Showing posts from May, 2022

Classification of Natural Dyes

Classification of Natural Dyes Dyes which are obtained from natural resources like plants, animals, and minerals are known as natural dyes .  So, natural dyes can be further classified into three types. 1. Natural Dyes obtained from Plants Dyes that are obtained from plant sources like roots, berries, bark, leaves, and wood are known as plant-based natural dyes .  For example, Logwood, Indigo, Henna, etc. They are also known as vegetable dyes and can be applied directly or with different mordants. 2. Natural dyes obtained from Animals Dyes that are obtained from animal sources like insects and invertebrates are known as animal-based dyes. Various shades of red and purple colors can be obtained from animal origin.  Cochineal, Tyrian Purple, and Lac are some common examples of animal dyes. 3. Natural dyes obtained from minerals Dyes that are obtained from mineral sources are called mineral dyes. They are produced by the metallic ions in the mordant salts.  Shades of the dye depend upon

Edible Dyes: Definition, Types, Properties and Applications

Definition of Edible Dyes Dyes that impart color when it is added to food or drink and can be consumed, are known as edible dyes . They come in many forms like powders, gels, and pastes and can be used in drinks, cookies, candies, etc. Types of Edible Dyes Based on the source, edible dyes are further classified into two types is Natural edible dyes and Synthetic edibles dyes. 1. Natural Edible Dyes Dyes that are obtained from natural sources like plants, leaves, flowers, seeds, roots, and animals are called natural dyes. Since they are obtained from natural sources, so there will be no harm to use natural edible dyes in preparing attractive food. Natural edible dyes also contain vitamins that are very essential for the body. Adding these ayes in food does not affect the taste of food and makes the food look more attractive. Examples of natural edible dyes are Annatto, Turmeric, Carmine, Paprika, etc. 2. Synthetic Edible Dyes Dyes that are obtained from petroleum-derived substances a

Vulcanization of Rubber: Definition, Properties and Applications

What is Vulcanization of rubber ? As we know that, natural rubber is soft and sticky and becomes even more so at high temperatures and brittle at low temperatures. Also, it is not resistant to the action of organic solvents and can be easily attacked by oxidizing agents.  So, to solve this problem, Charles Goodyear in 1839, found a process called Vulcanization , which can improve the physical and chemical properties of rubber. Vulcanization is a process that consists of heating raw rubber with sulfur at 373-415 K temperature. Since this process is slow, therefore additives like zinc oxide are used to accelerate the rate of vulcanization. During vulcanization, sulfur bridges or cross-links between polymer chains are introduced either at their reactive allylic positions or at the sites of the double bonds.  These cross-links make rubber hard and stronger and remove the stickiness of natural rubber because the individual chains can no longer lip over but are instead locked together in