LilySilk 22 Momme Oxford Silk Pillowcase AUJSP22

Doubting the purity of silk – My silk sheets have pilled with less than 6 times usage. I would not expect a pure fabric to pill, it usually happens when it has some content of synthetic??? I have quite an amount of silk from other brands including silk pillowcases and clothing that have had far more wear without pilling. Disappointed in this brand.