Polypropylene (PP): Properties, Uses and Grade Selection

Polypropylene (PP) is a thermoplastic resin used in molded parts, packaging, films, fibers and tapes. Choosing a PP raw material starts with the product and manufacturing process, then the resin family and grade. A material name or melt flow rate alone cannot establish that a replacement will meet the finished product’s requirements.

Polypropylene properties and uses

PP offers a useful balance of low weight and stiffness, but clarity, impact behavior and processing response differ between grades. The British Plastics Federation’s PP overview describes its families and industrial uses. Treat published general properties as background, then obtain the candidate grade’s technical data sheet (TDS).

Homopolymer, random copolymer or impact copolymer?

This is a screening framework, not a substitution chart. The family narrows the search; grades within it still differ. Document whether the resin contains fillers or functional additives before comparing it with an unmodified material.

Select the grade for the process

LyondellBasell’s material-selection guide organizes the decision around process, appearance, mechanical function and additive requirements. Turn those questions into a written specification for your part.

Read MFR and the TDS together

Melt flow rate (MFR) is useful for comparing flow under specified test conditions. Record the method, temperature and load beside the number; do not compare values measured under different conditions as if they were equivalent. LyondellBasell discusses why process requirements change the appropriate MFR range. No universal MFR number on this page qualifies a resin for every injection or extrusion line.

Create a comparison sheet with the approved control and candidate grade: producer and code, MFR conditions, mechanical test methods, impact temperature, dimensional requirements and required application documents. Separate a typical TDS value from a contractual acceptance limit or batch certificate. See flow data and batch consistency.

A controlled replacement trial

Agree acceptance criteria before running the candidate. Record resin lot, color concentrate, fillers and other additives; keep the process comparison controlled and record any setting changes. Check part dimensions, appearance and relevant mechanical performance as well as line behavior. If recycled input is proposed, include contamination and consistency checks.

One good-looking sample does not establish repeatable production. Keep the control sample and trial record so a later material or process change can be reviewed against the same requirements.

Prepare a useful material enquiry

Share the product, process, current approved grade if available, required tests, quantity and destination. Attach the specification and identify any contact-use or market requirements that need grade-specific documentation. This reference guide explains selection; commercial availability and suitability need confirmation for the actual candidate.

Content reviewed: 8 October 2026. Technical framework: BPF and LyondellBasell links above; existing ASTM classification references are listed in the technical-reference section.