Crystallization of vaterite and aragonite on chitin whiskers

The need for the possibility of producing calcium carbonate crystals by the evaporation method within five minutes and the growth of different calcium carbonate polymorphs on chitin whiskers within the same time frame at room temperature necessitated these report. Chitin whiskers (CHWs) were used as insoluble substrates, while poly (acrylic) acid (PAA) is used as soluble additive. The crystals were grown in chitin whiskers, Poly (acrylic) acid and CHW/PAA composites. The volume fractions for aragonite, vaterite, and calcite are 0.10, 0.25, and 0.65, respectively, in the absence of chitin whiskers or Poly (acrylic) acid. Calcite and aragonite volume fractions decrease in favour of vaterite when PAA and or CHWs were added. SEM images in the absence of CHWs and PAA shows rhombohedral calcites that display steady and step like plane appearances with an average edge of between 1.3 and 1.4 μm. In the presence of only CHWs, the SEM images show a mixture of ellipsoidal and spherical shape vaterites. The spherical vaterites have smooth, rough, and some irregular surfaces. Rod-like aragonite polymorphs were seen when only PAA was used as the template. In the presence of both PAA and CHWs, the rhombohedral shape showed roughness with irregular faces. Keywords: Chitin whisker, Calcium carbonate, Calcium, vaterite aragonite, Polymorph, Mole fractio

EFFECT OF FILLER CONTENT ON THE MECHANICAL PROPERTIES OF PERIWINKLE SHELL REINFORCED CNSL RESIN COMPOSITES

ABSTRACT Research into bio filler materials composite is gradually taking prominence due to its renewability. In this present work, three particle sizes (400µm, 600µm and 800µm) of milled periwinkle-shell (PWS) filled cashew nut shell liquid (CNSL) resin composites were developed by compression moldings technique with varying filler content (10% to 40% by weight). The developed PWS filled CNSL composites were then characterized by tensile, flexural and impact strength tests. The effect of filler content and particle size on the mechanical properties of the PWS filled CNSL composites was investigated. Results showed that, there was an improvement on the mechanical properties as the filler content increases while properties decreases as filler size increases. All properties tensile strength, flexural strength, % elongation, tensile modulus and impact strength slightly increased as the filler loading increases. While % elongation, tensile and flexural strengths decreases as particle sizes increases, tensile modulus and impact strength increases as particle sizes increases. The optimum properties were observed at 30% filler content and 400µm particle size

Evaluating Storage and Effective Moduli of In Situ Polymerised and Melt Extruded PA6 Graphite (G) Composites.

Four  PA6/graphite  (G)  composites  systems  were  made.  Two  using  in  situ  polymerisation  equivalent  in mixing strain and two systems melt extrusion of equivalent processing strain. The effective modulus of the carbons, room temperature storage modulus and storage modulus  at  80⁰C  were  evaluated.  The composite/unfilled PA6 ratios at E25 and that at E80 for the in situ polymerised system IG 40/10 are 1.37 and  1.63,  respectively.  For  the  in  situ  polymerised  system  IG  20/20,  the  same  were  1.96  and  2.28, respectively. For the melt-extruded systems, G 100/6 had the best E25 ratio of 1.67 and E80 of 2.03, whereas the same for G 200/3 system were respectively 1.87 and 2.64. While the better storage modulus properties exhibited by IG 20/20 in the in situ polymerised system is associated with a better filler connectivity network that enhanced heat dissipation. The better values shown in the G 200/3 melt-extruded system is associated with the lesser extrusion, which significantly reduced the tendency to thermal decay. Effective modulus for the in situ polymerised systems IG 40/10 and IG 20/20 were 7.5GPa and 8.9GPa while that of melt-extruded systems G200/3 and G100/6 tallied at 8.2 GPa

Multivariate modeling of some metals concentrations in agrarian soils: distribution and soil fertility implications in the tropics

Predicting metals concentration in agricultural soils is a sine qua non in establishing environmental policies and evaluating the soils’ agricultural potentials in an area. The relevance of metals to ecological health, agriculture and pollution has sprung a lot of related studies. This study was setup to determine the concentration and profile distribution of aqua regia (AR) extractable Fe, Al, Mn, Mg and K in agricultural soils, and to predict AR extracted elements via Al2O3 (Alx), K2O (Kx), physical and chemical properties for soil fertility interpretations. One soil pit was randomly sited in each slope transition obtained via digital elevation models (DEM), resulting in 27 composite soil samples. Soil samples meant for AR and X-ray florescence were analyzed in triplicate. The soils were dominated by AR extractable Fe with mean concentrations showing the trend; Fea > Ala > Mga > Mna ≈ Ka and ranges of 639.09–125,719.46, 1252.63–14,895.13, 67.61–2408.36, 4.51–2162.91 and 161.84–1356.23 mg/kg, respectively. The distribution of AR metals in the entire soils was quite similar, however, higher values of soluble Fe occurred in the 0–37 cm depth of IH1P1. Multiple linear regression functions were within acceptable and best prediction criteria (R2 = 0.55–0.77). The best performing models were Ka and Mna, with lower errors. The models selected Kx, Mg and CEC which contributed 89.9, 79.9 and 73.4%, respectively to the 44.2% contribution of PC1 to data variation. The dominance of Kx and Alx with ranges of 2381.0–50,401.0 and 57,766.67–119,433.35 mg/kg, respectively, over Ka and Ala is due to limitations associated with AR extraction of elements in silicate minerals, hence the necessity for extracting soil mineral elements by more than one method

Mechanical and Thermomechanical Properties of Clay-Cowpea (Vigna Unguiculata Walp.) Husks Polyester Bio-Composite for Building Applications

This study investigates the feasibility of creating a clay polymer-based composite using cowpea husk (CPH) as filler for production of roof tiles. Polymeric composites were fabricated by mixing unsaturated polyester (UPT) resin with cowpea husk at different filler weights and curing. A hybrid composite was produced with the addition of 3 wt.% clay and all samples produced were subjected to flexural, hardness and dynamic mechanical analysis (DMA) tests. The effect of clay addition on the mechanical and thermo-mechanical behaviour of formulated composites was investigated. The morphological analysis of the mono and hybrid system shows a rough and coarse inhomogeneous surface with voids created due to the addition of CPH filler for the mono reinforced and clay uniformly filling the voids that were created by the CPH in the hybrid composite. It is observed that hardness, tensile modulus and flexural modulus of hybrid composites increase with an increase in the CPH contents, while the strength and flexural strength all decrease with filler content. The optimal composition was obtained using Grey relational analysis (GRA) at 18% CPH for both mono and hybrid composite. The results imply that the composite combination can be used in making rooftiles and/or also in applications where low strength is required

Estimating soil organic matter: a case study of soil physical properties for environment-related issues in southeast Nigeria

The different deposition periods in sedimentary geological environment have made the build-up and estimation of soil organic matter ambiguous to study. Soil organic matter has received global attention in the ambience of international policy regarding environmental health and safety. This research was to understand the inter-relationship between soil organic matter and bulk density, saturated hydraulic conductivity (Ksat), total, air-filled and capillary porosities for organic matter estimation, via different multiple linear regression functions (i.e., leapbackward, leap forward, leapseq and lmStepAIC), in soils developed over the sedimentary geological environment. Eight mapping units were obtained in Ishibori, Agoi Ibami and Mfamosing via digital elevation model. Two pits were sited within each mapping unit, and 53 soil samples were used for the study. In soils over shale–limestone–sandstone, two pits were sited, six in alluvium, four in sandstone–limestone and four in limestone. Overall correlation between SOM with Ksat (r = 0.626) and BD (r = − 0.588) was significant (p < 0.001). The strongest correlation was obtained for SOM with BD (r = − 0.783) and Ksat (r = 0.790) in soils over limestone. In contrast, soils over shale–limestone and sandstone geological environment gave the weakest relationship (r < 0.6). Linear regression gave a similar prediction output. The best performing was leapbackward (RMSE = 11.50%, R2 = 0.58, MAE = 8.48%), which produced a smaller error when compared with leap forward, leapseq and lmStepAIC functions in organic matter estimation. Therefore, we recommend applying leapback linear regression when estimating soil organic variation with physical soil properties for solving soil–environmental issues towards sustainable crop production in southeast Nigeria

Mechanical and Thermomechanical Properties of Clay-Cowpea (Vigna Unguiculata Walp.) Husks Polyester Bio-Composite for Building Applications

This study investigates the feasibility of creating a clay polymer-based composite using cowpea husk (CPH) as filler for production of roof tiles. Polymeric composites were fabricated by mixing unsaturated polyester (UPT) resin with cowpea husk at different filler weights and curing. A hybrid composite was produced with the addition of 3 wt.% clay and all samples produced were subjected to flexural, hardness and dynamic mechanical analysis (DMA) tests. The effect of clay addition on the mechanical and thermo-mechanical behaviour of formulated composites was investigated. The morphological analysis of the mono and hybrid system shows a rough and coarse inhomogeneous surface with voids created due to the addition of CPH filler for the mono reinforced and clay uniformly filling the voids that were created by the CPH in the hybrid composite. It is observed that hardness, tensile modulus and flexural modulus of hybrid composites increase with an increase in the CPH contents, while the strength and flexural strength all decrease with filler content. The optimal composition was obtained using Grey relational analysis (GRA) at 18% CPH for both mono and hybrid composite. The results imply that the composite combination can be used in making rooftiles and/or also in applications where low strength is required