- Email: [email protected]
Thermoplastic Elastomer (TPE)
Chapter 39
Thermoplastic Elastomer (TPE) Category: Elastomer, thermoplastic. General Description: Thermoplastic elastomers (TPEs) are a diverse family of materials that process and recycle like thermoplastic materials yet provide the properties generally found in rubber materials. Santoprene® is a product of Advanced Elastomer Systems. Sterile Applications: Tubing and medical devices. Sterilization Resistance: TPEs, in general, are resistant to radiation at normal sterilizing doses (may crosslink with commensurate reduction in elongation), autoclaving (121°C, 15 psi for 20 min), and ethylene oxide gas sterilization. Dry heat is not recommended.[141][142] Devices and products made from medical grades of Santoprene rubber can be sterilized effectively using steam autoclaving, gamma radiation, and ethylene oxide with no loss of performance. Repeated sterilizations do not lead to any significant changes in hardness and tensile stress-strain properties, nor to toxicity development during subsequent storage.[143] Gamma Radiation Resistance: Radiation resistance, optical properties, hardness, and compression set varies with chemistries.[142] Medical grades of Santoprene can be exposed to up to 4 megarads of cobalt 60 gamma radiation with only minimal change in physical properties and no development of toxicity during subsequent storage of the irradiated rubber. The irradiation appears to cause significant, but tolerable, losses of tensile strength and ultimate elongation. The aging after irradiation results in no further loss up to a period of one year.[25]
The agarose overlay method was used to determine the cytotoxicity of the irradiated and subsequently stored specimens. No significant toxicity developed at exposures of 4.2 megarads and lower, and only slight toxicity developed at 5.3 megarads.[25] Ethylene Oxide (EtO) Resistance: Five standard hospital EtO sterilization cycles give no significant loss in hardness or tensile stress-strain properties for both 73 Shore A and 40 Shore D grades. Immediately after sterilization, samples sterilized with EtO had residual amounts of 0.03% to 0.06% and samples sterilized with ethylene chlorohydrin and ethylene glycol had residual amounts of 0.02% to 0.03%. The residual amounts virtually disappeared after 31 days.[25] Steam Resistance: Test specimens were evaluated for changes in hardness, tensile stress-strain properties, and swell after exposures of 10, 25, 50, 75, and 100 cycles. The changes in tensile properties are quite minor, insignificant, and well within accepted ASTM D2000 limits. The hardness changes are only marginally significant, but within accepted ASTM limits. The weight change does not significantly change properties.[25] Regulatory Status: Santoprene medical grades have USP Class VI Certificate of Compliance for biocompatibility. Santoprene 281 grades are certified non-toxic by MEM elution test.[35] Sterilization Data by Material Supplier Trade Name: See Tables 39-01 and 39-02.
246
EFFECT OF STERILIZATION METHODS ON PLASTICS AND ELASTOMERS
Table 39-01. Effect of Steam Sterilization on Santoprene 281-45 and 281-55 Olefinic Thermoplastic Elastomers Material Family Material Supplier/Name
OLEFINIC THERMOPLASTIC ELASTOMER Advanced Elastomer Systems Santoprene 281-45
Material Note
Advanced Elastomer Systems Santoprene 281-55
Medical grade
Reference Number
25
EXPOSURE CONDITIONS Type Number of Cycles
Steam autoclave 10
25
50
75
Note
100
10
25
50
75
100
Live steam cycle, 5 min rise, 5 min at 134°C, 5 min cool
Temperature, °C
134
Time, hours
0.083
PROPERTIES RETAINED (%) Ultimate Tensile Strength
91 (jw)
68 (jw)
93 (jw)
95 (jw)
91 (jw)
86 (jw)
85 (jw)
84 (jw)
92 (jw)
91 (jw)
Ultimate Elongation
103 (jd)
77 (jd)
103 (jd)
101 (jd)
96 (jd)
86 (jd)
81 (jd)
81 (jd)
78 (jd)
80 (jd)
88 (b)
86 (b)
89 (b)
95 (b)
94 (b)
92 (b)
95 (b)
93 (b)
104 (b)
99 (b)
A1 (gn)
A1 (gn)
A1 (gn)
A2 (gn)
A2 (gn)
A2 (gn)
A1 (gn)
A4 (gn)
A4 (gn)
A4 (gn)
100% Modulus SURFACE AND APPEARANCE Hardness Units Change
Table 39-02. Effect of Steam Sterilization on Santoprene 283-40 Olefinic Thermoplastic Elastomer Material Family
OLEFINIC THERMOPLASTIC ELASTOMER
Material Supplier/Name
Advanced Elastomer Systems Santoprene 283-40
Material Note
Medical grade
Reference Number
25
EXPOSURE CONDITIONS Type Number of Cycles
Steam autoclave 10
Note
25
50
75
100
Live steam cycle, 5 min rise, 5 min at 134°C, 5 min cool
Temperature, °C
134
Time, hours
0.083
PROPERTIES RETAINED (%) Ultimate Tensile Strength
96 (jw)
96 (jw)
95 (jw)
98 (jw)
95 (jw)
Ultimate Elongation
98 (jd)
96 (jd)
94 (jd)
86 (jd)
82 (jd)
100% Modulus
105 (b)
106 (b)
106 (b)
116 (b)
120 (b)
D2 (gn)
D1 (gn)
D0 (gn)
D2 (gn)
D1 (gn)
SURFACE AND APPEARANCE Hardness Units Change
THERMOPLASTIC ELASTOMER (TPE)
247
Graph 39-01. Post autoclave retention of elongation for Advanced Elastomer Systems Santoprene rubber.[143]
248
EFFECT OF STERILIZATION METHODS ON PLASTICS AND ELASTOMERS
Graph 39-02. Post autoclave retention of tensile strength for Advanced Elastomer Systems Santoprene rubber.[143]
Thermoplastic Elastomer (TPE) Category: Elastomer, thermoplastic. General Description: Thermoplastic elastomers (TPEs) are a diverse family of materials that process and recycle like thermoplastic materials yet provide the properties generally found in rubber materials. Santoprene® is a product of Advanced Elastomer Systems. Sterile Applications: Tubing and medical devices. Sterilization Resistance: TPEs, in general, are resistant to radiation at normal sterilizing doses (may crosslink with commensurate reduction in elongation), autoclaving (121°C, 15 psi for 20 min), and ethylene oxide gas sterilization. Dry heat is not recommended.[141][142] Devices and products made from medical grades of Santoprene rubber can be sterilized effectively using steam autoclaving, gamma radiation, and ethylene oxide with no loss of performance. Repeated sterilizations do not lead to any significant changes in hardness and tensile stress-strain properties, nor to toxicity development during subsequent storage.[143] Gamma Radiation Resistance: Radiation resistance, optical properties, hardness, and compression set varies with chemistries.[142] Medical grades of Santoprene can be exposed to up to 4 megarads of cobalt 60 gamma radiation with only minimal change in physical properties and no development of toxicity during subsequent storage of the irradiated rubber. The irradiation appears to cause significant, but tolerable, losses of tensile strength and ultimate elongation. The aging after irradiation results in no further loss up to a period of one year.[25]
The agarose overlay method was used to determine the cytotoxicity of the irradiated and subsequently stored specimens. No significant toxicity developed at exposures of 4.2 megarads and lower, and only slight toxicity developed at 5.3 megarads.[25] Ethylene Oxide (EtO) Resistance: Five standard hospital EtO sterilization cycles give no significant loss in hardness or tensile stress-strain properties for both 73 Shore A and 40 Shore D grades. Immediately after sterilization, samples sterilized with EtO had residual amounts of 0.03% to 0.06% and samples sterilized with ethylene chlorohydrin and ethylene glycol had residual amounts of 0.02% to 0.03%. The residual amounts virtually disappeared after 31 days.[25] Steam Resistance: Test specimens were evaluated for changes in hardness, tensile stress-strain properties, and swell after exposures of 10, 25, 50, 75, and 100 cycles. The changes in tensile properties are quite minor, insignificant, and well within accepted ASTM D2000 limits. The hardness changes are only marginally significant, but within accepted ASTM limits. The weight change does not significantly change properties.[25] Regulatory Status: Santoprene medical grades have USP Class VI Certificate of Compliance for biocompatibility. Santoprene 281 grades are certified non-toxic by MEM elution test.[35] Sterilization Data by Material Supplier Trade Name: See Tables 39-01 and 39-02.
246
EFFECT OF STERILIZATION METHODS ON PLASTICS AND ELASTOMERS
Table 39-01. Effect of Steam Sterilization on Santoprene 281-45 and 281-55 Olefinic Thermoplastic Elastomers Material Family Material Supplier/Name
OLEFINIC THERMOPLASTIC ELASTOMER Advanced Elastomer Systems Santoprene 281-45
Material Note
Advanced Elastomer Systems Santoprene 281-55
Medical grade
Reference Number
25
EXPOSURE CONDITIONS Type Number of Cycles
Steam autoclave 10
25
50
75
Note
100
10
25
50
75
100
Live steam cycle, 5 min rise, 5 min at 134°C, 5 min cool
Temperature, °C
134
Time, hours
0.083
PROPERTIES RETAINED (%) Ultimate Tensile Strength
91 (jw)
68 (jw)
93 (jw)
95 (jw)
91 (jw)
86 (jw)
85 (jw)
84 (jw)
92 (jw)
91 (jw)
Ultimate Elongation
103 (jd)
77 (jd)
103 (jd)
101 (jd)
96 (jd)
86 (jd)
81 (jd)
81 (jd)
78 (jd)
80 (jd)
88 (b)
86 (b)
89 (b)
95 (b)
94 (b)
92 (b)
95 (b)
93 (b)
104 (b)
99 (b)
A1 (gn)
A1 (gn)
A1 (gn)
A2 (gn)
A2 (gn)
A2 (gn)
A1 (gn)
A4 (gn)
A4 (gn)
A4 (gn)
100% Modulus SURFACE AND APPEARANCE Hardness Units Change
Table 39-02. Effect of Steam Sterilization on Santoprene 283-40 Olefinic Thermoplastic Elastomer Material Family
OLEFINIC THERMOPLASTIC ELASTOMER
Material Supplier/Name
Advanced Elastomer Systems Santoprene 283-40
Material Note
Medical grade
Reference Number
25
EXPOSURE CONDITIONS Type Number of Cycles
Steam autoclave 10
Note
25
50
75
100
Live steam cycle, 5 min rise, 5 min at 134°C, 5 min cool
Temperature, °C
134
Time, hours
0.083
PROPERTIES RETAINED (%) Ultimate Tensile Strength
96 (jw)
96 (jw)
95 (jw)
98 (jw)
95 (jw)
Ultimate Elongation
98 (jd)
96 (jd)
94 (jd)
86 (jd)
82 (jd)
100% Modulus
105 (b)
106 (b)
106 (b)
116 (b)
120 (b)
D2 (gn)
D1 (gn)
D0 (gn)
D2 (gn)
D1 (gn)
SURFACE AND APPEARANCE Hardness Units Change
THERMOPLASTIC ELASTOMER (TPE)
247
Graph 39-01. Post autoclave retention of elongation for Advanced Elastomer Systems Santoprene rubber.[143]
248
EFFECT OF STERILIZATION METHODS ON PLASTICS AND ELASTOMERS
Graph 39-02. Post autoclave retention of tensile strength for Advanced Elastomer Systems Santoprene rubber.[143]