States of Aggregation in Polymers – Introduction
- by Chun Do
In the posts on “The Chemical Nature of Plastics,” various methods of synthesizing polymers were briefly discussed. This chapter will delve into the physical states of aggregation of these polymers, while the three subsequent chapters will explore the effect of molecular structure on the properties of polymers. Simple molecules, such as water, ethyl alcohol, and […]
Read MoreThe chemical nature of plastic – CONDENSATION POLYMERISATION
- by Chun Do
In this form of polymerisation, initiation and termination stages do not exist and chain growth occurs by random reaction between two reactive groups. Thus in contradistinction to addition polymerisation an increase in reaction time will produce a significant increase in average molecular weight. An increase in temperature and the use of appropriate catalysts, by increasing […]
Read MoreThe chemical nature of plastic – ADDITION POLYMERISATION (Ionic Polymerisation) – Part 2
- by Chun Do
Let’s continue with the remaining part. Please refer the previous part here. Anionic polymerization, under precise control, can yield a nearly monodisperse polymer sample, where all molecules have the same size. This is in contrast to free radical polymerizations, which, due to the randomness of initiation and termination, result in polydisperse polymers with a wide […]
Read MoreThe chemical nature of plastic – ADDITION POLYMERISATION (Ionic Polymerisation) – Part 1
- by Chun Do
Several significant addition polymers are manufactured through ionic mechanisms. While the procedure encompasses initiation, propagation, and termination stages. The developing unit is an ion rather than a radical. The electron distribution around the carbon atom (marked with an asterisk in Figure 1) in a growing chain can exhibit various forms. In Figure 1(a), there’s an […]
Read MoreThe chemical nature of plastic – Polymerization kinetics
- by Chun Do
Polymerization kinetics will be briefly discussed here to highlight key technological points. Due to the complexity of the topic, certain simplifications will be made. Readers interested in a more in-depth understanding of polymer chemistry kinetics should consult more comprehensive studies.In a straightforward free radical-initiated addition polymerization, the primary reactions include (assuming termination by combination for […]
Read MoreThe chemical nature of plastic – ADDITION POLYMERISATION
- by Chun Do
Addition polymerization links vinyl monomers by activating their double bonds, following a chain addition process with initiation, propagation, and termination steps. The initiation phase can be triggered by either free radical or ionic systems. Here, we’ll focus on a free radical system. A substance that decomposes into free radicals through warming, the presence of a […]
Read MoreThe chemical nature of plastic -THERMOPLASTIC
- by Chun Do
In all of the examples given so far in Introduction, the result of polymerization yields long-chain molecules known as thermoplastics. These materials can flow, becoming essentially plastic, above a specific temperature when molecules can slide past each other due to sufficient energy to overcome intermolecular attractions. Below this temperature, they behave like solids. Thermoplastics are […]
Read MoreThe chemical nature of plastic – Introduction
- by Chun Do
Defining ‘plastics materials’ precisely can be challenging and may not yield significant value. Still, it’s useful to examine the chemical structure of common polymers, which all share the feature of consisting of large molecules. When considering certain naturally-occurring substances like bitumen, shellac, and amber, their compositions are intricate and varied. However, in all other instances, […]
Read MoreOther Thermoplastics Containing p-Phenylene Groups
- by Chun Do
The successful development of poly(ethylene terephthalate) fibres such as Dacron and Terylene stimulated extensive research into other polymen containing p-phenylene groups in the main chain. This led to not only the now well-established polycarbonates (see Chapter 20) but also to a wide range of other materials. These include the aromatic polyamides (already considered in […]
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