PVC, or Polyvinyl Chloride, is a versatile plastic with a variable hardness level that can be adjusted through the addition of plasticizers. In its pure form, PVC is rigid and hard, classified as uPVC (unplasticized PVC), commonly used in construction for pipes and window frames due to its durability and resistance to environmental degradation. The hardness level of PVC is measured on the Shore hardness scale; rigid PVC often falls within the range of 70-100 on the Shore D scale, indicating a high level of hardness. However, with the introduction of plasticizers, PVC can become flexible and soft, used in applications like cables and clothing. Thus, the hardness of PVC can vary widely depending on its formulation, catering to a broad spectrum of uses.

When choosing a polymer, consider application requirements, environmental exposure, and processing methods. Polymers are broadly categorized as thermoplastics, which soften when heated and harden when cooled, and thermosets, which irreversibly set upon heating. For mechanical applications requiring stiffness and strength, consider high-performance polymers like PEEK or PAI. For chemical resistance and temperature stability, fluoropolymers (PTFE) and silicones are ideal. Electrical insulation benefits from materials like PVC and polyethylene. Biocompatibility is crucial for medical devices; silicone and PEEK are often used. UV exposure can degrade some polymers, necessitating additives or coatings. Sustainability and recyclability are growing concerns, favoring bioplastics and materials with good recycling rates. Processing techniques also influence selection; injection molding suits thermoplastics, while thermosets excel in compression molding. Evaluate cost, performance, and sustainability to make an informed choice.

Young's modulus, often referred to as the elastic modulus, is a measure of the stiffness of a material. For polypropylene, a common thermoplastic polymer, Young's modulus typically ranges from 1300 to 1800 MPa, demonstrating its relatively flexible nature compared to more rigid plastics or metals. This variability can depend on the molecular orientation and processing method of the polypropylene. Understanding the Young's modulus is crucial for engineers and designers who utilize polypropylene in applications where flexibility and strength are key concerns, such as in automotive parts, containers, and packaging. Adjustments in the polymer processing can alter its mechanical properties, including Young's modulus, to suit specific application requirements.