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This work focused on investigating the efficacy of clay nanoparticles loading in the medium velocity impact resistance of kenaf/polylactic acid (PLA) biocomposites. Kenaf/PLA biocomposites with different nanoclay loadings of 0, 3, 5 and 7% by weight were fabricated and their medium velocity impact resistance tested on a gas gun. Results indicate that the addition of nanoclay in the biocomposites improved the medium velocity impact resistance of the biocomposites, specifically the perforation threshold limit, energy absorbed, crack and damage resistance. Improvements on these properties were thought to be due to enhancements brought about by the nanoclays on interfacial bonding and microstructural properties of the biocomposites revealed through scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. The nanoclays reduced the micro-voids thereby improving bonding between PLA and kenaf fibres. SEM–EDX analysis detected silicon and aluminium elements which were from the nanoclays and the elemental maps showed that all the elements were uniformly distributed in all cases with good dispersion of the nanoclays. However, incidences of nanoclay agglomeration were observed at 7 wt% nanoclay content which had adverse effects on the biocomposites properties. Optimum results were achieved with 5 wt% nanoclay content, beyond which a reduction in the medium velocity impact resistance was observed. The perforation threshold, energy absorption capacity, resistance to damage and prevention of crack propagation increased by 41.9, 109, 26.5 and 28.9%, respectively, at the 5 wt% nanoclay content level. The study shows that the addition of nanoclay improves the impact properties of kenaf/PLA biocomposites within the medium velocity range. The novel nanoclay impregnated biocomposite material developed is suitable for applications where good impact properties are required.

Focus on biofibre-reinforced biopolymer composites as sustainable alternatives to non-biodegradable composites in high-performance applications is increasing. This work focused on characterising the performance of kenaf non-woven mat/PLA biocomposites under medium velocity impact loads. Biocomposite laminates of different fibre contents were fabricated and then analysed for their resistance to medium velocity impact on a high speed gas gun. The perforation threshold limit was determined and impact-induced damages analysed using non-destructive techniques. Results showed that kenaf non-woven mat/PLA biocomposites have a perforation threshold limit of 26 m/s and doubling of fibre content improved the perforation threshold limit by 42.3 %. The impact damage resistance of kenaf non-woven mat/PLA biocomposites increased by 27.6 % when fibre content was doubled. The failure modes resembled that of some conventional fibre-reinforced composites. It was concluded that kenaf non-woven mat/PLA biocomposites have a potential to cushion against medium velocity impacts and hence could be good replacements for the non-biodegradable composites used for cushioning against secondary debris in the medium velocity range.

In this study, the possibility of producing layered silicate-reinforced acrylonitrile butadiene styrene (ABS) using additive manufacturing procedures was investigated. In particular, this investigation presents novel methods for making nanoclay-infused acrylonitrile butadiene styrene composite spur gear. The gear was developed by introducing different weight percentages of nanoclay (0–5 wt%), on each acrylonitrile butadiene styrene layer. A square panel of 6 layers with varying proportions of nanoclay was fabricated using a 3D printer. The effect of nanoclay loading on the mechanical properties such as impact, tensile, flexural, and DMA of spur gears created using pure acrylonitrile butadiene styrene and nanoclay-infused nanocomposite was investigated and compared. The strength of the developed spur gear varies with different loading of nanoclay. The results that the spur gear, with 2 wt% nanoclay, offered superior properties. The micrographs showed the dispersion of nanoclay strongly bonded with the matrix, resulting in improved strength and stiffness. The improvement in mechanical properties depicts the effectiveness of additive manufacturing procedure with an enormous benefit for the mass production of gears of different types.

Carbon black (CB)-filled polylactic acid (PLA) composites attract a significant interest due to their superior structural and functional performances. Properties of CB-filled PLA composites depend on physical and chemical interactions in them. In this study, interactions within CB (N220)-filled PLA composites as a function of processing method, filler concentration, and their effect on mechanical properties are investigated via mechanical tests. Strong interface interaction at intermediate concentration of 2.5 wt.% CB with PLA was confirmed through mechanical tests. Moreover, a 2.5 wt.% of CB-formed networks within PLA composites, which added the fracture resistance in the weaker phase, thereby improving their mechanical properties. Beyond 2.5 wt.%, a linked skeletal grid was formed, enhancing the fracture path in a weaker phase and deteriorating the mechanical properties. Experimental results on density and elastic modulus were compared with the theoretical model predictions. This study gives an insight on interactions controlling physical and mechanical properties related to various processing techniques and weight percent of CB in PLA composites.

Nanotechnology, in general, and nanomaterials in particular, have conferred and are continuing to confer many benefits to mankind, just as the advent of "plastics" did in previous generations. In the case of carbon nanotubes, which can be produced in vast quantities, documented methods to manage this carbon nanotube waste by recycling and or safe disposal are so minimal that it is a matter of great concern that the paucity of studies on managing carbon nanotube waste may lead to complacency. The latter could be a trigger for human illnesses, through poor handling of carbon nanotube waste. The present study investigated ways to manage recycling and disposal of waste carbon nanotubes and a limited study of some aspects of the toxicity of waste carbon nanotubes in the environment. An eclectic approach was adopted for this study, involving an application and analysis of questionnaires, to ascertain the current practices used by practitioners in carbon nanotube research, as well as experimental work to determine the potential toxicity of carbon nanotubes. This investigation was undertaken to determine if a change from current practice is warranted in the light of the potential toxicity of carbon nanotubes (CNTs). Analysis of the questionnaires revealed the use of differing practices for the recycling and disposal of engineered nanomaterials (ENMs), implying that there is a dire need for a uniform code of practice. The toxicity study showed that carbon nanotubes did not kill earthworms in soil. However, worms were observed to be highly sensitive to increased concentrations of carbon nanotubes. The leaching in a soil column test showed that the movement of carbon nanotubes was inhibited, being confined mainly to the topmost layers of the soil. This is taken to imply that the water table is safe from possible contamination by CNTs.

The objective of this work is to study the influence of nanoclay addition in PP sheet during infrared (IR) heating assisted thermoforming process. The effect of nanoclay on viscoelastic, friction and dimensional characteristics during sheet forming was examined. The result indicated that the nanoclay addition improves the sagging (sagging depth and sagging disintegration) and plugging (plug depth and friction) properties during sheet forming. The plugging properties of nanoclay filled PP sheet resulted in the improved physical characteristics (minimal change in thickness (Δt) and % dimensional elongation) when compared with unfilled PP sheet. The nanoclay filled formed PP sheet resulted in improved tensile and dynamic mechanical properties when compared with unfilled formed PP sheet.

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The objective of this work is to study how the rheological factors of unfilled and nanoclay-filled HDPE–PP blend series influence the structure, morphology, and mixing characteristics. For this study, a series of HDPE–PP blends (0–100 wt % HDPE), with and without nanoclay, was prepared by using melt-mixing method. Nanoclay was varied from 0 to 5 wt % in all the blend and polymer series. The rheological properties were examined by melt viscosity, scanning electron microscopy, and theory of mixing. The result indicated that the viscosity of the blend increased as HDPE and nanoclay content increased, and also affected the structure and morphology of the resulting blend. The thermal properties were examined by using differential scanning calorimetry and suggest improved crystalline and melting characteristics of PP and PP-rich phase of blend. The structure of nanoclay-filled blend was examined by X-ray diffraction and transmission electron microscopy, confirming the formation of nanocomposite with improved tensile properties.

Diglycidyl ether of bisphenol — A (DGEBA) epoxy resin — clay nanocomposites was synthesized with diamino-diphenyl methane (DDM) curing agent. Nanocmposites were synthesized at different curing temperatures (60°C, 80°C, 100°C and 120°C), at various level of clay content in matrix (1–3% and 5%). The aim of this work is to study the effect of curing temperature on nanocomposite structure and properties. It is observed that property and structure of nanocomposites is governed by curing temperature and clay content in the matrix. Higher curing temperature shows increased mechanical properties over low temperature curing. Maximum increase in tensile properties is observed for 2 wt% nanoclay concentration irrespective of curing condition.

This study deals with the wear rates and quasi-static mechanical properties of polypropylene (PP) infused with layered organo-modified montmorillonite nanoclays. Test results show that PP infused with 2 wt.% of organo-modified montmorillonite gives improved mechanical strength, higher fracture toughness, and lower wear rates. Transmission electron microscopy shows that the structure of the modified nanocomposite changes from an exfoliated structure at 1 wt.% nanoclay loading to an intercalated structures at 5 wt.% nanoclay loading. The general improvement in properties, which includes but not limited to the thermal barrier properties, may be attributed to the change in structure.