Engineering Plastics in Medicine

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Engineering Plastics are increasingly being used for the manufacturing of medical equipment, components, and devices. This sector utilizes science-based, high-quality raw material that ensures compliance with health and international standards. However, there are a number of factors that determine the suitability and manufacturing feasibility of medical grade plastic for highly sensitive medical components. For effective selection, manufacturers should be aware of the most suitable plastic type and grade for their specified product.

Here are some of the most important physical and chemical properties of the engineering grade plastic that make the manufacturing of precise medical instruments possible. The manufacturer must consider these properties while making a choice for the right material.

Mechanical properties

Each medical instrument may have specific requirements for the raw plastic and materials used in the manufacturing processes. These requirements look closely into the mechanical properties of engineering plastic, such as impact strength, tensile and compressive strength, wear resistance, and bending stiffness. Some excellent engineering plastics that are most suitable may include thermoplastics such as polyacetal, POM, PPSU, PC, nylon and PEEK. Temperature variations can also have a great impact on sophisticated medical devices and their functional integrity.

Dimensional stability

The function of a medical instrument can be greatly impacted by the dimensional stability of the engineered material used in the making of it. Exposure to high temperatures, different chemicals and environments may impact the physical behavior of the instruments based on its material, such as shrinking. This requires a great dimensional stability and tolerance of the material. Some common engineering plastics which are dimensionally stable for medical devices include PEI, PSU, PES, PC, and PPSU.

Drug Flow Path

Some medical instruments may be directly exposed to the flow of drugs that are administered into the patient’s body. The material should be neutral when exposed directly to a range of drugs.

Conductivity

The conductivity of a material can also impact the drug delivery and dosage. If the delivered drug gets attracted by the thermoplastic, it can deliver incorrect dosage. Therefore, the permanently antistatic compounds are used in many medical devices which can reduce or eliminate the static build-up of the drug.

Biocompatibility

The plastic material that is used for the manufacturing of sensitive medical instruments must be biocompatible with the chemicals and the environment that it is exposed to. Biocompatibility test is conducted to check for biocompatibility. These standard tests include USP class VI and ISO 10993. The ISO standard test is highly stringent and sophisticated. 

Aesthetics and Durability

Medical devices may need to undergo transportation and other rough conditions. This requires these medical devices made from plastic to be durable and strong. Another important characteristic is the aesthetics for the patient, such as the pleasantness and comfort while using the device.

Resistance

The medical grade engineered plastics should be resistant to a range of chemicals, such as disinfectants and hospital cleaners. There are several kinds of plastics which can react with other chemicals or deteriorate upon exposure to other active agents, such as bleach, isopropyl alcohol, and peroxides. They should also be resistant to the process of sterilization which is extremely important for medical instruments that come in contact with body fluids or tissues.

Lubrication

Medical devices may consist of sliding and mechanically moving parts. Without proper resistance, these parts may undergo friction and wear. Some of the examples of such parts may include sliding covers, implants, and the moving gears. Additives can be used to improve the lubrication and water resistance of the material, such as silicone and PTFE.

Radiopacity

Radiopacity can be defined as the ability of a material to be seen under the fluoroscope or X-ray imaging. To make the engineered plastic polymer radiopaque, certain additives can be added.

 

The options of available plastics are not limited. However, it is imperative to find the one that performs the best. Apart from the above mentioned highly important physical and chemical properties of medical plastic, there are several other characteristics that may be specifically considered, such as:

·         Arc Resistance

·         Chemical resistance

·         The coefficient of Linear Thermal Expansion

·         Comparative Tracking Index

·         Creep

·         Deflection Temperature under Load

·         Density and Specific Gravity

·         Dielectric Constant

·         Dielectric Strength

·         Dissipation Factor

·         Elasticity

·         Environmental and Chemical Stresses

·         Flammability

·         Flexural Strength

·         Impact Strength

·         Inherent flame retardancy.

·         Low wear

·         Lubricity

·         Melting Point

·         Mold Shrinkage

·         Opacity and Luminous Transmittance

·         Tensile Elongation

·         Tensile Strength

·         Thermal Conductivity

·         Volume Resistivity

·         Water Absorption

Conclusion

Because of their unmatched performance in demanding and stressful applications, engineered plastics are growingly becoming popular in the medical manufacturing industry. In most cases, these materials are chosen because of their work efficiency in diverse applications. Various properties of a plastic are important to be considered while choosing it for a particular use, such a thermal, chemical, physical, sterilization, mechanical and electrical properties. A great understanding of the manufacturer’s part is required for successful production of these materials that can comply with the stringent standards. Therefore, choosing the right supplier for the engineering grade plastic for medical instruments is of utmost importance.