Shrinkage during the Carbon Fiber Process

Line shrinkage in the carbonization stage is, nominally of the order 5-8%, and determined thus  

Drive speed (Exit oxidation) — Drive speed (collection) Drive speed (Exit oxidation) 

A low shrinkage value signifies a high fiber tension. If the tension is too high, then the fiber will break, and if it is too low, then the increased fiber catenary will permit the fiber to drag along the furnace floors, degrading the fiber cosmetics. 

Bahl and Mathur [64] established that for a 6k 1.5 denier Toho Beslon PAN (with 3% MA) oxidized for 100 min at 240°C and subsequently heat treated to 1000°C, the best carbon fiber properties were attained with a shrinkage of about 7%. A Toho Beslon [55] patent, however, suggests a shrinkage of 40-70%, whilst a Japan Exlan [65] patent quotes 0-50%. 

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