Products · PP
Polypropylene (PP) is a versatile polyolefin produced by polymerization of propylene using Ziegler-Natta or metallocene catalysts. PP is available in three main grades: homopolymer (highest stiffness and HDT, but brittle at low temperature), random copolymer (improved clarity and impact strength, slightly lower HDT), and impact copolymer (also called block copolymer; highest impact strength, lower stiffness). PP is the workhorse for packaging (food containers, bottle caps, films), automotive interior, consumer goods, and medical devices. The combination of low cost, easy processing, and broad grade availability makes PP the highest-volume polymer by tonnage globally. Reference grades from LyondellBasell (Moplen, Pro-fax), SABIC, and Sinopec cover the full property range.
Section 1
A reference overview of the molecular architecture and the design variables that govern the performance of this polymer family.
PP is a polymer of propylene (CH2=CH–CH3) with the methyl group on every other backbone carbon. The stereochemistry of the methyl groups (isotactic, syndiotactic, atactic) determines the crystallinity and properties. Isotactic PP (iPP), with all methyl groups on the same side of the chain, is the commercially dominant form and is highly crystalline (up to 70%). Random copolymer PP introduces small amounts (1-7%) of ethylene or butene to disrupt crystallinity, giving improved clarity, flexibility, and impact strength. Impact copolymer PP has a continuous iPP matrix with dispersed ethylene-propylene rubber (EPR) phase, giving much higher impact strength at low temperature.
Section 2
Typical property ranges across commercial grades. Test methods are listed in the rightmost column for traceability to public manufacturer data sheets.
PP offers the lowest density among commodity plastics (0.90-0.92 g/cm³ for homopolymer), high stiffness, good chemical resistance, and easy processability. The trade-off vs other engineering polymers is lower HDT (100-115°C for homopolymer) and brittleness at low temperature for homopolymer grades.
| Property · 性能 | PP Homopolymer | PP Impact Copolymer | Test Method · 测试方法 |
|---|---|---|---|
| Density · 密度 | 0.90 – 0.92 g/cm³ | 0.90 – 0.92 g/cm³ | ASTM D792 |
| Melt Point · 熔点 | 160 – 170 °C | 160 – 170 °C | ISO 3146 |
| Tensile Strength · 拉伸强度 | 30 – 40 MPa | 25 – 35 MPa | ASTM D638 |
| Flexural Modulus · 弯曲模量 | 1.3 – 1.8 GPa | 1.0 – 1.5 GPa | ASTM D790 |
| Elongation at Break · 断裂伸长 | 100 – 300 % | 200 – 500 % | ASTM D638 |
| HDT (0.45 MPa) · 热变形 | 100 – 115 °C | 85 – 100 °C | ASTM D648 |
| Izod Notched Impact (23°C) · Izod 缺口冲击 | 20 – 50 J/m | 200 – 500 J/m | ASTM D256 |
| Water Absorption (24h) · 吸水率 | < 0.01 % | < 0.01 % | ASTM D570 |
Section 3
The major application areas for this polymer family, each illustrated with a brief description of how the material is specified and used.
PP is the dominant material for food packaging: yogurt cups, margarine tubs, bottle caps, microwaveable food containers, and films. The combination of low cost, high heat resistance (microwaveable), low moisture absorption, and FDA food-contact compliance makes PP the workhorse for food packaging.
PP is the highest-volume polymer used in automotive interior: instrument panels, door panels, pillar trim, console components, and seat back panels. PP impact copolymer grades with 10-30% glass fiber or talc reinforcement are widely used in structural interior parts where high stiffness, low cost, and impact strength are required.
PP is used in a wide range of consumer goods: housewares, storage containers, toys, garden furniture, and luggage. The combination of low cost, colorability, and processability for mass production is valued.
PP is used in medical devices: syringes (non-prefilled), pill bottles, sample containers, and tubing. The combination of low cost, low extractables, autoclave compatibility (homopolymer up to 121°C), and chemical resistance is valued in disposable and reusable medical applications.
Section 4
Key processing parameters and equipment considerations. Contact our business manager for grade-specific processing recommendations.
| Melt Temperature | 200 – 250 °C (homopolymer); 200 – 240 °C (copolymer) |
| Drying | Not required (PP is essentially non-hygroscopic) |
PP is one of the easiest polymers to process — low melt viscosity, broad processing window, and no drying required. Mold shrinkage is higher than amorphous polymers (1-2.5%) and must be accounted for in mold design. PP is sensitive to UV — outdoor applications require UV-stabilized grades or carbon black pigmentation. For high-temperature applications (>100°C continuous), PP is limited; consider PA or PPA.
Section 5
A summary of when this polymer family is the right choice and what to consider as alternatives. For project-specific grade selection, contact our business manager.
Choose PP homopolymer for highest stiffness, HDT, and lowest cost; choose random copolymer for clarity, flexibility, and food contact; choose impact copolymer for low-temperature impact and structural applications. For higher temperature (above 100°C continuous) or higher stiffness, consider PA or PPA. For transparent applications, consider PP random copolymer, PET, or PMMA. For medical or food contact, verify PP grade compliance with relevant regulations (FDA, EU, USP).
Section 6
Reference grades from publicly available manufacturer catalogs. Complete catalog available on request.
| Grade | Manufacturer | Key Properties | Typical Use |
|---|---|---|---|
| Pro-fax® 6323No vendor TDS · source on request | LyondellBasell | Homopolymer · General purpose · High stiffness | Packaging · Consumer · Industrial |
| Moplen® EP548SNo vendor TDS · source on request | LyondellBasell | Impact copolymer · High flow · High impact | Automotive interior · Thin-wall packaging |
| Moplen® RP348RNo vendor TDS · source on request | LyondellBasell | Random copolymer · High clarity · Food contact | Food packaging · Clear containers · Film |
| Sinopec PP T30S | Sinopec (中石化) | Homopolymer · Standard · 国产 | 国产替代 · 包装 · 通用 |
Section 7
Cross-references to industry-specific applications and case studies.