Effect of Glycerol on the Properties of 100 % Biodegradable Thermoplastic Based on Wheat Flour

This paper reports the effect of glycerol on thermal, mechanical and morphology of the wheat-flour based thermoplastic sheets (<3 mm) fabricated using single screw extrusion followed by compression molding. The amount of glycerol (plasticizer) added during the formulation varies from 20 to 35 % w/w (20, 23, 25, 30 and 35 % w/w). Results indicate that increase in the amount of glycerol in the starch based thermoplastic sheets, lowers its hardness and tensile properties while an increase in the melt flow index. Variation in the glycerol content from 20 to 25 % w/w increases the impact strength of the thermoplastic sheets beyond this limit it decreases. The contact angle analysis shows that glycerol has effect on the surface energy and work of adhesion of the thermoplastic sheets. However, the presence of glycerol has no significant influence on the thermal stability of thermoplastic sheets above 200 °C.     

Mechanical–Thermal Properties and VOC Emissions of Natural-Flour-Filled Biodegradable Polymer Hybrid Bio-Composites

The mechanical–thermal properties and volatile organic compound (VOC) emissions of natural-flour-filled, biodegradable polymer bio-composites were investigated according to variation in porous inorganic filler types. At a porous inorganic filler content of 3%, the tensile and flexural strengths of the hybrid bio-composites were not significant changed. However, the coefficient of thermal expansion and thermal expansion of the bio-composites were slightly decreased. Furthermore, the incorporation of the porous inorganic materials into bio-composites slightly increased the E’ values of the hybrid bio-composites over the entire temperature range, although the tan δ_max temperature (T _g) of the hybrid bio-composites was not significantly changed. At a porous inorganic filler content of 3%, the various odor and VOC emissions of the hybrid bio-composites were significantly decreased because the various oxidation and thermal degradation gases of the natural flour and matrix were absorbed in the pore structures of the porous inorganic fillers and thereby prevented the migration into the final products.     

Experimental Processing of Biodegradable Drip Irrigation Systems—Possibilities and Limitations

The increased cost associated with the waste removal and disposal of conventional agricultural plastic in contact with the soil combined with the gradually decreasing cost of the biodegradable plastics allowed the commercialization of biodegradable mulching films. Since the conventional thin wall or tape drip irrigation system lies under the mulching film and is used for one season only, it would be desirable to replace it with a biodegradable one. This paper presents the results of a research work investigating the possibilities and limitations in developing biodegradable drip irrigation thin wall pipes and pipes. The first ever experimental biodegradable drip irrigation thin wall pipes were produced. Rigid pipes were also produced for experimental purposes. Manufacturing problems were encountered in the processing of the biodegradable drippers and irrigation thin wall pipes with the experimental materials due to the complex formulation of the raw materials and the fact that the machinery used was specifically designed for PE processing. Experimental biodegradable thin wall pipes made of Bioflex with embedded drippers made of Mater-Bi were produced. The processing problems encountered with the production of thin wall pipes were surpassed during the experimental production of rigid type irrigation pipes. A biodegradable rigid irrigation pipe made of a grade of Mater-Bi, with embedded cylindrical drippers made of another grade of Mater-Bi was produced successfully. A better understanding of the thermal profile of the biodegradable raw materials and the use of processing equipment adapted to this profile might allow in the future the manufacturing of thin wall drip irrigation pipes for agricultural applications, and the use of alternative biodegradable materials.     

Influence of Geometry on the Mean Flow within Urban Street Canyons – A Comparison of Wind Tunnel Experiments and Numerical Simulations

A comparison between numerical simulations and wind tunnel modelling has been performed to examine the variation with streamwise aspect ratio (width/height, W/H) of the mean flow patterns in a street canyon. For this purpose a two-dimensional (2-D) cavity was subjected to a thick turbulent boundary layer flow perpendicular to its principal axis. Five different test cases, W/H = 0.3, 0.5, 0.7, 1.0 and 2.0, have been studied experimentally with flow measurements taken using pulsed-wire anemometry. The results show that the skimming flow regime, with a large vortex in the canyon, occurred for all the cases investigated. For the cavities with W/H 0.7 a weaker secondary circulation developed beneath the main vortex. The narrower the canyon, the smaller the wind speed close to the cavity ground, giving increasingly poor ventilation qualities. The corresponding numerical results were obtained with the Computational Fluid Dynamics (CFD) code CHENSI that uses the standard k- model. The intercomparison showed good agreement in terms of the gross features of the mean flow for all the geometries examined, although some detailed differences were observed.     

The Effect of UV-B Irradiation on the Biodegradability of Poly-β-Hydroxybutyrate (PHB) and Poly-ɛ-Caprolactone (PCL)

The biodegradability of poly--hydroxybutyrate and poly--caprolactone in soil compostage before and after irradiation of the polymers for 192, 425, and 600 h in a Weather-Ometer was examined. The biodegradability tests were done in soil compostage at pH 7.0, 9.0, and 11.0 to assess the influence of this parameter on degradation. The rate of degradation was directly proportional to the soil alkalinity. Poly--hydroxybutyrate showed the greatest weight loss and aging in a Weather-Ometer did not significantly increase the biodegradation, except when the polymer was aged for 425 h and buried in soil compostage of pH 11.0.     

Effect of temperature on VFA’s and biogas production in anaerobic solubilization of food waste

The effectiveness of methane fermentation treatment used in food waste processing is currently limited by solubilization and acidogenesis. In efforts to improve the treatment process, this study examined the effects of temperature on solubilization and acidogenesis. The solubilization rate of food waste, which was based on suspended solid removal, was 47.5%, 62.2%, 70.0%, 72.7%, 56.1% and 45.9% at 15 °C, 25 °C, 35 °C, 45 °C, 55 °C and 65 °C, respectively. Solubilization rate was accelerated from the middle to late experimental periods under mesophilic (35 °C and 45 °C) conditions. In contrast, overall solubilization rate was significantly lower under thermophilic (55 °C and 65 °C) conditions than under mesophilic conditions, although solubilization occurred rapidly in the early experimental period. The production of biogas was high under mesophilic conditions of 35 °C and 45 °C, at 64.7 and 62.7 mL/g-VS, respectively, while it was scarce under thermophilic conditions. Solubilization of food waste was accelerated under both mesophilic and thermophilic conditions; however, solubilization rate was observed to be particularly high under mesophilic conditions, and a shortening of the hydraulic retention time is expected under thermophilic conditions.     

Effect of Nano-SiO<Subscript>2</Subscript> and Bark Flour Content on the Physical and Mechanical Properties of Wood–Plastic Composites

The aim of this study is to evaluate the impact of nano-SiO₂ and bark flour (BF) on the natural fiber–plastic composites engineering properties made from high density polyethylene (HDPE) and beech wood flour (WF). For this purpose, WF and BF in 60 mesh size and weight ratio of (50, 0 %), (30, 20 %), (10, 40 %) and (0, 50 %) respectively were mixed with HDPE. In order to increase the interfacial adhesion between the filler and the matrix, the maleic anhydride grafted polyethylene was constantly used at 3 wt% for all formulations as a coupling agent. The nano-SiO₂ particles with weight ratio of 0, 1, 2, and 4 % were also utilized to enhance the composites properties. The materials were mixed in an internal mixer (HAAKE) and then the bark and/or wood–plastic composite samples were made utilizing an injection molding machine. The physical tests including water absorption and thickness swelling, and mechanical tests including bending characteristics and un-notched impact strength were carried out on the samples based on ASTM standard. The results indicated that as the BF content increased in the composite, mechanical and physical properties were reduced, but the given properties were increased with the addition of nano-SiO₂. The addition of nano-SiO₂ had a negative impact on the physical properties, but when it was up to 2 %, it increased the impact strength.     

Novative Biomaterials Based on Chitosan and Poly(ε-Caprolactone): Elaboration of Porous Structures

The swelling capability of chitosan was explored in order to use water both, as volatile plasticizer and as pore-forming agent. Chitosan powder was swelled in acidic aqueous solution and melt blended with poly(ε-caprolactone) (PCL). After stabilization at 57% RH and 25 °C, samples suffered a water mass loss of around 30 wt% without dimensions variation. Despite the low miscibility of these biopolymers, quite homogeneous dispersion of chitosan within the polyester matrix was obtained. Some interactions between both biopolymers could be observed. To obtain chitosan phase with a thermoplastic-like behaviour, the plasticization effect was also studied by the addition of 25 wt% glycerol as non volatile plasticizer. The equilibrium moisture content of samples increased with the incorporation of glycerol due to its hydrophilic nature. Morphology, thermal and mechanical properties of the blends were determined after stabilization. The preparation of rich PCL blends allowed the formation of macroporous structures since samples were not contracted after water loss and stabilization. These biomaterials with such a porous structure could be used for biomedical applications.     

Thermal and Biodegradable Properties of Poly(<Emphasis Type="SmallCaps">l</Emphasis>-lactide)/Poly(ε-Caprolactone) Compounded with Functionalized Organoclay

Poly(l-lactide) (PLLA)/Poly(ε-caprolactone) (PCL) blends were compounded with commercially available organoclay Cloisite 25A (C25A) and C25A functionalized with epoxy groups, respectively. Epoxy groups on the surface of C25A were introduced by treating C25A with (glycidoxypropyl)trimethoxy silane (GPS) to produce so called Functionalized Organoclay (F-C25A). The silicate layers of PLLA/PCL/F-C25A were exfoliated to a larger extent than PLLA/PCL/C25A. Incorporation of the epoxy groups on C25A improved significantly mechanical properties of PLLA/PCL/C25A. The larger amount of exfoliation of the silicate layers in PLLA/PCL/F-C25A as compared with that in PLLA/PCL/C25A was attributed to the increased interfacial interaction between the polyesters and the clay due to chemical reaction. Thermo gravimetric analysis revealed that the nanocomposites with exfoliated silicate layers were more thermally stable than those with intercalated silicate layers. The biodegradability of the neat PLLA/PCL and corresponding nanocomposite was studied under compost, and the rate of biodegradation of PLLA/PCL increased after nanocomposite preparation.     

Reply to the comment by D. Guyonnet,on “Comparison on percolation to batch and sequential leaching tests: Theory and data”

Reply to the comment by D. Guyonnet, on “Comparison on percolation to batch and sequential leaching tests: Theory and data”.     

Effect of Matrix–Particle Interfacial Adhesion on the Mechanical Properties of Poly(lactic acid)/Wood-Flour Micro-Composites

The influence of interfacial matrix/particle adhesion on the mechanical properties of poly(lactic acid) (PLA) micro-composites was investigated. The tensile strength of PLA/wood-flour micro-composites is almost independent of wood-flour content, suggesting only weak adhesion exists between the PLA matrix and the wood-flour particles. The addition of wood-flour resulted in an increase of up to 95% in the tensile modulus, in comparison with pure PLA, which showed a more resilient matrix. The addition of a coupling agent, methylenediphenyl-diisocyanate (MDI) to the composition resulted in an increase in tensile strength and tensile modulus of the micro-composites, of 10 and 135%, respectively, indicating enhanced matrix–particle interfacial adhesion. SEM and electron probe microanalysis provided evidence of improved interfacial adhesion between PLA and wood-flour particles from the addition of MDI. In contrast, addition of PEAA resulted in a micro-composite displaying substantially reduced tensile strength, up to 35% and a slightly increased in impact strength, up to 15%, consistent with the introduction of the rubbery PEAA component into the polymeric matrix. No evidence for increased matrix–particle adhesion was found for the PLA/wood-flour micro-composites containing PEAA.     

Evaluation of Material Biodegradability in Real Conditions–Development of a Burial Test and an Analysis Methodology Based on Numerical Vision

This work validated a burial protocol for in situ testing and presents a robust, repeatable and time-saving technique to measure degraded areas in the sample, i.e. an image analysis method. 1440 specimens of degraded samples have been compiled in a data base. To this end, twenty samples presenting different levels of biodegradability (i.e. PHBV/HV, PLA, PCL, PCL-Starch, paper, PE, PE-Starch) were buried at 4 different locations and then disinterred at 4, 6, 9, 12, 18, and 24-month intervals. The biodegradation levels of these samples were determined by computing weight and area loss. Weight loss was measured after careful cleaning, whereas area loss was quantified using image analysis. Image analysis gives reliable information on visual pollution while only requiring a rudimentary and thus quicker cleaning of the samples.     

Formulation and Characterization of Biodegradable Packaging Film Derived from Potato Starch &; LDPE Grafted with Maleic Anhydride—LDPE Composition

There is a paradigm shift from non renewal resources to renewable resources in view of problems of disposal of plastic products after their life cycle. This paper deals with the approach, preparation and product properties of polymer prepared by using polysaccharide based biodegradable polymer. Basic material has been prepared by mixing LDPE, LDPE-g-mA (LDPE grafted with (0.5%) maleic anhydride (1:1)) containing a polar group in the LDPE backbone. Prepared basic material has been compounded in twin screw extruder with 0, 2.5, 5.0, 7.5, 10.0, 12.5 & 15% of Potato Starch. Thereafter, after conditioning blown film samples were prepared using extrusion film blowing technique, under temperature profile ranging from 120 to 160 °C. Packaging films have been prepared with maximum 15% potato starch contents and have been characterized by FTIR, DSC, TGA, and XRD techniques to ascertain its impact on some structural and thermal properties like thermal stability, flexibility, crystallinity, crystal size etc.     

The effects on Thailand of China’s import restrictions on waste: measures and challenges related to the international recycling of waste plastic and e-waste

Journal of Material Cycles and Waste Management - This paper has outlined the measures and challenges facing Thailand, which was forced to address a surge in imports of plastic waste and e-waste...     

Environmental Degradation of Biodegradable Polyesters: 3. Effects of Alkali Treatment on Biodegradation of Poly(ε-Caprolactone) and Poly[(R)-3-Hydroxybutyrate) Films in Controled Soil

The poly(-caprolactone) (PCL) and poly[(R)-3-hydroxybutyrate] (R-PHB) films with a hydrophilic surface were prepared by the alkali treatment of their as-cast films in NaOH solutions of different concentrations. The alkali-treated PCL and R-PHB films, as well as the as-cast PCL and R-PHB films, were biodegraded in soil controlled at 25°C and the effects of alkali treatment or surface hydrophilicities on their biodegradation were investigated by the use of gravimetry, gel permeation chromatography (GPC), scanning electron microscopy (SEM), and polarization optical microscopy. It became evident that the alkali treatment enhanced the hydrophilicities and biodegradabilities of the PCL and R-PHB films in soil. The biodegradabilities of the as-cast aliphatic polyester films in controlled soil decreased in the following order: PCL > R-PHB > PLLA, in agreement with that in controlled static seawater.     

Effect of the water–oil ratio on brine/surfactant/alcohol/oil systems optimized for soil remediation

The optimum middle-phase microemulsion used for remediation of oily contaminated soils is often obtained by mixing a certain amount of a surfactant/alcohol mixture with oil and adjusting the salinity concentrations at a constant water–oil ratio. Upon introduction to the subsurface, however, the system may not be in the optimum state throughout the remediation process owing to the change in the water–oil ratio. This research has attempted to investigate the effect of the water–oil ratio on the phase behavior of systems containing brine, anionic surfactant, alcohols, and different oils. By systematically changing the water–oil ratio, while keeping the others variables constant, the systems exhibited different phase behavior. The results revealed that the effect of the water–oil ratio on system behavior was significant, and analogous to that of salinity. Increasing the water–oil ratio led the system change from winsor I → winsor III → winsor II. The greater the water–oil ratio the lower the salinity required to produce the middle-phase microemulsion, but the narrower the salinity range of the three-phase region. An empirical correlation has been developed in order to predict the changes in phase behavior with the changes in water–oil ratio. This provides a useful tool for designing optimum formulations suitable for soil remediation. Received: October 5, 1999 / Accepted: March 27, 2000