Risk for Mould Growth on Hemp-Lime at Different Relative Humidity

Microbial growth often thrives in humid conditions, at high relative humidity. Moulds are complex organisms; many types of mould are able to survive strong variations in humidity and temperature, such as those on building façades. For some building materials a critical relative humidity is determined, which functions as a theoretical threshold; at this (or lower) relative humidity microbial growth will likely not occur. Hemp-lime is a building material that consists of hemp shiv (the woody core parts of the hemp stem) and building lime. It is a material that can be used for walls, and even though it has been used for more than 20 years, thusfar little is known about its critical moisture levels for microbial growth. The aim of this research was therefore to determine at what relative humidity microbial growth occurs on carbonated hemp-lime material, and to study if there is a protective influence of a carbonated lime binder on the hemp shiv. The objective was to study microbial growth on hemp shiv, hemp-lime and on hemp with a thin layer of lime at three relative humidity (75 %, 85 % and 95 %) and at two different temperatures (15°C and 23°C); conditions that could occur naturally in a hemp-lime façade exposed to high rain loads in a northern European climate. Hemp shiv seems to have a relatively low resistance to microbial growth, similar to that of wood. However, because the hemp is protected by lime it can withstand much higher relative humidity without microbial growth occurring on the material. The critical moisture level for hemp-lime seemed to occur between 75 and 85 % RH, while the material was completely without microbial growth at 75 % RH. The lime had a protective effect on the hemp and acted as a mould inhibitor, both over time and with varying temperature and humidity.

The Moisture Sorption Characteristics of Dietary Potassium Diformate

Potassium diformate, a novel dietary additive, has been firstly authorized by the European Union as an alternative to antibiotic growth promoters. The moisture sorption characteristics of potassium diformate were measured by the means of the static gravimetric method. The results indicated that the moisture sorption velocity of potassium diformate is linearly dependent on the relative humidity at 30 °C during the first 12 h. Moreover, the equilibrium moisture content was significantly influenced by relative humidity. The critical relative humidity of potassium diformate is 46.2%. Study on moisture sorption characteristics of potassium diformate will provide the reference to choose operating conditions of preparation and post-processing.

Experimental Study on Hygroscopicity of Rapeseed (Brassica Napus)

The hygroscopicity property of the rapeseed at different temperature and humidity was experimental studied in this paper. Tested results show that: the moisture absorption rates increase with the increase of relative humidity at the early period of absorption, and higher temperature leads to earlier reach of moisture equilibrium; the critical relative humidity(CRH) increases with the increase of temperature; the optional relative humidity for safety storage of rapeseed should be controlled less than 60%.