Surface Scratch Resistance in Polycarbonate via Low-Level PMMA Dispersion

Civilizational assumption under test

Improving scratch resistance in transparent polycarbonate requires surface coatings, chemical hardening, or specialty additives, and cannot be achieved through simple physical blending without degrading optical clarity or impact resistance.

Why this assumption is load-bearing

Consumer electronics, automotive interiors, architectural glazing, and medical devices rely heavily on polycarbonate for impact resistance. However, surface scratching remains a dominant failure mode that shortens product lifespan and degrades usability.

Current mitigation strategies depend on coatings, multi-step surface treatments, or proprietary chemistries that add cost, complexity, and long-term failure risk through delamination or wear.

Edge of Practice experiment

Prepare polycarbonate samples containing a low loading of polymethyl methacrylate (PMMA) physically dispersed in the bulk polymer. No chemical compatibilizers, surface coatings, or post-process treatments are permitted.

Process material using standard twin-screw extrusion followed by injection molding into flat plaques suitable for optical and abrasion testing. PMMA loading should remain below levels associated with bulk phase separation or loss of transparency.

Hypothesis

During melt processing, PMMA preferentially migrates toward the polycarbonate surface, forming discrete, mechanically harder microdomains. These domains increase resistance to abrasion and scratching through purely physical reinforcement of the surface layer, without altering bulk mechanical performance.

Minimal test protocol

• Material preparation: Polycarbonate with ~10 wt% PMMA, injection molded into test plaques
• Environmental stability check: 72-hour exposure at 40°C and 75% relative humidity
• Functional test: Taber abrasion testing (1000 cycles) measuring haze increase or mass loss
• Control: Neat polycarbonate plaques processed under identical conditions

Failure condition

Any of the following outcomes constitutes failure of the assumption:

• Visible surface blooming or phase separation after humidity cycling
• Loss of optical clarity exceeding that of neat polycarbonate
• Taber abrasion haze increase or mass loss not reduced by at least 50% relative to control

What breaks if this assumption is false

The belief that surface durability in transparent polymers must rely on coatings or chemical modification remains intact, reinforcing higher-cost, higher-complexity manufacturing pathways and continued reliance on surface treatments with finite lifetimes.

What breaks if this assumption is true

A purely physical, coating-free pathway for improving scratch resistance in commodity polycarbonate becomes viable, challenging long-standing material selection and qualification practices across consumer, industrial, and architectural applications.

Status: Final · Immutable