Nucleation promoters/plasticizers

Other less common nucleation promoters/plasticizers for PET include V-ethyl-toluenesulfonamide and trioctyl trimellitate. 

The rate can be increased by applying other external modifications, solvents, plasticizers, or nucleation promoters. The extension of chain length... 

A number of organic pigments cause distortion in certain types of polyolefins, especially in HDPE. Pigments act as nucleating agents in such partially crystalline plastics i.e., they promote crystallization, which creates stress within the plastic product (Sec. 1.6.4.3). These pigments also enhance the shrinkage of polyolefins, particularly in the direction of the flow. 

In plastics, wear depends on adhesion and deformation of soft material. Frictional forces are proportional to velocity rather than load as in the case of metals. A number of additives can improve wear and slip properties. PTFE has lower friction coefficient than any other material. Additionally, its particles form a film on shearing surfaces thus decreasing friction. Its addition is very effective in high-pressure applications. Optimum additions are 20% in crystalline polymers and 15% in amorphous ones. Molybdenum disulfide is primarily used in PA compounds. It works as a nucleating agent, promoting increased crystallinity in PA, thus providing harder, more wear... 

Hence PBT is more commonly employed in the formulation of blends also. PBT has generally been preferred over PET in the engineering plastics industry because of its superior process-ability, faster crystallization rate, shorter molding cycles and better properties (DTUL/impact balance) in the molded parts, particularly in the unfilled form. Nevertheless, PET is also used primarily in glass or mineral reinforced form along with nucleators and crystaUization promoters. 

Adsorption-Enhanced Plasticity Models According to fractographic studies the cleavage fracture is not an anatomically brittle process, but occurs by alternate slip at the crack tip in conjunction with the formation of very small voids ahead of the crack. It is also thought that the chemisorption of environmental species facilitates the nucleation of dislocations at the crack tip, promoting the shear process responsible for brittle-like fracture (4). 

Nucleating agent, cell-control These agents promote symmetrical, cohesive expansion of cells within foamed polyurethane and polystyrene plastics also to a limited extent in polyethylene and polypropylene plastics. 

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