电子束灭菌如何影响伊士曼Tritan™共聚聚酯?

对医疗器械进行灭菌会对透明聚合物的光学和物理性能带来不利影响。
 
电子束(电子束)辐射是为医疗器械进行灭菌的最常用方法之一,此外还有伽马射线、环氧乙烷(EtO)、高压灭菌器以及低温等离子灭菌等其他灭菌方法。
 
Eastman开展研究以判断电子束辐射对Eastman Tritan共聚聚酯以及其他透明医用聚合物光学和物理特性的影响。
 
Formula Resin type
Eastman Tritan copolyester MX711 共聚聚酯
Eastar polyester MN052 polyester
Eastar copolyester MN211 共聚聚酯
Eastar copolyester MN006 共聚聚酯
DuraStar polymer MN611 共聚聚酯
Tenite propionate 360A40012 Cellulose acetate propionate (CAP)
Lipid resistant PC polycarbonate
TABS Transparent ABS
Medical grade acrylic Acrylic (PMMA)

The objective of sterilizing medical devices is to reduce the bioburden to a safe level with minimal effects on the desired properties of its constituent polymers.
 
Technology advances have improved the performance of e-beam radiation, making it a safe, efficient, and reliable source of energy for sterilization. High dose rates reduce the time of exposure, which can make e-beam a less costly alternative to gamma radiation.
 
To study the effect of e-beam radiation on Tritan MX711, Eastman measured color shifting and physical property retention after e-beam radiation.   

Optical properties
Samples were exposed to e-beam radiation (25 and 50 kGy), then stored in darkness and their color measured at Days 3, 7, 14, and 42 using HunterLab UltraScan Sphere 8000 and the CIE L*, a*, b* color scale. (Samples were stored in darkness and only exposed to light for color measurement.)
 
Figure 1 shows the changes in b* value, which measures the blue to yellow scale after e-beam exposure at 50 kGy. Photos of the molded samples before and after exposure are available upon request.

Figure 1. Eastman Tritan copolyester and other transparent resins after e-beam exposure at 50 kGY—b* color measurements




Figure 2 shows the difference in b* color values between unexposed samples and sterilized samples at Day 42—after e-beam radiation at both 25 and 50 kGy. 

Figure 2. Change in b* color 42 days after e-beam radiation—25 and 50 kGy  

Physical properties were measured before and after e-beam sterilization at 25 and 50 kGy. No physical property degradation was noted for Tritan MX711 or the other resins tested. The polyesters and copolyesters in the study showed no statistical change in molecular weight although Tenite propionate 360 did show a loss of molecular weight, as expected from an aliphatic polymer. 

For complete details of these studies or more information about the advantages of Eastman Tritan copolyesters, email Eastman today.