3. Results and discussion
3.1. Density and water absorption
The measured densities of the PC-mix, PVC-mix, and PS-mix
composites were 1.0, 1.03, and 0.87 g/cm3, respectively. The corresponding
values of natural hard wood, soft wood, and MDF were
0.66, 0.47, and 0.71 g/cm3 (see Table 3). The differences ranged
from 45% to 80%. This primarily depends on the specific gravities
of its ingredients’ interaction and their proportional formulation.
During the extrusion process, the moisture in the natural cellulose
fibers creates steam and vapor while plastic decomposition produces
a volatile organic compound at high melting temperatures,
leading to the development of internal air voids and porosity (see
Fig. 3)