Almost Uncharted Areas of Composite and Plastic Rheology

ALMOST UNCHARTED AREAS OF COMPOSITE AND PLASTIC RHEOLOGY 

Effect of Particle Size of Filler on Rheology of Wood—Plastic Composites Very few studies were published regarding the effect of particle size of wood fillers on rheology (e.g., a conference poster [34]). Tables 17.14-17.16 show the data. 

As one can see, there is no dependence of rheological behavior of the hot melts on species of wood fiber in this particular case. As a result of transition from 60% HDPE to 40% HDPE, viscosity of the hot melt increased by 2.6-3.2-fold, and the composite became significantly more sensitive to a change of the shear rate (the power-law index has noticeably decreased). 

with the increase of the wood fiber content, viscosity increases and the power-law index decreases. The viscosity of the hot melt becomes more sensitive to fluctuations of the shear rate hence, the higher might be fluctuations of pressure of the hot melt, the easier the hot melt can overshoot the critical shear rate, leading to rough profiles, sharkskin, and surface rupture (see below). 

TABLE 17.15 Effect of origin (species) of wood filler (40 mesh in all cases) in 40% wood liher-60% HDPE and 60% wood fiber-40% HDPE on rheological properties of the composite system 

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