Linear Low Density Polyethylene Matrix Research Articles

Enhancement of insulation properties of LLDPE by PPy-functionalized PS-NPs

The strategy of functionalized PS-NPs via PPy (PPy@PS-NPs) forming heterogeneous interface composition is highly efficient in increasing the insulation properties of linear low-density polyethylene (LLDPE). The morphology results show that PPy@PS-NPs are monodispersed in the LLDPE matrix after melting blend, which exhibits unparalleled engineering application value. The electrical insulation results show that PPy@PS-NPs introduced into the LLDPE matrix can reduce its DC electrical conductivity, enhance DC breakdown strength, and inhibit space charge accumulation. When the PPy@PS-NPs concentration is 0.5 wt%, the DC breakdown strength is 35.3 % higher than that of LLDPE. Mechanism research indicates that the depths of carrier traps are decreased due to high electron affinity caused by the introduction of PPy@PS-NPs, but the trap density is increased. The reported strategy of using functionalized polymer nanoparticles to improve the polymer insulation property provides new insights for developing future high-insulation materials and other functional materials based on functionalized polymer nanofillers.

Effect of graphene nanoplatelets and nano zinc oxide on gas barrier and antibacterial properties of thermoplastic nanocomposites

AbstractGraphene‐loaded thermoplastic nanocomposite films must be evaluated for antibacterial activity, mechanical, and barrier properties before being utilized as food packaging. Herein, economically feasible linear low‐density polyethylene (LLDPE)‐based flexible packaging materials were developed via the melt compounding technique at 170°C temperature by taking advantage of both graphene nanoplatelets (GNP) and nano zinc oxide (ZnO) fillers. Morphological studies reveal that in composites loaded with GNP/ZnO hybrid fillers, ZnO nanoparticles form a network‐like structure throughout the polymer matrix. Simultaneously, GNPs are uniformly dispersed. The inclusion of hybrid nanofiller considerably reduces both the oxygen transmission rate and the water vapor transmission rate (WVTR) in LLDPE nanocomposites. A maximum decrease of 36% and 67%, respectively, in both oxygen transmission rate and WVTR is observed for 3 wt% of hybrid filler loading in a thermoplastic matrix containing 1 wt% of nano ZnO. The antibacterial efficacy of the derived nanocomposite films is obvious against gram‐positive (Bacillus subtilis) and gram‐negative (Escherichia coli) bacterial strains. These nanocomposite films have the potential to be successfully utilized as flexible packaging materials owing to their improved thermal, barrier, and antibacterial effectiveness.Highlights GNP/ZnO was used as a hybrid reinforcing filler in the LLDPE matrix. ZnO nanoparticles establish a network‐like morphology. LLDPE nanocomposite films exhibited excellent antibacterial activity. Oxygen and water vapor barrier properties were significantly improved. The thermoplastic composite films could be used as food packaging materials.

Tribo-mechanical and structural characterizations of LLDPE matrix bio-composite reinforced with almond shell micro-particles: effects of the processing methodology

Abstract The objective of this research work is to examine the effect of mixing operation in the reinforcement of linear low density polyethylene (LLDPE) with almond shell powder (ASP). Two groups of bio-composites mixed in solid state and melt extrusion state were developed by the standard thermo compression molding process. For each group of bio-composites developed, the mass percentage of ASP was varied from 5 % to 40 %. Tensile and friction tests and micro structural analyzes were carried out. The main results show that the addition of ASP particles: decreases the maximum tensile stress and increases the rigidity of the two types of bio-composites produced. A significant improvement was observed in terms of maximum stress and Young’s modulus of the bio-composites mixed in the molten state compared to those mixed in the solid state. Microscopic observations concluded that the melt-blended ASPs were better covered by the LLDPE matrix and the dispersion was successfully achieved. Friction tests have shown an improvement in tribological performance thanks to the addition of an optimal percentage of ASP equal to 20 % in the case of bio-composites mixed in the molten state. From this research work, it can be concluded that the LLDPE/ASP homogenization method influences the mechanical and tribological properties of bio-composites.

Flexible, lightweight, high strength and high efficiently hierarchical Gd2O3/PE composites based on the UHMWPE fibers with self-reinforcing strategy for thermal neutron shielding

To tackle the challenge for materials in the fields such as deep space exploration with flexibility, light weight, high strength, and highly efficient neutron shielding properties, a novel organic-inorganic composites has been developed in this study. Based on ultrahigh molecular weight polyethylene (UHMWPE) fibers self-reinforcing linear low-density polyethylene (LLDPE) matrix method and hierarchical scattering and absorption strategy, a flexibly and light-weight multilayer structure has been designed with alternating gadolinium oxide (Gd2O3)/LLDPE layers and UHMWPE fiber layers by stacking hot-pressing to augment the mechanical properties and neutron shielding efficiency of the composites. Moreover, PE, including UHMWPE fibers and LLDPE matrix, and Gd2O3 has been utilized as neutron shielding element to enhance its neutron scattering and absorption capability via an abundance of hydrogen atoms and Gd element. The neutron shielding performance of the multilayer Gd2O3/UHMWPE/LLDPE composite, with a low density of ca. 1 g/cm3, has been verified by neutron shielding test and a simulation method of equivalent Gd areal density (EGdAD). As a result, an ca. 90.0% neutron shielding efficiency can be achieved with only 2 mm thickness of the composites (with 20 wt% Gd2O3), and an EGdAD value of 0.0489 g/cm3 is required to achieve 99% shielding efficiency. Moreover, the composites have a significant improvement in the tensile strength and modulus, with an average increase of 1000% (15.86 MPa–179.95 MPa) and 1238% (230.53 MPa–2787.55 MPa) compared to the Gd2O3/LLDPE composites, respectively. The comprehensive performance of our developed multilayer Gd2O3/UHMWPE/LLDPE composites is superior to previously reported results in the literatures. Therefore, it has great application prospect in the various fields like aerospace.

Montmorillonite Exfoliation in LLDPE and Factors Affecting Its Orientation: From Monolayer to Multi-Nano-Layer Polymer Films.

The motivations of the present work are to investigate the exfoliation of montmorillonite within a linear low-density polyethylene matrix and to control its orientation during the cast extrusion process. The first part is focused on the exfoliation of the montmorillonite through the melt extrusion process. The accuracy and relevance of each method used to determine the exfoliation state of montmorillonite have been examined, thanks to X-ray diffraction, transmission electronic microscopy, and rheology. All these methods have presented limitations, but the combination of all leads to a better estimation of the exfoliation state. Finally, the orientation of the montmorillonite is quantified systematically by X-ray texture analysis and correlated with process parameters to discern which one is affecting their orientation. The results have demonstrated an enhancement of the "in-plane" orientation of the montmorillonite with the exfoliation, especially at high concentration and when combined with cast extrusion. Finally, in the multi-nano-layer polymer film configuration, the reduction of the individual layers 29 nm thickness leads to some orientation improvements. However, these improvements are almost at the same level as the concentration effect in a monolayer system. This work gives an overview of all the parameters needed to achieve a significant organo-modified montmorillonite "in-plane" orientation.

Antimicrobial potential of linear low-density polyethylene food packaging with Ag nanoparticles in different carriers (Silica and Hydroxyapatite)

Silver nanoparticles incorporation into polymeric packaging aims to prevent microbiological contamination in food products, thus ensuring superior food safety and preservation. In this context, this study aimed to verify the antimicrobial efficacy of linear low-density polyethylene (LLDPE) films incorporated with silver nanoparticles (AgNPs) dispersed in silica (SiO2) and hydroxyapatite (HAP) carriers at different concentrations. AgNPs + carriers polymer films were characterized at 0.2, 0.4, and 0.6% concentrations using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission gun-scanning electron microscope (FEG-SEM), thermogravimetric analyzer (TGA), differential scanning calorimetry (DSC), and migration in acidic and non-acidic simulants. Antimicrobial action was investigated on Gram-positive Staphylococcus aureus, Gram-negative Escherichia coli, and the Penicillium expansum and Fusarium solani fungi with antimicrobial activity by direct contact test and bacterial imaging by scanning electron microscopy. AgNPs addition to the LLDPE matrix did not interfere with the films' chemical and thermal properties and presented no significant migration to the external medium. For antimicrobial action, silver nanoparticles showed, in most concentrations, an inhibition percentage higher than 90% on all microorganisms studied, regardless of the carrier. However, a greater inhibitory action on S. aureus and between carriers was found, making hydroxyapatite more effective. The results indicated that nanostructured films with AgNPs + hydroxyapatite showed more promising antimicrobial action on microorganisms than AgNPs + silica, making hydroxyapatite with silver nanoparticle potentially useful in food packaging, improving safety and maintaining quality.

Investigation of the effect of electron beam irradiation on tensile, thermal and gas barrier properties of graphene nanoplatelet loaded thermoplastic nanocomposite films

Packaging materials based on lightweight and flexible thermoplastic/graphene composite films are gaining popularity in both the academic and industrial sectors. In this research work, graphene nanoplatelet (GNP) of 1–5 wt% was integrated into linear low density polyethylene (LLDPE) by employing melt compounding technique at 160 °C to produce flexible composite films. The LLDPE/GNP nanocomposite films were irradiated with doses up to 50 kGy using a 2.5 MeV electron beam accelerator in air at ambient temperature. The uniform distribution of GNP in the thermoplastic matrix obtained from FESEM analysis improved the samples' mechanical characteristics. As the GNP concentration in the LLDPE matrix increases, both the thermal stability and impermeability qualities (oxygen and water vapor) get significantly improved. Electron beam irradiation of film samples further enhances the physico-mechanical, thermal and gas barrier properties compared to non-irradiated composite films and neat LLDPE film. The tighter connections between graphene and LLDPE chains as well as the development of cross-linked networks by E-beam irradiation are responsible for the improved performance properties. Therefore, GNP incorporation as well as electron beam irradiation of thermoplastic nanocomposite films could be a viable alternative for producing high-performance and high-barrier flexible LLDPE/GNP composite films for packaging applications.

The Improved DC Breakdown Strength Induced by Enhanced Interaction between SiO2 Nanoparticles and LLDPE Matrix.

Direct current (DC) power transmission systems have received great attention because it can easily integrate many types of renewable energies and have low energy loss in long-distance and large-capacity power transmission for electricity global sharing. Nanoparticles (NPs) have a positive effect on the insulation properties of polymers, but weak interaction between NPs and polymer matrix greatly decreases the effort of NPs on the enhancement of insulation properties, and thereby limits its engineering application. In this work, grafting strategy was used to link the modified NPs and polymer matrix to improve their interactions. Silica NPs (SiO2-NPs) were modified by 3-(methacrylyloxy) propyl-trimethoxysilane (MPS) to introduce highly active groups on the SiO2-NPs surface, followed by the pre-irradiated linear low-density polyethylene (LLDPE) being easily grafted onto the MPS modified SiO2-NPs (MPS-SiO2-NPs) in the melt blending process to obtain LLDPE-g-MPS-SiO2-NPs nanocomposites. Fourier-transform infrared (FT-IR) spectrum and X-ray photoelectron spectroscopy (XPS) confirm the successful incorporation of MPS into SiO2-NPs. Transmission electron microscopy (TEM) verifies that the modified SiO2-NPs exhibits more uniform distribution. The rheology result shows that the interaction between MPS-SiO2-NPs and LLDPE significantly improves. More importantly, the LLDPE-g-MPS-SiO2-NPs nanocomposites displays superior DC breakdown strength to that fabricated by conventional modification methods. When the addition of MPS-SiO2-NPs is 0.1 wt%, the highest DC breakdown strength values of 525 kV/mm and 372 kV/mm are obtained at 30 °C and 70 °C, respectively, and high DC breakdown strength can be well maintained in a wide loading range of NPs.

Effect of alkali treated groundnut shell powder in the basalt fiber reinforced polyethylene hybrid composites: A sustainable approach towards green composites

AbstractWith the widespread use of natural polymers in composites, advances in mechanical, thermal, and thermomechanical characteristics have become necessary. This study explores, the hybridizing effect of alkali‐treated groundnut shell powder (T‐GSP) to the basalt fiber (BF) reinforced linear low‐density polyethylene (LLDPE) composites in different weight fractions. Twin screw extrusion machines were used to mix fresh LLDPE matrix with various weight fractions of T‐GSP particles (0, 5, 10, and 15 wt%) and 20 wt% of fresh BF. It has been found to be that adding up to 15 wt% of T‐GSP with 20 wt% of fresh basalt fibers in the LLDPE matrix produced better results in the mechanical, thermal, and thermomechanical properties of the hybrid composites. FE‐SEM analysis was performed on the tensile fracture surfaces of the hybrid composites to determine the effect of the T‐GSP particles on the wettability and interfacial adhesion of the fiber and the LLDPE matrix. Likewise, mechanical properties of 15 wt% of T‐GSP with 20 wt% of BF hybrid composite reported an increment of 76.39% and 397.05% in tensile strength and modulus, 230.88% and 324.70% in flexural strength and modulus. Also, a decrement of 14.32% in impact strength of the hybrid composites was reported compared to fresh LLDPE polymer. Shore D hardness testing recorded a 27% increment in hardness, while TGA and DSC reported a reduction in degradation temperature and an increment in crystallization and melting temperature of the fabricated composites. dynamic mechanical analysis (DMA) shows an increment in the glass transition temperature of all the composites.

Eco-friendly tiles: fabrication and testing of composite tile made from industrial gypsum wastes

PurposeThe purpose of this study is to utilize two types of gypsum mold wastes from two different factories as novel and economical reinforcing fillers for composites that may be useful for building materials and floors. Two types of gypsum mold wastes from two different factories as raw materials were incorporated into linear low density polyethylene (LLDPE) aiming to get rid of that waste in one hand and obtaining useful economical composites suitable for building materials and floors.Design/methodology/approachComposites were prepared from two types of gypsum mold wastes substituted with different ratios from raw gypsum and LLDPE throughout the melt blending technique. The physico-mechanical and electrical investigations in addition to the morphology of the composites were included.FindingsThe mechanical results illustrate that substituting commercial gypsum with gypsum mold waste positively affects tensile strength, flexural strength and hardness shore D for the LLDPE composites. The tensile strength increased from 5 MPa for LLDPE filled with commercial gypsum as blank samples to 11.2 and 13.2 MPa for LLDPE filled with D and S waste. Also, electrical properties which include both permittivity ɛ′ and dielectric loss ɛ″ increased with increasing the waste content in the LLDPE matrix. In addition to the electrical conductivity values, σ lies in the order of insulation materials. Consequently, it is possible to produce materials with a gypsum matrix by adding industrial waste, improving the behavior of the traditional gypsum and enabling those composites to be applied in various construction applications as eco-friendly tiles.Originality/valueThis study aims to prepare eco-friendly composites based on LLDPE and waste gypsum mold to preserve resources for the coming generations, other than lowering the environmental footprint and saving the costs of getting rid of it.

Crystallization, Phase and Mechanical Behaviors of Linear Low Density Polyethylene/Thermoplastic Polyolefin Elastomer Blends

Blending polyethylene with thermoplastic polyolefin elastomers (TPOs) is a promising way to manipulate its structures and tailor its properties. Herein, three TPOs, i.e., two ethylene–octene copolymers (EOCs) and an olefin block copolymer (OBC) with different structures, were used to comparatively investigate the miscibility, crystallization, and phase behavior of their blends with a linear low-density polyethylene (LLDPE). It was found that large differences occurred in the crystallization and phase behaviors of the blends due to the different extent of similarity in the molecular structure between the TPO and the LLDPE matrix. In particular, a unique segregated phase morphology comprised a less stable crystalline phase and a rubbery phase was found in an LLDPE/EOC blend. The tensile performance and elasticity of the blends were also studied and correlated with the structures of the blends. This work not only provides novel results on the miscibility and phase behavior of the similar-structured LLDPE/TPO blends, but can also guide the design of LLDPE-based products with tailored performances.

Development of a Novel Extrusion Process for Preparing Rice Straw/LLDPE Composites

Straw utilization is a key issue related to agricultural production and air pollution control. In this study, a novel extrusion process was proposed to improve the physical and mechanical properties of the straw-reinforced linear low-density polyethylene (LLDPE) composite. Instead of crushing the straw and mixing it with plastic matrix, the new method mixes straw with plastic matrix in its original form. The intact long rice straws were parallelly spread on the LLDPE film and then rolled up together into a prefabricated roll. The rolls experienced three extrusion processes as follows: (1) twin-screw melting, cooling and crushing, single-screw extruding; (2) twin-screw melting and single-screw extruding; (3) directly single-screw extruding. The testing results showed that the straw/LLDPE composite (with a ratio of 6:4) prepared by Method (2) exhibited optimized properties. Characterization by scanning electron microscopy indicated that the damage to rice straw fibers was relatively minor, the orientation of long fibers was good, and the binding of fibers with the LLDPE matrix was excellent in this case. The results of dynamic mechanical testing (DMA), differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis demonstrated that composites prepared by the new process exhibited significantly improved thermal stability and energy storage modulus, compared with those prepared by conventional processes (e.g., extruded straw particles/LLDPE composite). The new proposed method yielded significantly enhanced mechanical properties while reducing dust pollution.

Polyethylene with MoS2 nanoparticles toward antibacterial active packaging

AbstractMolybdenum disulfide (MoS2) nanoparticles, obtained from liquid phase exfoliation in the presence of chitosan, were melt mixed with a linear low‐density polyethylene (LLDPE) matrix to produce novel antimicrobial active packaging materials. The LLDPE/MoS2 composites presented exfoliated nanoparticles forming aggregates that are well dispersed in the polymer matrix. These 2D‐layered MoS2 nanoparticles at concentrations of 0.5, 1.0, and 3.0 wt% rendered several functionalities to the LLDPE, as for example an antimicrobial behavior against Salmonella typhi and Listeria monocytogenes bacteria that can be explained not only by the photoactivity of the filler but also by changes in the composite surface. For instance, the composites presented a reduction in the water contact angle (i.e., an increased hydrophilicity) and relevant changes in the surface topography (i.e., reduced roughness) as compared with pure LLDPE. Regarding the barrier properties, while MoS2 dramatically increased the water vapor permeation (WVP) of the polymer matrix, until 15 times for composite with 3.0 wt% of filler, the oxygen permeation decreased around 25%. All these novel functionalities in the nanocomposites were obtained without significantly affecting the tensile mechanical properties of the pure LLDPE matrix. These results show that MoS2 is a promising filler for the development of antibacterial active packaging films with behaviors as similar as other 2D‐layered fillers such as graphene derivatives.

Characterization of linear low‐density polyethylene and halloysite nanotube (LLDPE/HNT) composites based on two‐roll calendering melt fabrication

AbstractIn preparation of polymer nanocomposites, achieving good mixing and uniform distribution of nanofillers is highly desired for property enhancement. Polyethylene (PE) and its nanocomposite with halloysite nanotubes (HNTs) possesses a myriad of potentials for advanced engineering properties. A high nanoparticle loading is preferred to capitalize the nano‐reinforcement, thermal, and barrier properties. The capability of a two‐roll calendaring machine to disperse HNT particles into a linear low‐density polyethylene (LLDPE) matrix at elevated processing temperatures was assessed. Morphological, thermal, mechanical, and rheological behavior of prepared nanocomposites were characterized. A homogeneous distribution of HNTs in concentrations up to 5 wt.% was evidenced by SEM analysis. TGA showed the 10 wt.% composite exhibited an overall outstanding thermal stability. DSC analysis revealed the 30 wt.% sample has the highest Tm and Tc, and the %crystallinity did not change much due to HNT incorporation for all samples. DMA showed the storage and loss moduli increased with increase in HNT loadings. The effect of loading HNTs into the LLDPE matrix on Tg was minimal, implying that LLDPE and HNTs are quite compatible. The results demonstrated that the two‐roll mill fabrication method can efficiently keep HNT particles unagglomerated and disperse them evenly into the LLDPE matrix.

Lithium Orthosilicate-Linear Low-Density Polyethylene Nano-Composite as Substrate for High Frequency Devices: Dielectric Characterization

Dielectric properties of nanosized Lithium Orthosilicate (Li 4 SiO 4 ) and linear low-density polyethylene composite at X-Band frequencies are investigated, to realize its utility as a substrate for microwave devices. Solid state technique is used to synthesize nano Li 4 SiO 4 . To confirm the structural and morphological properties of the synthesized nano Li 4 SiO 4 , X-ray diffraction, Fourier transformed infrared spectroscopy and transmission electron microscopy are used. Composites of nano Li 4 SiO 4 and linear low-density polyethylene matrix are synthesized with varying weight fraction of nano Li 4 SiO 4 viz. 2%, 4% and 6%. The lateral portion of a fractured sample (composite) is examined using scanning electron microscope to confirm homogeneous dispersion of nano Li 4 SiO 4 in linear low-density polyethylene matrix. Water absorption measurement of all the composites are carried out based on ASTM D570-98 . Densities of the composites are measured via hydrostatic weighing by using Archimedes principle. Complex permittivity and permeability measurement of the composites are recorded by utilizing Nicholson-Ross approach. For all weight fraction of the nano inclusions, the real component of permittivity and dielectric loss tangent of the composites in the X-band are found to be in the range of 2.2 – 2.6 and 10 -2 –10 -4 , respectively. Return losses for the composites are calculated from complex permittivity and permeability values to validate its applicability as substrate for various high frequency applications.

Development and Characterization of LLDPE Blends with Different UHMWPE Concentrations Obtained by Hot Pressing.

To modify its characteristics, expand its applicability, and, in some cases, its processability, new blends using ultra-high-molecular-weight polyethylene (UHMWPE) have been developed. In this study, three different formulations of linear low-density polyethylene (LLDPE) and UHMWPE blends were prepared with 15, 30, and 45% (% w/w) UHMWPE in the LLDPE matrix. All mixtures were prepared by hot pressing and were immersed in water for one hour afterwards at a controlled temperature of 90 °C to relieve the internal stresses that developed during the forming process. The thermal characterization showed that the blends showed endothermic peaks with different melting temperatures, which may be the result of co-crystallization without mixing between the polymers during the forming process. The mechanical characteristics presented are typical of a ductile material, but with the increase in the percentage of UHMWPE, there was a decrease in the ductility of the blends, as the elongation at rupture of the blends was higher than that of the pure components. The morphologies observed by SEM indicate that there were two phases in the blends. This is the result of the system’s immiscibility due to the mode of preparation of the blends, wherein the two polymers may not have mixed intimately, confirming the results found with the thermal analyses.

The effect of boron nitride, carbon nanotubes, and their synergy on the properties of LLDPE and LLDPE/wax blend

AbstractThis study deals with the effect of two types of conductive fillers (viz., boron nitride and single walled carbon nanotubes) on the properties of the linear low‐density polyethylene (LLDPE) matrix and LLDPE/paraffin wax (PW) blend. Pure LLDPE and paraffin wax/LLDPE blend (30/70) were melt‐mixed with 2 wt% content of boron nitride (BN) and single walled carbon nanotube (SWCNT), as well as their synergy at 2 wt%. Because it is well‐known that both conductive fillers were able to improve the thermal conductivity of the paraffin wax/polymer blends, the aim of this study was to focus on the effect of both conductive fillers on the dispersion of paraffin wax into LLDPE matrix, mechanical properties, crystallization behavior, and thermal stability of the LLDPE/wax blend. Scanning electron microscopy (SEM) images of the LLDPE/paraffin wax blends depicted a phase separated system, which was further supported by two separate peaks from the differential scanning calorimetry (DSC). The morphology of the system showed that the addition of boron nitride (BN) into the LLDPE/paraffin wax blend had no affinity with the paraffin wax, while the addition of single walled carbon nanotubes (SWCNT) showed better dispersion into the LLDPE/paraffin wax/BN blend composites. The incorporation of the SWCNT and its synergy with BN enhanced the thermal stability of the LLDPE.

A comparative study of Mechanical, morphological and vibration damping characteristics of wood fiber reinforced LLDPE processed by rotational moulding

The present work investigates the mouldability of Linear Low-Density Polyethylene (LLDPE) with Wood Dust (WD) as a potential reinforcement with enhanced mechanical, morphological, and vibration damping characteristics. This was achieved by incorporating treated wood particles in rotomoulded grade into the LLDPE matrix with the help of a lab model rotomoulding machine. The incorporation of natural fibers finds difficult in the processing of rotomoulded parts since the process itself is a powder processing technique. The rotomoulded parts developed here is distinct from the previous works reported as it utilizes melt-compounded composite granules of a significantly larger size than the matrix material which is in the powder form. The need for natural fiber composite is come into existent because of its availability in abundance and is cheap. This project aims to come up with a solution of the best polymer composite material with a given percentage of natural fiber as filler. In rotational molding, several natural fibers have been used such as coir, flax, agave, sisal, palymira, etc. In the present study, LLDPE powder is used as a base material and mixed with a different weight percentage of WD fillers. The mechanical characterization and morphological study results proved that a sufficient hike in strength is obtained for 10% WD fiber added composites. The Experimental Modal Analysis (EMA) results also prove that the incorporation of WD is effective in improving the vibration damping characteristics of the composites developed.

Effects of Surface Modification with Stearic Acid on the Dispersion of Some Inorganic Fillers in PE Matrix

To evaluate the effects of surface modification with stearic acid on the dispersion of some inorganic fillers in polyethylene (PE) matrix, masterbatches containing 20–40 wt% of stearic acid uncoated and coated inorganic fillers and the linear low-density polyethylene (LLDPE) films containing 3–7% stearic acid uncoated and coated inorganic fillers were prepared. Two types of inorganic fillers used in the masterbatch included bentonite and silica. The structural change of inorganic fillers, whose surface was modified with stearic acid, was studied using IR spectroscopy. The dispersion of inorganic fillers in LLDPE matrix was evaluated using scanning electron microscope (masterbatch samples) and optical microscope (film samples). Changes in the melting temperature of LLDPE in the presence of inorganic fillers were evaluated by using differential scanning calorimeter (DSC). The mechanical properties of the films were evaluated according to ASTM D882. Surface-treated fillers with stearic acid dispersed in the masterbatches and films better than untreated fillers did. Stearic acid did not change the melting temperature of the filler/PE masterbatches. The mechanical properties of the films containing stearic acid coated fillers were higher than those containing unmodified fillers.

Microstructure–sealing performance linkage of metallocene linear low density polyethylene and low density polyethylene blends

The microstructure–sealing performance linkages of linear low density polyethylene (LLDPE) and low density polyethylene (LDPE) blends using thermo-rheological tools are discussed. The effect of molecular architecture in metallocene catalyzed LLDPE (mLLDPE), Ziegler–Natta catalyzed LLDPE (ZN-LLDPE) on the miscibility, and rheological behavior of the blends with LDPE is shown. Even though the macro parameters like density, melt flow rate of the LLDPEs are comparable, subtle differences in the microstructure manifested by comonomer type and its distribution across molecular weight affects the sealing performance of the LLDPE/LDPE blends. For LLDPE matrix, tailor-made comonomer distribution affording thinner lamellas (viz., thickness <11.8 nm) is more critical to sealing process than having total higher comonomer content. For LLDPE/LDPE blends, the thicker lamellae of main chain polymer of LDPE co-crystallize with homo-polyethylene like fraction of LLDPE. The co-crystallization of LLDPE and LDPE helps to achieve hot tack sealing at lower percentage of molten polymer and it appears to be the dominating factor over diffusion of polymer chains across the melt interface to achieve sealing.