Showing papers in "Macromolecular Materials and Engineering in 2008"
TL;DR: In this article, a large number of scientific publications were investigated in order to provide a comprehensive overview of rapid prototyping methods for polymers and their applications, of currently available materials and research concerning additive processes.
Abstract: Additive processing technologies are rapidly growing in all fields of application. A large number of scientific publications were investigated in order to provide a comprehensive overview of rapid prototyping methods for polymers and their applications, of currently available materials and research concerning additive processes. The current problems of additive processes are described, together with their potential solutions. Furthermore, this article delivers an insight into possible future trends of additive technologies.
277 citations
TL;DR: In this paper, a dual experimental approach employing multiple processing and thermooxidation is proposed to model the life cycle of recycled high-impact polystyrene (HIPS) used in packaging applications, and in electrical and electronic equipment (EE).
Abstract: Polymeric waste materials should be considered resources for the manufacture of new products through recycling processes, with a similar status as virgin fossil-based plastics and biopolymers from renewable resources. Several efforts can be done to achieve this qualitative quantum leap and introduce recycled products in the market with competitive performance. Detailed scientific knowledge about the degradation processes to which polymeric materials are subjected under their life cycle is important when discussing their further waste recovery possibilities and the performance of recycled plastic. The development of fast and reliable analytical methods for the quality assessment of recycled plastics is fundamental to guarantee their performance in new applications. Three key quality properties have been previously defined for this quality analysis: degree of mixing (composition), degree of degradation, and presence of low molecular weight compounds (degradation products, contaminants, additives).A dual experimental approach employing multiple processing and thermooxidation is proposed to model the life cycle of recycled high-impact polystyrene (HIPS) used in packaging applications, and in electrical and electronic equipment (EE these effects ultimately influence the long-term stability, and the rheological and mechanical behaviour of HIPS. The PB phase has proved to be the initiation point of HIPS degradation throughout the life cycle. Thermo-oxidation seems to have more severe effects on HIPS properties; therefore, it can be concluded that previous service life may be the part of the life cycle with the greatest influence on the recycling possibilities and performance of HIPS recyclates in second-market applications.Different strategies are presented for the quality analysis of recycled styrenic polymers from packaging waste and electrical and electronic equipment. The results from the life cycle degradation simulation were compared with those obtained from real samples from a large-scale mechanical recycling plant. The presence and emission of low molecular weight compounds from recycled HIPS from packaging waste has been critically discussed using solvent and headspace extraction procedures. Special attention has been devoted to the determination of brominated flame retardants in recycled HIPS from electrical and electronic equipment using advanced extraction and chromatographic techniques, due to the legislative and environmental implications of these additives.
263 citations
TL;DR: A review of recent advances in the design of biodegradable polymers built from petroleum and renewable resources using reactive extrusion processing can be found in this paper, where the authors discuss the development of environmentally friendly polymer blends as well as (nano)composites from natural polymers, including natural fibers and nanoclays, as an efficient way to improve the interfacial adhesion between these components.
Abstract: This review reports on recent advances in the design of biodegradable polymers built from petroleum and renewable resources using reactive extrusion processing. Reactive extrusion represents a unique tool to manufacture biodegradable polymers upon different types of reactive modification in a cost-effective way. Partially based on our ongoing research, ring-opening polymerization of biodegradable polyesters will be approached as well as the chemical modification of biodegradable polymers, particularly natural polymers. The development of environmentally friendly polymer blends as well as (nano)composites from natural polymers, including natural fibers and nanoclays, through reactive extrusion, as an efficient way to improve the interfacial adhesion between these components, will be also discussed.
206 citations
TL;DR: The flame retardancy mechanisms of aluminium diethylphosphinate (AlPi) and its combination with melamine cyanurate (MC) in glass-fibre-reinforced poly(butylene terephthalate) (PBT/GF) were analysed using TGA including evolved gas analysis (TGA-FTIR), cone calorimeter measurements using various irradiations, flammability tests (limited oxygen index, LOI, UL 94) and chemical analyses of residues (FTIR, SEM/EDX) AlPi decomposed mainly through the formation of
Abstract: The flame retardancy mechanisms of aluminium diethylphosphinate (AlPi) and its combination with melamine cyanurate (MC) in glass-fibre-reinforced poly(butylene terephthalate) (PBT/GF) were analysed using TGA including evolved gas analysis (TGA-FTIR), cone calorimeter measurements using various irradiations, flammability tests (limited oxygen index, LOI, UL 94) and chemical analyses of residues (FTIR, SEM/EDX) AlPi decomposed mainly through the formation of diethylphosphinic acid and aluminium phosphate and influenced the decomposition of the PBT only slightly AlPi acted mainly through flame inhibition A halogen-free V-0 PBT/GF material was achieved with a LOI of 44% Additional charring influenced the flammability MC decomposed independently of the polymer and showed some fuel dilution effects
199 citations
TL;DR: In this paper, the effects of the nature of diisocyanate on the evolution of the kinetics, as well as the physical and mechanical properties and the thermal stability of different synthesized polyurethanes were investigated, and these complement data from the literature on equivalent systems.
Abstract: Polyurethanes based on vegetable oil were synthesized with castor oil and toluene diisocyanate, isophorone diisocyanate or hexamethylene diisocyanate, using dibutyltin dilaurate as a catalyst. The effects of the nature of the diisocyanate on the evolution of the kinetics, as well as the physical and mechanical properties and the thermal stability, of the different synthesized polyurethanes were investigated, and these complement data from the literature on equivalent systems. The polymerization kinetics, degree of swelling and mechanical properties were greatly affected by the diisocyanate nature, whereas the rheological properties and thermal stability were found to be similar for all polyurethanes.
198 citations
TL;DR: In this paper, a diaminodiphenylsulfon (DOPO)-based diaminic hardener was used to lead to flame-retardant systems while keeping relevant properties on a high level.
Abstract: 10-Ethyl-9-oxa-10-phosphaphenanthrene-10-oxide (1) can be nitrated using acetic anhydride and fuming nitric acid. The nitro group is reduced using palladium on charcoal and hydrogen. These reaction conditions are used for the synthesis of an analogous DOPO-based diaminic hardener (7). An evaluation of the curing behavior, mechanical properties and flammability of a neat resin made of DGEBA and 7 (DGEBA + 7) and of a carbon fiber-reinforced resin made of DGEBA, 4,4-diaminodiphenylsulfon (DDS) and 7 (DGEBA + DDS + 7) shows the potential of this hardener to lead to flame-retardant systems while keeping relevant properties on a high level; especially when compared to a similar system (DGEBA + DDS + 1).
148 citations
TL;DR: The morphological, electrical resistivity (ER), and electromagnetic interference (EMI) shielding effectiveness (SE) properties of poly(propylene) (PP), polystyrene (PS), PP/PS, and PP/ PS/ styrene-butadiene-styrene blends filled with 10 vol.-% high structure carbon black were studied.
Abstract: The morphological, electrical resistivity (ER), and electromagnetic interference (EMI) shielding effectiveness (SE) properties of poly(propylene) (PP), polystyrene (PS), PP/PS, and PP/PS/ styrene-butadiene-styrene (SBS) blends filled with 10 vol.-% high structure carbon black (CB) were studied. For the CB/PP/PS blends, TEM and SEM observations indicated that CB is preferentially localized in the PS phase. ER and EMI SE of the CB/PP/PS and CB/PP/PS/SBS blends were bounded between those of the PS composite (lower bound) and the PP composite (upper bound). In the PP/PS volume ratio ranging from (75/25) to (25/75), ER and EMI SE of the CB-filled blends were independent of the PP/PS volume ratio. The EMI SE obtained by the 2 mm thick plates made of 10 vol.-% CB-filled (100/0)-(10/90) PP/PS blends are adequate for computers shielding applications.
145 citations
TL;DR: In this article, the morphological structure of CB networks in elastomers and their flocculation dynamics under heat treatment and especially during vulcanization were analyzed by dynamic mechanical and dielectric spectroscopy.
Abstract: The morphological structure of CB networks in elastomers and their flocculation dynamics under heat treatment and especially during vulcanization are analyzed by dynamic mechanical and dielectric spectroscopy. Dielectric spectra in the MHz range show that nanoscopic gaps between adjacent CB particles develop during heat treatment or vulcanization. These gaps are maintained by immobilized polymer layers acting as flexible bonds between the particles. Low-frequency dielectric data indicate that the static percolation model qualitatively describes the dielectric properties of the conducting CB network on large length scales, but a superimposed kinetic aggregation process takes place on smaller length scales.
127 citations
TL;DR: In this paper, poly(e-caprolactone) (PCL) was grafted to the surface of starch nanocrystals (StN) via microwave-assisted ROP.
Abstract: Poly(e-caprolactone) (PCL) was grafted to the surface of starch nanocrystals (StN) via microwave-assisted ROP. The resultant nanoparticles were then incorporated into a poly(lactic acid) matrix to produce fully-biodegradable nanocomposites with good mechanical properties. A loading level of 5 wt.-% StN-g-PCL resulted in simultaneous enhancements of strength and elongation. The StN-g-PCL self-aggregated as rubbery microparticles to enhance the elongation by ca. 10-fold over that of neat PLA. Meanwhile, the grafted PCL chains were miscible with PLA and formed a stress-transferring interface to the StN, providing a reinforcing function.
108 citations
TL;DR: In this paper, a nanocellular PS/PMMA polymer blend foam was prepared, where bubble nucleation was localized in the PMMA domains, and the resulting blend was foamed with CO 2 at room temperature.
Abstract: A nanocellular PS/PMMA polymer blend foam was prepared, where bubble nucleation was localized in the PMMA domains. The blend, which contains dispersed nanoscale PMMA islands, was prepared by polymerizing MMA monomers in a PS matrix to form highly dispersed PMMA domains in the PS matrix by diffusion mixing. The resulting blend was foamed with CO 2 at room temperature. A higher depressurization rate at lower foaming temperature made the bubble diameter smaller and the bubble density larger, and a higher PS composition in the blend resulted in a larger bubble density. A void with 40-50 nm in average diameter and a pore density of 8.5 x 10 14 cm -3 was obtained as for the finest nanocellular foams.
86 citations
TL;DR: In this article, a binary blend of PFO/PMMA and PF + /PMMA was used to obtain high-aligned luminescent electrospun nanofibers.
Abstract: Highly-aligned luminescent electrospun nanofibers were successfully prepared from two binary blends of PFO/PMMA and PF + /PMMA. The PFO/PMMA aligned electrospun fibers showed a core/shell structure but the PF + /PMMA fibers exhibited periodic aggregate domains in the fibers. The aligned fibers had polarized steady-state luminescence with a polarized ratio as high as 4, much higher than the non-woven electrospun fibers or spin-coated film. Besides, the PF + /PMMA aligned electrospun fibers showed an enhanced sensitivity to plasmid DNA. Such aligned electrospun fibers could have potential applications in optoelectronic or sensory devices.
TL;DR: In this article, a short date palm tree lignocellulosic fibers were used as a reinforcing phase in commodity thermoplastic matrices [poly(propylene) and low density polyethylene] with the use of maleic anhydride copolymers.
Abstract: Short date palm tree lignocellulosic fibers have been used as a reinforcing phase in commodity thermoplastic matrices [poly(propylene) and low density polyethylene]. Compatibilization of the fibers was carried out with the use of maleic anhydride copolymers. The morphology, thermal and mechanical properties of the resulting composites were characterized using SEM, DSC and tensile tests. The reinforcing capability of the unmodified fibers was found to depend on the nature of the matrix and the main parameter governing the composite behavior was the degree of crystallinity of the matrix. Compatibilization was reported to enhance the mechanical performances for both sets of composites up to a critical amount of compatibilizer beyond which the degree of crystallinity of the matrix decreases.
TL;DR: In this paper, the effect of holding temperature, CHF length and enzyme treatment of CHF on mechanical properties and sound absorption have been studied and compared with jute/PP composites.
Abstract: Flexural, impact resistance, tensile, and sound absorption properties of composites from cornhusk fiber (CHF) and PP have been investigated. The effect of holding temperature, CHF length, CHF concentration, and enzyme treatment of CHF on mechanical properties and the effect of the latter two on sound absorption have been studied. Compared with jute/PP composites, CHF/PP composites have similar impact resistance, 33% higher flexural strength, 71% lower flexural modulus, 43% higher tensile strength, 54% lower tensile modulus, and slightly higher noise reduction coefficient. Enzyme treatment of CHF results in increased mechanical and sound absorption properties.
TL;DR: In this paper, the thermal properties of the pure linear low-density polyethylene (LLDPE) and nanocomposites were studied by differential scanning calorimeter (DSC).
Abstract: Nanocomposites of linear low-density polyethylene (LLDPE), with three different amounts of polyhedral oligomeric silsesquioxanes (POSS), were prepared through melt-mixing in a batchmixer at 1508C. The structure of the prepared nanocomposites was studied by X-ray scattering and opticalmicroscopy. Thesurface morphology ofthenanocompositeswasinvestigatedthrough field-emission SEM. The thermal properties of the pure LLDPE and nanocomposites were studied by differential scanning calorimeter (DSC). Thermomechanical properties were assessed on a Paar-Physics MCR501 rheometer using a solidstate rectangular fixture. Results exhibited a significant improvement in both the storage and loss moduli of the neat LLDPE upon the incorporationofthePOSSparticles.Asubstantial improvement in thermal stability was also observed in the high-temperature region.
TL;DR: In this article, the effects of processing parameters on the mechanical properties of injection molded thermoplastic polyolefin (TPO) foams have been investigated and the experimental results obtained from this study can be used to predict the microstructure and mechanical properties.
Abstract: In this study, the effects of processing parameters on the mechanical properties of injection molded thermoplastic polyolefin (TPO) foams are investigated. Closed cell TPO foams were prepared by injection molding process. The microstructure of these foamed samples was controlled by carefully altering the processing parameters on the injection molding machine. The foam morphologies were characterized in terms of skin thickness, surface roughness, and relative foam density. Tensile properties and impact resistance of various injection molded TPO samples were correlated with various foam morphologies. The findings show that the mechanical properties are significantly affected by foam morphologies. The experimental results obtained from this study can be used to predict the microstructure and mechanical properties of cellular injection molded TPO foams prepared with different processing parameters.
TL;DR: In this article, nano/micro-scale cellular structures were prepared from poly(propylene)/ thermoplastic polystyrene elastomer (PP/TPS) systems, specifically the copolymer blends PP/ hydrogenated polystrene-block-polybutadiene-blockpolystyrene rubber and PP/hydrogen-ated poly styrene-polyisoprene-blockspolypolypoly styrene block-polystructured polystructure (PSP/TPS), using a temperature-quench batch physical foaming method.
Abstract: Plastic foams with nano/micro-scale cellular structures were prepared from poly(propylene)/ thermoplastic polystyrene elastomer (PP/TPS) systems, specifically the copolymer blends PP/ hydrogenated polystyrene-block-polybutadiene-block-polystyrene rubber and PP/hydrogen-ated polystyrene-block-polyisoprene-block-polystyrene. These PP/TPS systems have the unique characteristic that the elastomer domain can be highly dispersed and oriented in the machine direction by changing the draw-down ratio in the extrusion process. A temperature-quench batch physical foaming method was used to foam these two systems with CO 2 . The cell size and location were highly controlled in the dispersed elastomer domains by exploiting the differences in CO 2 solubility, diffusivity, and viscoelasticity between the elastomer domains and the PP matrix. The average cell diameter of the PP/ TPS blend foams was controlled to be 200-400 nm on the finest level by manipulating the PP/rubber ratio, the draw-down ratio of extrusion and the foaming temperature. Furthermore, the cellular structure could be highly oriented in one direction by using the highly-oriented elastomer domains in the polymer blend morphology as a template for foaming.
TL;DR: In this article, the authors showed that the nucleation of PLLA is enhanced in the presence of PGA even at a PGA content as low as 0.1 wt.
Abstract: DSC indicated that the nucleation of PLLA is enhanced in the presence of PGA even at a PGA content as low as 0.1 wt.-%. However, the enhancing behavior of PGA was different to that of other nucleating agents for PLLA. Polarized optical microscopy revealed that the presence of PGA increased the number of PLLA spherulites per unit area. WAXD showed that in the PLLA/PGA films, PLLA and PGA crystallize separately to form their respective crystallites and PGA crystallites were formed at a PGA content at above 3 wt.-% (at least). FTIR spectroscopy indicated that that there are significant interactions between PLLA and PGA chains in amorphous regions. Such interactions should have enhanced the growth of PLLA crystallites from the surface of PGA crystallites.
TL;DR: In this article, a poly(propylene) (PP)/propylene-ethylene copolymer (PER) blend was prepared from a nano-scale cellular structures by controlling bubble nucleation sites and bubble growth in disperse PER domains.
Abstract: Plastic foam with nano-/micro-scale cellular structures was prepared from a poly(propylene) (PP)/propylene-ethylene copolymer (PER) blend by controlling bubble nucleation sites and bubble growth in disperse PER domains. Batch foaming experiments using a CO 2 pressure quench method were conducted at room temperature. The bubble size and location were highly controlled in disperse PER domains by exploiting the differences in CO 2 solubility and viscoelasticity between the PER domains and the PP matrix. The average cell diameter of PP/PER blend foams can be controlled within 0.5-2 μm by the PP/PER ratio, depressurization rate, and foaming temperature.
TL;DR: In this article, a new talc/PBAT hybrid material was prepared through reactive extrusion, where PBAT was free-radically grafted with MA to improve the interfacial adhesion between PBAT and talc.
Abstract: New talc/PBAT hybrid materials were prepared through reactive extrusion. First, PBAT was free-radically grafted with MA to improve the interfacial adhesion between PBAT and talc. Then, the resulting MA-g-PBAT was reactively melt-blended with talc through esterification reactions of MA moieties with the silanol functions from talc. Sn(Oct) 2 and DMAP were used as catalysts. Interestingly, the tensile properties for these compatibilized composites were improved due to a better interfacial adhesion between both partners. XPS showed the formation of covalent ester bonds between the silanol functions from talc particles, and the MA moieties grafted onto the polyester backbones.
TL;DR: In this paper, a glass fiber biobased composites have been prepared by ROMP of a commercially available vegetable oil derivative possessing an unsaturated bicyclic moiety, and DCPD.
Abstract: Glass fiber biobased composites have been prepared by ROMP of a commercially available vegetable oil derivative possessing an unsaturated bicyclic moiety, and DCPD. The resins and the corresponding composites have been characterized thermophysically and mechanically. Higher DCPD content yields materials with higher glass transition temperatures. Glass fibers significantly improve the tensile modulus of the resin from 28.7 to 168 MPa. These biobased composites utilize only a limited amount of a petroleum-based monomer, while employing substantial amounts of a renewable resource.
TL;DR: In this article, the photopolymerization process was investigated via real-time FTIR spectroscopy and the hybrid cured films showed a broad tan δ peak in DMTA demonstrating the high damping properties of the hybrid, cured formulations.
Abstract: Acrylic-epoxy interpenetrating polymer networks were prepared by means of UV curing. The photopolymerization process was investigated via real-time FTIR spectroscopy. The hybrid, cured films showed a broad tan δ peak in DMTA demonstrating the high damping properties of the hybrid, cured formulations. A decrease on shrinkage was achieved by increasing the epoxy-resin content in the photocurable formulation, with a consequent increase in adhesion properties.
TL;DR: The influence of an elongational flow on the morphology of PE/clay nanocomposite drawn fibers was studied in this paper, where an increase of elastic modulus and tensile strength as well as a decrease of the elongation at break were observed with increasing draw ratio.
Abstract: The influence of an elongational flow on the morphology of PE/clay nanocomposite drawn fibers was studied. An increase of the elastic modulus and the tensile strength as well as a decrease of the elongation at break are observed with increasing draw ratio. The applied elongational gradient orients the polymer chains and the clay particles along the spinning direction. When the applied flow results in the formation and the orientation of exfoliated nanoparticles, a pronounced increase of the mechanical properties is observed. The dispersed clay particles can be broken and oriented by the extensional flow, which might indicate a flow-induced intercalated/exfoliated morphology transition.
TL;DR: In this paper, a systematic study of glutaraldehyde crosslinking conditions of wheat gluten fibers is presented and shows that even low concentrations of glutaraldehyde (0.05%) can improve the strength and water stability of wheat-gluten fibers.
Abstract: Regenerated protein fibers from plant proteins including wheat gluten lack the mechanical properties and water stability desired for usual applications. Crosslinking has been used to improve the properties of regenerated proteins fibers. Although glutaraldehyde is commonly used to crosslink proteins, the effect of various crosslinking conditions on the properties of the materials has not been studied. In this work, a systematic study of glutaraldehyde crosslinking conditions of wheat gluten fibers is presented and shows that even low concentrations of glutaraldehyde (0.05%) can improve the strength and water stability of wheat gluten fibers.
TL;DR: In this paper, the results obtained from the polyhedral compounds were compared with those of a disordered framework obtained by the condensation of a silica precursor (MEMO), which created constraints in movement of polymer segments, which reflected in an increase in Tg of the hybrid nanocomposite coatings.
Abstract: Hybrid nanocomposite coatings were prepared by the UV-curing technique with a methacrylic oligomer and multifunctional methacrylic polyhedral oligomeric silsesquioxane blocks (POSS®). The results obtained from the polyhedral compounds were compared with those of a disordered framework obtained by the condensation of a silica precursor (MEMO). The inorganic domains generated during synthesis created constraints in movement of polymer segments, which reflected in an increase in Tg of the hybrid nanocomposite coatings. The films were transparent. The random structure obtained by the condensation of the MEMO showed a stronger effect on T g than that observed by introducing POSS®. The effect of inorganic domains reflected on thermal stability, surface hardness and mechanical properties of the hybrid nano-composite coatings.
TL;DR: In this paper, the thermal behavior of cellulose dissolved in ionic liquids was studied in comparison to NMMO solutions, and the cellulose solutions were characterized by reaction calorimetry and UV-vis spectroscopy.
Abstract: The thermal behavior of cellulose dissolved in ionic liquids was studied in comparison to NMMO solutions. The cellulose solutions were characterized by reaction calorimetry and UV-vis spectroscopy. Generation of chromophoric substances in cellulose/IL solutions is minimized by exposing to temperatures of above 100 °C for longer time periods. Dynamic calorimetric investigations revealed first thermal activities above 180 °C applying EMIMac and above 200 °C for BMIMCl and five other ILs tested. Moreover, even in the case of modified cellulose/IL solutions, e.g., activated charcoal, only a slight decline of onset temperatures was registered compared to modified cellulose/NMMO solutions.
TL;DR: In this paper, the effect of CNTs on storage modulus, T c, T m and Tg of piezoelectric polymers was studied, and it was observed that the electromechanical strain is observed at low actuation voltages, possibly due to enhanced local electric field in the presence of DWNTs.
Abstract: Dispersion of CNTs in polymers can yield impressive property enhancements at low volume fractions, thus maintaining the inherent processability of the polymer. In particular, they can improve the electromechanical response of piezoelectric polymers by lowering the actuation voltage and increasing strain and stress response. In this work, piezoelectric PVDF and DWNTs are solution-cast into films. SEM of fracture surfaces confirms good dispersion, and electrical conductivity measurements reveal a low percolation threshold (0.23 vol.-%). The effect of CNTs on storage modulus, T c , T m and Tg of PVDF is studied. Electromechanical strain is observed at low actuation voltages, possibly due to enhanced local electric field in the presence of DWNTs.
TL;DR: In this paper, Lignocellulosic fibers from date palm trees were employed to reinforce an epoxy matrix, and two fiber sizes were used, with the length and diameter in the range of 20-30 and 1.5-3 mm, respectively.
Abstract: Lignocellulosic fibers from date palm trees were employed to reinforce an epoxy matrix. Two fiber sizes were used, with the length and diameter in the range of 20-30 and 1.5-3 mm, respectively, for the so-called long fibers, and in the range of 5-15 and 0.25-0.75 mm, respectively, for the so-called short fibers. The morphologies of the resulting composites, as well as their thermal, mechanical, and water sorption properties were evaluated. Strong interactions between both components and etherification reactions may occur between the hydroxyl groups of the fibers and the epoxy groups of the epoxy-amine reactive mixture. These effects are emphasized when decreasing the size of the fibers.
TL;DR: In this article, short electrospun fibers were obtained by using UV cutting method and the length of obtained short fibers can be controlled by changing the width of the slits of the employed mask.
Abstract: Short electrospun fibers were obtained by using UV cutting method. Either polymers with double bonds with a photocross-linker (CL) and photoinitiator (PI) or known photochemistry of coumarin ([2 +2] cycloaddition reaction) without the addition of CL and PI is utilized for making short electrospun fibers. The electrospun fibers were irradiated by UV light in the presence of a mask with a defined width of slits. The uncovered parts of fibers were cross-linked and therefore became insoluble. The non-crosslinked parts were removed by immersion of the fibers into an appropriate solvent. The length of obtained short fibers can be controlled by changing the width of the slits of the employed mask.
TL;DR: In this article, the efficiency of melamine cyanurate and a clay filler for improving the flame retardancy and other physical properties of polyamide 6 was examined, and partially intercalated-exfoliated morphologies were obtained.
Abstract: The efficiency of melamine cyanurate and a clay filler for improving the flame retardancy and other physical properties of polyamide 6 was examined. Partially intercalated-exfoliated morphologies were obtained. Nanocomposites suffered from polymer degradation during compounding, while the molecular weight was enhanced in the case of the flame retarded samples. Silicates were shown to restrain crystallization, whereas melamine cyanurate induced heterogeneous nucleation. Both additives positively influenced the tensile modulus of the prepared samples, decreasing their ability to elongate. With respect to the UL94 flammability test, melamine cyanurate was proved to be not sufficiently capable of increasing the tendency of nanocomposites to drip, negatively affecting flammability.
TL;DR: In this paper, a procedure for the production of carbon nanotube (CNT) reinforced poly(vinylidine difluoride) (PVDF) powders has been developed.
Abstract: A procedure for the production of carbon nanotube (CNT) reinforced poly(vinylidine difluoride) (PVDF) powders has been developed. These powders are versatile precursors for a range of nanocomposite materials. The morphology of the CNT/PVDF powder can be related to the interaction between filler and matrix, which depends on the degree of modification of the polymer with grafted maleic anhydride (MAH-graft-PVDF). The mechanical performance of the nanocomposite containing 2.5 wt.-% CNT and 1.25 ppm of MAH increased in tensile modulus, tensile strength, and strain to failure by 34, 30, and 22%, respectively, as compared to PVDF.