Testing Tensile Strength in Carbon Fiber Reinforced Polymers

Dunstone was recently featured in Composites Science and Technology, a journal that focuses on the fundamental and applied science of composites. In a study titled “Comparative analysis of NOL-ring tensile strength in towpreg and slit-tape for filament winding: Influence of resin viscosity, tack, and consolidation,” researchers explored how different manufacturing methods and parameters influenced the tensile strength of carbon-fiber reinforced polymers (CFRPs).

A variety of composite materials were laid up and wound via different methods in order to produce several NOL-ring (Naval Ordnance Laboratories) specimens. Two of the specimens included the use of Dunstone 220R Hi-Shrink Tape. Each specimen was then tested for tensile strength and evaluated, with the benchmark for comparison being a specimen that had been cured via an autoclave (all other specimens were cured via an oven).

The results, viewed microscopically for overall compaction, revealed that specimens that used 220R Hi-Shrink Tape resulted in improved ply consolidation quality. There were a few specific improvements that are worth highlighting regarding enhancing composite consolidation:

  • External compaction — Dunstone 220R Hi-Shrink Tape provided compaction pressure estimated at 0.6 bar, providing compaction for specimens that used it but not for non-autoclave specimens. The autoclave specimen had compaction at 4 bars. However, note that autoclave pressures are also possible using Dunstone Hi-Shrink Tape alone.
  • Impact on consolidation — The use of Dunstone 220R Hi-Shrink Tape significantly reduced voids and delamination in the laminates, eliminating widespread defects with only localized defects remaining.
  • Improved tensile strength — Specimens utilizing 220R Hi-Shrink Tape showed higher tensile strength compared to specimens without external compaction.

Dunstone appreciates being included in this informative study on enhancing composite consolidation via different methods. Those interested can read the full text of the study here.

About Dunstone 220R Hi-Shrink Tape

Dunstone 220 Hi-Shrink Tape is one of our most popular products and is well-known and used in the market — and across numerous industries. Our 200 Series, which includes 220R, has been referred to as the Swiss Army knife of shrink tape. There are several good reasons for this:

  • Thinness — One of the thinnest offerings available, 220R measures just 0.002” (0.050 mm). This thinness equates to reduced material cost over other solutions because less is needed while still producing the desired consolidation and compaction. Pro tip: The first 2 in 220 refers to its thickness.
  • Shrink percentage — The 200 Series provides a wide range of shrink percentage options depending on the application. In the instance of the above study, the 220R product offers 20% shrink — the highest of the 200 line. This equates to 8.6 foot-pounds of shrink force. Pro tip: The 20 in 220 specifies the shrink percentage.
  • Release coatings — A release coating allows the tape to be easily removed from the layup, whereas normally you’d have to scrape it off or just leave it on depending on the application. Release coatings are available on one side of the tape or both. Additionally, our 220 Hi-Shrink Tape is available with a silicone release coating. Pro tip: Release coatings are specified after the number in the product name. 220R has a release coating on one side, 220RR is release coated on both sides, and 220S has no coating (S = standard).
  • Customization — Dunstone 220R Hi-Shrink Tape is available in a variety of widths, lengths, core sizes, and more, and all of this can be customized for your application. Additionally, many of our Hi-Shrink Tapes can be modified with perforations for applications where outgassing is required.

Start Enhancing Composite Consolidation with Dunstone — Request a Complimentary Sample

We offer free samples of any of our in-stock Hi-Shrink Tapes and Hi-Shrink Tubing. This allows you to test our materials in your production environment and determine if they’re the right fit. You can request a complimentary sample here — just tell us a few details about your application, and a sample will be mailed to you right away.

Of course, our engineering team is always available to help you customize or refine a Hi-Shrink Tape solution to maximize performance — simply reach out to us to get started.