Morphology and Mechanical Properties of Acrylonitrile-Butadiene-Styrene (ABS)/Polyamide 6 (PA6) Nanocomposites Prepared via Melt Mixing

Acrylonitrile-butadiene-styrene (ABS)/polyamide 6 (PA6) blends containing various amounts of organomontmorillonite (OMMT) were prepared using a twin-screw extruder followed by injection molding. The effect of OMMT on the microstructure and properties of the ternary nanocomposites is investigated by wide-angle X-ray diffraction (WAXD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and mechanical properties testing. The results showed the OMMT platelets were preferentially located and exfoliated in the PA6 phase, but some were located at the interface of the ABS and PA6 phase. The effect of the addition of the OMMT on the morphology and mechanical properties was also evaluated. SEM revealed that the dimensions of the dispersed PA6 droplets were greatly reduced when the concentration of the OMMT was less than 4 phr. The domain size was less than the neat ABS/PA6 blends with the increasing of the OMMT content. It was suggested that the OMMT can compatibilize the ABS/PA6 blend. In addition, the flexural strength and modulus increased with increasing OMMT content, but the tensile strength became maximal at 3 phr OMMT. The OMMT had a negligible effect on the impact strength of the ABS/PA6 blend nanocomposite.     

Synthesis, characterization and infrared emissivity study of polyurethane/TiO2 nanocomposites

In this study, polyurethane/titania (PU/TiO₂) nanocomposites were prepared in ultrasonic process and characterized by fourier transform IR spectroscopy (FT-IR), powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and infrared emissivity analysis. The TEM and SEM results indicated that the nanoparticles were dispersed homogeneously in PU matrix on nanoscale. TGA-DSC confirmed that the heat stability of the composite was improved. Infrared emissivity study showed that the nanocomposite possessed lower emissivity value than those values of pure polymer and nanoparticles.     

Structure and Properties of a cis-1,4-Polybutadiene/Organic Montmorillonite Nanocomposite Prepared via In Situ Polymerization

Cis-1,4-polybutadiene (cis-1,4-PB) is one of the most important synthetic rubbers, having superior performances such as wear resistance, cold resistance and high elasticity. However, its mechanical properties, including low tensile strength, tear resistance and thermal stability, limit its application in comparison to natural rubber and butadiene-styrene rubber that have excellent overall performances. Thus, the reinforcing of cis-1,4-PB is a necessity. The dispersion of clay in rubbers on the nanoscale can improve the mechanical, gas permeability and thermal properties of the resulting composites. In this paper, organic montmorillonite (OMMT) clay was dispersed into the cis-1,4-PB matrix via an in-situ polymerization method and the chemical structure, phase morphology, mechanical properties and thermal stability of the composite were investigated. The properties of the composite were analyzed by such techniques as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and thermal gravimetric analysis (TGA). In the in-situ polymerization, a Ni-based catalyst system with the presence of OMMT showed high efficiency and 1,4-selectivity for the polymerization of butadiene. The OMMT could be dispersed in the polymeric matrix on the nanoscale during the polymerization. The interfusion of OMMT had little influence on the thermal stability and the chemical micro-structure of the cis-1,4-PB when the content of cis-1,4 units was more than 95%. The loss tangent of the composite was higher than that of cis-1,4-PB from ?110 to ?55°C, the temperature range examined, and the mechanical properties of the cis-1,4-PB/OMMT nanocomposite (NC) were improved upon the addition of OMMT.     

Morphology and Crystallization in Polystyrene/polyamide 6 Blends: Influence of a Reactive Compatibilizer and Nano-TiO2

A polystyrene (PS)/polyamide 6 (PA6) (70/30, weight ratio) blend in the presence of terminal malic anhydride functionalized PS (FPS) and nano-TiO₂ were prepared using a meltmixing technique. The morphology of the blend was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The crystallization behavior of the PA6 phase in the blend was studied using DSC techniques. The results showed that by adding 7.5 phr nano-TiO₂, the size of the dispersed PA6 domains was dramatically decreased; An additional 1.5 phr FPS to the PS/PA6/TiO₂ blend, for reactive blending, caused the size of the dispersed PA6 domain to become even smaller and more uniform, and a weak, broad crystallization exotherm of PA6 was observed. However, the degree of crystallinity of PA6 in PS/PA6/TiO₂/FPS blend was sharply increased.     

Phase Morphology and Mechanical Properties of Polyamide-6/Polyolefin Elastomer-g-Maleic Anhydride Blends

The effects of addition of varying amounts of polyolefin elastomers (POE) (with and/or without grafted maleic anhydride) on the morphology and mechanical properties of polyamide-6 (PA6)-based blends were studied. Scanning electron microscopy (SEM) was employed to obtain some detailed quantitative analyses of the morphology of the fracture behavior for the blends containing 80 wt% PA6 and 20 wt% total elastomer. Impact strength, tensile strength, and flexural strength were also measured for these blends. The results showed that POE and PA6 were an incompatible system, but the POE-g-MAH was compatible and had a toughening effect on PA6. PA6-g-POE was formed through the reaction between POE-g-MAH and PA6 during the melt extrusion process, which reduced the size of the dispersed phase and improved the impact and tensile strength of the blends. The impact strength was improved by nine times compared with the pure PA6 or the binary blend PA6/POE when the blend ratio of the ternary blend PA6/POE/POE-g-MAH was 80/16/4.     

Study on Steady Shear,Morphology and Mechanical Behavior of Nanocomposites based on Polyamide 6

Nanocomposites of two different grades of polyamide 6 (PA6) with organically modified nanoclay were prepared via melt compounding in a twin‐screw extruder. The rheological behavior, morphology and mechanical properties of the nanocomposites were studied using a capillary rheometer, x‐ray diffraction (XRD), tapping‐mode atomic force microscopy (AFM), and tensile and flexural tests. XRD patterns indicate that the organically modified layered silicate was well dispersed in the PA6 matrix. From the AFM images the surface roughness of PA6 slightly increases with addition of organoclay. The rheological studies showed that the prepared nanocomposites have shear thinning behavior, obeying the power law equation. Addition of organoclay increases the shear stress and shear viscosity. At high rate of shear deformation the viscosity of nanocomposites are comparable to those of the pure polyamides. The activation energy of flow decreases with increasing nanoclay content. For most of the prepared nanocomposites the activation energy values increase with increasing shear rate. The tensile strength and flexural modulus and strength of the nanocomposites increase with increase of nanoclay content, but the extension at yield decreases with increasing clay loading.     

Assessment of the Microstructure and Mechanical Properties of Polycarbonate (PC)/Acrylonitrile Butadiene Rubber (NBR) Blends Reinforced with Multi-wall Carbon Nanotubes

Abstract

A series of polycarbonate (PC)/acrilonitrile butadiene rubber (NBR)/multi-wall carbon nanotube (MWCNT) nanocomposites were prepared via melt compounding in an internal mixer. The effect of the MWCNT content on the morphology and the thermal and mechanical properties of the prepared nanocomposites were studied. The morphologies of the samples were investigated by field-emission scanning electron microscopy (FESEM) and the thermal properties by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The tensile mechanical results of the nanocomposites showed a decrease in elongation at break with an increase of only 2?wt% of MWCNT content in the PC/NBR blends, and an increasing value in elastic modulus and tensile strength of the nanocomposites. The FESEM images showed that the MWCNTs had good affinity with the polymers and no compatibilizer was needed for making the nanocomposites. The DSC and TGA results showed an increase in thermal stability with addition of MWCNTs because of the more thermally stable carbon nanotubes particles which was uniformly dispersed within the nanocomposites.     

Surface functionalization, morphology and thermal properties of polyamide6/O-MMT composite nanofibers by Fe2O3 sputter coating

In the present work, the pure polyamide6 (PA6) nanofiber and PA6/organically modified montmorillonite (O-MMT) composite nanofiber were firstly prepared by a facile compounding process with electrospinning, and then coated by nanosize Fe₂O₃ using magnetron sputter technique. The effects of Fe₂O₃ sputter coating on structures, surface morphology and thermal stability were characterized by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), atomic force microscope (AFM) and thermogravimetric analyses (TGA), respectively. The SEM images showed that the diameters of composite nanofiber were decreased with the loadings of O-MMT and the nanosize Fe₂O₃ is well coated on the surface of the homogeneous and cylindrical nanofibers. The XPS spectra reflected the chemical features of the deposited nanostructures. The EDX confirmed the presence of the O-MMT and Fe₂O₃ in the fibers. The AFM observation revealed that there was a remarkable difference in the surface morphology of composite nanofiber before and after sputter coating. The TGA analysis indicated the barrier effects of silicate clay layers and catalysis effects of Fe₂O₃ improved thermal stability properties of the composite nanofiber.     

Crystallization,Flame Retardancy and Mechanical Properties of Poly(Butylene Terephthalate)/Brominated Epoxy/Nano-Sb2O3 Composites Dispersed By High Energy Ball Milling

Nano-Sb2O3 particles and brominated epoxy resin (BEO) powders were dispersed in poly (butylene terephthalate) (PBT) by high energy ball milling (HEBM). Then the nanocomposites were prepared by a twin screw extruder. The influence of the nano-Sb2O3 particles on the crystallization, thermal stability, flame retardancy and mechanical properties of the PBT/BEO/nano-Sb2O3 composites were investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), limiting oxygen index (LOI), UL-94 tests and scanning electron microscopy (SEM). The results showed that the nano-Sb2O3 particles improved the crystallizability, thermal stability and flame retardancy properties of the PBT/BEO/nano-Sb2O3 composites. When the content of nano-Sb2O3 particles was 2.0?wt%, the LOI of nano-Sb2O3/BEO/PBT composites increased from 22.0 to 27.8 and the tensile strength reached its maximum value (62.44?MPa), which indicated that the optimum value of flame retardancy and mechanical properties of PBT/BEO/nano-Sb2O3 composites were obtained.     

Thermal Characteristics of PVA-PANI-ZnS Nanocomposite Film Synthesized by Gamma Irradiation Method

Gamma irradiation is employed for in situ preparation of PVA-PANI-ZnS nanocomposite. The irradiation dose is varied from 10 to 40 kGy at 10 kGy intervals. The XRD result confirms the formation of crystalline phases corresponding to ZnS nanoparticles, PVA and PANI. Field emission scanning electron microscopy shows the formation of agglomerated PANI along the PVA backbone, within which the ZnS nanoparticles are dispersed.UV-visible spectroscopy is conducted to measure the transmittance spectra of samples revealing the electronic absorption characteristics of ZnS and PANI nanoparticles. Photo-acoustic(PA) setup is installed to investigate the thermal properties of samples. The PA spectroscopy indicates a high value of thermal diffusivity for samples due to the presence of ZnS and PANI nanoparticles. Moreover, at higher doses, the more polymerization and formation of PANI and ZnS nanoparticles result in enhancement of thermal diffusivity.     

Polyamide 6/modified Carbon Black Nanocomposites Prepared via In Situ Polymerization

Polyamide 6/modified carbon black (PA6/MCB) composites were prepared via in-situ ring opening polymerization of caprolactam in the presence of dispersed carboxyl group modified carbon black (MCB). The dispersion of MCB in the PA6 matrix, nonisothermal crystallization and melting behaviors, and volume resistivity of the composites were investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and a resistivity meter, respectively. The results indicated that MCB dispersed well in the PA6 matrix. When the MCB content was 5 wt%, the MCB particles were of a nanoscale. The conductivity percolation threshold of the PA6/MCB composites was 8 wt% due to the good dispersion of MCB in the PA6 matrix. The addition of MCB elevated the cold crystallization temperature of PA6, reflecting the effectiveness of MCB as nucleating agents. However, the MCB decreased the crystallization enthalpy of PA6 during both heating and cooling processes.     

Flowability and Mechanical and Thermal Properties of Nylon 6/Ethylene bis-Stearamide/Carboxylic Silica Composites

Nylon 6 (PA 6)/ethylene bis-stearamide (EBS)/SiO₂- carboxylic acid-functionalized silica nanoparticles (COOH) composites were prepared by in-situ polymerization of caprolactam. SiO₂-COOH was used to enhance the compatibility between SiO₂ and PA 6 matrix. For comparison, pure PA 6 and PA 6/EBS composites were also prepared via the same method. The PA 6/EBS/SiO₂-COOH composites with low content of EBS and SiO₂-COOH had greater melt-flow index (MFI) (the value of MFI increased by 50%–80%) than the pure PA 6. The results of mechanical properties showed almost no decrease in the tensile strength of PA 6/EBS/SiO₂-COOH composites, with the bending strength decreasing by 17%–21%. However, the Izod impact strength of the PA 6/EBS/SiO₂-COOH composites was greatly improved compared with pure PA 6, which indicated that the toughness of PA 6/EBS/SiO₂-COOH had been greatly improved. The morphology of Izod impacted fractured surfaces of PA 6/EBS/SiO₂-COOH was observed by scanning electron microscopy. The results revealed that the PA 6/EBS/SiO₂-COOH composites presented a typical ductile fracture behavior with large amounts of long and large strip-like cracks. When the content of SiO₂-COOH was 0.2 wt%, the SiO₂-COOH particles were uniformly dispersed over the entire body of the PA 6 matrix. The results from differential scanning calorimetry indicated that the melting point (T_m), degree of crystallinity (X_c), and crystallization temperatures (T_c) of PA 6/EBS/SiO₂-COOH composites were lower than the pure PA 6.     

Preparation and Combustion Behavior of Polyamide 6/Polypropylene/Clay Nanocomposites

Polyamide 6(PA 6)/Polypropylene (PP) blends as well as PA 6/PP/clay composites were prepared by melt compounding. The distribution of clay was characterized by transmission electron microscopy. The combustion surface morphology as well as product composition after burning were studied by scanning electron microscopy along with electro-probe microanalysis. Moreover, the flame retardance and thermal stability were evaluated by a cone calorimeter together with thermogravimetric analysis. The results showed that the clay was selectively located in the PA6 phase. It is proposed that, in the presence of clay, the combustion surface changed from a branch-shaped structure to a compact carbonaceous–silicate structure. When the clay content was 3 phr, the layered silicates became enriched on part of the surface and formed an island-like structure; the islands displayed a loose cinders structure with much higher silicon content, in contrast to a branch-shaped surface with low silicon content of the surrounding polymer substrate. As the clay content continued to increase, the char covered most of the combustion surface and more clay accumulated on the burning surface. In addition, the clay particles promoted the formation of the carbonaceous–silicate structure. The peak of the heat release rate of the PA6/PP blend decreased with increasing addition of clay and the thermal stability of the PA6/PP blend also improved.     

Syntheses and characterization of Mg(OH)2 and MgO nanostructures by ultrasonic method

Magnesium hydroxide nanostructures have been synthesized by the reaction of magnesium acetate with sodium hydroxide via sonochemical method. Reaction conditions such as the Mg²⁺ concentration, aging time and the ultrasonic device power show important roles in the size, morphology and growth process of the final products. The magnesium oxide nanoparticles have been prepared by calcination of magnesium hydroxide nanostructures at 400 °C. The magnesium hydroxide and magnesium oxide nanostructures were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), thermal gravimetric (TG) and differential thermal analyses (DTA).     

Effect of Maleated Styrene/Ethylene-co-Butylene/Styrene on the Dispersed Particles Size and Mechanical Properties of Polyamide 6/Poly(styrene-co-acrylonitrile)/Poly(styrene-b-(ethylene-co-butylene)-b-styrene) Ternary Blends

In this study, the effect of several parameters, including composition, order of mixing, viscosity, and interfacial tension, on the phase structure and size of dispersed particles of polyamide 6 (PA6)/poly(styrene-co-acrylonitrile) SAN/poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) ternary blends was investigated. Moreover, the effect of addition of different ratios of reactive SEBS (maleic anhydride grafted-SEBS) and non-reactive SEBS at a fixed order of mixing and composition of 70/15/15 (PA6/SAN/SEBS + SEBS-g-MAH) on the mechanical properties of ternary blends was examined. Scanning electron microscopy (SEM) micrographs showed that among the studied parameters, interfacial tension and viscosity of dispersed phases were the leading factors in the formation of morphology and size of dispersed droplets. Mechanical results revealed that in contrast to the expectation, formation of core/shell structure of PA6/SAN/SEBS ternary blends did not result in a significant increasing of impact strength. The highest impact strength was achieved when a 50/50 weight ratio of SEBS/SEBS-g-MAH was used.     

Preparation, characterization and surface morphology of novel optically active poly(ester-amide)/functionalized ZnO bionanocomposites via ultrasonication assisted process

Novel bionanocompoites (BNCs) were prepared using zinc oxide (ZnO) nanoparticles which functionalized by γ-methacryloxypropyltrimethoxysilane (KH570) as a coupling agent. Poly(ester-amide) (PEA) based on tyrosine natural amino acid was synthesized and used as a polymer matrix. PEA/ZnO BNCs were characterized by fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM). All the results confirmed that the surface of ZnO particle has sufficient compatibility with PEA through the link of the coupling agent between ZnO and polymer and also proved that the presence of ZnO nanoparticles appeared to be dispersed in nanosize in polymer composite matrix. In addition, thermogravimetric analysis (TGA) data indicated an enhancement of thermal stability of new BNC materials compared with the pure polymer.     

Friction and wear properties of PA6 filled PTFE composites under oil lubrication

Blending polytetrafluorothylene (PTFE) to PA6 at different compositions was produced in a corotating twin-screw extruder where, PTFE acts as the polymer matrix and PA6 as the dispersed phase. The tribological properties of PTFE composites filled with PA6 under oil lubrication were investigated. The worn surface morphologies of neat PTFE and its composites were examined by scanning electron microscopy (SEM) and the wear mechanisms were discussed. The presence of PA6 particles dispersed in the PTFE continuous phase exhibited superior tribological characteristics to unfilled PTFE. The optimum wear reduction was obtained when the content of PA6 is 30 vol%.     

Preparation of tuna skin collagen-chitosan composite film improved by sweep frequency pulsed ultrasound technology

To produce a natural food packaging film from tuna skin collagen (TSC) and chitosan (CTS) and improve its mechanical and physicochemical properties, the sweep frequency pulsed ultrasound (SFPU) was introduced as a new technology and compared with the conventional method. The optimum preparation conditions of the SFPU-TSC-CTS film were sweep frequency of 28 ± 0.5 kHz, power density of 100 W/L, sweep frequency cycle of 100 ms, pulse duty ratio of 77%, and ultrasonic time of 10 min. Significant increases in the tensile strength (27.14%) and elongation at break (16.54%) and a significant decrease in the water vapor permeability (12.15%) were observed by sonication. Thus, a moderate SFPU treatment can significantly improve the moisture resistance and mechanical properties of the film. These enhancements were achieved by a more ordered and compact structure, a good crystallinity and a higher thermostability of SFPU-TSC-CTS film, which were verified by the Fourier transform infrared spectroscopy (FTIR), circular dichroism (CD), scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermal stability indexes. Moreover, SFPU-TSC-CTS film also presented good antioxidant and antibacterial activities. Therefore, SFPU was an effective auxiliary technology for improving the quality of food packaging film and can be deeply explored.     

Mechanical Properties,Rheology, and Crystallization of Epoxy-Resin-Compatibilized Polyamide 6/Polycarbonate Blends: Effect of Mixing Sequences

Blends of polyamide 6 (PA6)/polycarbonate (PC)/epoxy resin (EP) were melt blended with three different mixing sequences. Their mechanical properties, crystallization, and rheological behaviors, as well as the morphology, were investigated via mechanical testing, differential scanning calorimetry (DSC), dynamic rheometry, and scanning electron microscopy (SEM). It was noted that the mixing sequences affected the distribution of EP in the PA6 matrix, as well as the reactivity of EP with PA6 and PC. Mechanical testing showed that the blends prepared by the first (S₁, blending PA6, PC, and EP simultaneously) and second mixing sequences (S₂, blending PC with a premixture of PA6/EP) had higher notched Izod impact strengths due to the formation of PA6-EP-PC block copolymer (named as the AEC structure) during compounding, as evidenced by the results of dynamic rheology and SEM. Whereas for the third sequence (S₃, blending PA6 with a premixture of PC/EP), EP could barely react with PA6 and PC, leading to little formation of AEC structure, which resulted in a poor notched Izod impact strength of the blends. The incorporation of EP actually acted as a plasticizer to improve the elongation at break of the S₃ blends. In addition, the DSC results and SEM observations showed that there were distinct differences in the crystallization and morphology of the samples prepared by the different mixing sequences.     

Study on Emulsion Polymerization of PMMA/OMMT Nano‐Composites by Redox Initiation

A study on the polymerization and characterization of poly (methyl methacrylate)/organo‐montmorillonite (PMMA/OMMT) nano‐composites is reported. An effective method through emulsion polymerization was carried out for the preparation of nanocomposites using a redox initiation system; ammonium persulfate was used as the oxidizing agent and sodium sulfite as the reducing agent. The structure and morphology of the nanocomposites were studied by X‐ray diffraction and transmission electron microscopy and the exfoliated morphology was confirmed. The thermal properties were analyzed by thermogravimetric analysis and differential scanning calorimetry. It was found that the thermal properties were enhanced with the addition of organo‐montmorillonite.