We have two types of polymers, high-density polyethene and polypropylene, with voids forming in the material. We observed the void at the cross-section of the material. The material is a recycled polymer, which we melted and reshaped in a moulding by cooling the polymer at room temperature. Is there a relationship between the coefficient of thermal expansion and the void formation in a thermoplastic material?
Shouldn't the the voids volume expand by the same coefficient as the solid polymer?
The relaxation time and initial stress parameter significantly affect the displacement, stress, temperature change, and volume fraction field distributions in initially stressed thermoelastic half-space with voids due to thermal source. The optimal flow velocity changes non-linearly with respect to fabric anisotropy and the preferable flow direction, affecting inter-bundle void formation in HDPE.
Void formation in HDPE is related to irregularities in the grain-boundary structure of films, and the rate of observable hole formation is accounted for by either void growth at a grain-boundary triple-point junction or by grain-boundary grooving. The predictive model for volatile-induced void formation in thermoplastic polymeric materials incorporates material properties, processing conditions, and part thickness to predict void growth.
Particle size, density, gas flow rate, bed height, and model width affect void formation and breaking in a packed bed, and correlations have been proposed to predict void formation and breaking. Voids have complex internal structure and dynamics, with a hierarchy of structures in the density field and velocity field. Hot-compaction of polypropylene and polyethylene composites significantly alters their thermal expansion behavior, with mechanical and thermal anisotropy being most pronounced in polyethylene composites.
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