Durastream CPVC Compound for Profiles

Durastream CPVC for Profiles

High-quality Durastream CPVC is a heat-resistant, flame-retardant compound available in a variety of colors. It’s perfect for building components, such as siding substrates, windows, doors, ceilings and fences.

Parts comprising Durastream compounds maintain shape and color without deformation, even under high temperatures. In fact, you can see the cost efficiency of Durastream products first during manufacturing and later through the longevity of the parts.

Advantages of CPVC Products

What Are the Differences Between CPVC and PVC?

Polyvinyl chloride (PVC) is a trusted thermoplastic that manufacturers often use for piping and fitting in residential and commercial building applications.

Meanwhile, chlorinated polyvinyl chloride (CPVC) is a PVC homopolymer that we produce through a chlorination reaction involving either heat or light. We add chlorine (Cl2) to the PVC and react it through a basic free radical mechanism. See the figure below.

The resulting CPVC resin is more resistant to heat, pressure and fire than the PVC it came from. In fact, the degree of chlorination for CPVC links to this improved performance. For example, if the degree of chlorination increases by 1%, heat deflection temperature (HDT) likely increases by 4% to 5%.

Durastream CPVC for Profiles: Applications

Durastream CPVC is excellent for profiles. Here are just a few examples:

1) Deck or WPC products
2) Window profiles
3) Sidings
4) Fences
5) Industrial or building plates

Burn Resistance

When exposed to fire, Durastream CPVC self-extinguishes under normal atmospheric conditions. 

According to NASA, Earth’s atmosphere comprises 21% oxygen. Meanwhile, Durastream CPVC self-extinguishes under normal atmospheric conditions because CPVC needs approximately 60% oxygen content to continue burning. For the same reason, Durastream CPVC also resists ignition.

Oxygen Index Testing

This test determines the flammability of plastics by comparing the limiting oxygen index (LOI). Note that the flame retardancy improves by increasing the chlorine content. For example, CPVC’s LOI is double that of PVC.

Flammability and Flame Spread

Manufacturers have tested and trusted Durastream CPVC’s flammability for many years. A few applications include fire sprinkler pipes, aircraft sheeting and window profiles.

Durastream CPVC has achieved the highest rating of V-0 under the UL 94 flammability standards. The V-0 rating indicates the specimen does not burn with flaming combustion for more than 10 seconds after application of the test flame.

Plastic JIS Standard UL94
Oxygen Index (%) Combustion Test
CPVC 60 V-0
PVC 28-38 V-0
PE 18-19 HB
PP 18-19 HB
PS 18-19 HB
PMMA 17-18 HB

Fire Performance

Calorific value is a measurement of the total energy released as heat when a substance undergoes complete combustion with oxygen.

CPVC has a lower calorific value than PVC and thus improved flame retardancy, as you can see by comparing the materials’ ignition timing. For instance, PVC starts igniting after 40 seconds, whereas CPVC starts after 335 seconds. Furthermore, Durastream CPVC has lower smoke generation rates.

Weather-Induced Deformation

Building profiles in window frames, sidings, decks and fences suffer the elements every day. As a general rule, temperatures rise during the day and fall at night. Due to this temperature cycle, the mold profile expands and shrinks daily, which gradually damages and degrades profiles.

Drawing on decades of experience and testing, Durastream CPVC products use a unique blending technology that mitigates shrinking and bending. In other words, using Durastream CPVC for profiles is a wise choice.

Results Remark
DURASTREAM CPVC 0.7-0.9% No Curvature
CPVC Other Supplier 1.5-3.0% Curvature
General PVC 2.0-2.5% Curvature

Heat Storage and Exterior Applications

As we previously noted, profiles in window frames, sidings, decks and fences are at risk of deformation due to ongoing heat variances. Thermoplastics that absorb or store this heat undergo greater deformation.

The testing below demonstrates Durastream CPVC’s lower heat absorption rate vs. that of competitors’ CPVC compounds. This feature is one of many competitive benefits of using Durastream CPVC for profiles.


Light Source 3 Infrared Lamp
Temperature Measurement Instrument Non-Contact Thermometer
Distance Between Light – Sample 30 cm

Testing Process

Here’s the general testing process:

1. Irradiate the sample with a light source at a distance of 30 cm from the top.

2. Measure the sample surface temperature every minute.

3. Irradiate for 10 minutes and complete.


UV Exposure

Profiles and sidings on buildings’ exteriors can also become discolored or deteriorated due to heat and UV exposure. Via extensive testing and development, SEKISUI has developed Durastream CPVC to be more color-stable than competitor materials, even in direct sunlight and heat. Durastream CPVC is also compatible with other thermoplastics that are commonly in outdoor applications such as profiles.

Evaluation Condition

Test Equipment UV Long Life Fade Meter
Room Temperature 40 °C (104 °F)
Panel Temperature 63 °C (145 °F)
Evaluation Time 500 Hours (Every 100 Hours, Sampling)

Test Results

Impact Strength Test

Continuous exposure to UV rays can damage the integrity of the thermoplastic in use. Beyond discoloration, the material can become brittle and more prone to failure.

Impact resistance retention rate (IZOD) is a reliable method to measure and compare the deterioration level and structural integrity of any material. This evaluation recreates continuous exposure to sunlight. A higher retention rate implies less deterioration and greater remaining impact strength. 

As you can see, the results clearly show that Durastream CPVC maintains impact strength better than competitor materials in continuous sunlight.

Test Condition

Test Equipment UV Long Life Fade Meter
Room Temperature 40 °C (104 °F)
Panel Temperature 63 °C (145 °F)
Evaluation Time 500 Hours (Every 100 Hours, Sampling)

SEKISUI has been a leading supplier of CPVC for over 40 years. We manufacture high-quality and stable products throughout the production chain.

From PVC polymerization to the manufacturing and sale of finished final products like pipes and fittings, our expertise covers all the products and processes involved. Our Durastream CPVC resin is the result of 40 years of aggregate chlorination experience, sophisticated technologies and quality controls. With our advanced knowledge of CPVC products and processes, we’re ready to help customers in a wide variety of industries bring the benefits of Durastream CPVC resin to their products, including profiles.

Questions? Visit our CPVC FAQ.

Download our Durastream CPVC Compound brochure for more information on standard specifications and comparative test data.