the effect of common sterilization techniques

Du Pont de Nemours Intl. SA, PO Box 50, CH-1218 Grand Saconnex 1

Authors: Teresa Rodon, DuPont UK

Ernst Poppe, DuPont INTL SA Alexandra Fabbro, DuPont INTL SA Tom Baltus, E.I. DuPont Canada Co.

July, 2010

The effect of common sterilization techniques on th e

mechanical properties of

DuPont Performance Polymers

Special Control (SC) and Premium Control (PC) grades

Index

0. - Summary

1. - Introduction of Sterilization

2. - Sterilization Methods

2.1. - Steam

2.2. - Ethylene Oxide

2.3. - Radiation

2.4. - Dry Heat

2.5. - Plasma

3. - General Considerations of Polymers for Sterilization

4. - Results of Sterilization on DuPont Engineering Polymers

- Sterilization effects on Physical Property Retention

4.1. - Steam Sterilization

4.2. - Gamma

4.3. - E-beam

4.4. - EtO

5. - Conclusions

6. – Disclaimer


0. - Summary DuPont Performance Polymers offer resins for components in medical devices. Certain single-use devices undergo one sterilisation process whilst others designed for multiple-use, must be sterilized several times. It is vital to ensure that the sterilisation process does not affect the material properties but is successful in destroying microbes. This study was devised in order to predict the behaviour of DuPont Special Control and Premium Control grades following sterilization by methods that are often used in the healthcare industry. Due to their good thermal stability and excellent chemical resistance, engineering polymers can withstand most sterilization processes. An overview is given in the table below:

1. – Introduction

Medical devices may be classified into 3 categories as follows:

• A non-critical device where the device has a limited surface contact with non damaged skin, • A semi-critical device where the device has direct contact with tissues or damaged skin, • A critical device which penetrates the skin, or the mucosa during use and which gets in direct

contact with blood, tissues, organs and trauma Depending on the above described category, appropriate sterilization of these medical devices will be an essential step in the manufacture of healthcare products to ensure both their shelf-life and reliability when in use. “It is a challenged process of the highest order used to render a product free of all forms of viable micro-organisms.” 1 1 Wayne Rogers, “Sterilization of Polymer Healthcare Products”, Rapra Technology Ltd.


Sterilization may be defined as the inactivation or destruction of viable micro-organisms. ISO 11135:1994 defines sterility as “State of being free from viable micro-organisms”.

2. - Sterilization Methods There are few agents capable of sterilizing polymer components. Typical methods are:

• Steam • Ethylene oxide (EtO) • Radiation (Gamma, Ebeam) • Dry Heat • Plasma

2.1. - Steam Sterilization Steam sterilization, or autoclaving, is a widely used method. It can be performed with relatively low-cost equipment using saturated steam. The process is robust, easy to control, safe and environmentally friendly. Typical process conditions are 20 min at 121 ºC or 5 min at 134 ºC. The limiting factor for many standard polymers is their heat resistance (Tg, dimensional stability), particularly for single-use devices, and their hydrolytic resistance in the case of multiple sterilisation cycles. 2.2. - Ethylene Oxide Sterilization (EtO) EtO sterilization is a gaseous method involving the highly diffusive, permeable and toxic EtO gas. This destroys bacteria and other micro-organisms. Due to the nature of the process it is particularly suitable for medical devices containing electronic components. This technique requires thorough process control to eliminate any residuals on the sterilized components. Well trained personnel and safe practices during operation are required to avoid any leakage of this flammable, explosive, carcinogenic gas. Typical EtO sterilization processes involve several stages of gas removal; humidification, EtO exposure and air washes. Process pressures are close to vacuum and temperatures used are around 50 ºC. Most plastic materials are compatible with EtO sterilization. 2.3. - Radiation Radiation is a type of “cold” sterilization. Gamma Sterilization Sterilization by gamma radiation uses the radioisotope Cobalt 60 as its energy source. Once formed, Cobalt 60 instantly begins to decay, releasing energy in the form of gamma rays. The artificially activated Cobalt 60 pellets are encapsulated in stainless steel “pencils” held in a source rack. To deliver the sterilization dose the source rack is raised from a deep pool of water and the product is passed around this radiation source on a conveyor system. The energy emitted is insufficient to induce radioactivity in any material, irrespective of the length of exposure to the source. Sterilising products by gamma radiation is a sophisticated process requiring extensive knowledge of the kinetics of microbial inactivation, polymer selection and process controls. Gamma Irradiation possesses excellent penetrative capability. The unit of absorption is the Gray, expressed in kGy. This absorbed dose is impacted by product density, pack size, dose rate, exposure time and to some degree by part design. The main disadvantage associated with gamma irradiation concerns the potentially damaging effects of gamma rays on the product, particularly those products that contain polymeric components. Another drawback with this technique is the bulky shielding required to store the radioisotope.


Electron Beam Sterilization using an Electron Beam involves emitting electrons from a heated tungsten filament gun and accelerating them down an evacuated tube. This beam then passes through an oscillating magnetic field which “scans” it back and forth across the sample ensuring a uniform dose of radiation. The e-beam process achieves lethality using ionising radiation which acts on cellular constituents in a similar manner to Gamma radiation. E-beam sterilization has a number of advantages over gamma irradiation including its ability to be switched on and off at will, greater product compatibility and potentially very high throughput. Disadvantages include higher machine complexity and poor material penetration. In addition, validation and control of this technology is more demanding. 2.4. - Dry Heat Dry Heat Sterilization is generally conducted at 160°C-170°C for a minimum of two hours. Specific exposures are dictated by bioburden concentrations and temperature tolerances of the products. Appropriate conditions will enable complete sterilization of the material. The equipment required is forced-air type ovens with temperature monitoring capabilities. This type of sterilization is highly dependent on the temperature resistance of the polymer. 2.5. - Plasma Plasma is a gas in which a certain portion of the molecules are ionized. Different gases can be used, but Hydrogen Peroxide is most commonly used in this methodology. The process is easy to use, is safe, and can be considered as an alternative to the EtO method but it is more expensive. It is typically used where devices cannot handle high sterilization temperatures.

3. - General Considerations of Polymers for Sterili zation

Designers of medical devices require multiple skills to ensure safe and reliable components for healthcare applications. In addition to their medical engineering capabilities they need to be experts in function integration to enable component cost to be minimized and they also require advanced material knowledge for the appropriate polymer selection. In most projects the sterilization method is already known at an early stage. Therefore, it is necessary to check the polymer material candidates’ resistance to the selected sterilisation method upfront, which will help avoid any surprises during the later stages of device development.


4. - Results of Sterilization on DuPont Engineering Polymers

For the purpose of the study, ISO 2BA tensile bars (thickness = 2mm) were moulded and submitted to sterilization. All recordings were made through tensile testing. 4.1. - Steam Sterilization Conditions: 1 cycle = 1 wash in ultrasonic bath at 87°C + 3 min. at 134°C Hytrel® SC/PC Grades Hytrel PC945 (TPC-ET)

Autoclave Sterilization vs. Tensile Modulus - Hytrel PC945

0

10

20

30

40

50

60

1 25 100

Cycles

Mod

ulus

(M

Pa)

Reference Sample Sterilized

Autoclave Sterilization vs. Stress at 10% - Hytrel PC945

0

1

2

3

4

5

1 25 100

Cycles

Stre

ss a

t 10%

(MP

a)

Reference Sample Sterilized Autoclave Sterilization vs. Stress at break

- Hytrel PC945

0

5

10

15

20

25

1 25 100

Cycles

Stre

ss a

t bre

ak (M

Pa)


Autoclave Sterilization vs. Elongation at break - Hytrel PC945

0100200300400500600700

1 25 100

Cycles

Elo

ngat

ion

at b

reak

(MP

a)



Hytrel SC/PC948 (TPC-ET)

Autoclave Sterilization vs. Tensile Modulus - Hytrel SC/PC948

0

10

20

30

40

50

1 25 100

Cycles

Ten

sile

Mod

ulus

(Mpa

)


Autoclave Sterilization vs. Stress at 10% - Hytrel SC/PC948

0

1

2

3

4

5

1 25 100

Cycles

Stre

ss a

t 10%

(MP

a)


Autoclave Sterilization vs. Stress at Break - Hytrel SC/PC948

0

5

10

15

20

25

1 25 100

Cycles

Stre

ss a

t bre

ak (M

pa)


Autoclave Sterilization vs. Elongation at break

- Hytrel SC/PC948

0

100

200

300

400

500

1 25 100

Cycles

Elo

ngat

ion

at b

reak

(%)

Reference Sample Sterilized Hytrel PC946 (TPC-ET)

Autoclave Sterilization vs. Tensile Modulus - Hytrel PC946

0

20

40

60

80

100

1 25 100

Cycles

Ten

sile

Mod

ulus

(MP

a)


Autoclave Sterilization vs. Stress at 10% - Hytrel PC946

0123456789

10

1 25 100

Cycles

Stre

ss a

t 10%

(MP

a)



Autoclave Sterilization vs. Stress at Break - Hytrel PC946

0

5

10

15

20

25

1 25 100Cycles

Str

ess

at B

reak

(MP

a)


Autoclave Sterilization vs. Elongation at Break - Hytrel PC946

0

100

200

300

400

500

1 25 100Cycles

Elo

ngat

ion

at B

reak

(%)

Reference Sample Sterilized Hytrel SC/PC952 (TPC-ET)

Autoclave Sterilization vs. Tensile Modulus- Hytrel SC/PC952

0

40

80

120

160

200

1 25 100

Cycles

Ten

sile

Mod

ulus

(MP

a)


Autoclave Sterilization vs. Stress at 10%- Hytrel SC/PC952

0

5

10

15

20

1 25 100

Cycles

Stre

ss a

t 10%

(MP

a)


Autoclave Sterilization vs. Stress at break- Hytrel SC/PC952

05

10152025303540

1 25 100

Cycles

Stre

ss a

t bre

ak (M

Pa)


Autoclave Sterilization vs. Elongation at break - Hytrel SC/PC952

0

100

200

300

400

500

1 25 100

Cycles

Elo

ngat

ion

at b

reak

(%)



Hytrel SC/PC956 (TPC-ET)


0

50

100

150

200

1 25 100

Cycles

Ten

sile

Mod

ulus

(Mpa

)



0

5

10

15

20

1 25 100

Cycles

Stre

ss a

t 10%

(MP

a)

Reference Sample Sterilized Autoclave Sterilization vs. Stress at Break

- Hytrel SC/PC956

0

10

20

30

40

1 25 100

Cycles

Stre

ss a

t bre

ak (M

pa)



0

100

200

300

400

500

1 25 100

Cycles

Elo

ngat

ion

at b

reak

(%)



0

50

100

150

200

250

300

1 25 100

Cycles

Ten

sile

Mod

ulus

(Mpa

)



0

5

10

15

20

1 25 100

Cycles

Stre

ss a

t 10%

(Mpa

)




0

10

20

30

40

1 25 100

Cycles

Stre

ss a

t bre

ak (M

pa)


Autoclave Sterilization vs. Elongation at Break - Hytrel SC/PC966

0

50

100

150

200

250

300

350

1 25 100Cycles

Elo

ngat

ion

at B

reak

(%)

Reference Sample Sterilized Hytrel SC969 (TPC-ET)

Autoclave Sterilization vs. Tensile Modulus - Hytrel SC969

0

50

100

150

200

250

300

1 25 100

Cycles

Ten

sile

Mod

ulus

(Mpa

)


Autoclave Sterilization vs. Stress at 10% - Hytrel SC969

0

5

10

15

20

1 25 100

Cycles

Stre

ss a

t 10%

(Mpa

)


- Hytrel SC969

0

10

20

30

40

1 25 100

Cycles

Stre

ss a

t bre

ak (M

pa)


Autoclave Sterilization vs. Elongation at break - Hytrel SC969

0

100

200

300

400

500

1 25 100

Cycles

Elo

ngat

ion

at b

reak

(%)



Hytrel SC976 (TPC-ET)

Autoclave Sterilization vs. Tensile Modulus - Hytrel SC976

0

100

200

300

400

500

600

1 25 100

Cycles

Ten

sile

Mod

ulus

(Mpa

)


Autoclave Sterilization vs. Stress at 10% - Hytrel SC976

0

5

10

15

20

25

30

1 25 100

Cycles

Stre

ss a

t 10%

(Mpa

)


- Hytrel SC976

0

10

20

30

40

50

1 25 100

Cycles

Stre

ss a

t bre

ak (M

pa)


Autoclave Sterilization vs. Elongation at break - Hytrel SC976

0

100

200

300

400

500

1 25 100

Cycles

Elo

ngat

ion

at b

reak

(%)



0200400600800

100012001400

1 25 100

Cycles

Ten

sile

Mod

ulus

(Mpa

)



0

10

20

30

40

50

1 25 100

Cycles

Stre

ss a

t 10%

(Mpa

)




0

10

20

30

40

50

60

1 25 100

Cycles

Stre

ss a

t bre

ak (M

pa)



0

100

200

300

400

500

1 25 100

Cycles

Elo

ngat

ion

at b

reak

(%)

Reference Sample Sterilized Zytel Due to the hydrophilic behaviour of nylons (PA), test samples naturally pick up moisture during the steam sterilization process. In order to minimize the effect of the moisture all test samples were conditioned at 23°C, 50%RH. Zytel SC/PC310 (PA 66)

Autoclave Sterilization vs. Tensile Modulus - Zytel SC/PC310

0

200

400

600

800

1000

1200

1 25 100

Cycles

Ten

sile

Mod

ulus

(Mpa

)


Autoclave Sterilization vs. Stress at Yield - Zytel SC/PC310

0

10

20

30

40

50

60

1 25 100

Cycles

Stre

ss a

t Yie

ld (M

pa)

Reference Sample Sterilized Autoclave Sterilization vs. Elongation at

yield - Zytel SC/PC310

0

10

20

30

40

1 25 100

Cycles

Elo

ngat

ion

at y

ield

(%)


Autoclave Sterilization Yellowness Index D1925

- Zytel SC/PC310

0

5

10

15

20

25

30

1 25 100

Cycles

Yel

low

ness

Inde

x



Zytel SC315 (PA 612)

Autoclave Sterilization vs. Tensile Modulus - Zytel SC315

0200400600800

100012001400

1 25 100

Cycles

Ten

sile

Mod

ulus

(Mpa

)


Autoclave Sterilization vs. Stress at Yield - Zytel SC315

0

10

20

30

40

50

60

1 25 100

Cycles

Stre

ss a

t Yie

ld (M

pa)


Autoclave Sterilization vs. Elongation at yield - Zytel SC315

0

10

20

30

40

1 25 100

Cycles

Elo

ngat

ion

at y

ield

(%)


Autoclave Sterilization Yellowness Index D1925

- Zytel SC315

0

5

10

15

20

25

30

1 25 100

Cycles

Yel

low

ness

Inde

x

Reference Sample Sterilized Delrin SC/PC Grades (POM)

Autoclave Sterilization vs. Tensile Modulus for Several Delrin SC and PC Grades

0

1000

2000

3000

4000

SC655 SC/PC652 SC/PC631 SC690

Delrin Resin Grade

Ten

sile

Mod

ulus

(MP

a)

Reference 25 Cycles

Autoclave Sterilization vs. Stress at Yield for Several Delrin SC and PC Grades

0

10

20

30

40

50

60

70

80


Delrin Resin Grade

Ten

sile

Stre

ss a

t Yie

ld (M

pa)

Reference 25 Cycles


Autoclave Sterilization vs. Elongation at break for Several Delrin SC and PC Grades

0

10

20

30

40

50


Delrin Resin Grade

Elo

ngat

ion

at b

reak

(%)

Reference 25 Cycles

Autoclave Sterilization vs. Notched Charpy Impactfor Several Delrin SC and PC Grades

0

2

4

6

8

10

12


Delrin Resin Grade

Not

ched

Cha

rpy

(KJ/

m^2

)

Reference 25 Cycles

Crastin SC/PC164 (PBT)

Autoclave Sterlization vs. Tensile Modulus - Crastin SC/PC164

0

500

1000

1500

2000

2500

3000

1 25

Cycles

Ten

sile

Mod

ulus

(MP

a)


Autoclave Sterlization vs. Tensile Stress at Yield- Crastin SC/PC164

0

10

20

30

40

50

60

70

1 25

Cycles

Stre

ss a

t Yie

ld (M

Pa)


Autoclave Sterlization vs. Elongation at Break- Crastin SC/PC164

0

20

40

60

80

100

120

1 25

Cycles

Elo

ngat

ion

at B

reak

(%)


Autoclave Sterlization vs. Elongation at Yield- Crastin SC/PC164

0

2

4

6

8

10

1 25

Cycles

Elo

ngat

ion

at Y

ield

(%)



Autoclave Sterlization vs. Notched Charpy Impact- Crastin SC/PC164

0

1

2

3

4

5

1 25

Cycles

Not

ched

Cha

rpy

(KJ/

m^2

)


4.2. -Gamma Sterilization Test conditions: 40kGy radiation Hytrel SC/PC Grades (TPC-ET) Hytrel® SC/PC938

1 Cycle Gamma Irradiation: effect on physical properties of Hytrel SC/PC938

0

5

10

15

20

25

Tensile Modulus(Mpa)

Stress at Yield(Mpa)

Strain at Yield(%)

Stress at Break(%)

Reference Gamma Irradiated 40kGy

Hytrel (TPC-ET)

1 Cycle Gamma Irradiation (40kGy) vs. Tensile Modul us - Hytrel SC/PC grades

0

50

100

150

200

SC/PC938 PC945 SC/PC948 SC946 SC/PC952 SC/PC956

Hytrel SC/PC Grades 30 - 55 Shore D

Ten

sile

Mod

ulus

(MP

a)


1 Cycle Gamma Irradiation (40kGy) vs. Tensile Modul us - Hytrel SC/PC grades

0

200

400

600

800

1000

1200

1400

SC/PC966 SC969 SC976 SC/PC988


Ten

sile

Mod

ulus

(MP

a)



1 Cycle Gamma Irradiation (40kGy) vs. Stress at 10% - Hytrel SC/PC grades

0

5

10

15

20



Stre

s at

10%

(MP

a)


1 Cycle Gamma Irradiation (40kGy) vs. Stress at 10% - Hytrel SC/PC grades

0

5

10

15

20

25

30

35

40



Stre

ss a

t 10%

(MP

a)

Reference Gamma Irradiated 40kGy Note: no data for Hytrel® SC/PC938

1 Cycle Gamma Irradiation (40kGy) vs. Stress at Bre ak - Hytrel SC/PC grades

0

10

20

30

40

50



Ten

sile

Stre

ss a

t Bre

ak (M

Pa)


1 Cycle Gamma Irradiation (40kGy) vs. Stress at Bre ak - Hytrel SC/PC grades

0

10

20

30



Stre

ss a

t Bre

ak (M

Pa)


1 Cycle Gamma Irradiation (40kGy) vs. Elongation at Break - Hytrel SC/PC grades

0

100

200

300

400

500



Elo

ngat

ion

at B

reak

(%)


1 Cycle Gamma Irradiation (40kGy) vs. Elongation at Break - Hytrel SC/PC grades

0

100

200

300

400



Elo

ngat

ion

at B

reak

(%)

Reference Gamma Irradiated 40kGy Note: no data for Hytrel® SC/PC938


Zytel SC/PC Grades (PA) DAM tensile bars tested.

1 Cycle Gamma Irradiated (40kGy) vs. Tensile Modulu s - Zytel SC/PC Grades

0

200

400

600

800

1000

1200

1400

SC/PC310 SC315

Zytel SC/PC Grade

Ten

sile

Mod

ulus

(MP

a)


1 Cycle Gamma Irradiated (40kGy) vs. Stress at Yiel d - Zytel SC/PC Grades

0

10

20

30

40

50

60

SC/PC310 SC315

Zytel SC/PC Grade

Ten

sile

Str

ess

at Y

ield

(M

Pa)


1 Cycle Gamma Irradiated (40kGy) vs. Elongation at Yield - Zytel SC/PC Grades

0

5

10

15

20

25

30

SC/PC310 SC315

Zytel SC/PC Grade

Elo

ngat

ion

at Y

ield

(%)


1 Cycle Gamma Irradiated (40kGy) vs. Stress at Brea k - Zytel SC/PC Grades

0

10

20

30

40

50

60

SC/PC310 SC315

Zytel SC/PC Grade

Stre

ss a

t Bre

ak (M

Pa)


1 Cycle Gamma Irradiated (40kGy) vs. Elongation at Break - Zytel SC/PC Grades

0

50

100

150

200

250

300

SC/PC310 SC315

Zytel SC/PC Grade

Elo

ngat

ion

at B

reak

(%)


1 Cycle Gamma Irradiated (40kGy) vs. Yellowness Ind ex D1925 - Zytel SC/PC Grades

0

10

20

30

40

50

SC/PC310 SC315

Zytel SC/PC Grade

Yel

low

ness

Inde

x D

1925



1 Cycle Gamma Irradiated (40kGy) vs. Viscosity Numb er - Zytel SC/PC Grades

0

20

40

60

80

100

120

140

160

SC/PC310 SC315

Zytel SC/PC Grade

Vis

cosi

ty N

umbe

r (m

l/g)


Zytel® SC310 (PA66): SEM before Gamma radiation Zy tel® SC310 (PA66): SEM after Gamma radiation

Zytel® SC315 (PA612): SEM before Gamma radia tion Zytel® SC315 (PA612): SEM after Gamma r adiation

PA 612 becomes more brittle after gamma sterilization, whereas PA 66 maintains its properties. Since the viscosity measurements do not show any difference between the radiated and the reference samples it must be concluded that only the surface of PA 612 is being attacked. The SEM pictures clearly show the surface deterioration of the PA 612, whereas the surface of PA 66 is not affected. It can be concluded that the loss of properties of PA 612 parts is due to crack propagation from the surface inwards. Therefore, the use of PA 612 should be avoided when sterilizing by gamma radiation.


Delrin SC/PC Grades (POM)

1 Cycle Gamma Irradiation (40kGy) vs. Tensile Modul us - Delrin SC/PC Grades

0

500

1000

1500

2000

2500

3000

3500

4000

SC/PC631 PC650 SC/PC652 SC690 PC691

Delrin SC/PC Grade

Ten

sile

Mod

ulus

(M

Pa)


1 Cycle Gamma Irradiation (40kGy) vs. Stress at Bre ak - Delrin SC/PC Grades

0

10

20

30

40

50

60

70

80


Delrin SC/PC Grade

Ten

sile

Str

engt

h at

Bre

ak (

MP

a)


1 Cycle Gamma Irradiation (40kGy) vs. Elongation at Break - Delrin SC/PC Grades

0

10

20

30

40

50

60


Delrin SC/PC Grade

Elo

ngat

ion

at B

reak

(%

)

Reference Gamma Irradiated 40kGy Gamma radiation severely damages the backbone of the polyacetal molecules. This is reflected in the loss of elongation as well as toughness and an increase in the melt flow rate. Therefore, POM should not be used when components are gamma radiated. Crastin SC/PC164 Zytel HTN51G35HSL (PPA)

1 Cycle Gamma Irradiation (40kGy) vs. Physical Prop erties - Crastin SC/PC164

0

10

20

30

40

50

60

70

Tensile Modulus(Mpa X 10^2)

Stress at Break(Mpa)

Elongation atBreak (%)

Elongation atYield (%)


1 Cycle Gamma Irradiation (40kGy) vs. Physical Prop erties - Zytel HTN 51G35HSL NC010

0

50

100

150

200

250

Tensile Modulus(Mpa X 10^2)


Elongation atBreak (%)

Elongation atYield (%)



4.3. - Electron Beam (E-beam) Test Conditions: 50kGy radiation Hytrel SC/PC Grades (TPC-ET)

1 Cycle E-Beam Irradiated (50kGy) vs. Tensile Modul us - Hytrel SC/PC Grades 30 - 55 Shore D

0

50

100

150

200

SC/PC938 SC945 SC/PC948 SC946 SC/PC952 SC/PC956

Hytrel SC/PC Grade

Ten

sile

Mod

ulus

(MP

a)

Reference E-Beam Irradiated 50kGy

1 Cycle E-Beam Irradiation (50 kGy) vs. Tensile Mod ulus - Hytrel SC/PC Grades 63 - 82 Shore D

0

200

400

600

800

1000

1200

1400


Hytrel SC/PC Grade

Ten

sile

Mod

ulu

s (M

Pa)


1 Cycle E-Beam Irradiated (50kGy) vs. Strength at 1 0% - Hytrel SC/PC Grades 30 - 55 Shore D

0

5

10

15

20


Hytrel SC/PC Grade

Stre

ngth

at 1

0% (M

Pa)


1 Cycle E-Beam Irradiation (50 kGy) vs. Strength at 10% - Hytrel SC/PC Grades 63 - 82 Shore D

0

5

10

15

20

25

30

35

40


Hytrel SC/PC Grade

Str

engt

h at

10%

(MP

a)


Note: no data for Hytrel® SC/PC938

1 Cycle E-Beam Irradiated (50kGy) vs. Strength at B reak

- Hytrel SC/PC Grades 30 - 55 Shore D

0

10

20

30

40


Hytrel SC/PC Grade

Stre

ngth

at B

reak

(MP

a)


1 Cycle E-Beam Irradiation (50 kGy) vs. Strength at Break - Hytrel SC/PC Grades 63 - 82 Shore D

0

10

20

30

40

50


Hytrel SC/PC Grade

Stre

ngt

h at

Bre

ak (M

Pa)



1 Cycle E-Beam Irradiated (50kGy) vs. Elongation at Break - Hytrel SC/PC Grades 30 - 55 Shore D

0

100

200

300

400

500


Hytrel SC/PC Grade

Elo

ngat

ion

at B

reak

(%)


1 Cycle E-Beam Irradiation (50 kGy) vs. Elongation at Break - Hytrel SC/PC Grades 63 - 82 Shore D

0

100

200

300

400


Hytrel SC/PC Grade

Elo

nga

tion

at B

reak

(%)



Zytel SC/PC Grades (PA) Testing on DAM Tensile bars

1 Cycle E-Beam Irradiation (50 kGy) vs. Tensile Mod ulus - Zytel SC/PC Grades

0

200

400

600

800

1000

1200

1400

1600

SC/PC310 SC315

Zytel SC/PC Grade

Ten

sile

Mod

ulus

(Mpa

)


1 Cycle E-Beam Irradiation (50 kGy) vs. Stress at Y ield - Zytel SC/PC Grades

0

15

30

45

60

SC/PC310 SC315

Zytel SC/PC Grade

Stre

ss a

t Yie

ld (M

pa)


Note: the stress at break is similar to the stress at yield

1 Cycle E-Beam Irradiation (50 kGy) vs. Elongation at Yield - Zytel SC/PC Grades

0

5

10

15

20

25

30

SC/PC310 SC315

Zytel SC/PC Grade

Elo

ngat

ion

at Y

ield

(%)


1 Cycle E-Beam Irradiation (50 kGy) vs. Elongation at Break - Zytel SC/PC Grades

0

50

100

150

200

250

300

SC/PC310 SC315

Zytel SC/PC Grade

Elo

ngat

ion

at B

reak

(%)



1 Cycle E-Beam Irradiation (50 kGy) vs. Yellowness Index D1925

- Zytel SC/PC Grades

0

10

20

30

40

50

60

SC/PC310 SC315

Zytel SC/PC Grade

Yel

low

ness

Inde

x D

1925


Delrin SC/PC Grades (POM)

1 Cycle E-Beam (50 kGy) vs. Tensile Modulus - Delrin SC/PC Grades

0

500

1000

1500

2000

2500

3000

3500

4000


Delrin SC/PC Grade

Ten

sile

Mod

ulus

(MP

a)


1 Cycle E-Beam (50 kGy) vs. Stress at Break - Delrin SC/PC Grades

0

10

20

30

40

50

60

70

80


Delrin SC/PC Grade

Stre

ss a

t Bre

ak (M

Pa)

Reference E-Beam Irradiated 50kGy 1 Cycle E-Beam (50 kGy) vs. Elongation at Break

- Delrin SC/PC Grades

0

10

20

30

40

50

60


Delrin SC/PC Grade

Elo

ngat

ion

at B

reak

(%)

Reference E-Beam Irradiated 50kGy The use of polyacetals is to be avoided in components that are sterilized with electron beam radiation.


Crastin SC/PC164 (PBT) Zytel HTN51G35HSL (PPA)

1 Cycle E-Beam (50 kGy) vs. Physical Properties - Crastin SC/PC164

0

10

20

30

40

50

60

70

Tensile Modulus(Mpa X10^2)


Elongation at Yield(%)


1 Cycle E-Beam (50 kGy) vs. Physical Properties - Zytel HTN51G35HSL NC010

0

50

100

150

200

250



Elongation at Break(%)


4.4. - EtO Sterilization Test Conditions: at 50°C, shallow vacuum, 2 hours exposure Hytrel SC/PC Grades (TPC-ET)

1 Cycle EtO (50 'C, 2 hrs.) Sterilized vs. Tensile Modulus - Hytrel SC/PC Grades 30 -55 Shore D

0

20

40

60

80

100

120

140

160

180

200


Hytrel SC/PC Grade

Ten

sile

Mod

ulus

(MP

a)

Reference EtO Sterilized

1 Cycle EtO (50 'C, 2 hrs) Sterilized vs. Tensile M odulus - Hytrel SC/PC Grades 63 - 82 Shore D

0

200

400

600

800

1000

1200


Hytrel SC/PC Grade

Ten

sile

Mod

ulus

(MP

a)


1 Cycle EtO (50 'C, 2 hrs.) Sterilized vs. Stress a t 10%

- Hytrel SC/PC Grades 30 -55 Shore D

0

2

4

6

8

10

12

14


Hytrel SC/PC Grade

Stre

ss a

t 10%

(MP

a)


1 Cycle EtO (50 'C, 2 hrs) Sterilized vs. Stress at 10% - Hytrel SC/PC Grades 63 - 82 Shore D

0

5

10

15

20

25

30

35

40


Hytrel SC/PC Grade

Stre

ss a

t 10%

(MP

a)




1 Cycle EtO (50 'C, 2 hrs.) Sterilized vs. Stress a t Break - Hytrel SC/PC Grades 30 -55 Shore D

0

5

10

15

20

25

30


Hytrel SC/PC Grade

Stre

ss a

t Bre

ak (M

Pa)


1 Cycle EtO (50 'C, 2 hrs) Sterilized vs. Stress at Break - Hytrel SC/PC Grades 63 - 82 Shore D

0

10

20

30

40

50


Hytrel SC/PC Grade

Stre

ss a

t Bre

ak (M

Pa)


1 Cycle EtO (50 'C, 2 hrs.) Sterilized vs. Elongati on at Break

- Hytrel SC/PC Grades 30 -55 Shore D

0

50

100

150

200

250

300

350

400

450

500


Hytrel SC/PC Grade

Elo

ngat

ion

at B

reak

(%)


1 Cycle EtO (50 'C, 2 hrs) Sterilized vs. Elongatio n at Break - Hytrel SC/PC Grades 63 - 82 Shore D

0

100

200

300

400


Hytrel SC/PC Grade

Elo

ngat

ion

at B

reak

(%)



Zytel SC/PC Grades (PA)

1 Cycle EtO (50 'C, 2 hrs.) Sterilized vs. Tensile Modulus


0

200

400

600

800

1000

1200

1400

SC/PC310 SC315

Zytel SC/PC Grade

Ten

sile

Mod

ulus

(MP

a)


1 Cycle EtO (50 'C, 2 hrs.) Sterilized vs. Stress a t Yield - Zytel SC/PC Grades

0

10

20

30

40

50

60

SC/PC310 SC315

Zytel SC/PC Grade

Stre

ss a

t Yie

ld (M

Pa)

Reference EtO Sterilized Note: the stress at break is similar to the stress at yield


1 Cycle EtO (50 'C, 2 hrs.) Sterilized vs. Elongati on at Yield


0

10

20

30

SC/PC310 SC315

Zytel SC/PC Grade

Elo

ngat

ion

at Y

ield

(%)


1 Cycle EtO (50 'C, 2 hrs.) Sterilized vs. Elongati on at Break


0

50

100

150

200

250

300

SC/PC310 SC315

Zytel SC/PC Grade

Elo

ngat

ion

at B

reak

(%)


1 Cycle EtO (50 'C, 2 hrs.) Sterilized vs. Yellowne ss Index D1925


0

5

10

15

SC/PC310 SC315

Zytel SC/PC Grade

Yel

low

ness

Inde

x

Reference EtO Sterilized Delrin SC/PC Grades (POM)

1 Cycle EtO (50 'C, 2 hrs.) vs. Tensile Modulus - Delrin SC/PC Grades

0

500

1000

1500

2000

2500

3000

3500

4000


Delrin SC/PC Grade

Ten

sile

Mod

ulus

(MP

a)


1 Cycle EtO (50 'C, 2 hrs.) vs. Stress at Break - Delrin SC/PC Grades

0

10

20

30

40

50

60

70

80


Delrin SC/PC Grade

Stre

ss a

t Bre

ak (M

Pa)



1 Cycle EtO (50 'C, 2 hrs.) vs. Elongation at Break - Delrin SC/PC Grades

0

10

20

30

40

50

60


Delrin SC/PC Grade

Elo

ngat

ion

at B

reak

(%)

Reference EtO Sterilized Crastin SC/PC164 (PBT) Zytel HTN51G35HSL (PPA)

1 Cycle EtO vs. Physical Properties - Crastin SC/PC164

0

10

20

30

40

50

60

70



Elongation at Yield(%)


1 Cycle EtO vs. Physical Properties - Zytel HTN51G35HSL NC010

0

50

100

150

200

250



Elongation at Break(%)


5. – Conclusions

The following conclusions can be drawn from this study:

• Zytel® PA is subject to yellowing in most sterilisation techniques, except EtO. • Zytel® PA66 can be sterilized by any of the methods investigated. • Zytel® PA612 should not be used in components that are Gamma radiated. • Delrin® POM should not be used in components that are Gamma or E-Beam radiated. • Delrin® POM shows good steam sterilisation behaviour up to 25 cycles • Hytrel® can be sterilized by any of the methods investigated. Only soft grades need to

be watched in terms of E-modulus with autoclaving. • Crastin® can be sterilized by any of the methods investigated. High cycle (100+)

autoclaving must be validated. • Zytel® HTN can be sterilized by any of the methods investigated.


6. - Disclaimer The information provided in this report corresponds to our knowledge on the subject at the date of its publication.This information may be subject to revision as new knowledge and experience becomes available. The data provided fall within the normal range of product properties and relate only to the specific material designated; these data may not be valid for such material used in combination with any other materials, additives or pigments or in any process, unless expressly indicated otherwise. The data provided should not be used to establish specification limits or used alone as the basis of design; they are not intended to substitute for any testing you may need to conduct to determine for yourself the suitability of a specific material for your particular purposes. Since DuPont cannot anticipate all variations in actual end-use conditions DuPont makes no warranties and assumes no liability in connection with any use of this information. Nothing in this publication is to be considered as a license to operate under or a recommendation to infringe any patent rights. DuPont advises you to seek independent counsel for a freedom to practice opinion on the intended application or end-use of our products. Not an offer of sale. DuPont reserves the right not to sell this product for selected applications. CAUTION: Do not use this product in medical applications involving permanent implantation (more than 30 days in the human body or in contact with human body fluids or tissues). Proposed applications involving temporary implantation (30 days or less) require a prior written contract with DuPont. See “DuPont Medical Caution Statement”, H-50102’.

The DuPont Oval Logo, DuPont™, The miracles of science. and Zytel® are trademarks or registered trademarks of DuPont Company. Copyright© 2006.

0

1

2

3Gamma

ETO

E-BeamSteam 25X

Steam 100X

POM

PA 6/6

PA 6/12

TPC-ET

PBT

Ranking: 1: significant loss in key properties 2: slight loss of some key properties 3: key properties unaffected

the effect of common sterilization techniques

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