Shrinkage of polyester

Figure 8-6. Free shrinkage of Figure 8-5. Free shrinkage of polyester polyester filament yam (medium...

The primary motivations for blending the thermoplastic polyesters with other polymers are (a) to improve the solvent resistance and process-ability of amorphous polymers such as PC, styren-ics, PPE, etc., (b) to reduce the mold shrinkage of polyesters associated with their crystallization,... 

Fig. A shows the effects of CoOc and MEKPO contents on setting shrinkage of polyester resin concrete. The setting shrinkage increases with rising contents of CoOc and MEKPO. In particular, the shrinkage is remarkably affected by MEKPO (catalyst) content rather than CoOc (accelerator) content.

Figure 5. Relationship between curing time and setting shrinkage of polyester...

Fig. 10 shows the comparison of data on setting shrinkage of polyester resin concrete determined by the experimental automatic apparatus and embedded strain gages. 

The setting shrinkage of polyester resin concrete increases with a rise in contents of catalyst and accelerator, and is markedly affected by catalyst content rather than accelerator content. 

The shrinkage of polyester resin concrete decreases with increasing content of styrene contained in its binder. 

A partially crystalline polymer that is not fully crystallized during processing will shrink when heated to a certain temperature. When the chain mobility is increased enough for the chain to begin to form into crystallites, the polymer will shrink, since the crystallites occupy less volume than the amorphous regions. This behavior can be seen if one heats a nonoriented PET or nylon film. Most often it is associated with nonpackaging applications like the shrinkage of polyester fabrics when washed in water that is too hot. 

BS 2782, Method 644A. Determination of total volume shrinkage of polyester and epoxide ca.sting resins. 1979. 

Neubert, C., Effect of Colorants on the Shrinkage of Polyester, Society of Plastics Engineers, Tech. P ers ANTEC 94,... 

Figure 11.21. Shrinkage of polyester film plasticized with variable amounts of octyl epoxy soyate at different shrinking temperatures. [Data from US Patent 5,589,126.]...

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