Physicochemical properties Sample Clauses

Physicochemical properties. The exact physicochemical properties of product groups with tolerances are contained in the Product Specification provided to the Customer at his request.

Physicochemical properties. Table 3.5 illustrates the nanospecific considerations regarding the REACH Standard information Requirements for physicochemical properties. 7.1. State of the substance at 20 °C and 101.3 kPa No nanospecific recommendations provided in ECHA guidance. As no differences are detected between bulk forms and nanoforms, in most of the materials this endpoint is not considered as nanospecific. Nonetheless, in some cases e.g. colour may differ from bulk to nanosize (e.g. depending on the shape and size, gold nanocrystals have different colours ranging from blue-purple to red) (▇▇▇▇▇▇ and ▇▇▇▇▇▇ 2004) and this information should be reflected in the dossier. 7.2. Melting / freezing point No nanospecific recommendations provided in ECHA guidance. Nanoparticles exhibit lower melting point temperatures as compared to their bulk counterpart (temperature depression phenomena) because of the large fraction of (more reactive) surface atoms. The melting temperature in nanoparticles is inversely proportional to the radius of the nanoparticles (▇▇▇▇▇▇▇▇▇ et al. 1992, ▇▇▇▇▇ et al. 2005). For example, the melting point of bulk silver is 962 °C but for a 2 nm diameter silver nanocrystal the melting point drops about 800 degrees below that of the bulk form, i.e. to 127 °C (experimentally) (Little et al. 2012). This information should be properly addressed when characterising the substance in the nanoform and when applying endpoint specific rules. OECD has concluded that the Test Guideline relevant to characterising melting point/melting range (i.e. OECD TG 102) is considered to be applicable to NMs (OECD 2009). 7.3. Boiling point No nanospecific recommendations provided in ECHA guidance. ECHA Guidance (ECHA 2015) advices to use OECD TG 103 for testing boiling point of a substance. OECD (2009) concluded that TG 103, though applicable for determining the boiling point of manufactured NMs, is probably not relevant to existing solid NMs. It should be noted that REACH does not require the determination of boiling point for solids which either melt above 300 °C or decompose before boiling. This in practice means that determination of boiling point may not be required for certain NMs. Yet, the dependency of melting temperature from the radius of a nanoparticle should be properly addressed when characterising the substance in the nanoform and when applying endpoint specific rules. Although the boiling temperature (like the melting temperature) of NMs is expected to decrease when the parti...