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Linear low‐density polyethylene (LLDPE) is a polyolefin known for its superior low‐temperature heat seal ability, low‐temperature tolerance, and bag‐tear resistance which are important features for the polymeric packaging sector. In this work, to improve the mechanical properties and expand the range of applications of LLDPE, the microfibrillar clay mineral palygorskite (PAL) was added. However, the use of PAL as a reinforcing agent for polymers depends on its purification process to extract accessory minerals such as calcite, dolomite, and quartz. In addition to this purification process, two surface modifications were used on the purified PAL (PALp) to improve interactions with LLDPE: silanization with aminosilane (PALs) and organophilization by incorporating an organic compound (PALo). The PAL were characterized according to their morphological properties using transmission electron microscopy (TEM), X‐ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT‐IR). The films of LLDPE/PAL, with varying levels (1, 3, and 5 wt%) and types of PAL (raw PAL, PALp, PALs, and PALo), were prepared by an extrusion process, and films were prepared by compression molding, without preferred orientation. The films were characterized by rheological analyses, tensile tests, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and water vapor permeability. Incorporating modified PAL was significant in enhancing the mechanical properties of the nanocomposites. LLDPE/PALs with the addition of 3 wt% PALs showed a 14% increase in elastic modulus (281.08 ± 8.25 MPa) compared to the nanocomposite with 3 wt% of raw PAL (243.43 ± 15.01 MPa). Highlights: The PAL is a clay mineral with a fibrous morphology and has a low cost.The technique to purify PAL is a quick, simple, and inexpensive technique.Comparison between of two technique surface modification of PAL.The effectiveness of modifications of PAL was confirmed in LLDPE films.The surface modification with silanization was more effective. [ABSTRACT FROM AUTHOR]

Hybrid polymer nanocomposites based on polyvinylidene fluoride (PVDF) as the matrix, carbon nanotubes (CNTs) as the primary conductive filler, and metal nanoparticles as secondary fillers were fabricated by melt mixing. Secondary nanofillers with different geometry and properties (nickel nanowire (NiNW), silver nanowire (AgNW), nickel nanoparticle (NiNP), and silver nanoparticle (AgNP) were selected to investigate the effect of geometry and properties of secondary filler on the hybrid polymer nanocomposites' properties. Electrical conductivity, electromagnetic interference (EMI) shielding effectiveness, and complex microwave properties of the fabricated hybrid nanocomposites were studied in X‐band frequency (8.2–12.4 GHz). The hybrid nanocomposites containing CNT/AgNW demonstrated superior conductivity and EMI shielding compared to individual fillers such as CNT, AgNW, NiNW, AgNP, NiNP, or hybrid system such as CNT/NiNW. The novelty of the present study lies in the unique synergy arising from the combination of nanofillers with similar geometry and high electrical conductivity, which resulted EMI shielding effectiveness as high as 27 dB for a shield with only 1.1 mm thickness. The EMI shielding mechanisms, including negative permittivity were studied and explained in details in the manuscript. [ABSTRACT FROM AUTHOR]

Electrical conductive nanostructures made of nanofibers of poly (amide 6) (PA6) with carboxyl functionalized multiwall carbon nanotubes (MWCNTCOOH) and anchored MWCNTCOOH were produced. The nanotubes were surface activated with carboxyl groups, dispersed in formic acid and added to a formic acid solution of PA6. The mixture was electrospun by applying a voltage of 30 kV; afterwards, the nanofiber's mats were immersed in an aqueous dispersion of MWCNTCOOH containing a nonionic surfactant. The chemical structure, morphology, thermal stability, and electrical conductivity of the nanostructures were evaluated by UV spectroscopy, scanning (SEM), and transmission electron microscopy (TEM), thermal gravimetric analyses (TGA) and volumetric conductivity measurements. The efficiency of the functionalization was confirmed by the UV peaks in the range between 220 and 250 nm (corresponding to a carbonyl group conjugated with a carbon-carbon double bond). SEM and TEM micrographs showed the pullout of the MWCNTCOOH from the nanofibers and the formation of a stable, percolated, and anchored MWCNTCOOH network on the nanofibers due to the anchoring of the MWCNTCOOH from the surfactant solution on the MWCNTCOOH of the nanofibers. The coated nanostructures had higher thermal stability and higher electrical conductivity than the noncoated ones, showing the efficiency of this simple procedure. POLYM. ENG. SCI., 55:1263-1272, 2015. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

This study investigates the dielectric properties of multiwalled carbon nanotube (MWCNT)/polystyrene (PS) composites over the broadband frequency range, i.e., 10−1 to 106 Hz. The results showed that the real permittivity and imaginary permittivity increased remarkably with increased MWCNT concentration. For instance, at 100 Hz, the real permittivity and imaginary permittivity of the pristine PS was 2.71 and 0.01, respectively, which increased to 5.22 × 104 and 3.28 × 107 at 3.50 wt%, respectively. The increase in the real permittivity was related to the formation of a large number of nanocapacitor structures, i.e., MWCNTs as nanoelectrodes and polymer matrix as dielectric material, i.e., interfacial polarization. The increase in the imaginary permittivity with MWCNT loading was attributed greater number of dissipating charges, enhanced conductive network formation, and boosted polarization loss arising from interfacial polarization. It was also observed that the real and imaginary permittivities were frequency independent in the insulative region, whereas they decreased drastically with frequency in the conductive region. The descending trend of real permittivity with frequency in the conductive region was related to charge polarization relaxation, whereas the reduction in imaginary permittivity with frequency was attributed to lower Ohmic loss and polarization loss. POLYM. ENG. SCI., 55:173-179, 2015. © 2014 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

In this study, acrylic tri-block-copolymers of different compositions and constituents were used to modify an epoxy resin. In epoxy the block-copolymers self-assembled to generate different nanostructured phases. Spherical micelles and vesicles were formed due to preferential interactions among constituents of the blends. The effect of modifier concentration and morphology on the resulting mechanical properties was investigated. At a modifier content of 5 wt% a more than threefold increase in strain energy release rate was observed relative to the unfilled epoxy for the block-copolymer/epoxy systems studied. This improvement was accompanied by slight reductions in tensile stiffness, strength and glass transition temperature of developed epoxy blends. Microstructural studies revealed that during crack propagation, vesicle and micelle structures respectively underwent debonding and cavitation followed by shear yielding of the substrate matrix. POLYM. ENG. SCI., 54:1047-1055, 2014. © 2013 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

A corotating plasticating twin screw extruder (TSE) was excited by changing feed rate according to predesigned random binary sequence (RBS) and stair type excitation. A high density polyethylene was used as processing material in this study. Empirical models were developed relating two output variables, melt pressure at die ( P), and melt temperature at die ( T), with feed rate ( F). Classical linear system identification technique was used to develop models. Models were developed using a data set obtained from RBS excitation. Stair type excitation data were used to validate the developed models. The structure of the obtained models was autoregressive moving average with exogenous input (ARMAX). Models with ARMAX structure and order of 2 were found to be sufficient to capture the dynamic behaviors of P and T when F was changed. A delay-gain model was proposed for P and was found to capture the response quite satisfactorily. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The article evaluates the effect of mixing protocol on the morphology of compatibilized polymer blends made with premade compatibilizer and reactivity formed in-situ compatibilizer in a custom-built miniature mixer Alberta Polymer Asymmetric Minimizer. The effects are complex since the dispersed phase particle size and distribution of the compatibilized blends may be smaller or larger when compared with the uncompatibilized system, depending on the material's physical and chemical properties.

Investigates the polyethylene (PE) or polycarbonate drop deformation and the breakup mechanism in a PE melt under shear flow using numerical simulations. Details on the morphology generation during melting; Means of developing polymers; Difference in the distribution of shear field on the surface of the melting pellet.