Passive Thermal Buffering in Polyethylene Films

Civilizational assumption under test

Commodity polyethylene films are thermally passive barriers and cannot meaningfully moderate temperature spikes without encapsulated phase change materials, chemical modification, or multilayer composites.

Why this assumption is load-bearing

Food packaging, medical transport, cold-chain logistics, and consumer goods protection all assume polyethylene films transmit ambient heat changes essentially unchanged. As a result, thermal buffering is delegated to foams, gels, or discrete PCM inserts—adding cost, complexity, and waste.

If polyethylene itself can moderate temperature rise rates using only physically confined additives, large portions of thermal management infrastructure could be simplified or eliminated.

Edge of Practice experiment

Introduce a small fraction of paraffin wax (C20–C28) into low-density or linear low-density polyethylene and process into standard films. The wax is not encapsulated, chemically bound, or coated.

When properly confined within the amorphous regions of polyethylene, the paraffin undergoes a solid–solid or solid–liquid phase transition during heating, absorbing latent heat and reducing the rate of temperature increase.

Minimal test protocol

• Compound LDPE or LLDPE with 5–10 wt% paraffin wax (C20–C28)
• Extrude into 50–150 μm films using standard film extrusion equipment
• Apply a controlled heat ramp while measuring surface or internal temperature versus time
• Compare against neat polyethylene films of identical thickness

Failure conditions

The assumption fails if both of the following are observed:

• No measurable reduction in peak temperature rise rate or time-to-peak temperature compared to neat polyethylene
• Visible wax migration, oiling, or >1% mass loss after 48 hours at 40 °C

Success criteria

• ≥20% reduction in peak temperature rise rate under identical heating
• ≥10% increase in time to peak temperature
• No visible exudation or ≤1% mass loss in contact/migration testing

What breaks if the assumption is false

Thermal moderation can no longer be treated as requiring specialized materials or discrete PCM systems. Commodity polyethylene becomes a rate-controlling thermal material, not merely a passive barrier.

Status: Final · Immutable