丁醛等离子体处理云母粉对其表面特性及与聚合物界面特性的影响

THE EFFECT OF PLASMA TREATMENT OF MICA POWDER ON ITS SURFACE CHARACTERISTICS AND INTERFACE REHAVIOR WITH LINEAR MACROMOLECULES

用电容耦合式等离子体聚合方法对云母粉进行丁醛等离子体处理,通过测定各种液体对密堆积云母粉的渗透速度,确定了液体在云母粉表面的接触角,估算了云母粉的表面张力及与典型线形聚合物的界面张力。结果表明,极性液体在云母粉表面的浸润性因处理而削弱,非极性液体的浸润性基本来变;云母粉表面张力由处理前的41.34(N·m^(-1)·10^(-3))下降到处理5min时的31.51和处理30min时的25.59(N·m^(-1)·10^(-3));处理对云母粉与线形聚合物界面张力的影响因聚合物而不同,但该界面张力的极性分量均因处理而减小。

Plasma treatment of fillers or reinforcements has become an important concern for scientists and engineers to improve performances of filled or reinforced polymer composites. The effects of the plasma treatment are not clear on the surface structure and properties of treated fillers and on the interface behavior of the treated fillere with macromolecules. In this work mica powder was treated by n-butyl aldehyde plasma of radio frequency at first. Then the apparent contact angle of different liquids on the powder was determined by measuring the penetration rate of the liquids through the packed powder. The surface tension of mica powder and interface tension between the powder and typical linear macromolecules were calculated from the obtained data of contact angle based on Fowkes' theoretical assumption. Three conclusions were shown as follows: (ⅰ) For polar liquids, wetting the treated mica is more difficult than wetting untreated one and for non polar liquids there seems no such a difference. (ⅱ) The surface tension of mica powder drops from 41.34 (N·m_(-1)·10_(-3)) to 31.51 after 5 min of the plasma treatment and to 25.59 (N·m_(-1)·10_(-3)) after 30 min of the plasma treatment. (ⅲ) The polar component of interface tension between mica powder and any linear macromolecule monotonically decreases with the plasma treating time. However, the whole interface tension changes with plasma treatment, depending on the polymer properties, It decreases for fluoropolymers of smaller surface tension with certain polar component and increases for poly (vinyl chloride) and polyamide of greater surface tension. For polyethylene and polystyrene with very small polar component of the surface tension, the interface tension decreases when the treating time is shorter but increases if the treatment is prolonged.