Why Heat Shrink Sleeve Longitudinal change Matters

1. Heat shrinkable material

Plasticity linear polymer or polymer alloy as base material , with high-energy radiation or chemical method to make the polymer chains become partially cross-linked network structure to obtain the elastic "memory effect" , after heating expand become a certain cooling setting. When heated to a certain temperature, the tube will shrink to the pre-expansion shape and size. This material called heat shrinkable material.

2. Heat shrinkable sleeve

The above polymer or a polymer alloy obtained by extrusion molding to a predetermined size tubular intermediate product, irradiation ( or chemical ) crosslinking and then heat expansion and cooling to get a certain size heat shrinkable sleeve.

3. The definition of longitudinal change

Through the center perpendicular to the plane of the circle is called the axial direction (tube axis direction).When shrinking, the axial direction length is the longitudinal change.

4. Reasons of longitudinal change

In heat shrink Busbar sleeve expansion processing, the inner diameter becomes larger, will generate a pulling force at both ends. If the expansion processing is not properly controlled, it can lead to sleeve severely unnormal contraction. Longitudinal change is a key standard to measure whether the heat shrink busbar sleeve is qualified or not.

5. How to calculate longitudinal change:

Formula: S = [(Lo-L) / Lo] × 100%

ΔS = (max-Lmin / Lo) × 100%

Explain as follows:

S --- Shrinkage rate, including vertical and horizontal shrinkage rate

ΔS ---Shrinkage rate tolerance

Lo---- Length or flat width before shrink

L --- Length or flat width after shrink

Lmax --- Maximum length or flat width after fully shrink when testing sample

Lmin --- Minimum length or flat width after fully shrink when testing sample