Heat Treatment Conditions For Optimal Polyethylene Crystallization

Ceramic materials are known for their strength, yet they are vulnerable to surface cracking, which causes internal structural weakness. Given the ductile nature of polymers, a composite may be designed to combat the ceramic's brittleness with the addition of only a small polymer fraction. The composite of focus is high-density polyethylene (HDPE), a semicrystalline polymer, coprocessed with wollastonite (CaSiO?), which will then undergo gas reactive hydrothermal liquid phase densification (g-rHLPD) and heat treatment processing.

During heat treatment, the polymer component experiences a phase transformation, assuming some amount of crystallinity, which is dependent on the rate of cooling. Therefore, in the range of 125–150 °C, there may exist a temperature of heat treatment that produces a maximum amount of crystallinity, corresponding to the energy required for optimum phase transformation.

The thermal behavior of HDPE in particle sizes of 10–100 µm and 100–300 µm is analyzed with differential scanning calorimetry. For 10–100 µm HDPE, there was a maximum of 75.2% crystallinity observed at 140 °C, and for 100–300 µm HDPE, there was a maximum of 68.1% crystallinity at 130 °C.

Different quantities of crystalline polymer may affect not only the toughness, but also the strength of the ceramic. To study this relationship, samples of the material for each polymer in multiple compositions will be evaluated at various heat treatment temperatures. Compressive strength testing is used to observe the yield strength and deformation behavior, where it is hypothesized that the largest strength will be demonstrated in the samples that have been heat-treated at a temperature that ensures maximum crystallinity.