PET Bottles

Clifford's Main Rocket Page Home Page
PET Bottles are formed by molding plastic into "preforms", which are heated and blown into molds (usually at the bottling plant). Here are some preforms:


Some bottles are mono-layer, and some are multi-layer (bottles made from recycled material are usually multi-layer). This affects the way they fail in water rockets - the new symmetrical splice that folk are using prevents the most common failure when using asymetrical splices, which is caused by shear forces between the layers.


PET is somewhat porous, and is etched severely by acid-cure silicones. Bottling plants have a quality program aimed at minimising the amount of material which goes into the bottles while still maintaining an adequate shelf-life (the fizz is gradually lost through the plastic).

Crystallising PET

PET plastic which is warned to the optimum temperature of about 94 degrees Centigrade can crystallise. The plastic goes opaque, becomes more brittle, and is stronger.

Clifford's Home Page