Study of Scratch Resistance of Polyethylene and its Composite Reinforced with Nano-Sized Calcium Carbonate

Subject Areas : journal of New Materials

N. Bazobandi ¹ , S.M Zebarjad ² , S.A. Sajadi ³

1 - کارشناس ارشد مهندسی مواد دانشگاه فردوسی مشهد
2 - استاد دانشگاه فردوسی مشهد
3 - استاد دانشگاه فردوسی مشهد

Received: 2014-01-04 Accepted : 2014-01-04 Published : 2013-12-22

Keywords: Polyethylene, Nano-sized calcium carbonate, Film swface deformation, Scratch,

Abstract :

In this study, scratch test was performed at different conditions to examine the effects of calcium carbonate on scratch resistance of polyethylene (PE). To do this, PE reinforced with different content of nano-sized calcium carbonate (0, 5, 7.5 and 10 wt.%) were produced. The samples of PE and PE-10%CaCO₃ recrystallized in toluene solvent to study their microstructures using potassium permanganate solution as etchant. Nanocomposite samples were scratched by a conical indenter at the normal loads of 5, 15, and 25 N and scratch speed of 1 mm/s. In order to represent the materials resistance to scratch deformation, the scratch hardness of each sample was calculated. The scratch groove of some samples was examined by scanning electron microscopy (SEM). The microstructures illustrate that the reinforcement of polyethylene with calcium carbonate causes the decrease the average diameter of spherulites. The results of scratch test indicate that the scratch hardness is increased by increasing CaCO₃% for all normal loads; although for small normal loads, this positive effect is much higher than that of big loads. The deformation mechanism of PE and PE-CaCO₃% is ductile ploughing and this is similar at the loads which are smaller than 25N. However, it is fish-scale for PE and plastic drawing for PE-10%CaCO₃ at the load of 25N.