Trends in Mechanical Testing of Medical Plastics

Medical plastics are among the most exciting and fastest growing areas of the specialty plastics market. In this interview, AZoM speaks with Erik Berndt (EB), Medical Industry Manager for Zwick/Roell, to discuss material testing trends in the medical plastics industry.

Briefly describe some of the trends impacting the provision of plastic materials for medical applications. 

Manufacturers of medical grade plastics are called upon to meet high levels of quality due to regulations governing the medical industry.  As OEMs seek suppliers capable of consistently delivering to high quality standards, compounders must ensure that proper characterization of raw materials and components is undertaken.

What is your perspective on the driver(s) for these trends?  How is Zwick responding to them?

Increasingly, OEMs are pushing traceability requirements down to suppliers, which leads to changes in the management of testflows and the degree to which testing labs maintain records in the event of a US Food & Drug Administration audit.

Zwick has developed an expanded traceability function in its testXpert ® II measurement and control software platform.  Available for the entire suite of Zwick testing systems, testXpert II allows the operator to generate a complete set of electronic records, including the test parameters and test results, as well as data on which operator performed the test and when the tests were conducted.

Can you provide an example of a compounder who is managing these challenges? 

A good example would be Innovative Polymer Compounds Limited, a specialist compounder of Medical Grade Engineering Polymers based in Kilbeggan, County Westmeath, Ireland.

IPC is a joint venture company between Associated Plastics of Ireland Ltd, a polymer compounding company, and National Chemical Company Ltd., a polymer and chemicals distribution company. Both companies have over 30 years of experience in the polymer industry.

What materials does IPC work with? 

IPC processes polymers from Arkema, Lubrizol, BASF, EMS, DuPont, Evonik and Solvay. IPC compounds these polymers with other polymers, pigments, radiopaque fillers such as barium sulphate or bismuth oxychloride and, more recently, antimicrobial additives.

What kind of testing environment does IPC utilize?

IPC uses a state of the art compounding facility encompassing all of the features a customer would require of a 100K clean room, with accurate control of air quality, dust extraction and temperature control in each of the material process halls.

IPC performs its own color matching using a base range of FDA approved pigments which achieves tighter and more consistent color tolerances as well as short lead times for colored compounds to Pantone, Munsell or RAL references.

What sorts of quality assurance challenges does IPC face and how does the enterprise manage them?

The company faces unique quality assurance challenges including the careful selection and testing of incoming raw materials. As processing and environmental systems are tightly controlled, batch to batch variability of raw materials would cause concern in maintaining product quality. IPC ensures that this variability is kept to a minimum.

Customers in the medical device business demand very tight process controls. IPC achieves tight control by storing, processing and testing products in a temperature controlled environment. A detailed certificate of analysis is generated for each batch including tensile strain at various elongation values.

Does adherence to standards play a role in this as well?

ISO 9001 accreditation is a pre-requisite requirement. IPC also recently completed its accreditation to ISO 13485 (Medical Device Standard).

What types of tests are involved in the characterization of medical plastics?

Verification of product quality is determined by carrying out a range of tests including characterization of melt-flow, moisture and tensile properties.

IPC uses a 5kN capacity Zwick/Roell ProLine table top testing machine equipped with a Longstroke extensometer for tensile property testing using a range of injection molded and punched dumb-bell samples. Based on previous tests of the same formulation, decisions on product quality can be determined.

IPC’s Zwick ProLine Z005 TN for tensile property testing of injection molded and punched dumbbell samples. Image credit: ZwickRoell Gmbh Co. KG

Briefly explain the importance of tensile testing to this area of application. 

Tensile properties are of great benefit when processing hygroscopic polymers such as polyurethanes and polyamides as this data can provide information on processing conditions or issues encountered during batch production.

Trend analysis of the data provides valuable insights into the IPC process and can warn the quality assurance team of possible quality issues before they have a major impact on product quality.

What was the motivation for the selection of Zwick testing equipment for this application? 

IPC examined other testing systems but settled on the Zwick system as it offered an easy user interface and test reports are clear and easily understood. In day to day use the system is reliable and repeatable.

Zwick’s testXpert II software used by the Zwick ProLine systems offers the capability to create presentation-type reports for customers which further enhances IPC’s reputation for high quality.