How to Set Impact Modifier Dosage for PC/ABS

Separate a test formulation from a dosage recommendation

The published RC-701, RC-721 and RC-732 PC/ABS dataset uses PC / ABS / modifier / additive / additive = 85 / 10 / 4.5 / 0.3 / 0.2. The 4.5 share identifies the modifier level in that controlled source formulation; it is not a guaranteed optimum for every PC/ABS compound. Different PC molecular weight, ABS rubber content, PC-to-ABS ratio, recycled content, flame retardant package, pigment, filler, moisture history and processing conditions can change the required level and the tradeoffs.

RC-756 is not part of that same PC/ABS table. Its published PC evidence uses PC / RC-756 / PETS / 1010 = 95 / 5 / 0.5 / 0.5. Do not take the five-percent value from that separate formulation and rank it directly against the 4.5 share in the PC/ABS dataset. Both values are evidence context for planning a customer trial, not universal instructions.

Choose a defensible starting point

If the customer already uses an impact modifier successfully, begin with the current addition level and treat that formula as the incumbent control. When there is no incumbent, ask the candidate supplier for a grade- and resin-specific starting range supported by current documentation. Use the published controlled formulation only as a reference point and record why the selected ladder is technically reasonable for the actual PC/ABS system.

A useful ladder has enough separation to show response without changing several variables at once. Include an unmodified control where practical, the current commercial formula, and several candidate levels centered on the justified starting point. Do not publish or apply arbitrary universal increments. Keep the total formula normalized and decide in advance whether another component will be adjusted as modifier level changes.

Control compounding and molding variables

• Use one lot of each resin and additive and document the complete formulation by mass.
• Dry PC, ABS and regrind according to the controlled process and verify moisture where it is a known risk.
• Keep feeder calibration, addition sequence, extrusion temperatures, screw speed, throughput and residence time stable.
• Record torque, pressure, strand quality, pellet appearance, deposits and signs of poor dispersion or degradation.
• Condition pellets and molded specimens consistently; hold molding temperatures, back pressure, screw recovery and cycle conditions constant.

Measure the property balance

Impact response should be measured using the customer’s required method, temperature, geometry and conditioning. Examine the failure mode and scatter, not only the average. Test room-temperature and low-temperature performance when both matter. For finished parts, include the actual drop, assembly, screw-boss, snap-fit or other functional check that drove the project.

Track the properties most likely to move with modifier level: melt flow or process pressure, tensile and elongation, flexural strength and modulus, HDT or Vicat where relevant, surface and color, dimensional stability and flame performance if the formulation is flame-retardant. More modifier is not automatically better. A higher level can produce diminishing impact gains while increasing cost or changing stiffness, heat, flow and appearance.

Select, confirm and lock the approved level

Choose the lowest candidate level that consistently clears the full acceptance window with an appropriate margin. Repeat that condition, mold representative parts and confirm the process window. If recycled PC/ABS is involved, repeat across relevant feedstock lots because composition and degradation vary. Document the exact resin sources, modifier grade and lot, formulation revision, equipment, conditions and test methods so that production can reproduce the result.

Before commercial release, connect the approved RC grade to the current TDS, sample or batch COA, packaging and change-control expectations. Confirm the same material identity will be supplied in the order. Public prices remain indicative and reference only; the final quotation must state grade, quantity, delivery basis and validity. Evaluate cost per ton of approved compound at the approved addition level rather than comparing modifier price alone.

Products for Evaluation and D1 Price Status

Reference price range only. Actual price depends on grade, quantity, destination and current market conditions. Please contact us for today's confirmed CIF quotation.

Controlled Evidence and Related Resources

Frequently Asked Questions