Abstract: A fiber composition, along with a method for toughening fiber compositions, are described. A fiber composition contains at least three loops along the length of said fiber, wherein the loops are bonded using sacrificial junctions comprising a bonding material that is chemically distinct from the fiber material. In some preferred embodiments, the loops have a circumference of at least one centimeter, and the bonding material is an ultraviolet light-cured adhesive. When a suitable force is applied, one or more sacrificial junctions can break without breaking the continuous fiber. The fiber compositions described herein have a toughness that is many times greater than the toughness of otherwise equivalent compositions of the fiber material which lack any such loops.