PVC Degradation mechanism reactionn.pptx

degradation

1. PVC Degradation formed unsaturated C =C double-bonds and thus the polymer backbone degrades into smaller fragments . The visual result of degradation is the discoloration of the polymer As the molecular weight of the polymers is reduced, the material gets brittle

2. Free radicals are formed when UV-light breaks C–H bonds on the polymer backbone Olefins, aldehydes and ketones are expected products of radical termination reactions, and these should be more susceptible to photo-initiated degradation, because they contain unsaturated double bonds. As the molecular weight of the polymers is reduced, the material gets brittle . PP Degradation

3. PET can undergo photo-induced autoxidation  via  radical reactions Photo-oxidation results mainly in chain scission.  The formed carboxylic acid end group has a promoting effect on thermo oxidative degradation PET is susceptible to hydrolytic degradation . The rate of hydrolysis is higher under acidic or basic conditions ,  thus hydrolysis of PET is an autocatalytic reaction when carboxylic end groups are formed . The visual effect of these degradation processes is the yellowing of the polymer . PET Degradation

4. Disadvantages of PET Very susceptible to heat degradation. Excessive shear heat should be avoided , therefore low screw speed and back pressure required .

5. Weathering of PET (With UV-Stab, Hy-Stab, and without Stabilizer)

6. hazing is mostly caused by forming surface defects and crystallites within the bulk material Weathering of PET (With UV-Stab, Hy-Stab, and without Stabilizer

7. Degradation of PET memiliki serapan (90-100) Degradation of PET

8. Degradation of UV-Stab and Hy-Stab Degradation of UV-Stab memiliki serapan sampai 200 Degradation of Hystab memiliki serapan sampai 40 Lebih bagus menggunakan UV-Stabilizer dibandingkan Hidrolisis stabilizer untuk mencegah degrasi PET

9. Karakteristik PET Degradation of PET lebih mudah dibandingkan dengan degradasi PVC dan PP. Adanya efek hazing akibat paparan UV. Mencegah degradasi PET dapat menggunakan UV-Stabilizer dibandingkan menggunkan Hidrolisis stabilizer.