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Recycling of PET

Mechanical properties and electrical conductivity of carbon-nanotube filled polyamide-6 and its blends with acrylonitrile/butadiene/styrene

Improvement of thermal stability, rheological and mechanical properties of PLA, PBAT and their blends by reactive extrusion with functionalized epoxy

A new type of geopolymer composite was synthesized from two industrial wastes, red mud (RM) and rice husk ash (RHA), at varying mixing ratios of raw materials and the resulting products characterized by mechanical compression testing, X-ray diffraction, and scanning electron microscopy to assess their mechanical properties, microstructure, and geopolymerization reactions. Prolonged curing significantly increases the compressive strength and Young’s modulus, but reduces the ductility. Higher RHA/RM ratios generally lead to higher strength, stiffness, and ductility, but excessive RHA may cause the opposite effect. The compressive strength ranges from 3.2 to 20.5 MPa for the synthesized geopolymers with nominal Si/Al ratios of 1.68–3.35. Microstructural and compositional analyses showed that the final products are mainly composed of amorphous geopolymer binder with both inherited and neoformed crystalline phases as fillers, rendering the composites very complex composition and highly variable mechanical properties. Uncertainties in the composition, microstructure, the extent of RHA dissolution, and side reactions may be potential barriers for the practical application of the RM–RHA based geopolymers as a construction material.

Synthesis and characterization of red mud and rice husk ash-based geopolymer composites

Homogeneously dispersed organic–inorganic hybrid nanocomposites can be obtained by increasing the interfacial interactions between both components via the formation of hydrogen bonds or covalent bonds, by mixing various polymers or via the adequate choice of the inorganic precursors The mechanical response of these advanced functional materials is an issue of paramount importance when industrial applications are targeted Large progress in the understanding of the mechanical properties of O–I hybrids has been gained by testing these materials under different conditions (static and dynamic, low and large deformations up to fracture) and using specific techniques developed for the mechanical characterization of conventional materials such as polymers, glasses or ceramics However, the mechanical properties of hybrid O–I materials are dependent on their micro- and nanostructures and on the nature and extent of the O–I interfaces Consequently, predictable mechanical properties for hybrids still represent a major challenge for hybrid materials science Industrial attraction for hybrid materials has been emphasized by the development of new functional coatings An important issue is the interface between the film and the substrate since strong adhesion can be tailored and ensures that delamination of the film will be limited

Mechanical properties of hybrid organic–inorganic materials

Born more out of necessity, the "awareness-attitude" of our society has caused the channeling of technological developments toward immediate economic and ecological benefits The polymer industry has a newfound interest in fillers from industrial by-products and other waste materials having potential "recyclability" This new class of fillers includes fillers from natural sources (eg, natural fibers), industrial by-products (eg, saw dust, rice husks), and a recent entry in the form of rice husk ash-an industrial waste material-obtained by burning rice husks Their recyclability and utilization has become a major driving factor in their acceptance and employability, as well as low cost and abundant availability However, their performance in composites and processing requirements has hindered their applicability within the current economic framework The present article reviews the performance of rice husk ash, or silica ash, in polymeric composites Silica ash, composed mainly of silica, is obtained after burning rice husks and is a major industrial waste material in rice growing countries Optimism surrounds the application of silica ash as a potential filler in a variety of polymeric composites, however, its performance has been limited by its inherent characteristics This paper emphasizes the need for better characterization of silica ash to obtain an in-depth understanding of its behaviour with the view to identifying suitable modifications to improve its performance as a filler It is emphasized that poor understanding of silica ash as a filler is linked to the lack of surface characterization, since its behaviour is significantly linked with its surface properties Based on this analysis, a new approach to silica ash modification is proposed

Recycling rice hull ash: A filler material for polymeric composites?

Shear and extensional rheological measurements were conducted in conjunction with laser light scattering (LLS) on ethylene-vinyl acetate copolymer (EVA) nanocomposites. The materials were prepared by melt-mixing EVA and commercially acquired layered silicates. Wide Angle X-Ray Scattering (WAXS) was used to ascertain the degree of layer swelling. This could be attributed to the intercalation of polymer chains into the interlayer of the silicates. The nanocomposites prepared were determined to be predominantly intercalated in nature. In shear rheological tests, the nanocomposites exhibited an increase in viscoelastic properties compared to the pure EVA. The extent of this property enhancement was not as pronounced as had been reported in many instances with respect to other polymer nanocomposites. This could be attributed to the absence of a network structure normally observed in an exfoliated system. The extensional rheological tests showed an increase in extensional flow properties. This was confirmed by the LLS, which indicated that the filled systems had higher deformability than the unfilled one. Polym. Eng. Sci. 44:1220–1230, 2004. © 2004 Society of Plastics Engineers.

Morphology of EVA based nanocomposites under shear and extensional flow

Sol–gel derived composites from poly(silicic acid) and 2-hydroxyethylmethacrylate: thermal, physical and morphological properties

The polymer industry has a newfound interest in fillers from industrial by-products and other waste materials having potential recyclability. This new class of fillers includes fillers from natural sources (e.g., natural fibers), industrial by-products (e.g., saw dust, rice husks) and a recent entry in the form of silica ash – an industrial waste material –obtained by burning rice husks. Rice hulls possess an unusually high percentage of `opaline silica'. Its annual worldwide output is more than 80 million tons, which corresponds to 3.2 million tons of silica. Silanol groups present on the surface of rice hull ash can positively influence its reinforcing character ash as a filler, however, being hydrophilic, it suffers fromfiller-aggregation and moisture absorption. Present article reviews the performance of rice husk ash, or silica ash, in polymeric composites. This paper emphasizes the need for better characterization of silica ash to obtain an in-depth understanding of its behaviour with the view to identifying suitable modifications to improve its performance as a filler. It is emphasized that poor understanding of silica ash as a filler is linked to the lack of surface characterization, since its behaviour is significantly linked to its surface properties. Based on this analysis, a new approach to silica ash modification is proposed.

Understanding rice hull ash as fillers in polymers: A review

Recycled poly(ethylene terephthalate) (R-PET) was chain extended with pyromellitic dianhydride (PMDA) in a commercial size twin-screw reactive extrusion system. Temperature-modulated differential scanning calorimetry (TMDSC) was used to evaluate the effect of the chain extension process on the thermal transitions and crystallinity of R-PET. Reactive extruded recycled PET (RER-PET) samples were tested based on different PMDA concentration and reactive extrusion residence times. The glass transition temperature (Tg) did not show a significant change as a function of PMDA addition or the extrusion residence time. Melting temperature (Tm) and crystallisation temperature (Tc) decreased with increasing PMDA concentration and with increasing extrusion residence time. RER-PET samples showed double melting peaks, it is believed that different melting mechanism is the reason behind this phenomenon. The crystallinity of RER-PET samples is lower than that of R-PET. RER-PET samples at constant PMDA concentration showed a decrease in crystallinity with increasing extrusion residence time. Results suggest that the reactive extrusion process is more dependent on PMDA concentration rather than reactive extrusion process residence time.

F. Cser

Papers

Recycling rice hull ash: A filler material for polymeric composites?

Morphology of EVA based nanocomposites under shear and extensional flow

Sol–gel derived composites from poly(silicic acid) and 2-hydroxyethylmethacrylate: thermal, physical and morphological properties

Understanding rice hull ash as fillers in polymers: A review

The effect of chain extension on the thermal behaviour and crystallinity of reactive extruded recycled PET