No abstract

Recently, there have been many reports of silicon rubber (SR) hoses becoming brittle in juice factory within one month of purchase. The damage is a new phenomenon, and its cause is unknown. We have collected the damaged hoses attached to UHT sterilizer (ultra-high-temperature) in juice factory and examined them for chemical changes. In addition, we have analyzed the hose-washing chemicals (NaOH and HNO 3 ) that used in juice factory and investigated the effect of NaOH and HNO 3 on a new hose surface in an attempt to establish a probable chemical chain reaction that could attack of the Si-O-Si backbone and cause such degradation. According to WDXRF (Wavelength Dispersive X-Ray Fluorescence), CHNS (Carbon Hydrogen Nitrogen and Sulfur) elemental analysis and FE-SEM photo mapping (Field Emission Scanning Electron Microscope) results, the amount of silicon (Si) and the oxygen (O) concentration were much lower in the damaged hoses than in new SR hose ones. These findings reveal that oxygen-containing silicon-based backbone may leach out from the hose by washing chemicals. As a result, the hoses became brittle after one month of use in juice factory. EDS (Energy-Dispersive-Spectroscopy) peak shows that low concentration of sodium was inserted into the damaged hose surface, due to hose cleaning by NaOH. UV-Vis Spectrometer was used to detect the Si from hose washing chemicals. It was found that the elemental composition of the damaged SR hose changed significantly and both the pH of washing chemicals (NaOH and HNO 3 ) and the exposure UTH temperature have direct effect on the brittleness of the silicon hose in juice factory.