水镁石粉体表面改性及表面能测算

Surface Modification and Surface Free Energy Calculation of Brucite

水镁石粉体是聚合物的常用填料,但水镁石极性较大,与基材的相容性也较差,因此必须通过表面改性,降低水镁石粉体表面能,增强亲油疏水性,从而增加与聚合物之间的相容性,而阴离子表面活性剂是合适的改性剂之一。水镁石粉体改性后的表面性能,可以用固体表面能数值的变化来表征,本文选择丙三醇、水、1-溴代萘为探针液体,用直接测定法与Washburn方程间接计算法获得了改性前后水镁石的接触角,通过Lifshitz-van der Waals acid base三参数法计算其表面能。研究结果表明,不同的阴离子基团中,羧酸类、磷酸较之磺酸类硫酸类改性效果有明显优势,表面能的碱分量γ-S和酸分量γ+S降为0;随着改性剂中非极性链烃的碳原子个数增加,表面能非极性分量γLSW下降很多,最终导致总表面能下降,接触角增加,疏水性增强。

Brucite was often used as a filler in polymer materials.However,because of its strong polarity and poor compatibility with polymers,it was necessary to modify the surface of brucite before adding it.After modification,its surface energy decreased,surface hydrophobicity increased while the compatibility with polymers got improved.Anion surfactant was an ideal surface modification agent for brucite.Since the surface free energy could express the solid surface properties,it was studied to evaluate the modification effect.Water,glycerol,and 1-naphthalene bromide were chosen to be probe liquids.Contact angle of brucite was determined by direct determination method and indirectly by using Washburn equation,while the surface energy was measured by Lifshitz-van der Waals acid base method.The results show that carboxylic acid type and phosphoric acid type surfactants have an advantage over sulfoacid type and sulphuric acid type surfactants in terms of modification effect,polar electron donor γ-S and electron acceptor γ＋S components of surface free energy decrease to 0.With the increase of carbon number in anion surfactants,apolar γLWS component of surface free energy sharply declines,which finally leads to the decrease of surface free energy,the increase of contact angle and hydrophobicity.