The Potential of Chicken Eggshell Waste as a Bio-filler Filled Epoxidized Natural Rubber (ENR) Composite and its Properties

Eggshell calcium carbonate (ECC) and eggshell calcium carbonate treated with high temperature (ECC-600) were prepared from chicken eggshell waste. ECC was obtained by crushing eggshell waste, eliminating membranes and followed by sieving. In the case of ECC-600, ECC powder was additionally heated at 600 °C for 2 h. Both were used to promote as fillers compared to that of commercial light-precipitated calcium carbonate (commercial CaCO₃) with various loading levels (i.e., 0, 25, 50 and 75 phr) in epoxidized natural rubber containing 25 mol% of epoxide group (ENR-25). Among the three types of fillers (i.e., ECC, ECC-600 and commercial CaCO₃), ECC filled materials showed superior vulcanization characteristics by the increasing of maximum torque (M_H) and cure rate index (CRI) with the reducing of cure time (t_c90) and scorch time (t_s2). The highest tensile properties as well as the lowest tension set value were also observed. Morphological property revealed that ECC was greater interfacial adhesion than those of others. In addition, dynamic mechanical properties of vulcanizates containing ECC, storage modulus (E′) was the highest and glass transition temperature (T _g ) shifted toward high temperature. Increasing of loading levels of any fillers affected the increase of M_H and CRI with reducing of t_c90 and t_s2. However, tensile properties decreased with increasing filler content but it did not affect T _g shifting except for a series of vulcanizates containing ECC.     

Effect of Nucleating Agents on Physical Properties of Poly(lactic acid) and Its Blend with Natural Rubber

Poly(lactic acid) (PLA) presents high strength and modulus, but very low toughness as well as slow crystallization. Natural rubber (NR) was blended to enhance the toughness and nucleating agent was added to improve the crystallization. Cyclodextrin (CD), considered as a green compound, as well as calcium carbonate (CaCO₃) and talc were used as nucleating agents. Effects of these nucleating agents on crystallization, mechanical properties and morphology of neat PLA and PLA/NR blend were investigated. It was found that the addition of talc and CD decreased cold crystallization temperature (T_cc) of the PLA. Same result was obtained in PLA/NR blend containing talc. All nucleating agents increased the degree of crystallinity (Χ_C) of PLA, whereas only talc and CaCO₃ increased Χ_C of PLA in PLA/NR blends. The enhanced toughness of PLA by the addition of nucleating agent was attributed to its increased crystallinity, as well as decreased spherulite size. For PLA/NR blends, the increase in toughness was mainly contributed by the presence of the rubber.     

Utilization of Porous Carbons Derived from Coconut Shell and Wood in Natural Rubber

The porous carbons derived from cellulose are renewable and environmentally friendly. Coconut shell and wood derived porous carbons were characterized with elemental analysis, ash content, X-ray diffraction, infrared absorbance, particle size, surface area, and pore volume. The results were compared with carbon black. Uniaxial deformation of natural rubber (NR) composites indicate the composites reinforced with the porous carbon from coconut shell have higher tensile moduli at the same elongation ratio than the composites reinforced with wood carbon. 40 % coconut shell composite showed a fivefold increase in tensile modulus compared to NR. Polymer–filler interactions were studied with frequency dependent shear modulus, swelling experiments and dynamic strain sweep experiments. Both linear and non-linear viscoelastic properties indicate the polymer–filler interactions are similar between coconut shell carbon and wood carbon reinforced composites. The swelling experiments, however, showed that the polymer–filler interaction is greater in the composites reinforced with coconut shell instead of wood carbon.     

Cetyltrimethyl Ammonium Bromide Modified Kaolin as a Reinforcing Filler for Natural Rubber

Cure characteristics, Mooney viscosity and physico-mechanical properties of natural rubber (NR) containing CTAB modified kaolin have been studied. NR mix containing 6 phr (parts per hundred part rubber) of CTAB modified kaolin showed significant increases in cure rate and state of cure as compared to gum NR compound and a mix containing the same amount of unmodified kaolin. Lower Mooney viscosity of the NR mix containing CTAB modified kaolin suggested improved processability. Reinforcing effect of CTAB modified kaolin in NR was evident from higher chemical crosslink density index, tensile modulus, hardness, tensile strength and tear strength. Besides, the NR vulcanizate containing 6 phr of CTAB modified kaolin showed lower abrasion loss and heat build-up which could be beneficial for applications such as tire treads.     

Biodegradability and Thermal Properties of Novel Natural Rubber/Linear Low Density Polyethylene/Thermoplastic Starch Ternary Blends

This work aimed to prepare biodegradable thermoplastic elastomers based on NR/LLDPE/TPS ternary simple blends to achieve some exclusive properties, i.e., good biodegradability in terms of water absorption and weight loss after burial, together with reasonable mechanical and thermal properties. A comparative study on biodegradability and other related properties of NR/LLDPE binary and NR/LLDPE/TPS ternary blends was performed. It was found that increasing the TPS proportion decreased storage modulus and complex viscosity. In addition, the size of dispersed TPS domains in the NR/LLDPE co-continuous matrix increased with TPS proportion, while the mechanical properties in terms of 100% moduli, tensile strength, elongation at break, and hardness decreased. This might be attributed to decreased interfacial adhesion with increasing size of TPS domains. Furthermore, increasing the TPS loading in the blend reduced the temperatures for 5 or 50% mass loss (T₅ or T₅₀) and the degradation temperature (T _d ). However, the biodegradability improved, in terms of increased water absorption and weight loss after burial in soil, with the loading level of TPS.     

Study of Fatigue Life and Filler Interaction of Paper Sludge Filled Epoxidized Natural Rubber (ENR) and Maleated Natural Rubber (MNR) Composites

An investigation on the effect of epoxidation and maleated natural rubber (MNR) on fatigue and rubber-filler interaction properties of paper sludge filled natural rubber composites was elucidated. Paper sludge loading was varied from 0 to 40 phr and conventional vulcanisation system was used while compounding was carried out on a laboratory sized two roll mill. Two different types of natural rubber, SMR L and ENR 50 having 0 and 50 mole% of epoxidation were used in order to investigate the effect of epoxidation on the composites. Results indicate that, at a fixed filler loading, ENR 50 vulcanizates exhibit higher fatigue life than SMR L vulcanizates especially at filler loading below 20 phr which might be associated with better rubber-filler interaction. In the case of composites with the addition of maleated natural rubber (MNR), a higher fatigue life was observed due to presence of physical and/or chemical linkages, which increases the interfacial adhesion. Scanning electron microscopy (SEM) micrographs of fatigue fracture surfaces and rubber-filler interaction study supported the observed result on fatigue life.     

Tensile Strength, Elongation, Hardness, and Tensile and Flexural Moduli of PLA Filled with Glycerol-Plasticized DDGS

Rapid growth of the biofuel industry is generating large amounts of coproducts such as distillers dried grains with solubles (DDGS) from ethanol production and glycerol from biodiesel. Currently these coproducts are undervalued, but they have application in the plastics industry as property modifiers. The objective of this research effort is to quantify the effects on mechanical properties of adding DDGS and glycerol to polylactic acid (PLA). The methodology was to physically mix DDGS, as filler, with PLA pellets and injection mold the blends into test bars using glycerol as a plasticizer. The bars were subject to mechanical testing procedures to obtain tensile strength, tensile and flexural moduli, elongation to break, and surface hardness of blends from 0 to 90?%, by weight, of plasticized filler. Blends were typically relatively brittle with little or no yielding prior to fracture, and the addition of glycerol enabled molding of blends with high levels of DDGS but did not increase strength. Any presence of filler decreased the tensile strength of the PLA, and 20?C30?% filler reduced strength by 60?%. The 35?C50?% filled PLA had about one-fifth the value for pure PLA; at 60?C65?% filler level, about 10?% tensile strength remained; and over 80?% filler, 95?% of the strength was lost. Over 20?% filler, the tensile modulus decreased. The 35?% plasticized, filled blend yielded about one-half the stiffness as the pure PLA case; flexural modulus trended in the same manner but demonstrated a greater loss of stiffness. Most blends had less than 3?% elongation to break while surface hardness measurements indicated that up to 60?% filler reduced Shore D hardness by less than 20?%. The tensile strength and modulus data are consistent with the findings of other researchers and indicate that the type of filler and amount and sequence of plasticization are secondary effects, and the total PLA displaced is the dominant factor in determining the mechanical strength of the PLA and DDGS blends. Up to 65?% plasticized DDGS filler can be injection molded, and sufficient mechanical strength exists to create a variety of products. Such a novel material provides higher-value utilization of the biofuel coproducts of glycerol and DDGS and maintains the biodegradable and biocompatible nature of PLA.     

Mechanisms contributing to the thermal analysis of waste incineration bottom ash and quantification of different carbon species

The focus of this study was to identify the main compounds affecting the weight changes of bottom ash (BA) in conventional loss on ignition (LOI) tests and to obtain a better understanding of the individual processes in heterogeneous (waste) materials such as BA. Evaluations were performed on BA samples from a refuse derived fuel incineration (RDF-I) plant and a hospital waste incineration (HW-I) plant using thermogravimetric analysis and subsequent mass spectrometry (TG–MS) analysis of the gaseous thermal decomposition products. Results of TG–MS analysis on RDF-I BA indicated that the LOI measured at 550 °C was due to moisture evaporation and dehydration of Ca(OH)₂ and hydrocalumite. Results for the HW-I BA showed that LOI at 550 °C was predominantly related to the elemental carbon (EC) content of the sample. Decomposition of CaCO₃ around 700 °C was identified in both materials. In addition, we have identified reaction mechanisms that underestimate the EC and overestimate the CaCO₃ contents of the HW-I BA during TG–MS analyses. These types of artefacts are expected to occur also when conventional LOI methods are adopted, in particular for materials that contain CaO/Ca(OH)₂ in combination with EC and/or organic carbon, such as e.g. municipal solid waste incineration (MSWI) bottom and fly ashes. We suggest that the same mechanisms that we have found (i.e. in situ carbonation) can also occur during combustion of the waste in the incinerator (between 450 and 650 °C) demonstrating that the presence of carbonate in bottom ash is not necessarily indicative for weathering. These results may also give direction to further optimization of waste incineration technologies with regard to stimulating in situ carbonation during incineration and subsequent potential improvement of the leaching behavior of bottom ash.     

Preparation and Characterization of PVC Matrix Composites with Biochemical Sludge

Biochemical sludge (BS), generated in the waste water treatment of paper mills, was pretreated by enzyme hydrolysis. The effect and action mechanism of the enzymatic treatment on the properties of polyvinyl chloride (PVC) matrix composites with BS were discussed. Results showed that when the filler content was 30 wt%, the tensile strength of the PVC composites filled with BS and its modified products which were pretreated by laccase, cellulase and hemicellulase can be increased by 38.64, 67.4, 63.5 and 66.3% than the PVC composite filled with calcium carbonate. When the dosage of filler was 40 wt%, the elastic modulus of PVC composites filled with BS and its above three modified products decreased by 53.3, 52.3, 50.0 and 46.3%, respectively. Meanwhile, the thermal stability of PVC composites can also be improved at the temperature of over 340 °C. It can be concluded that the enzyme pretreatment can improve the application performance of BS usage in PVC matrix composites.     

Mercury leaching characteristics of waste treatment residues generated from various sources in Korea

In this study, mercury (Hg) leaching characteristics of the waste treatment residues (fly ash, bottom ash, sludge, and phosphor powder) generated from various sources (municipal, industrial, medical waste incinerators, sewage sludge incinerator, oil refinery, coal-fired power plant, steel manufacturing plant, fluorescent lamp recycler, and cement kiln) in Korea were investigated. First, both Hg content analysis and toxicity characteristic leaching procedure (TCLP) testing was conducted for 31 collected residue samples. The Hg content analysis showed that fly ash from waste incinerators contained more Hg than the other residue samples. However, the TCLP values of fly ash samples with similar Hg content varied widely based on the residue type. Fly ash samples with low and high Hg leaching ratios (R_L) were further analyzed to identify the major factors that influence the Hg leaching potential. Buffering capacity of the low-R_L fly ash was higher than that of the high-R_L fly ash. The Hg speciation results suggest that the low-R_L fly ashes consisted primarily of low-solubility Hg compounds (Hg₂Cl₂, Hg⁰ or HgS), whereas the high-R_L fly ashes contain more than 20% high-solubility Hg compounds (HgCl₂ or HgSO₄).     

Dehydrochlorination behavior of polyvinyl chloride and utilization of carbon residue: effect of plasticizer and inorganic filler

The dehydrochlorination behavior of plasticizer (DOP) and inorganic filler (CaCO₃) contained in PVC samples and the properties of the activated carbons produced from those carbon residues have been investigated. In the dehydrochlorination process, both additives contributed not only to a decrease in HCl yield but also to the prolonged evolution of HCl. Part of the Cl species were observed to be stabilized as CaCl₂ by reaction with calcium ions when CaCO₃ was added. More than 80% of chlorine removal was achieved in all samples at 533 K. The use of potassium as an activation agent led to the production of activated carbon with a specific surface area greater than 1000 m²/g at the low temperature of 1023 K and assisted also in the elimination of residual Cl species by the formation of KCl during activation. Chemical Feedstock Recycling & Other Innovative Recycling Techniques 6     

Production of technical grade phosphoric acid from incinerator sewage sludge ash (ISSA)

The recovery of phosphorus from sewage sludge ash samples obtained from 7 operating sludge incinerators in the UK using a sulfuric acid washing procedure to produce a technical grade phosphoric acid product has been investigated. The influences of reaction time, sulfuric acid concentration, liquid to solid ratio and source of ISSA on P recovery have been examined. The optimised conditions were the minimum stoichiometric acid requirement, a reaction time of 120 min and a liquid to solid ratio of 20. Under these conditions, average recoveries of between 72% and 91% of total phosphorus were obtained. Product filtrate was purified by passing through a cation exchange column, concentrated to 80% H₃PO₄ and compared with technical grade H₃PO₄ specifications. The economics of phosphate recovery by this method are briefly discussed.     

An investigation on pollutant emissions from co-firing of RDF and coal

Pollutant emissions from co-firing of refuse derived fuel (RDF) and coal were investigated in a vortexing fluidized bed combustor (VFBC). RDF-5 was made of common municipal solid waste (MSW). CaCO₃ was injected in the combustor to absorb HCl at 850 °C. The results show that NO_x and HCl emissions increase with RDF-5 co-firing ratio. The NO_x concentration in flue gas at the bottom of the combustor is higher than that at the top. However, the trend of HCl released is reverse compared with NO_x emissions. It was found that the HCl concentration decreases with increasing the molar ratio of Ca/Cl. However, the effect of CaCO₃ addition on HCl retention is not significant when the molar ratio of Ca/Cl is higher than 5. The chlorine content in fly ash increases obviously with the molar ratio of Ca/Cl. PCDD/Fs emissions decrease slightly with an addition of CaCO₃. In this study incomplete combustion is regarded as the main cause for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) formation.     

Tensile Strength, Elongation, Hardness, and Tensile and Flexural Moduli of Injection-Molded TPS Filled with Glycerol-Plasticized DDGS

Continuing growth of biofuel industries is generating large amounts of coproducts such as distillers dried grains with solubles (DDGS) from ethanol production and glycerol from biodiesel. Currently these coproducts are undervalued, but they have application in the plastics industry as property modifiers. This research effort has quantified the effects on mechanical properties of adding DDGS and glycerol to a commercial thermoplastic starch (TPS). The methodology was to physically mix DDGS, as filler, with the TPS pellets and injection mold the blends into test bars using glycerol as a processing aid. The bars were then mechanically tested with blends from 0 to 65 %, by weight, of plasticized filler. The test bars were typically relatively brittle with little yielding prior to fracture with elongation between 1 and 3 %. The addition of glycerol enabled molding of blends with high levels of DDGS but did not increase strength. Any presence of filler decreased the tensile strength of the starch, and up to 30 % filler, the tensile strength drops about 15 %. The 20 and 50 % blends (without glycerol) have slightly greater stiffness than pure starch. With some other blends, the presence of plasticized filler degrades the tensile modulus with 35 % filler yielding about 1/3 the stiffness. Changes in the flexural modulus are much more pronounced as 20–25 % filled TPS has a 30 % increase in flexural stiffness. In terms of surface hardness, blends up to 60 % filler are within 20 % of the TPS baseline.     

Recovery of glass fibers from glass fiber reinforced plastics by pyrolysis

Fiber-reinforced plastic sheets containing unsaturated polyester cross-linked with styrene, CaCO₃ and glass fibers as fillers were pyrolyzed in a helium and steam atmosphere in order to recover glass fibers and valuable organic pyrolysis products. Glass fibers were separated from CaCO₃ and CaO by dissolving calcium salts in hydrochloric acid. Residual organic material was burnt afterwards. Best results were obtained at a pyrolysis temperature of 600 and 700 °C, resulting in a large liquid fraction high in styrene, leaving little residual organic material on the surface of the glass fibers. At a pyrolysis temperature of 500 °C, the degradation of the polymer matrix was incomplete, and at 900 °C, glass fibers were destroyed in the presence of CaO, leaving CaSiO₃ as a product.     

Biomass Carbon Ratio of Polymer Composites Measured by Accelerator Mass Spectrometry

The evaluation method of biomass carbon ratio of polymer composite samples including organic and inorganic carbons individually was investigated. Biodegradable plastics and biobased plastics can have their mechanical properties improved by combining with inorganic fillers. Polymer composites consisting of biodegradable plastics and carbonate were prepared by two different methods. Poly(lactic acid) (PLA) composite was prepared by synthesis from l-lactide with catalyst and calcium carbonate (CaCO₃) powders from lime. Poly(butylene succinate) (PBS) composite was prepared by hot-pressing the mixture of PBS powder and CaCO₃ powders from oyster shells. The mechanical properties of composite samples were investigated by a tensile test and a compression test using an Instron type mechanical tester. Tensile test with a dumbbell shape specimen was performed for PBS composite samples and compression test with a column shape specimen for PLA composite samples. Strength, elastic modulus and fracture strain were obtained from the above tests. Biomass carbon ratio is regulated in the American Standards for Testing and Materials (ASTM). In ASTM standards on biomass carbon ratio, it is required that carbon atoms from carbonates, such as CaCO₃, are omitted. Biomass carbon ratio was evaluated by ratio of ¹⁴C to ¹²C in the samples using Accelerator Mass Spectrometry (AMS). The effect of pretreatment, such as oxidation temperature and reaction by acid, on results of biomass carbon ratio was investigated. Mechanical properties decrease with increasing CaCO₃ content. The possibility of an evaluation method of biomass carbon ratio of materials including organic and inorganic carbons was shown.     

Preparation,sintering behavior,and expansion performance of ceramsite filter media from dewatered sewage sludge,coal fly ash,and river sediment

The main aim of this study is to assess the preparation, sintering behavior, and expansion performance of ceramsite filter media (CFM) from dewatered sewage sludge, coal fly ash, and river sediment without using any natural resources. The results showed that the investigated physical properties of lab made CFM met with the China’s industrial standard of CJ/T 299-2008 and the concentration of heavy metals in the lixivium was lower than the threshold of GB 5085.3-2007. During the sintering process, the relationships between ignition loss rate, expansion rate, and sintering temperature could be well described simultaneously by the 3-order polynomial fitting curve, with high correlation coefficient values (R ² > 0.999). The fitting curves of the ignition loss rate and expansion rate had one peak and one valley, respectively, and their cut-off point that is the sintering temperatures were the same (700 °C). The whole sintering process could be divided into two stages. The ignition loss rate was gradually increased in both the stages. At the same time, the expansion rate was decreased in the first stage and then increased in the second stage. The significance of this work is to pursue the concept of sustainable development.     

Some limitations of sluiced fly ash as a liming material for acidic soils

Innovative methods are currently being sought to safely utilize and reduce the amount of sluiced fly ash stored in on-site facilities at thermal electric power facilities in Ontario, Canada. The objective of this study was to investigate the possibility of utilizing sluiced fly ash as a liming material on acidic soils. A greenhouse experiment was established to examine the influence of the ash on soil pH values and the yield and chemical composition of corn, soybeans, wheat and alfalfa grown on amended soil.The sluiced ash had an initial pH value of 9.1 (1:1 H₂O) and contained an equivalent CaCO₃ content of 11.5% (±0.2%) based on total content of Ca and Mg in the ash. Fly ash was applied at rates of up to 167 tonnes ha⁻¹ to samples of the surface horizon (0–15 cm) of an acidic clay textured soil found local to the power plant. Application of fly ash increased soil pH values but a high concentration of boron in the added ash limited plant growth. Results indicated that the sluiced ash could be used as a liming material at application rates of up to 110 tonnes ha⁻¹, on acidic, clay textured soils provided boron tolerant crops such as alfalfa were grown. Further research is required to establish the potential for leaching of boron to ground water and to determine the potential for plant uptake of other trace elements such as As and Se.     

Microbial Degradation of the Natural Rubber in Tire Tread Compound by a Strain of Nocardia

Tread compound of truck tires is based primarily on natural rubber or blends of natural rubber (NR) and synthetic polymers in combination with high grade carbon black. When the tread compound is attacked by a strain of Nocardia capable of degrading NR, part of the NR in the compound is mineralized, and part is disintegrated to very small black particles. The small black particles consist of the residual rubber and inorganic fillers. At higher NR content, large and deep cavities are formed on the surface of the pieces of the tread compound after microbial disintegration. At lower content of NR, large but very shallow cavities or very small pits can be seen on the tread surface. During microbial growth on the tread compound, isoprene oligomers with molecular weight of about two thousand are produced. Not only the isoprene oligomers, but also butadiene oligomers are produced during microbial disintegration of the tread compound of NR/synthetic rubber blend.