En studie om hur koncentrerad saltsyra vid hög temperatur påverkar PP, PVC och CPVC
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesisAlternative title
An investigation of how high concentration hydrochloric acid at elevated temperature affects PP, PVC and CPVC (English)
Hydrochloric acid is commonly used in pickling plants where temperatures may be up to 90 °C. In such corrosive environments, pipes or containers of metals cannot be used and the use of plastic materials is therefore a more suitable option. For example it may be possible to use polypropylene (PP), polyvinyl chloride (PVC) and chlorinated PVC (CPVC) for these applications. Plastics are not standardized materials; therefore the chemical resistances of commercially available plastics need to be tested individually.
The effect of hydrochloric acid (HCl) at high temperatures on commercially available materials from different manufacturers was studied. Totally five PP, five PVC and two CPVC materials were investigated. The materials were exposed to concentrated HCl at 60 °C for up to 8 weeks. The chemical changes were analyzed with Fourier Transfer Infrared Spectroscopy (FTIR). Differential Scanning Calorimetry (DSC) was used to measure the Oxidative Induction Time (OIT). The mechanical properties were studied with Charpy impact testing and tensile testing. An indicator technique was used to measure the diffusion of HCl in the materials. Quantification of how much HCl the materials absorb was performed with Ion chromatography (IC).
The results showed that the PP samples lost antioxidants as seen in both FTIR spectra and changes in OIT. The PVC materials had a decrease in filler content where the acid had penetrated. The mechanical properties seemed to be unchanged after exposure for 8 weeks. Only two PVC materials seemed to have a decrease in stress at yield. Concluding, most of the tested PVC and CPVC materials are suitable for the use in contact with concentrated HCl. All PP, PVC and CPVC materials can be used in contact with concentrated HCl in 60 oC up to 8 weeks.
Place, publisher, year, edition, pages
2015. , 79 p.
Pipe, corrosion, pickling plant, PP, PVC; CPVC
IdentifiersURN: urn:nbn:se:kth:diva-170731OAI: oai:DiVA.org:kth-170731DiVA: diva2:839628