Online interferometric study of viscoelastic rupture and necking deformation of as‐spun (iPP) fibres due to creep process

Creep deformation under constant load leads to rupture when the polymer chains can no longer separate and accommodate the load. This fracture phenomenon is investigated interferometrically. The creep behaviour of as‐spun isotactic Polypropylene (iPP) fibres is studied at different stresses, different initial lengths and different radii. The creep rate, which defines the velocity of the creep deformation and the dimensional stability of the material, is studied. The failure time and stress of iPP due to creep process is determined. The necking deformation was in situ detected during creep process. The mean refractive indices (n^P and) profiles of iPP fibres were determined at different positions along the fibre axis before and after necking. The relation between the creep behaviour and different optical and structural parameters is investigated. Microinterferograms are given for illustration.     

Physicochemical characteristics and renneting properties of camels' milk: A comparison with goats', ewes' and cows' milks

A great variability in physicochemical and microscopic characteristics of individual milk has been observed leading to the presence of differences in kinetics of the renneting reaction and in drainage ability. Furthermore, this study shows that casein concentration, total calcium content and mean diameter of casein micelles are the principal variables explaining the major part of the variation in the renneting properties. Finally, several relationships between coagulation characteristics, drainage ability and some compositional parameters of these kinds of milk were highlighted.