			Home About us Contact

Clay Samples (clay + sample)

Distribution by Scientific Domains

Humanities and Social Sciences	60%

Selected Abstracts

Barrier and mechanical properties of injection molded montmorillonite/polyesteramide nanocomposites

POLYMER ENGINEERING & SCIENCE, Issue 1 2005
M. Krook
Properties of injection-molded biodegradable polyesteramide composites containing 5 and 13 wt% octadecylammonium-treated montmorillonite clay have been studied. Oxygen transmission rates and mechanical properties were measured. X-ray diffraction was used to assess the degree of intercalation of the clay layer stacks, and transmission electron microscopy (TEM) was used to assess the morphology and degree of layer delamination. A substantial reduction in oxygen permeability was observed when clay was added to the composites. The oxygen permeability of the 13 wt% clay sample was only 20% of that of the pure polymer. The in-plane stiffness and in-plane strength of the sheets were greatly improved without any embrittlement. These beneficial effects were probably due to the high degree of clay layer exfoliation and orientation observed by TEM. Heat shrinkage, toughness analysis, and cutting operations suggested that the polymer chains and the clay layers were oriented parallel to the plane of the sheet. TEM and X-ray showed that stacked layers were still present but that these were significantly intercalated. The clay-layer periodic spacing increased from 25 Å to approximately 35 Å during processing. POLYM. ENG. SCI. 45:135,141, 2005. © 2004 Society of Plastics Engineers [source]

Mycenaean pottery from the Argolid and Achaia,a mineralogical approach where chemistry leaves unanswered questions

ARCHAEOMETRY, Issue 2 2002
A. Hein
The chemical classification of Mycenaean pottery from the Northern Peloponnese by neutron activation analysis (NAA) resulted in two groups with very similar chemical compositions assigned to production centres in the Argolid and in Achaia, respectively. The statistical separation of these two groups on the basis only of their chemical composition was difficult, and not clear-cut for all of the examined samples. A complementary mineralogical examination by X-ray diffraction (XRD) of some selected samples indicated differences in the mineralogical composition, which confirmed the determined chemical differences. Furthermore, a clay sample was examined, which showed a composition similar to that of the pottery. [source]

Quantifying the effects of aggregation, particle size and components on the colour of Mediterranean soils

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2004
M. SÁnchez-Marañón
Summary Aggregation, particle size, and chemical composition affect the colour of the soil. We have attempted to quantify and understand these effects in 12 Mediterranean soils. We measured the CIELAB colour variables hab, L*, and C*ab in aggregated and dispersed soil samples, and also in coarse sand, fine sand, silt, and clay samples before and after sequential removal of organic matter, carbonates, and Fe oxides. Grassmann's colour-mixing equations adjusted by regression analysis described the colour of the dispersed soil from its particle-size fractions with an error of 1% for hab, 4% for L*, and 9% for C*ab. This suggests that the contribution of each fraction to the colour of the dispersed soil can be accurately calculated by its colorimetric data weighted by its content and a regression coefficient, which was greatest for clay. We inferred the influence of a component within each fraction by measuring the colour changes after its removal. Iron oxides reduced hab of the silicated substrate by 19%, reduced L* by 12%, and increased C*ab by 64% in all particle-size fractions. Carbonates and organic matter had little influence: the former because they impart little colour to the silicates and the latter because there was little of it. The CIELAB colour-difference between dispersed and aggregated soil (mean ,E*ab = 15.3) was due mainly to ,L* (,14.7). Aggregation contributed to diminishing L* of dispersed soil by 34%. Scanning electron microscopy showed that Fe oxides and organic coatings cover the surface of aggregates thereby influencing soil colour. [source]

Gabbroic clay sources in Cornwall: a petrographic study of prehistoric pottery and clay samples

OXFORD JOURNAL OF ARCHAEOLOGY, Issue 3 2004
Lucy Harrad
Summary., This analysis of prehistoric pottery and clay samples from Cornwall demonstrates that the clay used to make Cornish gabbroic pottery in prehistory originated around the gabbro rock outcrop in a small area of the Lizard peninsula. The research uses petrographic and chemical analysis to subdivide the prehistoric pottery into six groups. Owing to the unusual geology of the Lizard these groups can be attributed to specific locations. The most abundant pottery fabric, Typical Gabbroic, was made using coarse clay which is mainly found in a 1 km2 area near Zoar. A finer version of this clay, found higher in the soil profile or slightly transported and redeposited, was used to make Fine Gabbroic pottery and an even finer variant called FNS (Fine Non-Sandy) Gabbroic. We identify for the first time here a Loessic/Gabbroic pottery fabric which can be matched exactly to clay found at Lowland Point. Serpentinitic/Gabbroic pottery was made using clay from the gabbro/serpentinite border zone. Pottery made from the Granitic/Gabbroic fabric did not match any clay from the Lizard, showing that gabbroic clay was sometimes removed and made into pottery elsewhere in Cornwall. The main clay source near Zoar was used for clay extraction throughout the Bronze Age and Iron Age for pottery which was traded all over Cornwall. Other gabbroic clay sources produced pottery only during certain periods and exclusively supplied particular settlements, such as the Loessic/Gabbroic fabric which was found only at Gear and Caer Vallack. The results suggest that pottery was produced by several small-scale cottage industries, which may have operated on a seasonal, part-time basis and probably formed only part of a wide range of activities located around the Lizard area. [source]