Post-shrinkage

In addition to mechanical reinforcement, LCP addition improved the dimensional stability and thermal resistance of the PP matrix. The former appeared as remarkably reduced post-shrinkage and lower linear thermal expansion coefficient, the latter as significantly increased heat deflection temperature (HDT). The HDT values increased from the level of 52°C for neat PP to 78°C for PP/LCP 70/30 and 110°C for 50/50 blends. Even greater improvements were found for blends with another, copolyesteramide-type LCP (Vectra B950) the HDT value for PP/ 30wt.% B950 was as high as 132°C [4]. 

Mold shrinkage a) injection b) compression and post shrinkage % DIN 53464 [37]... 

The molding shrinkage increases with increasing cavity temperature. Lower cavity temperatures reduce the molding shrinkage, but also increase uncontrollable and undesirable post-shrinkage. 

After painting the sample parts, surfaces can be judged the shrinkage that is brought into the mold can be checked for accuracy after the post-shrinkage and painting process. In short, with the first components from the manufactured mold, there are numerous operations that deal with the comparison between the intended original... 

Annealing is the heat treatment of molded plastic parts subsequent to their processing in order to release residual stresses, in particular in thick-walled molded parts, and to initiate post crystallization in less-than-optimally crystallized molded parts. Annealing can lead to warping in the molded part caused by stress release and post-crystallization. Post-crystallization always leads to dimensional reduction (post-shrinkage), but on the other hand, it increases density and hardness [502]. 

Shrinkage Processing shrinkage 0.2-2.5%, depending on type and component. Post shrinkage decreases as processing shrinkage increases. 

Shrinkage Immediate mould shrinkage 0.5 to 0.9% in flow direction 0.7 to 1.1% normal to flow direction Post shrinkage Up to 0.4%... 

Shrinkage Processing shrinkage and post shrinkage are practically zero... 

In the labeling market, hot melts provide the capability to bond non-porous films to plastic cans and bottles. Hot melt usage has grown with the prevalence of such plastic to plastic laminations. The choice of hot melts depends on the equipment, the substrates, whether the bottles are filled or unfilled, and any post-labeling processing (e.g. pasteurization, or heat shrinkage of the film). 

Combination of the results with solvent extraction/liquid chromatography data may elucidate the role of free, unreacted monomer in the post-curing process. The main conclusions have already appeared elsewhere (9). Here we report in much more detail on the experimental techniques as well as on new results on the delay of shrinkage with respect to chemical conversion. 

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