Blend Surface Research Articles

Synthesis, structural, optical, and thermal properties of LaFeO3/Poly(methyl methacrylate)/Poly(vinyl acetate) nanocomposites for radiation shielding

This work is an attempt to develop flexible radiation shielding based on a blend of polymethyl methacrylate (PMMA)/polyvinyl acetate (PVAc) and LaFeO3 nanoparticles (NPs). LaFeO3 and LaFeO3/PMMA/PVAc were made using simple chemical techniques. A high-resolution transmission electron microscope (HR-TEM) and X-ray diffraction (XRD) showed that well-crystallized LaFeO3 NPs with particles 79 nm in size and an orthorhombic shape were obtained. In addition, XRD confirmed the existence of PMMA, PVAc, and LaFeO3 in the nanocomposite films. Fourier transform infrared (FTIR) confirmed that the LaFeO3 NPs and the reactive functional groups in the blend interacted with each other. Field emission-scan electron microscope (FE-SEM) analysis showed that PMMA and PVAc form a homogenous blend and that the LaFeO3 NPs were spread out inside and on the blend surface. The samples showed transmittance in the range of 30–74% and a small extinction coefficient (≤ 0.08). The samples exhibited a dual-band gap structure, and the direct (indirect) band gap shrank from 5.1 to 4.7 eV (4.9 to 4.4 eV). The thermal analyses showed that the samples are thermally stable up to 260 °C. The Phy-X/PSD software was used to figure out the theoretical gamma-ray attenuation parameters, such as the mass attenuation coefficient, the mean free path, and the half-value layer, for different PMMA/PVAc + x% LaFeO3 composites. It is demonstrated that the PMMA/PVAc + 10 wt% LaFeO3 sample exhibits much better shielding effectiveness than PMMA/PVAc, and hence it is suitable for protecting against radiation.

Nanoscale wear evolution on a polystyrene/poly (n-butyl methacrylate) blend

We have investigated the formation of surface nanostructures caused by early-stage wear of polystyrene (PS) and poly(n-butyl methacrylate) (PnBMA) thin films as pure materials, or mixed in the form of a 1:1 blend. To this end, atomic force microscopy (AFM) was used to repeatedly scratch the sample surfaces, measure the accompanying friction forces, and image the resulting features. In the very first stage ordered ripples are formed in all cases. As the process goes on, hillocks are nucleated on the crests of the ripples, and progressively released in the form of nanoplastics while the ripples become wider and less regular. On the blend surface the more compliant PnBMA presents more corrugated ripple structures and larger friction oscillations than PS in the beginning, but the scenario becomes again more complex as the wear test is repeated and the original ‘rim and hole’ geometry of the blend is disrupted. Quite noticeably, the wear damage is reduced if the surfaces are scraped forth and back and not only in one direction. The influence of the scan pattern (distance between scan lines) and of the normal force (well below and above the force threshold of about 50 nN leading to surface ripples in the first stage) have been also addressed.

PRODUCTION AND CHARACTERIZATION OF PHB, PHBV ELECTROSPUN FIBERS AND THEIR BLENDS

Polhydroxbutyrates (PHBs) are well-known bio-based and biodegradable bacterial polyesters. In this study, the effects of polymer type, solution concentration and feeding rate on the electrospinnability of Poly(3-hydroxbutyrate) (PHB) and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) PHBV nanofibers were investigated. First, PHB, PHBV and PHB/PHBV solutions with different polymer concentrations ranging between 5-11% wt. were prepared and characterized in terms of viscosity. Afterwards, electrospinning was performed and ultrafine fibers were produced. The surface morphology and the fiber diameters of the samples were investigated by scanning electron microscopy (SEM) analyses. Pore sizes of the samples were also calculated. In order to understand the wettability of the samples, contact angle measurements were conducted. The thermal properties and the crystallinity of the samples were investigated differential scanning calorimetry (DSC) analyses. The solution viscosities increased dramatically above %9 wt. of polymer concentration. SEM images revealed that decreasing feeding rate and increasing solution concentration resulted in fewer bead formation. On the other hand, fibers with diameters from 1.2 to 5.4 μm were produced with the increasing solution concentration and increasing voltage. All samples showed contact angle values above 90° indicating that they are hydrophobic. The PHB/PHBV blend surface showed the highest contact angle. DSC analyses showed that PHBV surface had significantly lower crystallization degree than PHB surface produced at the same concentration. It can be concluded that PHB fibers can be successfully produced by electrospinning.

Partially Bio‐Based Polyester Bead Foams via Extrusion Foaming of Poly(butylene terephthalate)/Poly(butylene furanoate) Blends

AbstractThe interest in bio‐based alternatives to classical polyesters such as poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT) is steadily growing to achieve a more sustainable approach to polymer materials. In this study, PBT/poly(butylene furanoate) (PBF) blends are prepared, characterized and extrusion foamed. PBF as a bio‐based polyester offers two advantages. The ecological footprint of the material is reduced, and additionally, it can be used in Diels‐Alder reactions at the blend surface to support fusion of the foamed beads. The blending behavior of the polyesters is investigated using samples prepared in a microcompounder, particularly focused on the miscibility of the blends and transesterification reactions. The blends are thermodynamically immiscible but show a certain degree of transesterification according to nuclear magnetic resonance (NMR) spectroscopy. The morphology of blend beads produced by an extrusion foaming process is analyzed regarding their cell density, cell size distribution, and open‐cell content. It is shown that PBF has a positive effect on the bead foam morphology. The use of a bifunctional linker designed for chemical fusion of the bead surfaces allows to obtaining of molded parts, in contrast to beads containing pure PBT.

Enhancing the microstructural, optical, and tensile properties of the PVC‐PMMA blend film: The role of PbO nanoparticles incorporation

AbstractPVC‐PMMA and PVC‐PMMA‐PbO PNC films were prepared. HR‐TEM confirmed the nanoparticle structure of PbO, while XRD assured its purity, tetragonal structure, with crystallites measuring 35.71 nm. SEM showed the blend surface appeared smooth and homogenous with a fingerprint shape, and loading increased the surface roughness. PbO was reported to be evenly distributed across the blend surface. FTIR confirmed that all blend functional groups are present and the formation of hydrogen bonds between PVC and PMMA, besides the strong interactions between PbO and blend chains. Different optical constants were investigated using UV–vis‐IR spectroscopy. The transmittance of the blend was 81.99% and decreased to 48.14% after loading 4 wt.% PbO (at 500 nm). Loading causes an increase in absorption. The extinction coefficient shows low extinction coefficients (k < 10−6). Loading PbO narrowed the blend band gaps and increased the refractive index n. The carrier's concentration to the electron effective mass was reported. Optical conductivity, energy loss functions, and nonlinear optical parameters were also studied. Tensile properties revealed that loading increased Young's modulus, tensile strength, and elongation at break. The enhancements in optical and mechanical characteristics of PNC films illustrate the possibility of extending their applications to include the semiconductor, electronics, and optics industries.

Synthesis and modification of the structural, optical, and thermal properties of PVA–PEO by LDH nanoplates

Nanocomposites with thermal stability and tunable optical properties became essential for developed optoelectronic and electrochemical devices. This work represents an attempt to synthesize PVA–PEO polymeric blend and modifies its structural, optical, and thermal properties. This was performed by incorporating different ratios of double-layered hydroxide (Zn/Fe-LDH) nanoplates (NP) which were prepared by the co-precipitation process. XRD results revealed that the incorporation of LDH, 43 nm in size and rhombohedral phase, influenced the degree of crystallinity (X C) of the blend. FE-SEM analysis showed the uniform distribution of LDH NP in the polymer matrix until 7.0 wt% content, beyond this ratio some voids were formed in the blend surface and particle agglomeration took place. FTIR spectroscopy illustrated the good miscibility of the polymers forming the blend, the interaction, and complexation between LDH NP and the blend functional groups. UV–vis-NIR spectroscopy analysis was performed to study the transmittance of the nanocomposites, extinction coefficient, refractive index, and optical conductivity. Besides, the direct and indirect band gaps of the films were found to decrease with increasing LDH NP content until a certain limit, after which they increased again. TGA&DSC analysis revealed the thermal stability of the films until 240 °C, and the DSC curves indicated three endothermic peaks. The obtained results confirmed that LDH NP incorporation is an interesting approach for tuning the optical and thermal properties to widen the technological applications based on PVA–PEO blend.

Improving the optical, dielectric properties and antimicrobial activity of Chitosan–PEO by GO/MWCNTs: Nanocomposites for energy storage and food packaging applications

This work is an attempt to improve the multifunctionality of chitosan–polyethylene oxide (Ch.–PEO) blend for different industrial applications including energy storage and food packaging applications. Graphene oxide (GO)/blend and multi-walled carbon nanotubes (MWCNTs)/GO/blend films were prepared by the solution casting method. FTIR analysis indicated the existence of Ch. and PEO functional groups and the positive interaction between the added nanofillers and the blend chains. XRD data confirmed interfacial compatibility between PEO and Ch. and showed that the semicrystalline nature of the blend was decreased after the incorporation of the filler. SEM analysis displayed that the blend surface is homogenous and crack-free, and the MWCNTs/GO were well-dispersed and uniformly distributed on the surface. The blend showed transmittance in the visible and NIR regions in the range of 76–91%. Loading MWCNTs/GO reduced this range and significantly increased the extinction coefficient of the blend. The indirect/direct band gap decreased from 4.3/5.2 eV to 3.0/3.8 eV with increasing fillers content. Moreover, the optical constants of the blend and nanocomposite films were determined. The dielectric measurements revealed that MWCNTs/GO doping increases the defects and results in a larger number of dipoles inside the blend and hence increases the dielectric constant of the blend. In addition, tan (δ) for all films is very small (˂ 0.05) and MWCNTs/GO/blend exhibits conductivity four times greater compared with the pure blend. The conduction mechanism, dielectric modulus, and Cole-Cole plots in the temperature range of 30–110 °C and frequencies in the range of 10−2 Hz–10 MHz were reported. The thermal analyses (TGA and DSC) for the blend and nanocomposite films were performed in the temperature range of 25–550 °C. TGA and DTG revealed three distinct weight-loss events for the samples; 25–122 °C, 229–360 °C, and 365–440 °C. The doped samples were more thermally stable where the blend lost 20% of its weight at 180.9 °C, while after doping with GO and codoping with MWCNTs, this temperature increased to 190.5 and 210.2 °C, respectively. The blend and nanocomposite solutions showed a wide antimicrobial activity against gram-positive and gram-negative bacteria, yeast, and fungi. Specifically, both GO/Ch.–PEO and 0.004%MWCNTs/GO/Ch.–PEO represented the highest antimicrobial against all tested microbes. Staphylococcus aureus ATCC 8095 was founded to be the most sensitive among the examined microbes. Additionally, the least sensitivity to studied solutions was recorded by Penicillium roqueforti. The improvements in the optical and dielectric properties make the prepared nanocomposites suitable for energy storage devices, while the antimicrobial activity suggests the use of GO/Ch.–PEO and MWCNTs/GO/Ch.–PEO nanocomposites for food packaging applications.

Controlling the optical properties and analyzing mechanical, dielectric characteristics of MgO doped (PVA–PVP) blend by altering the doping content for multifunctional microelectronic devices

The solution-cast method was used to synthesize magnesia (MgO) nanoparticles filled poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) blend matrix (80/20 wt %) based polymeric nanocomposite (PNC) films (i.e., [PVA–PVP]–x wt % MgO; x = 0, 0.06, 0.3, 0.6, 3.1, and 6.25). Most of these PNC materials structures are amorphous, according to an X-ray diffraction investigation. The blend surface was smooth and homogeneous under SEM, confirming PVA and PVP compatibility. MgO loading, on the other hand, enhanced the surface roughness. According to optical investigations, the film's transmittance, and energy bandgap decreased as the Mg+2 -ions increased. Tensile strength has also improved from 5.92 MPa to 10.65 MPa, while Young's modulus has enhanced from 51.16 to 166.4 MPa. From 100 Hz to 1 MHz, the dielectric and electrical spectra of these films were measured. Due to the nanoconfinement effect, it has been determined that the dispersion of MgO nanoparticles in the PVA–PVP blend matrix dramatically increases the dielectric permittivity. With increasing frequency, the dielectric permittivity of these PNC films decreases while the ac electrical conductivity increases. When the temperature of a PNC film is raised, a nonlinear rise in dielectric permittivity is seen, and the dc electrical conductivity of the film follows the Arrhenius law. The nonlinear I–V curves improve with increased Mg+2 ion concentration. These findings suggest that PVA/PVP blend matrix loaded with MgO NPs provides appropriate structural, optical, and electrical characteristics, expanding its potential industrial uses, particularly in optical components and devices.

Study the effect of mercuric ions concentration on some optical properties of Polyvinyl (alcohol/pyrrolidone) blend film

In the present work, the casting process was used to prepare polymeric films based on Polyvinyl alcohol/Polyvinylpyrrolidone (PVA/PVP) loaded with various weight percentages of HgCl2. The morphology and the microstructure of the synthesized samples were studied using Scanning Electron Microscope (SEM), Atomic force microscope (AFM), x-Ray Diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR) techniques. UV/VIS/NIR spectrophotometer was implemented to scientifically check the optical elucidation. All films between the two phases are characterized by substantial integration of HgCl2 and PVA/PVP. The scanning electron microscope shows a morphology modification of the blend surface with the mercuric chloride substantive. The roughness calculated from AFM images increased with increasing HgCl2. The agglomeration of the particles made a significant influence on the optical transmittance properties of pure PVA/PVP. Due to the growth of distortion and imperfection in the structure of the blend matrix by the addition of HgCl2, there is a modification in the engineering bandgap, localized state’s order, coefficient of absorption, and optical conductivity. The dispersion and oscillator energies were calculated using the Wemple and Di Domenico (DDW) model for a single oscillator. Various theoretical relations between energy gaps and refractive indices were used to calculate the average refractive index of each sample. Further, the nonlinear refractive index and optical susceptibilities of polymer composite samples were enhanced by increasing the percentage of HgCl2. The influence of loading on the optical limiting of the blend was investigated via He-Ne and green diode lasers. The results indicate the ability to use our flexible films in various optoelectronic devices.

Visualizing Surface Phase Separation in PS-PMMA Polymer Blends at the Nanoscale.

Phase-separated polymer blend films are an important class of functional materials with numerous technological applications in solar cells, catalysis, and biotechnology. These technologies are underpinned by the precise control of phase separation at the nanometer length-scales, which is highly challenging to visualize using conventional analytical tools. Herein, we introduce tip-enhanced Raman spectroscopy (TERS), in combination with atomic force microscopy (AFM), confocal Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS), as a sensitive nanoanalytical method to determine lateral and vertical phase-separation in polystyrene (PS)-poly(methyl methacrylate) (PMMA) polymer blend films. Correlative topographical, molecular, and elemental information reveals a vertical phase separation of the polymers within the top ca. 20 nm of the blend surface in addition to the lateral phase separation in the bulk. Furthermore, complementary TERS and XPS measurements reveal the presence of PMMA within 9.2 nm of the surface and PS at the subsurface of the polymer blend. This fundamental work establishes TERS as a powerful analytical tool for surface characterization of this important class of polymers at nanometer length scales.

Segregation Behavior of Miscible PC/PMMA Blends during Injection Molding.

Miscible blends composed of bisphenol-A polycarbonate (PC) and poly(methyl methacrylate) (PMMA), in which one of them has low molecular weight, were employed to study the surface segregation behavior during flow. The blend samples showed typical rheological behaviors, such as simple polymer melts without a long-time relaxation mechanism ascribed to phase separation, demonstrating that they were miscible. After injection molding, the amounts of a low molecular weight component on the blend surface were found to be larger than the actual blend ratio. Because the injection-molded products were transparent despite a huge difference in refractive indices between PC and PMMA, they showed no phase separation. This result demonstrated that surface segregation of a low molecular weight component occurred under flow field, which expands the material design such as tough plastics with good scratch resistance and optical fibers with tapered refractive index.

Influence of NiO and La2O3 nanoparticles on the optical, mechanical and electrical properties of PVAc–PMMA blend: a comparative study

Nano-sized metal oxides are fascinating materials as fillers used for improving the polymeric materials’ performance and expanding their multifunctionality. Two metal oxides; NiO and La2O3 nanoparticles (NP) were prepared and introduced into poly(vinyl acetate)/poly(methyl methacrylate), PVAc/PMMA blend via solution casting route. XRD and HR-TEM analysis confirmed the preparation of a cubic NiO and a hexagonal La2O3 NP with an average crystallite size of 59.85 and 29.13 nm, respectively. Introducing NiO and La2O3 increases the films’ amorphous structure. FTIR analysis confirmed the existence of all blend’ functional groups and hydrogen bond formation. SEM investigation showed that NiO or La2O3 loading affects the blend surface morphology. A UV–vis-NIR study showed that NiO narrowed the direct bandgap of the blend from 4.1 to 3.3 eV, whereas La2O3 reduced it to 3.4 eV. 1.0 wt% NiO significantly improved the various optical constants of the blend. DMA revealed that storage modulus G′ increased with loading of 1 wt% NiO or La2O3 by 79.3% and 51.0%, respectively while G′ decreased with heating. The dielectric behavior of films is analyzed using several dielectric parameters. The maximum σ ac reported for 1.0 wt% NiO/blend film is 5.8 × 10−6 (S/cm). The AC conduction mechanism is discussed for all films in the temperature and frequency ranges (298−373 K) and (5 Hz−2 MHz). 1.0 wt%/PVAc/PMMA nanocomposite showed enhanced optical and mechanical properties, making it suitable for architectural, flexible display screens, and photovoltaic cell devices. Moreover, loading NiO and La2O3 improved the dielectric properties of the blend to be used in the semiconductor industry, besides energy storage devices and supercapacitors.

The effect of polyethylene‐graft‐maleic anhydride on ultrahigh molecular weight polyethylene/carboxymethyl cellulose blends

AbstractIn this study, it is aimed to produce biocompatible polymer blends by using ultrahigh molecular weight polyethylene (UHMWPE) as a matrix and a cellulose‐based polymer, carboxymethyl cellulose (CMC) as filler at different concentrations. Polyethylene‐graft‐maleic anhydride (PE‐g‐MA) was used as compatibilizer in order to ensure effective distribution of hydrophilic cellulose particles in hydrophobic UHMWPE matrix and its effect on blends was investigated. The UHMWPE/CMC blends were fabricated by sintering of two powder materials and effects of different sintering conditions such as sintering temperature and time were examined on the morphological and surface properties of blends. The hardness, air permeability, contact angle variations on the blend surfaces were investigated. 150°C–30 min sintering condition was determined as optimum sintering time and temperature to prepare the blends having adequate hardness with high‐air permeability properties. It was found that with the increase of CMC content in the blends the hardness, air permeability and contact angle values were decreased. The addition of PE‐g‐MA caused an increment for blends prepared at 150°C–30 min conditions having high‐air permeability.

Structural, morphological features, and antibacterial behavior of PVA/PVP polymeric blends doped with silver nanoparticles via pulsed laser ablation

Abstract Polyvinyl alcohol (PVA)/polyvinylpyrrolidone (PVP) blends doped with silver nanoparticles (AgNPs) have been fabricated using laser ablation technique in one spot. The physical features of AgNPs@PVA/PVP layers were detected by XRD, FTIR, and FESEM techniques. Regarding XRD analysis upon different laser ablation times, and silver content induces a variation of PVA/PVP peaks intensities. The surface morphology was exhibited as well size and particle distribution of AgNPs through the blend surfaces. Further, the particle size of AgNPs increases with ablation time from 45.3 nm to 55.4–81.3 nm for the t = 5.0 and 20.0 min, respectively. Besides, the roughness average increased from 60.99 nm at t = 0 min to 102.4 nm at t = 20 min. Besides, the highest contact angle of 61.3 ± 3.1° was detected for pristine PVP/PVP, which decreased with increasing silver content, reaching 38.1 ± 2.1° at t = 20 min. Moreover, the highest cell viability percentage is recorded by the highest silver content composite by 97.1 ± 3.2%. Further, the antibacterial activity was examined and showed that the inhibition zone reached around 17.3 ± 1.9 and 17.1 ± 2.1 mm against Escherichia coli and Staphylococcus aureus, receptively. The fabricated AgNPs@PVA/PVP films could be suggested to be utilized for wound healing/dressing application.

Enhanced antibacterial activity of chitosan, guar gum and polyvinyl alcohol blend matrix loaded with amoxicillin and doxycycline hyclate drugs

This study focusses on the synthesis of a series of semisynthetic polymeric blended membranes based on chitosan, guar gum and polyvinyl alcohol for the sustained delivery of antibacterial drugs" with "A series of semisynthetic polymeric blended membranes based on GG (guar gum), CS (chitosan) and PVA (polyvinyl alcohol) was fabricated for the sustained delivery of antibacterial drugs. The drug employed in this study includes amoxicillin and doxycycline hyclate. Different ratios of chitosan CS and GG were blended with constant ratio of PVA to synthesize membranes using solution casting method. Fourier transforms infrared (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD) study showed the blend formation, surface morphology and crystalline nature of polymeric membranes respectively. Successful bonding among the ingredients was confirmed by crystalline peak of CS cellulose at 22.6˚. Swelling test was used to analyze the water absorbing capacity of the membranes, indicating the hydrophilic nature, making these membranes more liable for drug release application. Results revealed that 25 mg was the ideal amount of drug loaded on blended membrane. Antimicrobial activity was promising against selected bacterial strains and cytotoxicity assay showed that the polymeric membranes have great potential for biomedical field. The membrane (B-2) was considered best amongst all based on the composition and ratio 3:1 of CS to GG, demonstrated good binding between constituents. These membranes can be employed for sustainable drug delivery process due to good swelling, antimicrobial and absorption characteristics.

High‐Efficiency Digital Inkjet‐Printed Non‐Fullerene Polymer Blends Using Non‐Halogenated Solvents

Inkjet printing (IJP) of polymer solar cells is ideal for small‐area off‐grid electronics with low power consumption. However, IJP is quite a complex technique compared with techniques such as spin coating or doctor blading. The IJP of polymer blends is reported based on ITIC derivatives as non‐fullerene acceptors (NFAs) using non‐halogenated solvents. The results show that fluorination of NFA is essential to form highly stable inks in o‐xylene, because ITIC has significantly insufficient solubility compared with ITIC‐4F. The importance of tetralin as a multifunctional co‐solvent for printing highly efficient PM6:ITIC‐4F blends is demonstrated, as even at very low concentrations, tetralin not only improves ink jettability and open nozzle time, but also improves drying behavior of the blend layer, resulting in blends with homogeneous micro‐ and nanoscale morphology. The resulting solar cells using inkjet‐printed polymer blends show a maximum efficiency of 10.1%. Moreover, IJP produces significant changes in the nanoscale and microscale morphology. In particular, the formation of a thin PM6 capping layer on the blend surface along with improved phase separation and crystallinity in both the donor and acceptor greatly reduces the recombination of charge carriers in thick blends, making inkjet‐printed photoactive films very promising for industrial applications.

Preparation of Polymeric films containing Schiff base as UV-Absorber with Good Resistance against UV-Photoaging

To increase the photostability of polystyrene, a new Schiff base has been added to the polystyrene mixture. The polystyrene films have been exposed to ultraviolet light for 300 hours. Schiff's base has been utilized as a long-term polystyrene optical stabilizer against ultraviolet radiation. Schiff base efficiency is widely recognized for using different techniques, including weight loss determinations, infrared spectroscopy, and electron microscopy (SEM) of PS films after 300 hours of irradiation. Polystyrene/Schiff base blend surface morphology was investigated by SEM technique, and the images demonstrated the formation of terrestrial crack materials due to the presence of photo-stabilizer within the polymer materials. Moreover, the carbonyl group indices were much lower for PS/stabilizer blend than for the blank polymer. The results showed that adding a Schiff base greatly improved the photostability of polystyrene. Furthermore, many unwanted alternations because of the exposure to ultraviolet light were treated by adding the Schiff base compared to the blank polymeric film. The photo-stabilizer absorbs the light and works as a free radical scavenger segment.

Functionalization of multi-walled carbon nanotube and its effect on shape memory behavior of nanocomposite based on thermoplastic polyurethane/polyvinyl chloride/multi-walled carbon nanotube (TPU/PVC/MWCNT)

Nanocomposites based on thermoplastic polyurethane/polyvinyl chloride/multi-walled carbon nanotubes were prepared by a solution method and their shape memory properties were studied. The blend ratios were 70/30, 60/40, and 50/50 (w/w) of thermoplastic elastomer polyurethane/polyvinyl chloride. To improve the dispersion of multi-walled carbon nanotubes, at 0.5% and 1% (wt), in polymer matrices, three-step chemical modifications were performed, including oxidation, chlorination and grafting of poly (ɛ-caprolactone) diol. The occurrence of surface modifications in MWCNTs was monitored using Fourier transform infrared spectroscopy, elemental analysis, scanning electron microscopy and thermal gravimetric analysis techniques. SEM micrographs revealed a good dispersion of MWCNTs in the polymer matrix due to better matrix-filler interactions compared to filler–filler interactions. The results showed that the main indices of shape memory behavior (shape fixity and shape recovery) of nanocomposite samples were affected by the polymer blend ratio, nanoparticle concentration and surface modification. Increasing the content of polyvinyl chloride led to reduced shape fixity and shape recovery, which was attributed to the lack of rigid structural nature of polyvinyl chloride. The presence of nanoparticles contributed to enhanced shape fixity and weaker shape recovery. This can be explained by lower polymer chain mobility in the presence of multi-walled carbon nanotubes. The reduction in chain mobility in nanocomposites reinforced by surface-modified multi-walled carbon nanotubes was more significant due to higher distribution efficiency of nano-scale fillers in the polymer matrix.

Modification of Surface Hydrophobicity of PLA/PE and ABS/PE Polymer Blends by ICP Etching and CFx Coating.

The flow regime inside the channel of 3D printed microreactors is defined by the surface properties of the channel walls. Polylactide (PLA) and acrylonitrile/butadiene/styrene (ABS) are two polymers that are the most common in additive manufacturing using fused filament fabrication, commonly known as “3D printing”. With the aim of developing new materials for the 3D printing of microreactors whose channel surface hydrophobicity could be modified, PLA and ABS were blended with cheaper and widely used polymers-high-density polyethylene (PE-HD) and low-density polyethylene (PE-LD). Polymer blend surfaces were treated with inductively coupled plasma (ICP) and coated by fluorocarbon-based material (CFx) plasma deposition treatment in order to modify surface hydrophobicity. It has been shown that the modification of surface morphology of PLA polymer blends can be achieved by ICP etching and CFx coating, while this was not possible for ABS polymer blends under the conducted treatment conditions. The treated surface of PLA/PE-HD 90/10 showed a contact angle of 121.6° which is 36° higher than the contact angle measured on the untreated surface. Surfaces that have achieved contact angles higher than 120° have an “island like” surface morphology. Samples with higher “islands” showed higher contact angles, that confirmed that the hydrophobicity also depends on the height of the “islands”. Furthermore, it has been found that etching time significantly impacts the contact angle values and surface morphology of the PLA polymer blends, while the CFx coating time does not have significant impact on the surface properties.

Sono-oxidation treatment of hazardous ABS/PC surface for its selective separation from ESR styrene plastics.

This study reports the selective hydrophilization of the ABS/PC blend surface using the peroxide-sonochemical system and then its selective separation by froth flotation technique from other ABS-based plastics (ABS, ABS/PMMA) and PS/HIPS in electronic shredder residue (ESR). FT-IR and XPS measurements confirm that the hydrophilic moiety development on the ABS/PC surface led to increasing the wettability of ABS/PC and then decreased its floatability. The confocal scanning results also support the enhancement of microscale roughness of the treated ABS/PC surface. The enhanced surface roughness is attributed to the oxidative process which degrades hydrophobic moieties and promotes hydrophilic functional groups on the ABS/PC surface using commercial oxidant peroxide and ultrasound. This study also investigated removal of Br-containing compounds on the ABS/PC surface. The optimum conditions for selectively ABS/PC separation are peroxide concentration 2%, power cycle 70%, treatment time 5min, temperature 50°C, floating agent concentration 0.4mg/L, flotation time 2min, and airflow rate 0.5L/min. ABS/PC was selectively separated from ESR styrene plastics with high recovery and purity of 98.9% and 99.8%, respectively. Hence, the developed novel surface treatments having removal of hazardous Br chemicals and none-formation of secondary pollutants should be applied for upgrading plastic recycling quality.