Polymer selection guide
PP and PE granules: select by application, not by grade name alone
A similar grade name or pellet appearance does not guarantee identical behavior in the machine or final product. A reliable selection starts with the part, conversion process, processing window, color, target properties, monthly demand, and the customer’s quality sensitivities.
How PP and PE differ in selection
PP is commonly chosen where stiffness, heat resistance, low density, or specific processing behavior is required, including injection molding, raffia, fibers, and many industrial parts. PE covers several families—low-density, high-density, and linear grades—used in film, blow molding, pipe, injection, and flexible applications. The polymer family alone is not enough; subtype, grade, and actual performance history matter.
Key purchasing parameters
Melt flow rate influences processability, but it is not a complete quality certificate. Color consistency, odor, moisture, ash or filler content, contamination, pellet uniformity, and variation between lots can all affect production. The relevant parameters must be selected for the intended application.
Why the sample must represent the offered lot
A sample from another batch, or from a non-representative part of the load, creates decision risk. The sample should be registered with the product and lot code, and its relationship to the offered material must remain clear. This is especially important for recycled and blended materials, where feedstock or formulation changes may alter performance.
Customer production trial
Laboratory data is useful, but acceptance should match real production. Record drying conditions, barrel temperatures, pressure, speed, cycle time, blend percentage, and part quality. Acceptance criteria should be explicit—for example mold filling, surface appearance, brittleness, warpage, odor, part weight, or another application-specific requirement.
Practical buying checklist
- Confirm the polymer family and subtype.
- Record the application and process.
- Define melt flow or agreed technical parameters.
- State limits for color, odor, filler, and contamination.
- Test a representative sample from the same lot.
- Save the trial result for repeat orders.
How PLASTIX adds value
PLASTIX records the requirement, compares available sources, keeps the sample connected to the lot, and follows trial results for future supplies. The objective is not to promote any available material; it is to identify a better match for the customer’s application.