Durastream CPVC Compound 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 made of Durastream compounds maintain shape and color without deformation, even under elevated temperatures. The cost efficiency of Durastream products can be seen initially during manufacturing, and long-term through the longevity of their components.

Advantages of CPVC Products

What Is the Difference Between CPVC and PVC?

PVC (polyvinyl chloride) is a trusted thermoplastic often used for piping and fitting in residential and commercial building applications.

CPVC (chlorinated polyvinyl chloride) is a PVC homopolymer that is produced through a chlorination reaction involving either heat or light. Chlorine (Cl2) is added to the PVC and reacted 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. The degree of chlorination for CPVC is linked to this improved performance. For example, if the degree of chlorination is increased by 1%, HDT (heat deflection temperature) would likely increase by 4% to 5%.

What are the profile applications?

1) Deck or WPC products
2) Window profile
3) Siding
4) Fence
5) Industrial or Building plates

Burn Resistance

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

According to NASA, Earth’s atmosphere is composed of 21% oxygen. Durastream CPVC will self-extinguish under normal atmospheric conditions because CPVC needs approximately 60% oxygen content to continue burning. Durastream CPVC also resists ignition for these same reasons.

Oxygen Index Testing

This test is used to determine the flammability of plastics by comparing the limiting oxygen index (LOI). Note that the flame retardancy improves by increasing chlorine contents. The LOI of CPVC is double that of PVC.

Flammability and Flame Spread

The flammability of Durastream CPVC has been tested and trusted for many years in fire sprinkler pipes, aircrafts 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 that the specimen did not burn with flaming combustion for more than 10 seconds after either 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 therefore improved flame retardancy, as can be seen by comparing both materials’ ignition timing. PVC starts igniting after 40 seconds, whereas CPVC starts after 335 seconds. Durastream CPVC also has lower smoke generation rates.

Weather-Induced Deformation

Building profiles used in window frames, siding, decks, and fences are exposed to the elements. Temperatures rise during the day and fall at night. Due to this temperature cycle, the mold profile expands and shrinks daily, causing damage and degradation of the profile over time.

Drawing on decades of experience and testing, Durastream CPVC products utilize a unique blending technology that mitigates shrinking and bending.

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 mentioned previously, profiles used in window frames, siding, decks, and fences are at risk of deformation due to daily and yearly heat variances. Thermoplastics that absorb or store this heat will undergo greater deformation.

The testing below demonstrates Durastream CPVC’s lower heat absorption rate when compared to competitor CPVC compounds. This feature is one of many competitive benefits of Durastream CPVC compounds.


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

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 siding used on building exteriors can also become discolored or deteriorated due to heat and UV exposure. Through 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 commonly used for outdoor applications.

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

Test of Impact Strength

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

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

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 Chemical Company has been a leading supplier of CPVC for over 40 years, manufacturing high quality and stable products throughout the production chain. From PVC polymerization to the manufacturing and selling of finished final products like pipes and fittings, Sekisui Chemical Group’s 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, Sekisui is ready to help customers in a wide variety of industries bring the benefits of Durastream CPVC resin to their products.

Questions? Visit our CPVC FAQ

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