Ecocomposition Research Articles

Production of eco composites based on natural rubber and recycled sugarcane bagasse waste to be utilised as a type of food contact

Natural fibres are abundant, renewable, and biodegradable, which has inspired numerous academics worldwide to investigate their possible applications in various industrial fields. The food packaging sector is seeking bio-based and biodegradable substitutes to increase sustainability. In this study, new composites were prepared from natural rubber (NR) and sugarcane bagasse fibres (SCB) with different concentrations of SCB (0, 2.5, 5, 10 &20 phr). The effect of SCB on the properties of natural rubber was studied before and after the alkaline treatment of the fibres. The biocomposites are characterized using Fourier transmission infrared spectroscopy, thermogravimetric analysis, scanning electron microscope, transmission electron microscope, and dielectric measurements in addition to rheological and mechanical analysis. The overall migration test for biocomposites loaded with 20phr SCB was performed to assess the biocomposite’s safety as food contact materials. The study’s results indicated that, adding SCB improved the conductivity, tensile strength, and elongation at break of natural rubber. Alkaline treatment strengthened the bonding between the filler and matrix and improved biocomposites’ thermal dielectric and mechanical properties. The overall migration test indicated that the alkaline treatment increased the overall migration to simulants. Accordingly, alkaline-treated NR-SCB biocomposites are effective eco-friendly food packaging candidates for certain types of food such as aqueous non-acidic products.

Eco composites with synergistic combinations of natural rubber latex and wood flour toughened recycled HDPE

The recycling of thermoplastic waste reinforced with agricultural products has gained significant attention owing to its benefits towards the economy and the environment. Natural rubber latex (NRL), abundantly found in South East Asia, and wood flour (WF) were added to recycled high-density polyethylene (reHDPE) forming a three-phase composite with the aim of improving the composite’s mechanical resilience, where WF strengthens the composite. The composition of reHDPE was fixed at 80 wt. % and the two fillers were varied to observe the effects of fillers on the mechanical properties, specifically impact resistance. The addition of only 5 wt.% NRL (WF15 NRL5) raises the impact resistance up to 100 % with respect to the composite with only 20 wt.% wood flour. The composition with 5 wt.% WF and 15 wt.% NRL (WF5 NRL15) exhibited the highest impact resistance of 483 J/m and the best processing conditions due to the dispersion of NRL in the polymer matrix. The flexible properties were improved in the NRL-dominated composition. Additionally, higher NRL content increases the decomposition temperature, thus allowing tunable adjustments to the compositions for practical applications. Processing a three-phase reHDPE/WF/NRL composite showed favorable results towards low-cost products from recycled raw materials.

A Method to Improve the Characteristics of EPDM Rubber Based Eco-Composites with Electron Beam.

A natural fiber reinforced composite, belonging to the class of eco composites, based on ethylene-propylene-terpolymer rubber (EPDM) and wood wastes were obtained by electron beam irradiation at 75, 150, 300, and 600 kGy in atmospheric conditions and at room temperature using a linear accelerator of 5.5 MeV. The sawdust (S), in amounts of 5 and 15 phr, respectively, was used to act as a natural filler for the improvement of physical and chemical characteristics. The cross-linking effects were evaluated through sol-gel analysis, mechanical tests, and Fourier Transform Infrared FTIR spectroscopy comparatively with the classic method with dibenzoyl peroxide (P) applied on the same types of samples at high temperature. Gel fraction exhibits values over 98% but, in the case of P cross-linking, is necessary to add more sawdust (15 phr) to obtain the same results as in the case of electron beam (EB) cross-linking (5 phr/300 kGy). Even if the EB cross-linking and sawdust addition have a reinforcement effect on EPDM rubber, the medium irradiation dose of 300 kGy looks to be a limit to which or from which the properties of the composite are improved or deteriorated. The absorption behavior of the eco-composites was studied through water uptake tests.

Poly (Lactic Acid)/Thermoplastic Starch Films: Effect of Cardoon Seed Epoxidized Oil on Their Chemicophysical, Mechanical, and Barrier Properties

In this work, biodegradable films based on poly (lactic acid) (PLA) and corn thermoplastic starch (TPS), additivated with epoxidized cardoon oil plasticizer (ECO) at 3% by weight with respect to PLA mass fraction, were prepared by melt extrusion process and compression molding. The effect of ECO on structural, thermal, mechanical, barrier, and spectral optical properties of the films was investigated. Spectroscopic analysis evidenced the development of physical interaction between oil and polymers, mainly PLA. In addition, no oil migration occurrence was detected after six months of film preparation, as evidenced by oil mass evaluation by precipitation as well as by 1H-NMR methods, thus highlighting the good inclusion of oil inside the polymeric network. The plasticizing action of the oil induced a lean improvement of the interfacial adhesion between hydrophobic PLA and hydrophilic TPS, particularly accentuated in PLA80_ECO composition, as evidenced by morphological analysis of blend fracture surfaces. TGA data underlined that, differently from TPS-based films, PLA-based systems followed one degradative thermal profile suggesting a slight compatibilization effect of epoxidized oil in these films. The shifting of Tg values, by differential scanning calorimetry (DSC) analysis, indicated a weak miscibility at molecular level. Generally, in the investigated blends, the phase separation between PLA and TPS polymers was responsible for the mechanical properties failing; in particular, the tensile strength evidenced a negative deviation from the rule of mixtures, particularly marked in TPS-based blends, where no physical entanglements occurred between the polymers since their immiscibility even in presence of ECO. The epoxidized oil strongly improved the barrier properties (water vapor permeability (WVP) and oxygen permeability (O2P)) of all the films, likely developing a physical barrier to water and oxygen diffusion and solubilization. With respect to neat PLA, PL80 and PL80_ECO films evidenced the improvement of surface wettability, due to the presence of polar groups both in TPS (hydroxyl residues) and in epoxidized oil (oxirane rings). Finally, following to the conditioning in climatic chamber at T = 25 °C and RH = 50%, PLA80 film became opaque due to TPS water absorption, causing a light transmittance decreasing, as evidenced by spectral optical analysis.

Sustainable eco–composites obtained from waste derived biochar: a consideration in performance properties, production costs, and environmental impact

Waste based activated biochar was used to manufacture wood/polypropylene biocomposites. The biochar used had no surface functional groups, however, possessed high surface area (335 m2/g). Therefore, it was hypothesised that less than usual amount (3–5 wt%) of compatibiliser (maleic anhydride) could be used, to reduce production costs, while maintaining similar mechanical and flammability properties of the biocomposite. The biocomposites were characterised mechanically through tension, flexural, impact, and micro–hardness tests. The flammability and thermal behaviours were determined using cone calorimetry and thermogravimetry, respectively. Infrared spectroscopy and X–ray diffraction were also employed to comprehend the chemical changes occurring in the biocomposites. It was found that the amount of compatibiliser could be reduced to 1 wt% (from 3 wt%) without compromising on the mechanical performance (especially, tensile strength/modulus, impact strength, and micro–hardness) and flammability properties of the biocomposites. Electron microscopy revealed that the lack of compatibiliser in the biocomposites was compensated by well–dispersed biochar particles whose pores were infiltrated by the polymer causing a mechanical interlocking. In general, addition of biochar improved the mechanical and fire performance of the biocomposites compared to the neat polymer. Reduction of compatibiliser to 1 wt% from 3 wt% in conjunction with biochar saves ∼18% of the biocomposite production costs.

Heeding the corpse in the cargo: The writing centre and the need to listen

Transformation is perhaps an overused word. It is not written in our constitution though it is used daily by politicians in the ANC. The eyes of many South Africans become glazed when they hear it. Yet it is crucial in a country which is still poised between chaos and progress, which still has the potential to dissolve into race related riots or build itself into a creative multicultural democracy. What might it mean specifically in terms of hopeful strategies at the Wits Writing Centre? This paper seeks to first describe through a short ethnographic description of cultural pattern, as modelled by Jones, Lea and Street (1998) elements of cultural stasis within the greater institutionalised culture of teaching and learning. Then using Jonathan Jansen’s theorising of embedded knowledges in contemporary South African universities (2009) it identifies types of knowledge present in this particular cultural pattern which repel change. The writing centre is understood through eco composition (De Wet 2011) as a small pocket within this macro environment which interacts with these often invisible and controlling knowledges present in our context. What can this pocket do to resist the overwhelming inertia of embedded knowledge and construct and maintain a space which allows for change? It will be argued that the primacy of the art of listening and the welcoming of opportunities for reflecting on dissonance, allows for the space of the writing centre to disrupt what Jansen terms ‘knowledge in the blood’.

First International Conference On Eco-Composites (ECOCOMP)

(2001). First International Conference On Eco-Composites (ECOCOMP) Materials Technology: Vol. 16, No. 4, pp. 253-255.