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PVC

Cloruro de Polivinilo (Rígido)

PVC·PVC·Amorphous

PVC (Rigid Polyvinyl Chloride, or uPVC = unplasticized) is the third most-produced plastic on the planet —130 million tons per year— and the material that replaced cast iron in pipes and aluminum in window profiles. With 57% chlorine by weight, it's the only common thermoplastic with halogens in the main chain, giving it unique characteristics: self-extinguishing (LOI 45), excellent chemical resistance, outdoor durability >50 years in profiles, and very low cost.

Dominant applications: cold water and DWV (drain-waste-vent) sanitary piping —#1 worldwide—, uPVC window profiles (Rehau, Veka, Schüco lead), siding (exterior cladding for homes), gutters, electrical conduits, and fittings (elbows, tees, reducers). Global producers include Westlake, Shintech, OxyVinyls, Formosa, INEOS Inovyn, and Solvay.

Processing-wise it's the most difficult thermoplastic in the conventional market: extremely narrow window (170-190°C), decomposition to HCl gas starting at 135°C accelerating above 200°C, requiring mandatory stabilizers (modern Ca-Zn, historically Pb/Sn) and specialized equipment. Most is transformed by extrusion, not injection; injection is reserved for fittings and short technical parts. Are you running PVC? Share your experience with stabilizers and degradation in the comments.

The ranges shown in these data tables were compiled by the MVPS team from various parameter sheets and literature, integrating the lower and upper limits for each material type.

This information must be carefully reviewed when developing injection molding processes. Final ranges and processing tolerances are the responsibility of the engineer in charge.

These ranges are not recommended for developing specific process tolerances. MVPS always recommends requesting and consulting the supplier's data sheet.

General Properties

Chemical StructureAmorphous
Specific Gravity (Density)1.45:1
L/D Ratio19 – 26
Compression Ratio2 – 3
Tonnage Factor3.86 – 5.41kN/cm²
Thermal Diffusivity0.1661mm²/s
Max Shear Rate20,0001/s
Shrinkage0.1 – 0.6%
Regrind⚠ Caution
Heat Deflection (HDT) @ 1.82 MPa80°C
Glass Transition (Tg) @ 10°C/min60°C
Vicat Softening @ 50N77°C

Drying

Drying Temperature71 – 79°C
Drying Time1 – 2h
Recommended Moisture0.2%
Recommended Dryer TypeAir
Dew Point-40°C

Temperatures

Melt185 – 204°C
Nozzle166 – 182°C
Front166 – 177°C
Middle166 – 177°C
Rear160 – 171°C
Demolding38 – 82°C
Mold (Cooling)21 – 71°C
Feed Throat10 – 49°C

Processing

Back Pressure4.1 – 6.9bar
Screw Speed35 – 70RPM
Injection SpeedLow
Barrel Occupancy20 – 80%
Injection Pressure1,500 – 2,500Pbar
Holding Pressure375 – 2,000Pbar
Cushion2.5 – 6.4mm

Mold

Runner Diameter4.06 – 8.13mm
Gate Diameter1.02 – 2.03mm
Gate Area0.81 – 3.24mm²
Wall Thickness1.02 – 5.08mm

Venting

Depth (Vent Depth)0.0203 – 0.0305mm
Land (Vent Land)0.508 – 1.02mm
Width (Vent / Clearance)3.05 – 10.2mm
Relief (Relief Channel)0.2032 – 0.4064mm

Frequently asked questions

PVC is polymerized from **vinyl chloride monomer (VCM, CH₂=CHCl)** —each repeat unit contains a large chlorine atom. Chlorine is **57% of the weight** of the final molecule, which gives PVC its distinctive properties: high density (1.40 g/cm³, higher than most plastics), inherent fire retardancy (doesn't propagate flame, LOI ~45), broad chemical resistance, and rigidity without needing reinforcement.
- **Rigid PVC (uPVC)**: PVC without plasticizer, maximum Shore D, profiles and pipes. - **FPVC (Flexible PVC)**: PVC + 20-50 phr plasticizer (DOTP, DEHP), Shore A 50-95, cables and medical tubing. - **CPVC (Chlorinated PVC)**: PVC post-chlorinated to raise Cl% from 57% to 67%, higher heat resistance (95°C vs 60°C), hot water and sprinklers. All three are made from the **same base PVC**; differences are additives (plasticizer) or post-processing (chlorination).
Melt: **170-190°C** (some grades tolerate up to 200°C at the front). Mold: **30-45°C**. Very narrow window: at 160°C it doesn't flow well, at 200°C+ it starts decomposing to HCl. **Moderate injection speed** —high speeds generate excessive shear that also degrades. **Maximum residence 5 minutes**; ideally less. If you stop production, purge immediately with HDPE or PP.
**Yes, lightly**: 1.5-2.5 hours at **75-90°C** in a desiccant dryer or hot air. PVC absorbs very little moisture (~0.1%) but the presence of chlorine ions means surface water causes silver streaks and small bubbles. In tropical climates or batches open for days, **drying is mandatory**.
**Stabilizers** are additives that prevent PVC thermal decomposition during processing. They capture nascent HCl and avoid chain reactions that would generate more HCl. **Families**: - **Pb (lead)**: classic, efficient, **banned in EU since 2015** for toxicity. Still used in some regions. - **Sn (organotin)**: USA standard in potable water pipe, very efficient. - **Ca-Zn (calcium-zinc)**: modern, non-toxic, dominant in Europe, food contact, and medical. - **Mixed metal (Ba-Zn)**: intermediate alternative. **2026 trend**: Ca-Zn captures ~70% of global market and growing.
Shrinkage **0.2-0.6%**, very low and predictable —ideal for fittings with strict tolerances (pipe unions that must seal under pressure). PVC is **amorphous** (no crystalline directionality) and shrinkage depends more on packing density than cooling. For extruded profiles, near-exact dimensions with vacuum calibration.
**uPVC wins on**: (1) **thermal insulation** (conductivity 0.17 W/m·K vs 200 for aluminum — uPVC windows eliminate thermal bridges), (2) **cost** (30-50% cheaper installed), (3) **no corrosion** (coastal areas, acid rain), (4) **zero maintenance** (no need to paint like wood), (5) **40-50 year service life with stable color**. **Aluminum wins on**: rigidity for large spans (>1.5 m), contemporary architectural aesthetic, real recyclability. **2026 trend**: uPVC dominates residential in Europe (>50% market), aluminum in commercial high-performance.
**Yes technically, but complicated in practice**. Recycling code **#3 (PVC)**, accepted in very few municipalities. Problems: (1) **contaminates other streams** —even traces of PVC in PET or HDPE ruin the batch through HCl decomposition in the recycling extruder, (2) **additives vary widely** between grades (stabilizers, pigments, plasticizers), making recompounding difficult, (3) **dioxins if incinerated improperly**. **Recovinyl** (EU industry) mechanically recycles ~800k tons/year of post-consumer profiles and pipes. In USA and Latam, most goes to landfill.
**Yes**: **NSF/ANSI 61 certified** for potable water contact when using non-toxic stabilizers (Sn, Ca-Zn). Residual VCM monomer is controlled to **<1 ppm** by global standard (was >100 ppm in the 60s before carcinogenicity findings). Modern PVC pipes have **service life >50 years** with no significant leaching. The controversy centers on **PVC with lead stabilizers** (legacy in pre-2000 pipes) or **phthalate plasticizers** (FPVC issue, doesn't apply to rigid).
**Thermal degradation with HCl release**, same as CPVC and FPVC. Symptoms: part with brown/black burns, pungent HCl smell, viscosity dropping inexplicably, visible corrosion on screw and barrel within months. **Causes**: exceeded temperature (>200°C sustained), residence time >5 min, dead zones in screw, **insufficient or expired stabilizer**. **Cure**: respect temperature, **purge with HDPE/PP** when stopping production, use high-quality chromed screws (Inconel not necessarily needed, rigid PVC is less aggressive than CPVC), validate received pellets by thermal analysis (TGA).

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