Eight standard polyacrylic acid ( paa ) samples with different molecular mass were obtained via an isothermal precipitation grading method by using dioxane as solvent and petroleum ether as precipitator .
以二氧六环为良溶剂，石油醚为沉淀剂，通过等温沉淀分级，制得8种不同分子量的聚丙烯酸标样。
It said that formaldehyde and 1,4 dioxane , chemicals found in small amounts in baby-care products , including those by j & j and sold world-wide , are known to cause cancer in animals .
