Composite musings

A week before writing this, I went to the hardware store
 to buy a pointed shovel. I had the choice of a shovel with a wooden handle, or one with a composite handle — pultruded fiberglass. I elected to buy the higher-priced composite-handled shovel, partly because I’m a composites geek but also because the shovel I was replacing has a composite handle that I broke prying up tree roots. The failure mode was benign in that the resin and fiber delaminated, but did not fully break under the heavy load. I could laminate some glass and resin over the top and it would still maintain some utility for light work. I know from empirical experience that the same force on a wooden handle would have snapped it in half, rendering that shovel completely unusable. That shopping experience led me to take inventory of what other composite products I own — those that can be purchased by anyone. Turns out I own a set of bypass pruners that have fiberglass handles, as well as two tree pruners with lightweight, extendible fiberglass poles, which are also electrically insulative, in case you are trimming branches up around power lines — a positive attribute, for sure!

Among my other tools, I have a stepladder with pultruded side rails, and several types of hammers with fiberglass handles. These are really great for vibration damping. And my sporting goods collection is replete with composites, including a half-dozen carbon fiber tennis racquets (used frequently), a set 
of golf clubs with carbon fiber shafts (used less than I like), 
a couple of carbon/glass fishing rods (that I haven’t used in years — need to correct that), two pairs of fiberglass downhill skis (used each winter) and a pair of carbon fiber downhill ski poles that have performed flawlessly for almost 15 years. I had
 a prototype pair of carbon fiber ski poles that I managed to break in under a season, prior to these. Considering the shovel and the poles, it sounds like I might have a future career as a product tester.

Speaking of sporting goods, why do manufacturers still use the term graphite when the product being used is what we insiders call carbon fiber? It’s such an archaic term from the 1980s. The Ford Econoline driveshaft that won the SPE Automotive Division Grand Award in 1984 is listed in the archives as a “vinyl ester/graphite/glass” product when the fiber that was used was a standard-modulus, AS4-type of carbon fiber. Several of my newer Wilson tennis racquets, in fact, have “Braided Graphite + Kevlar” printed on them, when it is obvious that standard-modulus carbon fiber is used. The truth is that the overwhelming majority of carbon fiber is produced with a carbon content of 93-97%.

To be labeled graphite, the fiber needs to see heat treatment well above 2000°C, and typically has more than 99% carbon assay. When processed at these temperatures, the fibers develop highly oriented graphitic structures and achieve very high modulus, as well as high densities (often above 1.9 g/cm³). Examples include Hexcel’s HM63 and Toray’s M60J in the PAN family, and the high-modulus and high-conductivity grades of pitch-based fibers. 
Very stiff and lightweight fishing rods and some golf shafts really do use high-modulus graphite fibers, often in combination with standard- and intermediate-modulus carbon fibers.

Although most of us deep in the industry call it carbon fiber, I’ve seen forums on fishing equipment sites where buyers are confused about terminology. In April of this year, I advocated here that we need a public relations effort to create more awareness
 of and provide education about composites among consumers. Perhaps something along the lines of the American Chemistry Council’s “Plastics Make It Possible” campaign would help. Maybe “Composites – Built to Last” or something like that?

An article in the May issue of CompositesWorld about composite foundation walls for residential housing made me want to go out and build a new house just to take advantage of what these panels offer in durability and energy efficiency — what an exciting development! Like the fiberglass-handled shovel, the cost of composite foundation walls is a bit more, so how do we help the producers of these innovative building solutions reach critical mass and generate pull from consumers, rather than depend
 on push through builders and contractors? This is what a strong public relations campaign could do for our industry.

And speaking of housing, I’ve come full circle. I’ve got some yard work to do around my current residence. Time to put that new shovel to use....