Effect which PVC heat Stabilizer has on the transparency of PVC products is determined by main factors as below:-
1. Refractive Index of PVC Heat Stabilizer
If PVC heat Stabilizer has the same or similar visible-light refractive index of 1.52~1.55 as PVC Resin, PVC finished products will have higher transparency, on the contrary, it will be lower.
2. Linear Length of PVC Heat Stabilizer Molecule ( Molecular Group )
If linear length of PVC Stabilizer molecule ( molecular group ) is smaller than that of visible wavelengths 400~735nm, it will have less refraction to visible-light, thus having better transparency, on the contrary, it will be lower.
3. Compatibility of PVC Heat Stabilizer with PVC Resin
Compatibility means the mutual affinity between two blended materials. Good compatibility may result in molecule-level dispersion. PVC Heat Stabilizer has excellent compatibility with PVC Resin under melting condition, thus not causing two phase. Compared with solid metallic soap type heat stabilizer, liquid PVC Stabilizer has better compatibility and relatively smaller linear length, so PVC finished products will have a better transparency.
Liquid organo-tin Heat Stabilizer will make PVC finished products have the best transparency. While Ba-Zn, Ba-Cd and Ca-Zn Stabilizer have limited compatibility and relatively big linear length, it will affect the transparency of PVC finished products.
Di-basis Lead Phosphite and Tri-basic Lead Sulfate have bad compatibility with PVC Resin and big molecular group, so it is used to manufacture non-transparent products.