance between rigidity and processability. It is widely used in automotive interior structural parts, appliance housings, and lighting fixtures.
TD40 (40% Talc) – High Rigidity Grade: TD40 has extremely high filler content, the strongest rigidity (flexural modulus can reach over 3500 MPa), and the best heat resistance, but poor toughness, high density, and high processing difficulty. Suitable for replacing metal in high-rigidity structural parts.
TD20 (20% Talc) – Most Commonly Used Grade: TD20 is the mainstream grade of PP-TD, offering the best balance between rigidity and processability. It is widely used in automotive interior structural parts, appliance housings, and lighting fixtures.
TD40 (40% Talc) – High Rigidity Grade: TD40 has extremely high filler content, the strongest rigidity (flexural modulus can reach over 3500 MPa), and the best heat resistance, but poor toughness, high density, and high processing difficulty. Suitable for replacing metal in high-rigidity structural parts.
II. Mechanical Property Laws and Yield-to-Trypsum Ratio
Mechanical properties of PP-TD exhibit a regular variation with talc content. Understanding this pattern allows for quick selection.
| Properties | TD10 | TD20 | TD30 | Test Standards |
| Density | ~0.96 g/cm² | ~1.04 g/cm² | ~1.20 g/cm² | ISO 1183 |
| Flexural Modulus | 1500~2000MPa | 2200~2800MPa | 3500~4500MPa | ISO 178 |
| Tensile Yield Strength | 28~32 MPa | 30~35MPa | 32~40 MPa | ISO 527 |
| Elongation at Break | 30~60% | 10~30% | 5~15% | ISO 527 |
| Notched Izod Impact (23℃) | 48kJ/m² | 35kJ/m² | 23kJ/m² | ISO 180 |
| Heat Deflection Temperature (0.45MPa) | 95~105℃ | 110~125℃ | 130~140℃ | ISO 75 |
| Heat Deflection Temperature (1.80Pa) | 50~60℃ | 60~75℃ | 80~95℃ | ISO 75 |
| Vicat Softening Point | 125~135℃ | 140~150℃ | 150~155℃ | ISO 306 |
| Molding Shrinkage | 1.0~1.4% | 0.8~1.2% | 0.6~0.9% | ISO 294-4 |
Comparison of Typical Properties with Different TD Contents
Note: Above are typical ranges for materials of same grade. Specific values may vary depending on talc mesh size, surface treatment, and matrix type (homopolymer/copolymer).
Yield Strength Ratio Analysis
Yield strength ratio (yield strength / tensile strength) of PP-TD follows these patterns: Low TD (TD10): Medium yield strength ratio (~0.6~0.7), with some plastic deformation capacity. Medium TD (TD20): High yield strength ratio (~0.7~0.8), fractures quickly after yielding. High TD (TD40): Very high yield strength ratio (~0.8~0.9), approaching brittle fracture.
Engineering Conclusion: PP-TD is a relatively brittle material, especially high-filler grades. In design, it cannot be expected to absorb energy through large plastic deformation. Sharp notches should be avoided in high-stress areas to prevent stress concentration leading to brittle fracture.
Key Process Parameters
Note: Above are typical ranges for materials of same grade. Specific values may vary depending on talc mesh size, surface treatment, and matrix type (homopolymer/copolymer).
Yield Strength Ratio Analysis
Yield strength ratio (yield strength / tensile strength) of PP-TD follows these patterns: Low TD (TD10): Medium yield strength ratio (~0.6~0.7), with some plastic deformation capacity. Medium TD (TD20): High yield strength ratio (~0.7~0.8), fractures quickly after yielding. High TD (TD40): Very high yield strength ratio (~0.8~0.9), approaching brittle fracture.
Engineering Conclusion: PP-TD is a relatively brittle material, especially high-filler grades. In design, it cannot be expected to absorb energy through large plastic deformation. Sharp notches should be avoided in high-stress areas to prevent stress concentration leading to brittle fracture.
Key Process Parameters
| Parameters | Recommended Range | Explanation |
| Barrel Temperature | 200~240℃ | Segmented heating; higher filler material temperature is acceptable. |
| Mold Temperature | 30~70℃ | Higher mold temperature → better surface finish and more uniform curing. |
| Injection Pressure | 80~140 MPa | Poor filler flowability necessitates higher pressure. |
| Screw Speed | 50~100 rpm | Excessive shearing can break up talc flakes. |
| Back Pressure | 5~15 MPa | Appropriate back pressure improves plasticization uniformity. |
III. Application Overview
PP-TD has a wide range of applications, from automobiles to home appliances to daily necessities; it can be used wherever rigidity, dimensional stability, and impact requirements are not high.
Automotive Applications
Automotive Applications
| Components | Common Grades | Key Requirements |
| Headlight/Taillight Rear Housing | TD20/TD30 | Heat resistance (high lamp operating temperature), dimensional stability, UV resistance |
| HVAC Housing/Dual Unit | TD20/TD30 | High rigidity, heat resistance, low odor |
| Dashboard Frame/Bracket | TD20/TD30 | High rigidity, dimensional stability, heat resistance |
| Door Module Bracket | TD20/TD30 | High rigidity, load-bearing capacity |
| Battery Tray/Bracket | TD30/TD40 | High rigidity, dimensional stability, heat resistance |
| Hood Underbody Panel | TD30/TD40 | High rigidity, heat resistance, vibration resistance |
| Air Conditioning Housing | TD20 | Rigidity, dimensional stability, low VOC |
Why use PP-TD for lamp housings? Headlights operate at temperatures reaching 80-100℃, requiring materials with sufficient heat resistance (high HDT) and dimensional stability. Simultaneously, lamp housing primarily bears its own weight and assembly stress, minimizing impact risk. PP-TD offers a perfect balance of rigidity, heat resistance, and cost.
Home Appliance Applications
Home Appliance Applications
| Components | Common grades | Key requirements |
| Washing machine inner drum/balance ring | TD20/TD30 | High rigidity, water resistance, dimensional stability |
| Air conditioner outer casing/air duct | TD20 | Rigidity, surface quality, weather resistance |
| Microwave oven door inner frame | TD20/TD30 | Heat resistance, dimensional stability |
| Refrigerator drawers/shelves | TD10/TD20 | Rigidity, transparency/appearance |
| Rice cooker/electric pressure cooker | TD20/TD30 | Heat resistance, food grade |
| Dishwasher components | TD20/TD30 | Hot water resistance, detergent resistance |
Other Applications
| Industry sectors | Typical Products |
| Electronics & Appliances | Sockets, Junction Boxes, Switch Panels (Flame retardant required) |
| Daily Necessities | Storage Boxes, Chairs, Flower Pots, Trash Cans |
| Building Materials | Pipes, Sheets, Door & Window Fittings |
| Industrial Products | Pump Housings, Valves, Gears (Low Load) |
IV. CAE Simulation
Simulation modeling of PP-TD is similar to that of PP+EPDM-TD, but due to its greater brittleness and stronger anisotropy, some special considerations are necessary.
| Models | Applications | Features |
| Elastic-plastic model | Static stiffness and strength analysis | Most commonly used, inputs stress-plastic strain curves |
| Drucker-Prager model | Multiaxial stress and press fit problems | Consides pressure-dependent yielding |
| Brittle fracture model | High-filler failure prediction | Brittle fracture needs to be considered for brittle materials such as TD40 |
| Viscoelastic/creep model | Long-term load and high-temperature creep | High-filler materials have good creep resistance but still need to be considered |
| Orthotropic model | High-precision structural analysis | Consides performance differences in flow direction and vertical direction |
| Simulation Types | Model Used | Results to Consider |
| Static Stiffness | Elastic-Plastic | Displacement, Stress Distribution |
| Modal/NVH | Linear Elastic | Natural Frequency, Mode Shape |
| Thermal Deformation | Thermo-Elastic-Plastic | Warpage, Residual Stress |
| Creep (Long-Term Load) | Viscoelastic/Creep Model | Long-Term Deformation |
| Drop/Impact | Elastic-Plastic + Damage | Crack, Failure Location |
| Vibration Fatigue | Elastic-Plastic + Fatigue Criteria | Fatigue Life |
Simulation Characteristics of Talc-Filled PP
Significant anisotropy: During injection molding, talc flake particles orient along flow direction, resulting in a 20-40% higher modulus in flow direction compared to perpendicular direction. High-precision simulation requires importing orientation tensors using Moldflow. Brittle Fracture: High-filler PP-TD (TD30 and above) approaches brittle material characteristics, with an elongation at break of only 5-10%. Large deformation assumptions cannot be used in simulations; brittle failure criteria must be considered. Temperature Sensitivity: Although talc increases HDT, modulus still decreases significantly at high temperatures. HDT under 1.8 MPa load is much lower than that under 0.45 MPa. Combined effects of load and temperature must be considered for load-bearing components.
Failure mode of PP-TD is similar to that of PP+EPDM-TD, but because it lacks EPDM toughening, brittle-related failures are more prominent. Problem: Sudden fracture under impact or high stress, with almost no signs of plastic deformation. Talc particles act as stress concentration points, and cracks propagate rapidly from filler interface.
Common Scenarios: Drop impact, excessive assembly stress, and loading at low temperatures.
Significant anisotropy: During injection molding, talc flake particles orient along flow direction, resulting in a 20-40% higher modulus in flow direction compared to perpendicular direction. High-precision simulation requires importing orientation tensors using Moldflow. Brittle Fracture: High-filler PP-TD (TD30 and above) approaches brittle material characteristics, with an elongation at break of only 5-10%. Large deformation assumptions cannot be used in simulations; brittle failure criteria must be considered. Temperature Sensitivity: Although talc increases HDT, modulus still decreases significantly at high temperatures. HDT under 1.8 MPa load is much lower than that under 0.45 MPa. Combined effects of load and temperature must be considered for load-bearing components.
Failure mode of PP-TD is similar to that of PP+EPDM-TD, but because it lacks EPDM toughening, brittle-related failures are more prominent. Problem: Sudden fracture under impact or high stress, with almost no signs of plastic deformation. Talc particles act as stress concentration points, and cracks propagate rapidly from filler interface.
Common Scenarios: Drop impact, excessive assembly stress, and loading at low temperatures.
| Direction | Specific Practices |
| Materials | Reduce TD content (from TD40 to TD20); switch to PP+EPDM-TD toughening system. |
| Materials | Talc surface treatment (coupling agent) to improve interfacial bonding. |
| Materials | Select high-mesh (fineer) talc powder to minimize stress concentration effect. |
| Design | Enlarge rounded corners to avoid sharp corners and notches; ensure uniform wall thickness. |
| Design | Avoid forced assembly to prevent high internal stress. |
Development Trends
High Flow and High Filler: Maintaining good flowability with high filler content (TD40 or even TD50), supporting thin-walled and large components. Low Warpage / High Dimensional Accuracy: Reducing anisotropy through filler morphology optimization (spherical/flaky blends) and orientation control. Functionalized PP-TD: Functional modifications such as electrical conductivity, thermal conductivity, antibacterial properties, and flame retardancy. Low Density and High Rigidity: Improving rigidity without increasing density through new technologies such as hollow microspheres and nanofillers. Long Glass Fiber Reinforced PP (LFT): Replacing short glass fibers and metals for structural components with higher load-bearing requirements. Microfoamed PP-TD: Chemical/physical foaming, reducing weight by 15-25% while improving sound and heat insulation. Recycled PP-TD: Improved quality of recycled materials, increasing applications in non-critical components such as home appliances and daily necessities. No Painting Required / High Gloss: Special color powders and surface modification technologies meet the requirements for no painting on home appliance exterior components.
High Flow and High Filler: Maintaining good flowability with high filler content (TD40 or even TD50), supporting thin-walled and large components. Low Warpage / High Dimensional Accuracy: Reducing anisotropy through filler morphology optimization (spherical/flaky blends) and orientation control. Functionalized PP-TD: Functional modifications such as electrical conductivity, thermal conductivity, antibacterial properties, and flame retardancy. Low Density and High Rigidity: Improving rigidity without increasing density through new technologies such as hollow microspheres and nanofillers. Long Glass Fiber Reinforced PP (LFT): Replacing short glass fibers and metals for structural components with higher load-bearing requirements. Microfoamed PP-TD: Chemical/physical foaming, reducing weight by 15-25% while improving sound and heat insulation. Recycled PP-TD: Improved quality of recycled materials, increasing applications in non-critical components such as home appliances and daily necessities. No Painting Required / High Gloss: Special color powders and surface modification technologies meet the requirements for no painting on home appliance exterior components.