Abstract:5·1·7 type basic magnesium sulfate whiskers （5·1·7W ） were synthesized at room temperature using different active MgO and magnesium sulfate heptahydrate as raw materials， with sodium citrate as an additive. The whiskers were characterized using X-ray diffraction（XRD）， scanning electron microscopy（SEM）， transmission electron microscopy（TEM）， and thermogravimetry-differential scanning calorimetry（TG-DSC）. The prepared 5·1·7W was used to modify polyvinyl chloride （PVC）， and its effects on the mechanical properties and flame retardancy of PVC were studied. The results indicate that when the sodium citrate content is 3%， the seed crystal content is 2%， the mass fraction of magnesium sulfate solution is 10%-15%， and MgO with a specific surface area <45 m²/g is employed， high-purity monodisperse 5·1·7W whiskers with a diameter of 100-150 nm， length of 10-20 μm， and an aspect ratio of 66.7-200.0 can be prepared. After high-temperature calcination， 5·1·7W can be transformed into MgO whiskers. 5·1·7W exhibits excellent improvement on the mechanical and flame-retardant properties of PVC.
