pmma vs polycarbonate lens: Complete Comparison

PMMA 透镜与聚碳酸酯透镜对比

Head-to-Head Comparison

Detailed Analysis

1. Performance

Let's start with what matters most in a lens: how much light gets through. PMMA delivers 92% transmission at 3mm thickness — that's about as good as it gets for a rigid thermoplastic. Polycarbonate sits at 88%, which doesn't sound like much until you're running a 100,000-lumen warehouse installation. That 4% difference means you're losing 4,000 lumens per fixture to the lens alone. On a 200-fixture job, that's 800,000 lumens you're paying for but not getting.

Here's the thing about real-world installations: I've seen PMMA lenses in office troffers that looked pristine after a decade indoors. But put that same lens in a parking garage where someone's dragging a ladder past it, and you'll be replacing cracked lenses within months. Polycarbonate's impact resistance — 600–850 J/m versus PMMA's 16–20 J/m — isn't just a lab number. It's the difference between a lens that survives a dropped wrench and one that shatters.

Thermal performance is where polycarbonate pulls ahead for high-power applications. Standard PMMA starts softening around 80°C continuous; I've seen it warp in enclosed fixtures running 100W COB arrays. Polycarbonate handles 120°C continuous, which gives you headroom for LED drivers that run hot or for fixtures in unconditioned spaces like attics or loading docks. Per UL 746B, the relative thermal index for PC is typically 30–40°C higher than PMMA.

2. Cost Analysis

Upfront, PMMA wins on material cost — roughly $2.80–$3.50 per kg versus $3.50–$4.80 for polycarbonate. For a typical 600x600mm office panel lens weighing about 0.8 kg, that's a savings of roughly $0.80–$1.60 per fixture. On a 500-fixture retrofit, you're looking at $400–$800 in material savings. But don't stop there.

What does this mean in practice? The total cost of ownership flips when you factor in replacement frequency. A PMMA lens in an outdoor wall pack might yellow visibly after 5 years, requiring replacement. That's labor cost — figure $25–$40 per fixture for a service call. Polycarbonate with UV stabilizers (like Bayer's Makrolon or SABIC's Lexan EXL grades) typically lasts 8–12 years before noticeable yellowing. Over a 15-year building lifecycle, you might replace PMMA lenses twice versus once for PC. The math: 2 replacements × $35 labor + $2.80 material = ~$75 per fixture for PMMA, versus 1 replacement × $35 labor + $4.30 material = ~$39 per fixture for PC. Polycarbonate saves you roughly $36 per fixture over 15 years.

3. Application Suitability

PMMA is your go-to for indoor applications where optical performance is king. Think retail display lighting, museum cases, office troffers, and any fixture where CRI and color consistency matter. The low haze (<0.5%) and high transmission mean your LED's spectral output reaches the target surface with minimal distortion. I've specified PMMA for art gallery track heads where the client was measuring color shift in delta E units — PMMA holds that.

Polycarbonate dominates in environments where things break. School gymnasiums, parking garages, industrial high-bays, and outdoor floodlights. The V-0 flammability rating per UL 94 also makes it mandatory for some building codes — particularly in plenum spaces or egress pathways where fire codes require self-extinguishing materials. And if you're dealing with high-heat LED arrays (think 50W+ per module), PC's 120°C continuous rating gives you safety margin that PMMA can't offer.

4. Pros & Cons

PMMA Pros: Highest light transmission (92%), excellent UV stability (yellowness shift ≤2 after 5000 hrs QUV), superior scratch resistance, fully recyclable, lower material cost. Cons: Brittle under impact (16–20 J/m Izod), limited to 80°C continuous, UL 94 HB only (slow burning), warps under high heat in enclosed fixtures.

Polycarbonate Pros: Extreme impact resistance (600–850 J/m), handles 120°C continuous, V-0 flammability rating, longer outdoor lifespan with UV stabilizers. Cons: Lower transmission (88%), higher haze (0.8–1.5%), scratches easily without hard coating, yellows faster without UV additives, higher material cost.

Best Use Cases

Final Recommendation