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Chemical Properties of DURAN®

The chemical resistance especially of DURAN® glass is more comprehensive than that of all other known materials.
DURAN® borosilicate glass is highly resistant to water, acids, saline solutions, organic substances and also halogens such as chlorine and bromine. Its resistance to alkali is also relatively good. Only hydrofluoric acid, concentrated phosphoric acid and strong alkali cause appreciable surface removal of the glass (glass corrosion) at elevated temperatures (>100 °C).

Hydrolytic resistance

 

DURAN® corresponds to Class 1 of the glasses that are divided into a total of 5 hydrolytic resistance classes in accordance with ISO 719 (98 °C). The amount of Na2O/g glass grain leached out after 1 hour in water at 98 °C is measured. For DURAN® the quantity of Na2O leached out is less than 31 μg/g of glass grain.

DURAN® also corresponds to Class 1 of the glasses divided into a total of 3 hydrolytic resistance classes in accordance with ISO 720: (121 °C). The quantity of Na2O leached out after 1 hour in water at 121 °C is less than 62 μg/g of glass grain.

Due to its good hydrolytic resistance, DURAN® meets the requirements of the USP, EP and JP for a neutral glass that corresponds to glass type 1. It can therefore be used in an almost unrestricted way in pharmaceutical applications and in contact with foodstuffs.

Hydrolytic attack on DURAN® as a function of time (100 °C)

Acid resistance

 

DURAN® corresponds to Class 1 of the glasses divided into 4 acid classes in accordance with DIN 12116. As the surface removal after boiling for 6 hours in normal HCl is less than 0.7 mg/100 cm2, DURAN® is classed as acid-resistant borosilicate glass.

The quantity of alkaline metal oxides leached out in accordance with ISO 1776 is less than 100 μg Na2O/100 cm2.

Acid attack on DURAN® as a function of acid concentration

Alkali resistance

 

DURAN® corresponds to Class 2 of the glasses divided into 3 alkali classes in accordance with DIN ISO 695. The surface erosion after 3 hours boiling in a mixture of equal volume fractions of sodium hydroxide solution (concentration 1 mol/l) and sodium carbonate solution (concentration 0.5 mol/l) is only 134 mg/100 cm2.

Alkali attack on DURAN® as a function of temperature