This research work reports the optimization and modeling of injection moulding parameters in the production of plantain fibre particles reinforced high density polyethylene (PFRHDPE) for impact responses evaluation. Composite materials have some limitations, and one of the most significant is their response to localized impact loading. The injection moulding process was designed using Taguchi robust design of experiment. Eight performance parameters were considered as control factors affecting the responses with the volume fraction of the fibre particulates being the only non-machine related parameter. The composite materials produced were prepared with three different particle sizes of the reinforcing plantain particulates. The optimization and modeling process for the impact responses evaluation was carried out through a classical use of two independent experimental approaches which we named integrated Taguchi-Response Surface Method (TRSM). This TRSM did optimally analyze the ultimate impact strength of plantain fibre particle filled HDPE matrix. The developed second order linear regression models for these composites were significant at the chosen 95% confidence interval, hence showing full response predictability.
The performance of concrete samples mixed with different water sources, namely: tap water, river, borehole and hand-dug well from small scale mining catchment areas (known as “galamsey” in Ghana) was assessed. Concrete in the “galamsey” areas are being produced with these water sources contaminated by the mining activities. The objective of the study was to assess the performance of concrete mixed and cured with the different water sources. Parameters assessed included compressive and flexural strength, Sulphate attack and Scanning Electron Microscopy (SEM) Analysis. Concrete mixing and casting were in accordance with BS EN 12390-2:2019 while compressive and flexural strength tests were in conformity to BS EN 12390-3:2019 and BS EN 12390-5:2019 respectively. Water parameters tests were conducted in accordance with GS 175-1:2009. Sulphate attack test was conducted based on ASTM C1012:2018. The results indicate that the compressive strength of concrete from all the water sources (river, hand-dug well and borehole) was about 90% and 70% of the control (tap water) specimens at the 28th and 180th days of curing respectively. It was noted that the concrete produced from the three water sources (borehole, hand-dug well and river) performed poorly against sulphate attack i.e. lost about 35%, 34% and 38% respectively of their compressive strength after 180 days of immersion in MgSO4 solution. Concrete mixed with the river and hand dug well water had lower alkalinity with pH values of 6.5 and 8 respectively. The morphological analyses at different magnifications showed deep and persistent cracks within the concrete mixed with the contaminated water. This study recommends that water from any of the water sources in the “galamsey” areas of Ghana should be treated before using for structural concrete and long term usage.
Chlorella vulgaris was isolated from the African Regional Aquacultural Centre Aluu, Rivers State. The culture was grown and was analysed for oil contents using three different extraction methods and was also analysed for pigments and the algae oil was characterized. Pigment analysis of the biomass had 7-12000 µg/g beta carotene, Astaxantin, Cantaxantin, Chlorophyll-a and Chlorophyll-b was 550,000 µg/g, 362,000 µg/g, 250-9630 µg/g and 72-5770 µg/g. Free fatty acid composition of the algae oil was tetradecanoic acid with a low peak height of 5.07%. The maximal peak height and component was n-hexadecanoic acid with the 17.83 minutes retention time and peak area of 18.24%, followed by the 9-octadecanoic acid (Z) Hexyl ester which had a peak area of 5.77% and a retention time of 24.80 minutes. The specific growth rate of 0.041 mg/Lday-1 for mixotrophic condition while heterotrophic had SGR of 0.054 mg/Lday-1. The study further identified that algal biomass from C. vulgaris has the potential of serving as both nutraceuticals and bioenergy feedstock. There is need for further studies around the algae oil oriented optimization as a veritable tool for biotechnological advancements.
Phytochemical analysis was carried out on the leaves and stem extracts of Commelinabenghalensis L and Acanthospermumhispidum DC plants to determine their corrosion inhibition potentials. The leaves and stem parts were processed by washing, air-drying under shade and then ground into powder. Stock solutions were then extracted from these materials using ethanol according to standard procedures. Quantitative and qualitative analysis were carried out on the extracts in accordance with standard procedures. These analyses showed the presence and composition of the extracts as alkaloids (7.2%), flavonoids (11.2%), saponins (4.1%), tannins (10.3%) and phenols (5.6%). The qualitative analysis also confirmed in addition, the presence of carbohydrates, glycosides and steroids. Anthraquinones were, however, found to be absent. These chemical substances are known to contain oxygen, nitrogen and sulphur atoms in their molecules which are regarded as adsorption centers in the process of corrosion inhibition. FTIR analysis was also used to identify the presence of functional groups in these extracts. The results of these analyses suggest that extracts of these plants could serve as materials for the production of corrosion inhibitors since they contain phyto-constituents that are known to have inhibitive properties against mild steel corrosion.
The industry of plastics has grown rapidly since its inception in the 1940s, the use of plastics as an optical material only really started to pick up in the 1970s and has had a much slower underlying growth than for the commodity industry e.g. packaging, closures, etc. After that, in this industry the advantage of material consistency and uniformity, full three dimensional machining capability and mass production are exploited to the full.
However, plastics in general are weaker and more costly than traditional materials and people still retain a ‘bad image’ of them because of their previous misuse. In the past, and to a certain extent today, plastic engineering components have been designed to directly replace components in traditional engineering materials, leading to poor performance and costly reproduction. For effective material substitution, the designer using plastics has to appreciate their benefits as well as their limitations. Today, designs are being produced that are not only unique to plastics but are also out-performing designs in traditional materials.
In a comparable way, prejudices prevent consumers trusting plastic lenses. Although they realize benefits such as thinner and lighter design, they worry about clarity and transparency, and the most common question is if plastic lenses harm their eyes or obstruct their vision.
Furthermore, in recent years the industry has confused consumers rather than informing them. Optical properties, like refractive index and Abbe value are not clearly defined by manufacturers (i.e. a given “n” is nd or ne?). Many people ask themselves why high index plastic lenses must be always multicoated? Another similar question is why high index plastic lenses mainly are designed as aspheric? Is chromatic dispersion more or less affected by the refractive index? What is the relation between Abbe value and chromatic performance of these materials?
Consequently, this review has to investigate mainly the above questions in order to search and estimate the performance of new plastic high index materials and to compare with traditional lens materials.