PVC, or Polyvinyl Chloride, is a widely used thermoplastic polymer. It is the third-most-produced plastic, after polyethylene and polypropylene. PVC is valued for its durability, resistance to environmental degradation, and versatility, being used in a variety of applications from construction materials like piping and window frames, to medical devices and clothing. It exhibits excellent water resistance and insulation properties, making it ideal for electrical cable insulation and plumbing solutions. PVC can be made softer and more flexible by adding plasticizers, the most famous being phthalates. This adaptability allows it to serve in both rigid forms, such as in pipes and window frames, and as a flexible material in products like cables and vinyl flooring. However, its production and disposal raise environmental concerns due to the release of toxic chemicals, leading to ongoing research for more eco-friendly alternatives.

Reducing ink density in Adobe InDesign is essential for avoiding saturation and ensuring print quality, especially on absorbent paper. To adjust this, you can use the 'Ink Manager,' accessible from the 'Swatches' panel or during the prepress process in the 'Print' dialog box. Here, you can limit the total ink coverage by adjusting the 'Total Ink Limit' settings, often required not to exceed 280%-300% for standard printing conditions. Another method is through color management and conversion by modifying individual color channels in your document's color settings, ensuring that the output uses less ink. Using lighter colors and adjusting the opacity of objects and images within your document can also indirectly reduce ink density. Remember, these adjustments might alter the appearance of colors, so always preview your changes and, if possible, conduct a print test.

In English, "emulsion" refers to a mixture of two or more liquids that are normally immiscible, meaning they do not mix or blend together under normal circumstances. This mixture is achieved by dispersing one liquid in another in the form of very fine droplets. An example of an emulsion is mayonnaise, which is an emulsion of oil in vinegar, stabilized with egg yolk. Emulsions are commonly used in various industries, including food, cosmetics, and paints, owing to their capacity to blend ingredients that would otherwise separate. The process of creating an emulsion often requires an emulsifying agent to stabilize the mixture and prevent the liquids from separating. Emulsions can be either oil-in-water (where oil is the dispersed phase and water is the continuous phase) or water-in-oil (where water is the dispersed phase and oil is the continuous phase), depending on their composition and intended use.