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Delrin® Technical Guide
The effect of common sterilization techniques
on the mechanical properties of Delrin® Special
Control (SC) and Premium Control (PC) grades
Delrin® | Technical Guide
Delrin® is a leading engineering polymer, behaving more like metal than other unreinforced plastics due to
its very high crystallinity. It’s often the first choice for designers seeking an optimum balance of strength,
stiffness and toughness with excellent molding characteristics. These unique properties of Delrin enables
components to be designed for maximum reliability, safety and manufacturability.
For these reasons, Delrin is often selected for key functional parts in medical device applications. Many of
these products are sterilized to minimize the risk of microbial contamination. This includes both single-use
devices that undergo one sterilization process and multiple-use products that must be sterilized several times.
With sterilization, it is vital the process does not affect the material properties but is successful in destroying
microbes. There are several processes capable of sterilizing polymer components. Table 1 outlines a subset
of typical sterilization methods and their respective process parameters.
Table 1. Process parameters for common sterilization methodsa
Radiation
Ethylene
Vaporized
Chlorine
Nitrogen
(gamma, X-ray
oxide
hydrogen
dioxide
dioxide
Steam
Property/Sterilization method
peroxide
e-beam)
-
25 – 50 kGy
200 – 800 mg/L
0.3 – 26 mg/L
1 – 30 mg/L
3 – 20 mg/L
Temperature
105 – 138°C
30 – 60°C
37 – 63°C
28 – 60°C
10 – 30°C
15 – 30°C
Relative humidity
≥ 40% RH
Dry
≥ 40% RH
≥ 50% RH
≥ 40% RH
≥ 40% RH
End-to-end process length
1 – 300 min
hours to days
hours to days
2 – 10 h
3–8h
6–8h
Sterilant concentration/dose
Various experts in the field and O’Dell, G.; Hodge, S. AAMI News. Alternative Sterilization Modalities to EtO:
Let’s Compare & Contrast. July 2024.
a
The information below is intended to provide designers with data to better understand the mechanical
property retention behavior of Delrin Special Control (SC) and Premium Control (PC) grades following
sterilization by methods that are often used in the healthcare industry. To do this, a selection of tensile bars
with thicknesses ranging from 2 mm to 4 mm were molded in Delrin SC and PC grades and sterilized under
various conditions at external partners. We report the mechanical property retention measured by uniaxial
tensile testing.
Steam sterilization
Exposure conditions: 1 cycle = 1 wash in ultrasonic bath at 87°C + 3 min. at 134°C
Steam sterilization 25 cycles at 134°C
Property Retention (%)
120%
100%
80%
60%
40%
20%
0%
Delrin® SC631
Tensile E-modulus
Delrin® SC655
Tensile strength
Delrin® PC652
Delrin® SC/PC690
Charpy notched impact
Strain at break
Delrin® | Technical Guide
Gamma sterilization
Exposure conditions: 40 kGy radiation
Gamma irradiation 40 kGy
Property Retention (%)
120%
100%
80%
60%
40%
20%
0%
Delrin® SC631
Delrin® SC655
Tensile E-modulus
Delrin® PC652
Stress at break
Delrin® SC/PC690
Strain at break
Electron beam (E-beam) sterilization
Exposure Conditions: 50 kGy radiation
E-beam irradiation 50 kGy
Property Retention (%)
120%
100%
80%
60%
40%
20%
0%
Delrin® SC631
Delrin® SC655
Tensile E-modulus
Delrin® PC652
Stress at break
Delrin® SC/PC690
Strain at break
Ethylene oxide (EtO) sterilization
Exposure conditions: 2 hours at 50°C with shallow vacuum
EtO sterilization 2h at 50°C
Property Retention (%)
140%
120%
100%
80%
60%
40%
20%
0%
Delrin® SC631
Delrin® SC655
Tensile E-modulus
Delrin® PC652
Stress at break
Delrin® SC/PC690
Strain at break
Delrin® | Technical Guide
Chlorine dioxide sterilization
Exposure conditions: chlorine dioxide dosage of 7,500 ppm-h at a chlorine dioxide concentration of 3 mg/L
deemed to be typical conditions for most medical devices.
Property Retention (%)
140%
Chlorine dioxide sterilization
Dosage: 7,500 ppm-h, ClO2 concentration: 3 mg/L
120%
100%
80%
60%
40%
20%
0%
Delrin® SC631
Tensile E-modulus
Delrin® SC655
Tensile strength
Delrin® PC652
Strain at break
Delrin® SC698
Charpy notched impact
Conclusions
The following conclusions can be drawn from this study:
• Delrin® POM is not recommended for components that are Gamma or E-beam radiated as the polyacetal
molecules are damaged by both processes, resulting in embrittlement.
• Delrin POM shows good compatibility with steam sterilization up to 25 cycles.
• Delrin POM shows good compatibility with ethylene oxide sterilization.
• Delrin POM shows good compatibility with chlorine dioxide under typical sterilization conditions.
• The results presented in this report are representative for other Delrin POM grades.
To learn more, contact your Delrin representative or visit Delrin.com.
The information and recommendations contained herein are offered as a service to our customers but are not intended to relieve the user from its responsibility to investigate and
understand other pertinent sources of information and to comply with all laws and procedures applicable to the safe handling and use of these materials. The information and
recommendations provided herein were believed by Delrin to be accurate at the time of preparation or obtained from sources believed to be generally reliable. However, Delrin
makes no warranty concerning their accuracy and Delrin will not be liable for claims resulting from any party’s use of or reliance on information or recommendations contained
herein regardless of whether it is claimed that the information or recommendations are inaccurate, incomplete or otherwise misleading. Caution: For medical applications, discuss
with a Delrin customer representative and consult the Delrin Medical Caution Statement.
Delrin is an industry-leading premium industrial polymer business. Grounded in strong innovation, Delrin is a category creator with a longstanding reputation for quality,
reliability, supply and product performance. The iconic Delrin brand, coupled with proprietary technology and deep application expertise make us a leader in the high-end
engineering polymer market. Delrin has exciting growth prospects from exposure to automation, actuation, healthcare, mobility and consumer applications.
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