Core Properties of PP Parts
Mechanical Properties
Lightweight and High Toughness: Density is only 0.89-0.91 g/cm³ (approximately 60% of ABS and 75% of PC), making it suitable for weight-sensitive applications (such as automotive interiors and portable containers). Copolymer PP has a Charpy notched impact strength of ≥20-50 kJ/m² (at room temperature), significantly higher than homopolymer PP (<10 kJ/m²). However, at low temperatures (<5°C), the impact strength may drop by over 50% (requiring the addition of a toughening agent).
Medium Rigidity: Flexural strength is 20-40 MPa, and elastic modulus is 800-1500 MPa (lower than engineering plastics such as PA and PC). Suitable for structural parts bearing small to medium loads (such as housings and brackets).
Fatigue Resistance: Creep is likely to occur under long-term dynamic loads (especially in high-temperature environments), so long-term load-bearing designs should be avoided.
Thermal Properties
Moderate heat resistance: Long-term operating temperature range -20°C to +100°C (short-term resistance 120°C), Vicat softening point approximately 150°C (homopolymer PP is higher, approximately 155-160°C), melting point approximately 160-170°C (processing temperature typically 180-240°C).
Low heat deflection temperature: approximately 50-80°C under a load of 1.82 MPa (copolymer PP), limiting its application in high-temperature environments (if resistance above 80°C is required, high-temperature modified PP or alternative materials should be used).
Chemical Properties
Excellent chemical resistance: Stable to most acids (e.g., sulfuric acid, hydrochloric acid, phosphoric acid), alkalis (e.g., sodium hydroxide, potassium hydroxide), saline solutions, and organic solvents (e.g., ethanol, acetone, gasoline) (no significant swelling or corrosion at concentrations below 90%), making it the material of choice for chemical storage tanks and laboratory equipment.
The only drawback is sensitivity to strong oxidizing acids (such as concentrated nitric acid and concentrated sulfuric acid >90%), halogenated hydrocarbons (such as carbon tetrachloride), and aromatic hydrocarbons (such as toluene). Swelling or stress cracking may occur.
Electrical Properties
Excellent insulation: Volume resistivity ≥10¹⁵Ω·cm (approximately comparable to PTFE), dielectric strength 20-30 kV/mm, dielectric constant 2.0-2.2 (at 1 kHz, virtually unaffected by frequency), making it suitable for high-frequency insulation components (such as wire and cable sheathing, electronic component housings).
Processability
Easy to process and mold: Excellent melt flowability (melt flow rate (MFR) adjustable from 0.1 to 100 g/10 min), injection molding temperature 180-240°C (adjusted depending on grade), mold temperature 20-60°C, shrinkage 1.0-2.5% (dimensional compensation must be accommodated during design).
Highly recyclable: 100% of waste can be crushed and re-pelletized (with slightly reduced performance of recycled PP, but significantly lower costs), meeting environmental standards.
Other Characteristics
Surface Properties: Low surface energy (approximately 30-32 mN/m), poor adhesion to inks and glues (requiring corona treatment or primer application for improvement), but easy to clean (non-porous structure).
Poor weather resistance: Long-term UV exposure can cause molecular chain breakage (yellowing, brittleness, and reduced strength). For outdoor use, UV absorbers (such as UV-531) and antioxidants (such as 1010) are required.
Non-toxic: Complies with FDA and LFGB food contact standards (e.g., copolymer PP is often used in microwaveable lunch boxes and baby bottles). It is tasteless and odorless, making it suitable for medical device and food packaging.
Core Advantages of PP Parts
Lightweight and Low Cost: An Economical Choice for Large-Scale Production
PP parts' ultra-low density (0.89-0.91 g/cm³) and low raw material costs (only 60% of ABS and 50% of PC) make them a top choice for weight- and cost-sensitive applications. For example:
Automotive interior parts: instrument panel frames and door panel linings (PP injection molded parts) are 30%-50% lighter than traditional metal parts, reducing fuel consumption;
Daily necessities: plastic basins, storage boxes, and water cups (PP blow molded/injection molded parts) are only 1/3-1/2 the price of glass or stainless steel parts, and are lightweight and unbreakable.
Chemical Resistance: A Reliable Partner for Chemical and Laboratory Applications
PP parts are far more resistant to acids, alkalis, salts, and common organic solvents than other general-purpose plastics (such as PS and PVC), making them particularly suitable for applications involving contact with corrosive media.
Chemical Storage and Transportation Equipment: Acid and alkali solution storage tanks and reagent bottles (PP blow-molded parts) can store sulfuric acid and sodium hydroxide solutions with concentrations below 50% for long periods of time.
Laboratory Equipment: Petri dishes, funnels, and graduated cylinders (PP injection-molded parts) can withstand cleaning with organic solvents such as alcohol and acetone without releasing any harmful substances.
Insulation and Safety: A "Functional Assistant" for Electronics and Home Appliances
The high insulation and non-toxicity of PP parts make them widely used in electronics and home appliances:
Wire and cable jackets: PP insulation layer (thickness 1-3mm), resistant to voltage breakdown (dielectric strength > 25kV/mm), and flexible (suitable for curved wiring);
Home appliance housings: Rice cooker inner pots and microwave lunch boxes (copolymer PP parts), heat-resistant up to 100°C (no toxic gases released during microwave heating), and non-slip (micro-textured surface design).
