High density polyethylene (HDPE) / ultra high molecular weight polyethylene (UHMWPE) blend is expected as an all-polyolefin recycle material that can achieve both mechanical properties and a ...continuous melt-mixing process. In order to improve the mechanical properties of polymer blends, optimal mixing is required to achieve both good dispersibility and low degradation. In this study, the effect of mixing conditions on the dispersion and degradation behavior of HDPE/UHMWPE blends were investigated. Neat HDPE and HDPE with 5% UHMWPE were obtained by melt mixing in internal batch mixer. Time of mixing, Specific Energy Input (SEI), and rotation speed of the rotors were changed. From the results of microscopic observation and a differential scanning calorimetry (DSC), the dispersibility progressed with the increase in SEI regardless of the rotor speed. The results of Gel Permeation Chromatography (GPC) show the molecular chain scission was also promoted by the increase in SEI. In the other hands, the results of oscillatory shear test show the increase in storage modulus G’ were promoted by increase in not only SEI but rotor speed. Furthermore, the molecular chain scission and increase in G’ were significantly suppressed by the nitrogen atmosphere.
•Chitin nanofillers were incorporated in thermoplastic starch matrix by melt-mixing.•Starch nanocomposites showed better mechanical properties than starch matrix.•Starch nanocomposites presented good ...thermal stability.•Materials with nanofibers showed better properties than those with nanocrystals.•These nanocomposites contribute to a breakthrough in chitin applications.
Chitin nano-size fillers, i.e. nanocrystals (CHNC) and nanofibers (CHNF), were incorporated in thermoplastic starch matrix via melt-mixing. The two types of thermoplastic starch-based nano-biocomposites (S/CHNC and S/CHNF) were characterized and compared in terms of morphology, chemical and crystal structure, thermal and mechanical properties, and water resistance. In general, all thermoplastic starch-based nano-biocomposites showed better thermal stability, mechanical properties, and storage modulus than thermoplastic starch matrix without chitin nano-size fillers. This can be linked to the good dispersion of the nano-size fillers in the matrix, resulting from their chemical similarity, and also to the strong nano-size fillers–matrix adhesion by hydrogen bonding interactions. The results showed that the final properties of the nano-biocomposites were dependent of the concentration and type of chitin nano-size filler introduced in the thermoplastic starch matrix. In general, the thermoplastic starch-based nano-biocomposites prepared with chitin nanofibers showed better thermal and mechanical properties and storage modulus than those prepared with chitin nanocrystals.
Abyssal peridotites and mid-ocean ridge basalts (MORB) offer only a partial glimpse into the mantle's composition and the magmatic process beneath the mid-ocean ridges. Recently, lower crustal ...cumulates have emerged as potential candidates for capturing a broader range of mantle heterogeneity and depicting a detailed process in MORB generating system. However, it remains uncertain to what extent the lower crustal cumulates can represent mantle source variability. In this study, we present detailed in-situ geochemical and isotopic data, including major and trace element compositions of minerals and in-situ Sr isotopic analysis on plagioclase from lower crustal cumulates collected at 14°45′N on the Mid-Atlantic Ridge (MAR). Trace element compositions of melt in equilibrium with clinopyroxenes from the lower crustal cumulates exhibit strong similarities to nearby MORBs. Exception is that the equilibrium melt of the core of a clinopyroxene oikocryst records a transitional MORB composition, different from the more enriched MORB composition at rims. This phenomenon, together with element changing in minerals from cores to rims, suggests a history of melt-rock interactions, during which more enriched melts transport through minerals that had previously crystallized from relatively more depleted melts. The in-situ 87Sr/86Sr ratios, which vary from 0.70249 to 0.70306, span the range of the global MORB Sr isotope values. Thus, both the trace element compositions and 87Sr/86Sr ratios of cumulate minerals confirm the coexistence of depleted and enriched melts. Our findings furtherly suggest that the melts from heterogenous mantle components underwent incomplete mixing in the lower oceanic crust, even in the crystal mush, thus preserving variable heterogeneities not seen in MORB. Through integrated analyses of geochemistry, isotopic data, and geophysical information from existing literature, we identify the most likely mantle components in the study area as depleted peridotites veined with recycled oceanic crust (pyroxenites).
•Gabbros in a single dredge location from the Mid-Atlantic Ridge at 14°45′N show segment scale isotopic heterogeneity.•Assimilation and fractionation melts from cores to rims in clinopyroxenes evolve from transitional to enriched MORB types.•Isotopic variability in cumulates implies incomplete mixing of melts that plumbing into the crystal mush.
This article reviews the recent development in performance and fabrication of carbon nanotubes (CNTs)‐based polymer nanocomposites synthesized by melt‐mixed process. CNTs have attracted enormous ...attention, since its presence (even in low concentration) causes drastic improvements in the mechanical and electrical properties of several polymer composites. It is suggested that the dispersion state of CNTs within polymer matrices is dictated by the cohesive strength of the CNTs “agglomerates.” Based on this suggestion, this review involves an in‐depth investigation on the origin of this CNTs “agglomerates” when present within polymer matrices. Attempts have also been done to investigate and correlate the varying extent of CNTs “agglomerates” in different polymer matrices. It is considered that the extent of dispersion of CNTs “agglomerates” depends on the interfacial interaction between the two phases, difference in their melt viscosities, and types of CNTs, compatibilizer and modifier used. A comprehensive study has been done on the effect of processing parameters used during melt‐mixing process; functionalization of CNTs, and the effect of compatibilizers and modifier on the final properties and morphology. Herein, an attempt has been done to study the correlation between the synthetic procedure, developed structure, and observed properties of nanocomposites of polymers and CNTs.
High molecular weight polyisobutylene (PIB) was modified by a mild and facile melt‐mixing process with thermoplastic polyurethane elastomer (TPU) in the presence of a compatibilizer, i.e., ...polypropylene‐g‐maleic anhydride (PP‐g‐MAH). Scanning electron microscopy (SEM) in combination with solvent etching revealed a significantly phase‐separated morphology due to different polarity of PIB and TPU. An evolution from dispersed phase to continuous phase for TPU was observed with the increase of TPU content, leading to an enhanced tensile strength of PIB/TPU blend in comparison to PIB. This phase‐separated morphology of PIB/TPU blend was confirmed by FTIR and thermal analysis. Rheological studies suggested that the PIB/TPU blend (30 wt% of TPU) exhibited a typical non‐Newtonian fluid behavior. More importantly, PIB/TPU blend was shown to possess enhanced thermal and oxidative/hydrolytic stability in comparison to TPU. SEM combined energy dispersive spectrometer (EDS) further elucidated that the surface chemical composition of PIB/TPU blend can be tailored through annealing, which further improved the biocompatibility as well as the oxidative/hydrolytic stability.
The genotoxic effect of microwave radiation on humans is one of the leading causes of some diseases like cancer. Despite many reported materials for microwave absorption, there is still a demand for ...a super‐thin and flexible microwave absorber. In the present work, we synthesized Fe3O4/graphene/polyaniline/nitrile butadiene rubber composites with a thickness of 0.7 mm using a melt mixing method. Then, we comprehensively studied the electromagnetic and microwave absorption properties of the composites from 8 to 12 GHz. The composite with 38 wt% Fe3O4 and 6 wt% graphene exhibited the highest microwave absorption of more than 8 dB in the entire range of 8–12 GHz, with a minimum reflection loss of −14 dB at 10.3 GHz. By increasing the weight content of Fe3O4 and graphene, the imaginary part of dielectric permeability and magnetic permeability initially went up and then declined, resulting in poor impedance matching. Hence, we precisely controlled the weight content of the fillers to reach the highest impedance matching and attenuation constant. Consequently, this work opened up a unique way for developing super‐thin, lightweight, flexible microwave‐absorbing materials.
•PLA/SiO2:Sr2+: Tb3+ composites were successfully synthesized by melt mixing and characterized.•TEM and XRD were used to determine the physical properties.•The thermal properties of the composites ...were determined using DSC and TGA.•Photoluminescent behavior of the composites was studied with laser PL.•All the samples emit in the blue vertex as shown by the CIE results.
SiO2 :0.4% Sr2+, x% Tb3+ (0 ≤ x ≤ 0.5) nanophosphor powders were prepared by sol-gel method. The powder samples were dispersed into the PLA polymer matrix through melt mixing method and compression molding to prepare the nanophosphor polymer composite. X-ray diffraction (XRD) patterns showed broad peaks with the position of the peaks shifting and more separating with an increase in Tb3+ concentration. The transmission electron microscope (TEM) images showed darker patches with the introduction of the nanophosphor, which indicates the incorporation of phosphor particles into PLA polymer. Differential scanning calorimeter (DSC) results revealed that the composites show an increase in the cold crystallization temperature (Tcc) and slight decrease in the glass transition temperature (Tg) as compared to the PLA. Thermogravimetric analysis (TGA) results showed that the thermal stability of the composites show an initial decrease with the incorporation of the fillers, but they become more thermally stable with higher Tb concentration in the fillers. Ultraviolet visible spectroscopy (UV–vis) results showed the decrease in transmittance for the composite compared to the PLA polymer. The photoluminescence (PL) results showed that the incorporation of the Sr2+doped SiO2 only affected the luminescence intensity, while co-doping with the incorporation of the Sr2+ and Tb3+ ions induced the emissions peaks at 487, 543, 582 and 621 nm, which could be attributed to the 5D4 → 7F3, 7F4, 7F5, and 7F6 transitions of Tb3+, respectively. The main aim of this study was to fabricate the light emitting polymer-based material.
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In this article, we successfully fabricated the bionanocomposites using cellulose nanocrystals (CNCs) and reduced graphene oxide (rGO) reinforced into biodegradable polylactic acid (PLA) matrix ...through melt‐mixing method. Due to the affinity difference between hydrophilic CNC and hydrophobic PLA, the surface modification of CNC was employed using quaternary ammonium salts (CTAB) as a surfactant. The nanocomposites were developed using different blend ratios of CNC/modified CNC (1, 2, and 3) wt% and (0.5 wt%) rGO into the polymer matrix. The morphology of CNC, q‐CNC (modified CNC), and nanocomposites were inspected by atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). It is demonstrated from tensile tests that, the nanocomposite with 1 wt% CNC and rGO showed maximum tensile strength compared with PLA and its nanocomposites. Moreover, the nanocomposite with 1 wt% CNC and rGO was also having maximum thermal stability. From cytotoxicity evaluation, it is observed that all the nanocomposites are nontoxic and cytocompatible to HEK293 cells. In addition to this, the nanocomposite with q‐CNC showed enhanced barrier properties compared with PLA and PLA/CNC/rGO nanocomposite. The results obtained from different characterizations showed that the incorporation of surfactant onto CNC improved the dispersion in PLA but at the same time deteriorated the PLA matrix.
