Polartec has decided to close its factory in Lawrence, Massachusetts, moving its operations to its other plants in Hudson, New Hampshire and Cleveland, Tennessee. The latter was acquired by Polartec in September from United Knitting. The Lawrence factory had been rebuilt by Malden Mills 20 years ago, after being devastated by fire. Polartec's new owner, Versa Capital, says the plant had become increasingly expensive to operate, as it has been only using 25 percent of its capacity in better years. More than 200 workers will be affected by the decision.