Macroplastics on Soil-Plant System: Inhibiting Effects of Macroplastics on the Growth of Green Amaranth (<i>Amaranthus viridis</i>)

In recent time Bangladesh faces a serious problem of soil pollution due to plastic contamination. However, the degree of the extent to which the effects of plastics on plant growth occur is not properly identified. An experiment was conducted to measure the effects of mixed plastic (polyethylene and disposable plastic glass) on the growth of Amaranthus viridis. Different doses of mixed plastics (T0, T1, T2, and T3) were applied with a fixed amount of soil for each of the treatments e.g., T0 (control), T1 (10 gm mixed plastics/3kg soil), T2 (15 gm mixed plastics/3kg soil) and T3 (20 gm mixed plastic/3kg soil), and the growth response of Amaranthus viridis against plastic was observed for six consecutive weeks. The growth was measured in terms of plant height and girth diameter. The results showed that the presence of mixed plastic had a significant effect on the growth of Amaranthus viridis and particularly in treatment T3 (3 kg soil/20gm mixed plastic), the plants showed a slower growth response compared to control and the rest of the treatments applied in case of both plant height as well as girth diameter. The statistical analysis (one-way Analysis of Variance) also proved the significance of the treatments (p-values < 0.05) for six consecutive weeks. The experiment was successfully able to set an index on which plastics had their effects on the growth of green amaranth. In addition, the obtained data will be helpful in future research of the study in determining the possible effects of plastic on plant growth viz. green amaranth.

Warpage and Shrinkage Optimization of Injection-Molded Plastic Spoon Parts for Biodegradable Polymers Using Taguchi, ANOVA and Artificial Neural Network Methods

In this study, it is attempted to give an insight into the injection processability of three self-prepared polymers from A to Z. This work presents material analysis, injection molding simulation, design of ex- periments alongside considering all interaction effects of controlling parameters carefully for green biodegradable polymeric systems, including polylactic acid （PLA）, polylactic acid-thermoplastic poly- urethane （PLA-TPU） and polylactic acid-thermoplastic starch （PLA-TPS）. The experiments were carried out using injection molding simulation software Autodesk Moldflov~~ in order to minimize warpage and volumetric shrinkage for each of the mentioned systems. The analysis was conducted by changing five significant processing parameters, including coolant temperature, packing time, packing pressure, mold temperature and melt temperature. Taguchi＇s [.27 （35） orthogonal array was selected as an efficient method for design of simulations in order to consider the interaction effects of the parameters and reduce spu- rious simulations. Meanwhile, artificial neural network （ANN） was also used for pattern recognition and optimization through modifying the processing conditions. The Taguchi coupled analysis of variance （ANOVA） and ANN analysis resulted in definition of optimum levels for each factor by two completely different methods. According to the results, melting temperature, coolant temperature and packing time had significant influence on the shrinkage and warpage. The ANN optimal level selection for minimiza- tion of shrinkage and/or warpage is in good agreement with ANOVA optimal level selection results. This investigation indicates that PLA-TPU compound exhibits the highest resistance to warpage and shrink- age defects compared to the other studied compounds.