Search results for "grinding"
showing 10 items of 31 documents
Influence of cryogenic grinding on properties of a self-emulsifying formulation
2003
Abstract Recently, self-emulsifying drug delivery systems (SEDDS) have been developed as a method to deliver lipophilic drugs. Gelucire® 44/14 is an excipient, from the lauroyl macrogolglycerides family, producing a fine oil-in-water emulsion when introduced into an aqueous phase under gentle agitation as SEDDS, improving thereby solubility of poorly water-soluble drugs and their bioavailability. The aims of this study were to process Gelucire® 44/14 into a powder by cryogenic grinding to produce solid oral dosage forms and to investigate influence of this process on different properties of a formulation made of Gelucire® 44/14 and ketoprofen (90/10). Cryogenic grinding produced Gelucire® 4…
The Grinding Resistance of the Wheat Grain Related to the Grinding Degree For The First Break In The Wheat Milling
2011
Breakage of wheat grain during first break roller milling depends on the characteristics of the wheat (including the distributions of kernel size, hardness and moisture content) and on the design and operation of the roller mill (including roll speeds and differential, roll disposition, fluting profile, number of flutes, fluting spiral, roll gap, the degree of roll wear and the feed rate). The effects of these factors are manifest in the particle size distribution exiting first break, the compositional distribution of those particles (as large particles tend to be richer in bran, while small particles are pure endosperm), the power required to mill the wheat and the rate of roll wear. For t…
Grinding Tungsten Carbide Used for Manufacturing Gun Drills
2015
This paper presents a study of grinding cemented carbide DK460UF (91 % WC and 9 % Co), a material used to produce cutting tools with solid cutting edges. The aim is to establish the manufacturing conditions that lead to high surface quality. A model of the main factors that influence the grinding process is presented first. Following that, grinding wheel wear and surface roughness are analysed. Grinding wheel wear is studied in experimental conditions under which small diameter gun drills were sharpened with two diamond grinding wheels of different grain sizes. Finally, the wear curve can be made. The "G ratio" is used to characterise the performance of the grinding process. Next, the exper…
Influence of plasticizers and cryogenic grinding on the high-cooling-rate solidification behavior of PBT/PET blends
2015
Two structurally different plasticizers (cyclic and linear) and the effect of cryogenic grinding on the solidification behavior at high cooling rates by a continuous cooling transformation approach of poly(butylene terephthalate)/poly(ethylene terephthalate), PBT/PET, blends are described. The solidification curve (density versus cooling rate) is confirmed as an effective tool to compare the differences in crystallization behavior under conditions mimicking processing. In comparison to the bulky cyclic plasticizer, the linear oligomeric one was found to have a more pronounced influence on the crystallization behavior. A 60/40 by weight PBT/PET blend shows a drop-off of density at ∼50 K/s. I…
Lignocellulosic fillers and graphene nanoplatelets as hybrid reinforcement for polylactic acid: Effect on mechanical properties and degradability
2020
Abstract This work investigates the effect of adding relatively low amounts of graphene nanoplatelets (GNP) to a biocomposite based on polylactic acid (PLA) and a lignocellulosic filler achieved by grinding Posidonia Oceanica leaves (Posidonia flour, PF). The ternary composites were prepared by melt extrusion and characterized from a morphological and mechanical point of view. Furthermore, hydrolytic degradation tests were performed under acidic, neutral and alkaline environment up to 900 h. Density measurements enabled to assess the degree of intraphase, i.e. the capability of polymer macromolecules to enter the voids of PF and a modified Halpin-Tsai model was presented and used to fit exp…
Effect of the preparation method and grinding time of some mixed valency ferrite spinels on their cationic distribution and thermal stability toward …
1996
Abstract The reactivity in oxygen of several mixed valency ferrite spinels, namely Fe3O4, FeCr2O4, Fe3 − xTixO4 and Fe3 − xMoxO4 was investigated by derivative thermogravimetry (DTG) analysis as a function of the conditions of preparation and grinding. For all these compounds, low temperature preparation or prolonged grinding time enables small particles ( 0.5 μm), it was observed that oxidation was starting at higher temperature and that the defect spinel phases could not be retained during oxidation. This behaviour was attributed to the presence of stresses induced by the lattice parameter gradient and promoting the formation of nuclei of the α-rhombohedral phase from the superficial γ-de…
Evaluation of the fracture performance of different rubberised bitumens based on the essential work of fracture
2017
The fracture performance of rubberised bitumen in addition to one pre-treated with a Warm Mix Additive (Sasobit®) was investigated using different test methods measuring different damage mechanisms. Two Recycled Tyre Rubber (RTR) modifiers together with two base binders were blended in the laboratory to produce various combinations of Recycled Tyre Rubber Modified Bitumens (RTR-MBs). The first RTR is a standard recycled polymer derived from discarded truck and passenger car tyres by ambient grinding. The second RTR consists of 100% recycled truck tyres derived by cryogenic grinding and pre-treated with special oil and WMA to allow further decrease of asphalt mixture production temperatures.…
Comparative assessment of surface roughness produced by hard machining with mixed ceramic tools including 2D and 3D analysis
2005
Abstract This paper provides a new comprehensive analysis of part surface finish in continuous dry turning of a hardened construction steel when using mixed alumina cutting tools. Consequently, the surface profiles (2D arragement) and surface microstereometries (3D arragement) generated during different hard part turning operations on a 40H low chromium alloy steel (equivalent to AISI 5140 or DIN 41Cr4), heat treated to the hardness of about 60 HRC, were evaluated. As a result, this paper aggregates the multi-parameters characterization of the surface roughness with the machined surface structure obtained at the three selected feed rates and constant cutting speed of 100 m/min. Results show…
PLA based biocomposites reinforced with Arundo donax fillers
2014
Abstract In this work, for the first time, a natural and almost inexpensive filler obtained by grinding the culms of Arundo donax was used to prepare PLA based biocomposites. The composites were prepared by melt compounding PLA with A. donax filler (ADF). The influence of the content and size of ADF on the morphology and on the mechanical and thermal properties of PLA–ADF composites was evaluated. Moreover, ADF was extracted from composites to evaluate the effect of processing on morphology and dimensions of the incorporated filler. Furthermore, the experimental elastic moduli of the biocomposites have been fitted, employing two theoretical models, i.e., Hill and Halpin–Tsai. The results sh…
Structure-property relationship of PLA-Opuntia Ficus Indica biocomposites
2019
Abstract In this work, a lignocellulosic flour was achieved by grinding the cladodes of Opuntia Ficus Indica and then added to a poly-lactic acid (PLA) in order to prepare biocomposites by melt processing. The influence of filler content and size on the morphological, rheological, and mechanical properties of the green composites was assessed. Moreover, solvent-aided filler extraction enabled to evaluate the homogeneity of filler dispersion, as well as the effect of processing on the geometrical features of the fillers. The experimental data obtained by tensile tests proved to be remarkably higher than those predicted by Halpin–Tsai model, presumably due to the capability of the polymer to …