Polycarbonate vs PVC: How to Choose Between the Two Plastics
Both are everywhere in machined and fabricated plastic parts — but polycarbonate vs PVC is not a close fight on any single axis. One is a clear, impact-resistant engineering plastic; the other is a cheap, chemically tough commodity. Here is how to pick.
IsoCNC Engineering Team
CNC Machining & DFM Engineers · Updated · 15 min read
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Quick Answer
Polycarbonate vs PVC comes down to four differences. Polycarbonate (PC) is two to four times more impact-resistant (notched Izod 640–850 J/m vs 105–360 J/m), glass-clear at 86–90% light transmission where standard rigid PVC is opaque, and heat-resistant to roughly 115–120 °C continuous versus about 60 °C for PVC. Rigid PVC (PVC-U) strikes back with a UL 94 V-0 self-extinguishing flame rating, excellent resistance to acids and alkalis, easy solvent welding, and a commodity price roughly one-half to one-third of PC sheet. Specify polycarbonate for transparent, impact-loaded, or hot parts — machine guards, safety glazing, clear manifolds. Specify PVC for pipes, tanks, ductwork, and chemical-handling parts where budget and corrosion resistance matter more than strength.
Polycarbonate vs PVC: Two Very Different Plastics
Polycarbonate is an engineering thermoplastic — an amorphous polymer specified when a part has to survive abuse: impact, heat, and optical duty. It sells in clear and tinted sheet and rod under names like Lexan and Makrolon, and it machines into guards, lenses, and structural transparent parts. Rigid PVC (unplasticized PVC, PVC-U or uPVC) is a commodity thermoplastic built on a chlorine-rich polymer chain. It is stiff, hard, and chemically inert, and its natural habitat is construction and fluid handling: schedule 40 and 80 pipe, fittings, duct, tank linings, and electrical conduit. When engineers debate polycarbonate vs PVC, they are really debating performance versus economics.
The confusion between them usually starts at the datasheet level: both are amorphous, both machine easily, both come in sheet and rod, and their tensile strengths are in the same neighborhood. But tensile strength is nearly the only property where they overlap. Once you look at impact, optics, temperature, flame behavior, and chemical exposure, the two materials separate fast. For a wider view of where both sit in the machining world, see our overview of CNC machining materials and the machinable plastics we stock.
| Property | Polycarbonate (PC) | Rigid PVC (PVC-U) |
|---|---|---|
| Tensile strength (ASTM D638) | 62–70 MPa (9,000–10,200 psi) | 50–58 MPa (7,300–8,400 psi) |
| Notched Izod impact (ASTM D256) | 640–850 J/m (12–16 ft·lb/in) | 105–360 J/m (2–7 ft·lb/in) |
| Heat deflection temp @ 1.82 MPa | 132–140 °C (270–284 °F) | 65–70 °C (149–158 °F) |
| Continuous service temperature | Up to ~115–120 °C | Up to ~60 °C |
| Density | 1.20 g/cm³ | 1.38–1.45 g/cm³ |
| Light transmission | 86–90% in clear grades | Opaque in standard grades |
| Flammability (UL 94) | V-2 standard; V-0 in FR grades | V-0 — inherently self-extinguishing |
| Chemical resistance | Weak to bases, ammonia, ketones, some solvents | Excellent to acids and alkalis; weak to ketones and aromatics |
| Fabrication | Machines well; needs stress control and sharp tools | Machines, saws, and solvent-welds easily |
| Relative material cost | Higher — roughly 2–3× PVC sheet | Low — commodity-priced |
Read the table this way: polycarbonate wins the left side of the mechanical and optical story; PVC wins flame, chemistry, and cost. Nothing in engineering plastics is free — PVC’s low price and chemical inertness are paid for with brittleness and a low temperature ceiling, while PC’s toughness and clarity cost you in chemical resistance and flame rating unless you buy specialty grades.
Impact Strength and Transparency: Polycarbonate’s Home Ground
Impact is where the gap between these materials is largest. Polycarbonate’s notched Izod impact of roughly 640–850 J/m (12–16 ft·lb/in) puts it among the toughest transparent plastics in production — the same chemistry used in bulletproof glazing laminates and riot shields. Rigid PVC, at roughly 105–360 J/m (2–7 ft·lb/in), is respectable for a commodity plastic but genuinely brittle compared to PC: a sharp corner, a drilled hole, or a machined notch becomes a crack starter, and cold temperatures make it worse. If the part is a guard, shield, cover, or housing that can get hit, PVC is off the list before the conversation starts.
Transparency runs the same direction. Polycarbonate transmits 86–90% of visible light — essentially glass-clear — and holds that clarity in thick machined sections, which is why clear manifolds, sight glasses, and inspection windows are PC parts. Standard rigid PVC is opaque white, gray, or colored; clear PVC exists but is a specialty product with smaller size ranges and lower toughness. For a direct look at PC against the other clear plastic, our acrylic vs polycarbonate comparison covers the trade-off between PC’s toughness and acrylic’s clarity and scratch resistance.
Heat, Flame, and Chemical Resistance: PVC’s Home Ground
Temperature splits the pair cleanly. Polycarbonate’s heat deflection temperature of 132–140 °C at 1.82 MPa means a machined PC part keeps its shape and strength near boiling water and in autoclave-adjacent duty; continuous service to about 115–120 °C is standard practice. Rigid PVC deflects at 65–70 °C and is normally limited to about 60 °C in service — fine for cold-water plumbing, not fine next to a motor or under a hot lamp. Above 60 °C, polycarbonate is the only one of the two still working.
Flame behavior reverses the verdict. Rigid PVC is inherently self-extinguishing — UL 94 V-0 without any flame-retardant additives — because its chlorine content snuffs combustion once the ignition source is removed. Standard PC burns on after ignition at a UL 94 V-2 rating, and only the flame-retardant grades (V-0 and 5VA) close that gap, at extra cost. One caveat on PVC: in a real fire it releases corrosive hydrogen chloride gas, which is why some electronics and transit specs restrict it despite the good UL rating.
Chemical resistance is PVC’s signature strength. It shrugs off most acids, alkalis, salts, and water treatment chemistry — the reason it lines plating tanks and carries corrosive fluids in pipe and duct. Its enemies are ketones, aromatics, and some chlorinated solvents. Polycarbonate is the opposite: it handles many dilute acids and oils but is attacked by bases, ammonia, acetone, and a long list of common solvents, and it stress-crazes when chemical exposure meets mechanical stress. If the part lives in chemical splash or fumes, PVC usually outlives PC at a third of the price.
Machining and Fabricating PC vs PVC
Both materials are friendly to CNC milling and turning, which is why both show up constantly in machined plastic work. Rigid PVC is the easiest of the two at the spindle: it cuts cleanly with standard sharp tooling, produces manageable chips, needs no coolant, and holds thin walls and fine detail without drama. Its one enemy in machining is its own low softening point — aggressive feeds and dull tools generate heat that smears rather than cuts, so sharp tools and honest chip loads matter.
Polycarbonate machines well but punishes sloppy practice. It is notch-sensitive, so internal corners need generous radii, clamping pressure should stay low, and sharp polished tools keep surface stress down. Heavy machining locks in residual stress that later shows up as crazing or cracks — annealing after roughing is cheap insurance on critical parts. Some water-based coolants chemically attack PC, so air blast or PC-safe coolants are the safe route. Where PVC also wins is assembly: it solvent-welds into strong, leak-tight joints, which is why tanks, manifolds, and duct assemblies are PVC fabrications. PC bonds too, but with more process sensitivity — and if you are planning a bonded transparent assembly, talk to us through an RFQ so we can flag the risks before you cut material.
Cost and Where Each Material Actually Gets Used
Rigid PVC is one of the cheapest rigid plastics you can buy — a true commodity — while polycarbonate sheet and stock shapes typically run two to three times the price. That gap shapes everything: PVC gets specified by default unless a performance requirement forces PC. A chemical tank, a run of duct, or a corrosion-proof valve body in PC would be money spent on impact strength and clarity the application never uses. A machine guard in PVC would be money saved on a part that cracks the first time a workpiece hits it.
| Application Area | Polycarbonate | Rigid PVC |
|---|---|---|
| Machine guards and safety glazing | Standard choice — impact and clarity | Not used; too brittle |
| Pipes, fittings, and ductwork | Rare — too costly | Dominant — schedule 40/80 pipe |
| Chemical tanks and fume handling | Poor chemical resistance rules it out | Standard for acids and plating lines |
| Electrical enclosures and conduit | FR grades where impact matters | Very common — UL 94 V-0, low cost |
| Windows, skylights, signage | Vandal-resistant glazing, bulletproof laminates | Only in special clear formulations |
| Valve bodies and manifolds | Clear manifolds needing strength | Chemical-duty valves and manifolds |
| Prototypes and fixtures | Clear, strong prototypes and check fixtures | Low-cost fixtures and templates |
The pattern is consistent across industries. PVC dominates fluid handling, chemical processing, water treatment, and electrical work — anywhere corrosion and cost rule the spec. Polycarbonate dominates guarding, glazing, optics-adjacent parts, and tough transparent structures — anywhere people or processes need protection plus visibility. Both are staples in our plastics machining work, and the choice between them is usually obvious once the duty conditions are on paper.
A Practical Decision Guide: PC or PVC on Your Next Drawing
Specify polycarbonate when any of these is true: the part must be transparent; it takes impact or abuse in service; it runs continuously above 60 °C; or it is a safety-related guard or shield. Expect to pay more for material, plan for radiused internal corners, note annealing on heavily machined parts, and call out a flame-retardant grade if the enclosure spec demands UL 94 V-0. Specify rigid PVC when the part handles acids or alkalis, lives outdoors or in wet service, needs solvent-welded assembly, must self-extinguish, or simply needs to be cheap and stiff — and keep it away from sharp impacts, notches, and heat.
On the drawing, the details that help a shop most are the same for both: an explicit material callout with grade (for PC, whether an FR or FDA grade is required; for PVC, whether it must be NSF-rated or Type I), honest tolerances rather than blanket precision, and a note on the service environment — chemicals, temperature, UV exposure, and impact. When neither material fits — say, clarity plus chemical resistance, or PVC’s price with PC’s toughness — that is exactly the conversation to have before ordering stock. Send the drawing and duty conditions through our instant quote and an engineer will flag the right material, whether that is PC, PVC, or something from the broader list of machinable materials.
FAQ: Polycarbonate vs PVC
Is polycarbonate stronger than PVC?
Yes, in almost every measure that matters for a part. Polycarbonate’s tensile strength runs 62–70 MPa against 50–58 MPa for rigid PVC, but the real gap is toughness: notched Izod impact for PC is roughly 640–850 J/m versus 105–360 J/m for PVC-U — two to four times the impact resistance, which is why PC is the default for machine guards, safety shields, and security glazing. PVC-U is a stiff, hard, dimensionally stable material, but it is comparatively notch-sensitive and brittle under sharp impact. If the part takes hits, polycarbonate wins; if it just holds shape against chemicals, PVC is fine.
Can you see through PVC like you can with polycarbonate?
Generally no. Standard rigid PVC sheet, pipe, and stock shapes are opaque — the base polymer can be made transparent, but commercial clear PVC is a specialty formulation with limited sizes and noticeably lower impact strength than polycarbonate. Polycarbonate is naturally glass-clear at 86–90% light transmission, comparable to acrylic, and stays clear in thick sections. So for windows, sight glasses, transparent guards, and any part where the operator needs to see the process, PC (or acrylic) is the realistic choice. If you are comparing clear plastics specifically, our acrylic vs polycarbonate guide covers that matchup in detail.
Which handles heat better, polycarbonate or PVC?
Polycarbonate, decisively. PC’s heat deflection temperature is 132–140 °C at 1.82 MPa, and it runs continuously to about 115–120 °C. Rigid PVC deflects at 65–70 °C and its practical continuous service limit is around 60 °C — above that it softens, creeps, and loses strength quickly. This is why PVC pipe is a cold-water and drainage material, and why CPVC exists for hot water. Any part near a heat source, motor, lamp, or sterilization cycle belongs in PC. The trade-off is flammability: hot-running PVC self-extinguishes when the flame is removed, while standard PC keeps burning.
Is PVC really self-extinguishing?
Yes. Rigid PVC carries a UL 94 V-0 rating, the highest standard flammability class: burning stops within about ten seconds after the flame source is removed, with no flaming drips. The chlorine content in the polymer gives PVC its inherent flame resistance without additives — a big reason it dominates electrical conduit, enclosures, and building products. Standard polycarbonate rates only UL 94 V-2 and continues to burn after ignition, though flame-retardant PC grades reach V-0 and even 5VA for demanding enclosures. One caution: burning PVC releases corrosive hydrogen chloride gas, which matters in fire-safety and electronics-corrosion assessments.
Which is easier to machine, polycarbonate or PVC?
Both machine cleanly on CNC equipment, and PVC is arguably the more forgiving of the two. Rigid PVC cuts like a hard wax — sharp standard tools, easy chips, no coolant needed, and thin walls hold up well. Polycarbonate machines well too, but it is notch-sensitive and prone to stress crazing: sharp tools, generous radii, low clamping pressure, and annealing after heavy machining keep it crack-free, and certain coolants can chemically attack it. PVC’s caution is heat — its low softening point means aggressive feeds will gum or smear the cut. For tight-tolerance transparent parts, PC is the only real option anyway.
Which should I choose: polycarbonate or PVC?
Choose polycarbonate when the part must be transparent, take impact, or survive heat above 60 °C — machine guards, safety shields, clear manifolds, structural glazing, and strong prototypes. Choose rigid PVC when the part handles chemicals, sits in a wet or corrosive environment, needs a UL 94 V-0 flame rating, or is cost-sensitive — pipes, tanks, ductwork, valve bodies, and electrical enclosures. PVC also wins when parts must be solvent-welded or bonded into assemblies. If you need clarity plus chemical resistance, neither is ideal — that is a conversation about acrylic or other plastics, and our engineering team can help you pick from the full material list.
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Polycarbonate, PVC, or Something Else? Send the Drawing.
IsoCNC machines both polycarbonate and rigid PVC daily — guards, manifolds, tanks, valve bodies, and fixtures — with material certs and inspection reports on every lot. Not sure which plastic your part needs? An engineer reviews every RFQ, typically within 1–2 business days.