The medical case for cyclic block copolymers

The advantages of cyclic block copolymers (CBCs) over other optical-grade plastics as well as the material’s benefits in an array of medical applications were outlined during a presentation at the co-located PLASTEC West and MD&M West event in Anaheim, CA, last week. Moh-Ching (Oliver) Chang, Vice President of R&D and Deputy Chief Technology Officer at the USI Group (Taipei), led the highly technical discussion.

Moh-Ching (Oliver) Chang
Moh-Ching (Oliver) Chang, USI Group.

The USI Group comprises seven companies engaged in various streams of the petrochemical industry supply chain. Two of those groups are involved in plastics and plastics processing, and Chang announced during the presentation that the company planned to inaugurate its first CBC plant in Taiwan this year.

The CBC manufacturing process described by Chang involves a two-step filtration process, once following polymerization of the material and again after hydrogenation, to optimize the material's properties, which include the following:

  • 92% high light transmission;
  • low extractables and leachables;
  • thermal stability;
  • low specific gravity (0.94);
  • visible and ultraviolet light stability;
  • low birefringence;
  • absence of bisphenol A and plasticizers;
  • low moisture uptake;
  • mechanical and barrier properties;
  • sterilizability; and
  • chemical resistance.

Given this package of properties, CBC is recommended for such medical applications as syringes, catheters, vials and medical packaging, said Chang, who highlighted three specific applications during his presentation: Biopharmaceutical products, orthodontia and diagnostic devices.

UBM America’s newest design and manufacturing trade show and conference debuts in Cleveland, OH, on March 29 and 30, 2017. On one show floor, Advanced Design & Manufacturing (ADM) Cleveland showcases five zones—packaging, automation and robotics, design and manufacturing, plastics and medical manufacturing. Numerous conference sessions are targeted to the medical manufacturing, automotive and other key industry sectors. Go to the PLASTEC Cleveland website to learn more and to register to attend.

Biopharma products benefit from CBC elastomers because of their 50A to 40 D hardness range, clarity, purity and compatibility with polyolefins, Chang noted. The material’s low moisture uptake, which results in high stress retention; crack and stain resistance; purity; clarity; and thermoformability make it suitable for orthodontia. Finally, for diagnostics applications, its key benefits include low autofluorescence, chemical resistance, mechanical stability, high flow, processability and biocompatibility. For microplate applications, in particular, CBC is superior to cyclic olefin copolymers and copolyester thermoplastic elastomers because of its higher UV transmission, better thermal oxidation stability (without N2 sealing, Chang stressed); higher flow; and lower density.

The material can be processed using most current techniques, including injection molding, extrusion and blowmolding, added Chang.

Before joining USI in 2015, where he is Vice President of R&D and Deputy Chief Technology Officer, Chang has performed R&D work with Monsanto, Bayer, GLS, Baxter and Hollister. He holds approximately 30 patents.

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