Sintering is a process that uses pressure and heat to improve the properties of a material. It is widely used in making items from metal, such as structural steel, self-lubricating bearings, and porous metals for filtering. The process can also be done with electrical currents.

Sintering can be applied to a variety of materials, including PTFE, and can increase their properties, such as their translucency and strength. In addition, it can be used to enhance the conductivity of materials. For example, PTFE can be densified at high temperatures, resulting in open holes that provide improved water contact.

Sintering of PTFE particles produces a three-dimensional network of small particles, surrounded by fibrils. The fibrils bind the PTFE particles together, which forms grains. After sintering, the grains become smaller and the pores are less pronounced. This leads to the membrane’s roughness and its hydrophobic qualities.

Extrudates made from FA and PTFE show a similar pore density, but the former has a higher vFA. PTFE particles begin to melt at lower temperatures than FA.

Comparative experiments were conducted to determine the heating rate and sintering temperature. At 340 degC and 360 degC, the particles still appeared on the fiber surface. However, at 390 and 380 degC, the sintering temperature was lowered, and the particles began to melt.

After sintering, the water contact angle of the PTFE/PVA membranes increased from 3:1 to 5:1. Moreover, the mass ratio of the PTFE/PVA component increased from 3:1 to 5:1, indicating that the sintering temperature is a significant factor in the formation of as-spun composite nanofiber membranes.

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