Polymer Processing and Material Properties: A Comprehensive Look

Posted on Feb 4, 2025 in Electromechanical Engineering

Polymer Forming Processes

  • Extrusion: Circulating granulated plastic inside a heated tube. The plastic mass is pushed out at one end of the tube, where it is given shape and cooled.
  • Blow Molding: A tube is extruded and enclosed inside a mold under pressure.
  • Injection Molding: Granulated plastic is circulated inside a heated tube. When the melt reaches the end of the tube, the screw is removed, and then the finished piece is ejected.
  • Foam Molding: The material is placed within a mold and heated. The plastic swells, occupying the entire volume of the mold, forming a solid but spongy mass.
  • Vacuum Molding: A mold with small channels for air circulation is used. A plastic sheet is placed on the mold and heated. Air is extracted using a vacuum pump, and the sheet, under pressure, is compressed against the mold, adopting its form.
  • Compression Molding: A two-part mold is used, one fixed and one mobile. The polymer is placed inside the fixed part, and the mold is closed. The material takes the form of the mold.
  • Calendering: Viscous material is circulated among rollers until it adopts the desired thickness and texture.

Artificial Wood

  • Plywood: Gluing sheets of natural wood together.
  • Particleboard: Formed from wood chips glued with synthetic resins and pressed.
  • TableX and MDF: TableX is made from pressed wet wood fibers without solvent. MDF is made using a dry process.
  • Laminboard: Made from softwood slats glued laterally with synthetic resins.
  • Natural Veneers: Obtained from tangential cuts of the trunk.
  • Synthetic Sheet: Made from synthetic resins.

Polymer Types

Thermoplastics

(Plastics that soften when heated and then harden when cooled, a process that can be repeated indefinitely):

  • Linear structure
  • Branched structure

Elastomers

(Exhibit elastic behavior without breaking):

  • Cross-linked structure

Thermosets

(Harden and cannot be re-softened):

  • Reticulated structure

Additives

  • Fillers: Minerals that improve mechanical strength and tenacity.
  • Plasticizers: Reduce the hardness and fragility of polymers, increasing ductility and tenacity.
  • Stabilizers: Increase resistance to ultraviolet radiation and oxidation.

Plastic Polymers (Plastics)

  • Thermoplastics: Can be molded repeatedly.
  • Thermosets: Break after one molding cycle.

Polymer Elastomers

(Very elastic)

  • Polyethylene: Cheap, flexible, tenacious, resilient, and an insulator against corrosion. Uses: Bags, cable coatings.
  • Polystyrene: Insulating, transparent, less resistant to moisture. Uses: Polystyrene foam.
  • Polyethylene Terephthalate: Resistant to traction, torsion, fatigue, moisture, acids, oils, and ultraviolet radiation. Uses: Sparkling drinks bottles.
  • Polypropylene: Light, tough, resistant to fatigue, bending, moisture, heat, and chemicals; also cheap. Uses: Food containers, garden furniture.
  • Polyurethane: Insulating, foamable. Uses: Insulation for refrigerators and houses.

Other Materials

  • Clay: Silica, alumina, impurities.
  • Refractories: Alumina, silica, magnesium.
  • Concrete: Portland cement, sand, and gravel.

Textile Fiber Properties

Resistance to traction, elasticity, uniformity, moisture absorption, insulation, softness to the touch, resistance to chemicals.