May 13, 2025 – With the vigorous growth of the healthcare industry, medical plastics, as a crucial component of medical devices, have their sterilization tolerance closely intertwined with the reliability and lifespan of products. Different sterilization methods exert diverse impacts on the properties of medical plastics, which has become a key consideration for modified plastics enterprises during the research, development, and production processes.
Currently, the main sterilization methods for medical plastics include steam sterilization, radiation sterilization, ethylene oxide sterilization, and chemical sterilization. As learned from the Color Masterbatch Industry Network, while these methods effectively eliminate microorganisms, they can alter the properties of medical plastics to varying degrees. Take steam sterilization, commonly known as autoclaving, as an example. It achieves sterilization through steam and high pressure. However, after multiple autoclaving cycles, the tensile strength and impact resistance of some plastics may decline. Moreover, thermal sterilization can affect the stability of certain materials, leading to changes in their physical and mechanical properties. Therefore, when selecting plastics for autoclaving, it is essential to fully understand their temperature limits and exposure durations to ensure the chosen materials can withstand the harsh conditions.
Radiation sterilization utilizes ionizing radiation such as gamma rays or electron beams to damage the DNA of microorganisms, typically conducted at a dose of ≤50 kGy. Nevertheless, this method can cause chain scission or cross-linking in polymers. For instance, polyethylene may undergo cross-linking under radiation, thereby affecting its flexibility. Hence, the use of radiation-resistant plastics is crucial for maintaining the structural integrity and performance stability of materials.
Ethylene oxide sterilization works by alkylating the DNA or RNA of microorganisms with ethylene oxide gas under specific temperature, humidity, and pressure conditions. However, ethylene oxide gas can easily cause swelling in some plastics, affecting their dimensional stability. Additionally, a long aeration period is required after sterilization to remove toxic residues, and its application is mostly limited to thermoplastic plastics.
Chemical sterilization employs liquid or gaseous chemicals with antibacterial properties, such as oxidants and halogens. During this process, the compatibility between plastics and sterilization chemicals becomes the key factor. Some plastics are prone to degradation or property changes when in contact with certain chemicals.
In addition to the impact of sterilization methods on the properties of medical plastics, medical-grade plastics are also subject to strict regulatory standards. The U.S. Food and Drug Administration (FDA) classifies medical devices into three categories, each corresponding to different approval processes and risk levels. The International Organization for Standardization (ISO) has developed a series of biocompatibility test standards, such as ISO 10993 and its related standards, which regulate aspects like cytotoxicity and sensitization. USP Class VI, a biocompatibility standard stipulated by the United States Pharmacopeia, sets stringent requirements for plastics used in medical devices that come into contact with patients for more than 24 hours. Passing this level of certification indicates that the plastics have extremely high biocompatibility and are suitable for long-term or permanent exposure. For modified plastics enterprises, only by accurately predicting the performance under extreme conditions during the formulation design stage and balancing sterilization tolerance and mechanical properties through scientific modification can they effectively enhance the core competitiveness of medical plastics and secure a position in the healthcare field.