What are nucleating agents?

Nucleating agents are used with polymers that can crystallize in order to speed cycle times. After melting, it is solidification rate of the plastic into a useful shape that controls processing and cycle time.

What is function of nucleating agent?

Nucleating agents are used to improve processing speed, dimensional stability, and physical properties in molded or extruded products. In foamed products, they improve dimensional stability and density by helping to control the formation of gas cells in either gas injection or chemical foaming applications.

What effect does the nucleating agent have on the grain structure?

The results showed that at the level of the aggregation structure, crystallinity increases and spherulite size tends to decline with increasing nucleating agent. At the same time, the nucleating agent also has an effect on both the crystal grain structure and the unit cell structure.

What is non Isothermal crystallization?

A non-isothermal crystallization is generally carried out under continuous cooling conditions and the temperature–time relationship can be described as follows:(1) where Ti is the initial temperature and Ω(t) is a function of time. In the simplest case, , where χ=dT/dt is the constant cooling rate.

What are nucleating agents give examples?

Chemicals used as nucleating agents were multiwalled carbon nanotubes (CNT), from NanoLab, USA; carbon nanofibers (CNF), Pyrograf III, from Applied Sciences, USA; lithium benzoate (LiBe), with a melting point of ~370°C, from Micronisers Ltd., Australia; and 1,3:2,4-bis(3,4-dimethylbenzylidene sorbitol), Millad 3988 ( …

What is the meaning of nucleation?

Nucleation, the initial process that occurs in the formation of a crystal from a solution, a liquid, or a vapour, in which a small number of ions, atoms, or molecules become arranged in a pattern characteristic of a crystalline solid, forming a site upon which additional particles are deposited as the crystal grows.

What is primary and secondary nucleation?

Primary nucleation occurs in the absence of crystalline material of its own kind and is a stochastic process. Secondary nucleation is the birth of new crystals in the presence of parent crystals of the same substance.

What is an example of nucleation?

Examples of the nucleation of fluids (gases and liquids) Clouds form when wet air cools (often because the air rises) and many small water droplets nucleate from the supersaturated air. Bubbles of carbon dioxide nucleate shortly after the pressure is released from a container of carbonated liquid.

What is nucleation in simple words?

What are the methods of secondary nucleation?

C. 1 Mechanisms. Secondary nucleation can occur through several mechanisms, including initial breeding, contact nucleation (also known as collision breeding), and shear breeding.

What is primary crystallization?

“Primary crystallization” is used to indicate spherulite build up until impingement and involves primary crystals that are active at the spherulite growth front. The influence of the different crystallization steps on subsequent melting behavior is discussed as well.

Does nucleation require energy?

Nucleation energy is the required amount of energy for any chemical reaction to happen. Nucleation specifically changes the phase of any system, whereas growth rate is controlled by various parameters like heat, pressure etc. When a NP nucleates, then these external physical parameters determines its growth.