A lot of people know these things, but I thought this summary might be useful for people new to the game or coming back after a long layoff. I should mention that I have played with a Butterfly Viscaria since 2007. I have played since I was a kid (with a couple of decades off after I started university) and have maintained a pretty reasonable standard of play. I am a pretty generic offensive-style table tennis player. But I am not a pro or anything like that.
When blades with carbon layers first came out, they were all quite fast by design and generally had a hard and glassy feel. The carbon weaves used were thicker and denser. The classic example of this would be a Butterfly Sardius. Nowadays, though, the presence of a composite layer does not necessarily mean that the blade is super fast, although they I don't know of any that are super slow.
The trend now is that a pure carbon mesh is crosswoven with some other polymer material. There are several of these, the most popular of which are Vectran (which Butterfly calls Arylate), Kevlar (and other similar aramids), and Zylon (which are often colored, blue or yellow). Some blades will actually have ONLY the polymer material (for example Butterfly markets various ZL blades which only have Zylon, and used to make several blades that only had Arylate, such as the Keyshot and the Moonbeam). Those blades are generally slower and often feel "softer" (I find them quite strange usually, for example the Butterfly Photino, the first example of a Zylon blade). There are also different ways of making the weave, for example Stiga uses pure carbon weave that is called Textreme that definitely feels different from other pure carbon blades. Butterfly uses different kinds of carbon weaves also. More on that below.
The blade companies don't actually make the composite layers, they buy these materials from other companies that use complex computer-controlled weaving machines to make them and are constantly developing new materials of this sort. They can vary the thickness and geometry of the weaving patterns (for example the uniaxial carbon weaves that were popular for awhile). They can use thick or thin fibers to make the weaves. The possible variations now are endless, just like anything else that is woven. You can see more here.
http://www.carbon.ee/en/n/carbon-fiber- ... -explained Table tennis blades are probably only a miniscule portion of the market that these composite companies sell too. They are used to make sails, ropes, bicycles, etc. etc. There are also competing companies selling different weaves from the same material. So, two companies that make an arylate-carbon blade may actually be buying the weave from different companies, and this could impact in some subtle way how the blade plays. This could also cause a change over time if a company changes the source of their composite, perhaps to reduce costs.
Because of the number of composites now, it is hard to generalize too much, but one big thing is that blades that contain Arylate or Zylon or Kevlar do not vibrate as much at high frequencies. A table tennis blade is like a musical instrument in that it vibrates simultaneously at many frequencies when the ball strikes it. (You could say that every blade has a timbre as well as a pitch to put it in musical terms, which is why a violin and a flute sound different even when the play the same note). So a big effect of those fibers is that it tends to "buzz" less and has a more "muted" feel. There is some technical information about why that is. I can dig up if someone wants to read the more engineering aspect of it. It has to do with the compressiblity of the fibers if I remember correctly (and I may not). Here is information on this for Vectran.
http://www.vectranfiber.com/properties/ ... n-damping/
A second effect is that nearly all composites tend to reduce the number of dimensions in which the blade vibrates at lower frequencies (flexes) and so this gives it the sensation of having a larger "sweet spot" when you hit the ball off-center. The presence of the composite layer can make the blade stiffer (meaning less low frequency vibration in all dimensions, or, as we might call it, less flex). That can give the sensation of a faster and perhaps less spinny blade. However, this can be compensated for by changing the shape of the neck region, making it a bit narrower, or even the overall size of the head of the blade (larger flexes more). Of course, one can also make the blade thinner. overall. Also, this effect of the composite is often less marked in a lot of newer blades because the carbon layers being used are spun from thinner fibers, and also, it depends a great deal on the weaving pattern that was used to make the composite layer. Some people think you get information from the very high frequency buzz that all wood blades can give, other people don't like that feel and find it distracting. I think it is a question of taste. I don't like a buzzy blade personally.
How close to the surface the composite layer is located matters a lot. Closer to the surface magnifies the effect. Carbon layers that are deeper in the blade play more like all wood. Deep composite layers are found in, for example, Butterfly Innerforce blades, and some of the very expensive DHS blades used by players like Ma Long. My blade, the Viscaria, has an ALC layer quite close to the surface.
In the year 2017 we are playing with heavier ball than at any time in the history of the sport. Back when carbon blades were first introduced, we still used 38 mm balls. Nowadays, probably >90% of top-level shakehand offensive players will use some sort of composite blade. Defenders tend to still use all-wood, but (but the Matsushita Pro Special blade was a carbon-arylate). I would suggest that this means that composite blades are probably useful to more players than before.
The composite material is only one of many things that matter. Actually people need to remember that the blades are still mostly wood. The thickness, shape, type of wood, and the luck of the day have a huge impact on how a blade plays -- still bigger than the composite layer. There are sticky threads here at OOAK to explain how the different kinds of woods impact the playing properties. The weight matters a lot (I personally like blades that are 90-92 grams). The handle shape matters A LOT, and people underestimate the importance of that. All-wood blades can be really fast and stiff (for example, the Butterfly Masunov) and composite blades can be slow (Butterfly Timo Boll Spark). No two things made of wood are ever identical, so two blades of the same model can be a bit different. I own several Viscarias, and one is just a lot better than the others (although none are bad). Carbon has made it possible to reduce the weight of very fast blades.
Should you use one? It is possible to get the impression at OOAK forum that you should never ever use a composite blade unless you are some sort of pro player -- certainly better than anyone who posts here -- and that to do so is the height of folly or the work of Satan. (That is a slight parody of an extreme view). I think that it is definitely not the case if you are trying to play a fairly standard offensive style of modern table tennis. A less extreme view is that you cannot learn proper technique unless you learn with a slow blade. Yes, there is a lot of truth there, but the question is at what level might a switch to a composite be a reasonable thing? And I am not sure there is one hard and fast answer for all people. Kids can definitely switch to composite at a lower level than adults and still progress.
As always, if money is an issue, you should probably not buy a blade you have not had a chance to hit with, perhaps a clubmate has one you could try for a few moinutes.
Here are some acronyms: ALC means carbon-arylate weave (remember arylate is another name for Vectran). ZLC means zylon-carbon weave. AL means only arlyate. ZL means only zylon. TBS is the Timo Boll Special (edit added, should be Spirit), one of the most popular ALC blades of all time, others being the Viscaria, the Iolite). Later Butterfly came out with the Timo Boll-ALC, similar to the TBS but with a slightly different handle shape. Later Butterfly came out with a Zhang Jike ALC blade (with a blue dragon on it) and jst a year or two later discontinued it to introduce a whole series of Zhang Jike composite blades (with black handles), including ZLC, ALC, super ZLC verions, etc. Zhang Jike does not use any of them, and prefers to use the Viscaria. The Timo Boll blades can also be bought with about every possible different composite.