Plastic kaise paida hota he
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प्लास्टिक (Plastic), शंश्लेषित अथवा अर्धशंश्लेषित कार्बनिक ठोस पदार्थों के एक बड़े समूह का सामान्य नाम है। इससे बहुत सारे औद्योगिक उत्पाद निर्मित होते हैं। प्लास्टिक प्रायः उच्च अणुभार वाले बहुलक होते हैं जिनमें मूल्य कम करने या अधिक कार्यक्षम बनाने के लिये कुछ अन्य पदार्थ भी मिश्रित किये जा सकते है।
प्लास्टिक पदार्थ और प्लास्टिक (पदार्थों के एक गुण) अलग-अलग हैं। एक गुण के रूप में प्लास्टिक उन पदार्थों की विशेषता का द्योतक है जो अधिक खींचने या तानने (विकृति पैदा करने) से स्थायी रूप से अपना रूप बदल देते हैं और अपने मूल स्वरूप में नहीं लौट पाते।
We've already seen that plastics are made from polymers, but how are polymers made? They're based on hydrocarbons (molecules built from hydrogen and carbon atoms) that we get mostly from things like petroleum, natural gas, or coal. Crude oil drilled from the land or sea is a thick gloopy mixture that contains thousands of different hydrocarbons, which have to be separated out before we can use them. That happens in an oil refinery, through a process called fractional distillation. It's a more involved version of the distillation you might have used to purify water. If we heat water, it eventually turns into steam, which we can then collect, cool, and condense back to water; that's distillation, and it produces highly purified or "distilled" water. We can heat and distill crude oil the same way, but all those many hydrocarbons it contains have molecules that are different sizes and weights, so they boil off and condense at different temperatures. Collecting and distilling the different parts of crude oil at different temperatures gives us a bunch of simpler mixtures of hydrocarbons, called fractions, which we can then use for making different types of plastics8
Hydrocarbons made in this way are the raw materials for polymerization, the name we give to the chemical reactions that make polymers. Some polymers are made simply by fastening hydrocarbon monomers together, like daisy chains, which is a process called addition polymerization. Others are made by joining together two small hydrocarbon chains and removing a water molecule (two hydrogen atoms and one oxygen), making a bigger hydrocarbon chain in a process known as condensation polymerization. The more often you repeat this, the longer the polymer gets.
Typically, we need to use other chemicals called catalysts to kick-start polymerization. Catalysts are simply substances we can add that make a chemical reaction more likely to happen and, though they may change temporarily during the reaction, they re-emerge at the end in their original form; in other words, they're not permanently changed as the reaction takes place. Ziegler-Natta catalysts, some of the most important for making polymers, were developed through the work of German chemist Karl Ziegler and Italian Giulio Natta, which won them a joint Nobel Prize in Chemistry in 1963.
Because we need plastics to do all sorts of things, we often have to add other ingredients to the basic hydrocarbons to produce a polymer with exactly the right chemical and physical properties. These extra ingredients include colorants (which, as the name suggests, turn plastics into all kinds of bright and happy colors), plasticizers (which make plastics more flexible, viscous, and easier to shape), stabilizers (to stop our plastics breaking apart in sunlight and heat), and fillers (typically low-cost minerals that mean we need less of the expensive, oil-based hydrocarbons to make our final plastic product—so we can make and sell it more cheaply).