Overview
Analysis
Solutions
Complete
·Feb 3, 2026The Core Insight
The physics that defeats NIR is irrelevant to thermal, electrical, and acoustic properties
- Thermal diffusivity (α = k/ρCp), dielectric constant (ε'), acoustic velocity (c = √E/ρ), and triboelectric charge affinity are all polymer-specific material properties that don't care about optical absorption.
- Carbon black is literally invisible to these measurement modalities—and in the case of thermal methods, it actually helps by absorbing excitation energy more efficiently.
Viability
Solvable with Effort
- Multiple proven physics pathways exist; barrier is integration engineering and potentially market constraints, not fundamental science.
Key Decision
If your downstream market accepts mixed PE/PP blends, triboelectric + density is complete. If not, flash thermography development is required for full discrimination.
Solution Paths
01READY NOW
Triboelectric Pre-Sort + Density Separation
Separates PET from polyolefins regardless of color using commercial equipment; cannot discriminate PE from PP
02NEEDS DEVELOPMENT
Flash Thermography Integration
Turns carbon black from obstacle to advantage; 12-18 month development but proven physics from NDT
Recommendation
- If this were my MRF, I'd start with three parallel tracks this month: First, I'd implement the color gate immediately—it's $30-75K and 6-8 weeks to capture value that's currently going to landfill.
- Even if chemical recycling only pays $200/ton, that's infinite ROI versus zero.
- This buys time while we develop better solutions.
- Second, I'd call ST Equipment for a triboelectric pilot test.
- If humidity control is tractable (and it usually is—industrial dehumidification is boring engineering), this solves PET separation regardless of color for under $300K.
- That's my highest-value stream locked in.
- Third—and this is the strategic move—I'd spend a few weeks talking to my downstream customers about mixed PE/PP acceptance.
- If they'll take it for lumber replacement or construction applications, I'm done.
- Triboelectric plus density separation gives me complete black plastic sorting with commercial equipment and no R&D risk.
- Only if the market validation fails would I pursue flash thermography development.
- The physics is proven, the components are commercial, but it's still 12-18 months and $300K to deployment.
- That's a last resort, not a first choice.
- The simplest solution that works is always the right answer—and triboelectric might be that solution if we're willing to question whether PE/PP separation is really required.