| 摘要 |
A process for making load limiting yarn comprising making block copolymer and then spinning the block copolymer into yarn. The process employs a twin screw extruder and comprises (A) forwarding aromatic polyester melt to an injection position in a twin screw extruder, (B) injecting lactone monomer into the molten aromatic polyester, (C) dispersing the monomer into the aromatic polyester melt so that a uniform mixture forms in less than about thirty seconds, and (D) reacting the uniform mixture resulting from step (C) at a temperature from about 250° C. to from a block copolymer. Steps (A) through (D) occur in less than about four minutes residence time in the twin screw extruder. The process is advantageous because high IV starting aromatic polyester can be used and the short reaction time at high temperature results in block copolymer with minimum transesterification, a high melting point, and a high melt viscosity.
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