Low-density Polyethylene Composites Research Articles

Preparation and properties of modified ammonium polyphosphate synergistic with tris(2-hydroxyethyl) isocynurate for flame-retardant LDPE

Abstract UF-SiAPP was prepared by modifying ammonium polyphosphate with the urea formaldehyde resin (UF), tetraethylorthosilicate (TEOS), and vinyltriethoxysilane (A-151). Moreover, a new intumescent flame retardant (IFR) used for low density polyethylene (LDPE) flame retardant was obtained by mixing UF-SiAPP with tris(2-hydroxyethyl) isocynurate (THEIC). The structure, morphology, and mechanical properties of flame retardants and LDPE composites were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, TG, and universal material testing machines. Furthermore, the flame-retardant properties of LDPE composites were comprehensively investigated by limiting oxygen index (LOI), UL-94, and cone calorimetry tests. The results show that UF-SiAPP exhibits excellent hydrophobic properties and good compatibility with LDPE after being modified by UF, TEOS, and A-151. And the flame-retardant properties of LDPE composites are significantly improved by adding IFR-containing UF-SiAPP. Especially, the LDPE composites attained the LOI value of 30.5% and reached the V-0 level after introducing 20.0 wt% UF-SiAPP and 10.0 wt% THEIC. And the tensile strength reached 13.55 MPa, which was 10.33% higher than that of LDPE/IFR with UF-APP and 13.21% higher than that of LDPE/IFR without THEIC in the same proportion. The smoke density tests demonstrate that the addition of UF-SiAPP not only effectively improves the residual carbon content and thermal stability of LDPE composites but also significantly reduces smoke emissions.

Effect of Functionalized Polyethylene Wax on the Melt Processing and Properties of Highly Filled Magnesium Hydroxide/Linear Low-Density Polyethylene Composites.

The poor processing and rheological properties of highly filled composites caused by the high loading of fillers can be improved with the use of maleic anhydride grafted polyethylene wax (PEWM) as compatibilizer and lubricant. In this study, two PEWMs with different molecular weights were synthesized by melt grafting, and their compositions and grafting degrees were characterized by Fourier transform infrared (FTIR) spectroscopy and acid-base titration. Subsequently, magnesium hydroxide (MH)/linear low-density polyethylene (LLDPE) composites with 60 wt% of MH were prepared using polyethylene wax (PEW) and PEWM, respectively. The equilibrium torque and melt flow index tests indicate that the processability and fluidity of MH/MAPP/LLDPE composites are significantly improved with the addition of PEWM. The addition of PEWM with a lower molecular weight leads to a substantial reduction in viscosity. The mechanical properties are also increased. The limiting oxygen index (LOI) test and cone calorimeter test (CCT) show that both PEW and PEWM have adverse effects on flame retardancy. This study provides a strategy to simultaneously improve the processability and mechanical properties of highly filled composites.

Development of Graphene Oxide/Polyethylene to enhance mechanical properties through melt mixing technique

Graphene Oxide (GO) was added to Low-Density Polyethylene (LDPE) to test the mechanical properties of the compound. Compared to other types of polyethylene, LDPE provides a good balance of mechanical properties and processability, which leads to its being chosen as the research’s matrix material. This experiment aims to prepare LDPE/GO through melt mixing technique and analyse mechanical properties of tensile strength/tensile elongation of LDPE/GO composite based on GO concentration (0, 0.5, 1.0 and 1.5 wt%). The compounding of LDPE/GO was blended using a five-stage twin-screw extruder under specific conditions before going through the moulding process at melting temperature. The composites were cut according to ASTM D638 specimen dimension. The tensile properties of LDPE composites were filled separately with different weight fractions of GO at a 50 mm/min rate. It was found that the values of Young’s modulus of the composites increased, but the values of the tensile elongation at break decreased with increasing the GO weight fraction. The relatively big interfacial area and excellent interfacial adhesion between the matrix and the GO may be responsible for the composites’ reinforcement. This study provided a basis for further development of GO-reinforced LDPE composites with desirable mechanical performance and good damage behaviour.

Effects of Maleic Anhydride-Grafted Polyethylene on the Properties of Artificial Marble Waste Powder/Linear Low-Density Polyethylene Composites with Ultra-High Filling Content.

The need to reach carbon neutrality as soon as possible has made the use of recycled materials widespread. However, the treatment of artificial marble waste powder (AMWP) containing unsaturated polyester is a very challenging task. This task can be accomplished by converting AMWP into new plastic composites. Such conversion is a cost-effective and eco-friendly way to recycle industrial waste. However, the lack of mechanical strength in composites and the low filling content of AMWP have been major obstacles to its practical application in structural and technical buildings. In this study, a composite of AMWP/linear low-density polyethylene (LLDPE) filled with a 70 wt% AMWP content was fabricated using maleic anhydride-grafted polyethylene as a compatibilizer (MAPE). The mechanical strength of the prepared composites is excellent (tensile strength ~18.45 MPa, impact strength ~51.6 kJ/m2), making them appropriate as useful building materials. Additionally, laser particle size analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and thermogravimetric analysis were used to examine the effects of maleic anhydride-grafted polyethylene on the mechanical properties of AMWP/LLDPE composites and its mechanism of action. Overall, this study offers a practical method for the low-cost recycling of industrial waste into high-performance composites.

A new bio‐based flame retardant simply synthesized: Improving the flame retardancy and thermal stability of low‐density polyethylene together with melamine cyanurate

AbstractA novel bio‐based flame retardant, MHPA, was synthesized with magnesium hydroxide (MH) and phytic acid (PA) and was added to low‐density polyethylene (LDPE) with melamine cyanurate (MCA) to investigate the flame retardant, mechanical property and thermal stability of the LDPE composites. The limit oxygen index (LOI) and cone calorimeter test (CCT) results showed that the combination of MHPA and MCA can increase the LOI of LDPE composite to 21.6%, and its peak of heat release rate (pHRR), total heat release (THR) and total smoke production (TSP) values reduced by 46.8%, 20%, and 31.6% respectively compared with pure LDPE, while the residue after CCT was increased to 24.4%. Moreover, the addition of MCA can effectively improve the thermal stability of LDPE/MHPA composites and suppress their early decomposition.

Kinetics of electric destruction of polymer compositions

The dependence of the electrical durability [Formula: see text] (time from the application of constant voltage until breakdown) on the temperature [Formula: see text] (in the range of 77–300 K) at different values of the electric field strength [Formula: see text] of polymer compositions of polypropylene and low-density polyethylene (PP–LDPE) with different supramolecular structures (SMS) was measured. At elevated temperatures ([Formula: see text] above 200 K), the dependence of lg[Formula: see text] is linear, indicating a thermofluctuational mechanism of breakdown preparation; at low temperatures ([Formula: see text] below 200 K) [Formula: see text] does not depend on [Formula: see text], which will allow us to conclude about its tunneling mechanism. The transition temperature of the linear dependence of [Formula: see text] on [Formula: see text] lies in the [Formula: see text] K range and depends on the value of the applied constant electric field.

Effect of antibacterial and compatibilizer agents on properties of low-density polyethylene composites

In this study, antibacterial low-density polyethylene (LDPE) composites were prepared using a silver-based antibacterial agent (Ag agent) and compatibilizer (linear low-density polyethylene-g-maleic anhydride (LLDPE-g-MA)), and their thermal, mechanical, and antibacterial properties were examined. The crystallization temperatures of the compatibilizer/antibacterial composites were higher than those of the composites prepared without a compatibilizer. LDPE is a crystalline material, and the addition of LLDPE-g-MA reduced the PE content and enthalpy of the composite and improved the dispersibility of the Ag agent between the substrates. The antibacterial activity test revealed that the addition of the Ag agent and compatibilizer to LDPE composites enhanced their antibacterial effects.

Silica/coconut shell charcoal/high-density polyethylene/linear low-density polyethylene composites

Silica/coconut shell charcoal/high-density polyethylene/linear low-density polyethylene composites

Thermal and Morphological Analysis of Linear Low-Density Polyethylene Composites Containing d-limonene/β-cyclodextrin for Active Food Packaging.

Composites made of linear low-density polyethylene (LLDPE) and β-cyclodextrin/d-limonene inclusion complex (CD-lim) were prepared by melt extrusion to develop a novel food packaging material. Scanning electron microscopy evidenced a fairly good dispersion of the filler within the polymeric matrix. Infrared spectroscopy coupled with thermogravimetric analysis confirmed the presence of CD-lim in the composites, proving that the applied technology of including the essential oil within β-CD cages allows for preventing a sizable loss of d-limonene despite a high temperature and shear applied upon extrusion processing. Moreover, the influence of the filler on the thermal properties of PE was assessed. It was found that the cyclodextrin-based inclusion complex significantly fastens the crystallization path of the polyethylene matrix with an improved crystallization rate of the PE/CD-lim composites compared to the neat polymer.

A Systematic Investigation on the Influence of Intumescent Flame Retardants on the Properties of Ethylene Vinyl Acetate (EVA)/Liner Low Density Polyethylene (LLDPE) Blends.

Because of their high filler loadings, commercial-grade clean flame-retardant materials have unstable mechanical properties. To address this issue, intumescent polymers can be used to develop clean flame retardants with very low levels of smoke and toxicity generation. An intumescent flame retardant (IFR) system composed of red phosphorus (RP), zinc borate (ZB), and a terpolymer of ethylene, butyl acrylate, and maleic anhydride (EBM) was used to prepare EVA (ethylene-vinyl acetate) and EVA/LLDPE (linear low-density polyethylene) composites; their mechanical and flammability properties were systematically investigated. The limiting oxygen index (LOI) of the EVA/LLDPE (as base material) composite containing RP and ZB mixed with nonhalogenated flame retardant, mainly magnesium hydroxide (MH) and coadditives, including processing aids and thermal stabilizers, was established. RP was found to have little effect on the tensile properties of EVA/LLDPE 118W/120 phr flame-retardant (MH + RP) composites. There was a minute difference in the effective trend of RP between tensile strength and elongation at break. Following the addition of ZB, the elongation at break of the composites gradually decreased with increasing RP content and then leveled off when the RP content was over 10 phr. Mechanical properties (elongation at break and tensile strength) can be best maintained at below 10 phr content of RP. The mechanical properties decreased with lower amounts of EBM content. In addition, flame retardancy increased when the EBM content decreased. The findings further revealed that MH and RP have poor compatibility, yielding poor mechanical properties. The LOI greatly increased with RP content, even though the total content of flame retardants (main + intumescent flame retardant) was the same in all formulations. Only over 5 phr RP content formulations passed V-0 of the UL-94 test. When under 5 phr, the RP content formulations did not pass V-0 of the UL-94 test.

The Influence of Different Hematite (α-Fe2O3) Particles on the Thermal, Optical, Mechanical, and Barrier Properties of LDPE/Hematite Composites.

There is an increasing need to develop new polymer composites with improved properties compared to conventional pure polymer materials. This work aims to develop composites of low-density polyethylene (LDPE) and iron oxide hematite particles. For this purpose, different types of hematite particles with well-defined shapes and narrow size distributions were synthesized: HC2 sample with pseudocubic hematite particles of an average diameter of 1020 nm, HE1 sample with ellipsoidal hematite particles of an average diameter of 533 nm, and HS1 sample with spherical hematite particles of an average diameter of 168 nm. The mass fractions of hematite in the composites were 0.25%, 0.5%, and 1%. Prepared LDPE/hematite composites were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and diffuse reflectance ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy. The mechanical and barrier properties were also studied. The obtained results showed that all prepared composites have improved properties compared to the pure LDPE, especially the composites with pseudocubic hematite particles of well-defined shapes. The results of this study indicate that LDPE/hematite composites can be promising materials for a wide range of applications, especially as packaging materials where improved thermal and mechanical properties as well as resistance to ultraviolet (UV) irradiation are required.

Improving the flame retardancy efficiency and mechanical properties of the intumescent flame retarded low‐density polyethylene by the dual actions of polyurea microencapsulation and aluminum hypophosphite

AbstractThe use of intumescent flame retardants to retard polyethylene usually had the disadvantages of low flame retardancy efficiency and poor compatibility between intumescent flame retardants and low‐density polyethylene (LDPE), which led to the reduction of mechanical properties of materials. In order to solve these issues, the microencapsulated ammonium polyphosphate (MAPP) and microencapsulated aluminum hypophosphite (MAHP) with polyurea were prepared through the interfacial polymerization of water‐in‐oil (W/O) microemulsions. The flame retarded polyethylene composites with MAPP and MAHP were manufactured. The LDPE composites with 17.3 wt% of MAPP and 3.9 wt% of MAHP possessed a LOI value of 27.3% and achieved the V‐0 standard. The PHRR and THR were remarkably decreased by 30.3% and 31.1% compared with that of the LDPE. Furthermore, the tensile strength of LDPE/MAPP‐MAHP was 19.1% higher than that of LDPE/APP‐AHP because of good dispersion and compatibility of MAPP and MAHP with LDPE. This work provides a new method to prepare flame‐retardant LDPE with high performance and the related mechanisms were discussed in detail.

Life Cycle Assessment of Calcium-Rich Industrial Waste Reinforced Polypropylene and Low-Density Polyethylene Composites Using the Cradle-to-Gate Approach

The first life cycle assessment (LCA) of injection-molded composites made of low-density polyethylene (LDPE) and polypropylene (PP) reinforced with calcium-rich flue gas desulfurization (FGD) gypsum and marble waste is shown in this work. The life cycle phases of the manufacturing of polymer composites were assessed using the methodological framework of IS/ISO 14044:2006. Midpoint indicators were evaluated by the ReCiPe method. To determine the composition, the physicochemical properties of the used FGD gypsum and marble waste were analyzed to ensure utilization in subsequent composite materials. American Society for Testing and Materials (ASTM) standards were followed for mechanical testing to check the quality of the developed composites. The flexural strength of the developed polymer composites was higher than that of pristine specimens with a 20–80 wt % filler concentration. Using the openLCA software and ecoinvent database, a cradle-to-gate LCA was performed for the developed composites. The global warming potential of the MW-PP composites is 1.01–1.06 times less than those of the other developed reinforced composites. The results of the present research are useful for creating environmentally friendly technologies, particularly the injection-molding practice.

Low density polyethylene composites based on flax fibers modified by a combination of coupling agent

AbstractThis investigation proposes a natural fiber surface modification approach based on the use of a system of coupling agents (CAs) to improve the mechanical properties of polymer composites made of flax fibers and low‐density polyethylene. This system combines the coating of the NaOH treated (mercerized) flax fibers by a CA (Epolene C18 [M‐C18]) in a solution under moderated heat (70°C–80°C), followed by the addition of 1% or 3% wt. of another CA (Epolene E43 [M‐E43]) during the injection molding. The comparison between the solution modified and the neat and mercerized flax fibers using scanning electron micrograph (SEM), thermogravimetric analysis (TGA), and density underscored some differences ascribed to the presence of M‐C18 onto the modified fibers. The mechanical properties showed that the combination of solution modification and direct introduction during the injection‐molding step of 1% of M‐E43 was efficient as the corresponding composites exhibited an improvement of 9.1%, 15.9%, and 11.1% of his tensile, flexural, and impact strengths respectively compared to the neat fiber composite. Due to their good impact and flexural strengths, these composites can be suitable for automotive parts such as keyboard.

Tribological, thermal, dynamic and mechanical characteristics of low density polyethylene composites with iron scale

The evaluation of wastes in various processes is an alternative to the production of innovative materials as well as eco-friendly. In the current paper, an industrial waste with high iron content (iron scale, F2O3) was incorporated into LDPE at different contents (5–20% by weight) and particle sizes (30–200 µm). The raise of iron scale content and particle size under 10 N and 15 N loads caused an increase in the volume loss of the composites. The highest and lowest specific wear rates for all contents and particle sizes of iron scale under 10 N and 15 N loads were observed at 30 µm and 120 µm, respectively. The wear phenomenon occurred in the form of cracking and delamination mechanisms. As the particle size increased from 30 µm to 200 µm, the hardness value increased and the highest hardness (shore D = 49) was reached in the presence of 20% iron scale. The raise of iron scale content increased the elongation at break and did not significantly affect the tensile strength. The increase of particle size caused an increase in tensile strength, while a decrease in elongation at break was observed. The incorporation of iron scale did not significantly change the initial degradation temperature of LDPE and composites. Although there are partial differences at lower temperatures in terms of elastic and loss modulus of the samples, the general trend is a decreasing trend with the raise temperature. Overall, LDPE composites outperformed the pure LDPE in terms of mechanical and wear properties.

Polyethylene/carbon fiber composites reinforced by a non-covalent compatibilization approach for flexible electric heater and structural self-monitoring

The rational modulation for the interfaces of polymer/filler composites is the key to maximizing its mechanical property and functional performance. In this work, the interface of recycled carbon fiber (CF) enhanced linear low-density polyethylene (LLDPE) composites was modulated via graphene oxide (GO) bridging and alkyl group modification to increase the interface roughness and improve the compatibility. The optimized composite displays improved mechanical, thermal, and electrical properties due to the modulated interface synergistic effect, particularly as a flexible heater, the composites film displayed excellent electrical heating behavior at a fast speed of heating up in 50 s to a steady-state temperature of 40 °C under the low voltage of 5 V. In addition, the structural self-monitoring of this conductive composite could be reflected by the electrical resistance change based on the results of finite element analysis (FEA) and in-situ resistance-tensile measurements. This facile compatibilization approach and in-situ self-monitoring method provide a new route for expanding the application of functional polyethylene materials.

The fabrication of phytate and LDH-based hybrid nanosheet towards improved fire safety properties and superior smoke suppression of intumescent flame retardant LDPE

An effective fire retardant system was developed composed by traditional intumescent flame retardant (IFR) and a new-typed nano-synergist (PAMA-SDBS-LDH, P@L), and their synergistic effect and mechanism on the thermal stability and flammability properties of low-density polyethylene (LDPE) was comprehensively studied. Briefly, the nano-synergist was successfully prepared by using melamine, phytic acid and Zn-Ni-Al layered double hydroxide (LDH) according to hydrothermal method. By adding 0.5% PAMA-SDBS-LDH and 29.5% IFR, the fire retardant properties of LDPE composite (LDPE/I/P@L) reached V-0 rating in UL-94 test. The total smoke production of LDPE/I/P@L decreased by 69.8% compared with LDPE. It is confirmed that PAMA-SDBS-LDH nanosheet is an efficient synergist to promote the formation of high-quality char layer via multiple fire retarding mechanisms. The good mechanical properties of LDPE/IFR system are also maintained by incorporating PAMA-SDBS-LDH. Undoubtedly, this study will provide valuable insights into improving the fire retardant efficiency and practical application of traditional IFR.

Effect of biodegradation conditions on morphology of ternary compositions of low density polyethylene with poly(lactic acid) and starch

Polyethylene–poly(lactic acid)–starch ternary compositions were obtained in a rotor disperser under conditions of shear deformation. Their biodegradation under the action of mold fungus spores and soil was investigated using IR spectroscopy and SEM. The changes under the fungal action revealed that the ternary blends represented a nutrient medium, while the exposure to soil led to alteration in morphology due to the whole range of numerous environmental factors.

Tribological behavior of particulates reinforced sustainable composites: Effect of composition, load, and sliding speed

Low friction coefficient with good wear resistance makes plastics an extensively researched tribo-material. In the present study, nine different thermoplastic composites of varying compositions were developed by using different types of waste plastics, namely, low-density polyethylene (LDPE), and high-density polyethylene (HDPE) and polypropylene (PP) as matrices, incorporating Rice Husk Ash (RHA) and sand as fillers. The wear behavior as a function of applied loads and sliding speeds were studied. The minimum volume losses at 34.32, 56.87, 68.15, 79.43 and 90.71 (N) were found to 0.02982, 0.03759, 0.04670, 0.05013 and 0.10027 (cm3) for HD70R15S15, HD90R5S5, LD70R15S15, LD80R10S10 and LD80R10S10, respectively. Similarly, for the given sliding speeds of 0.5388, 0.7184, 0.8980, 1.0776 and 1.4369 (m/s), the minimum volume losses were found to 0.04192, 0.04670, 0.03734, 0.10027 and 0.10026 (cm3) for PP90R5S5, LD70R15S15, PP70R15S15, LD80R10S10 and LD80R10S10, respectively. Moreover, the LDPE composites showed a better abrasive wear performance under high load conditions than HDPE and PP composites. The abrasive wear of the composites increases at high sliding speeds. The composite LD70R15S15 and LD80R10S10 showed a good abrasive wear performance at low and high sliding speeds, respectively, while the mixed PP70R15S15 results in minimum abrasive wear at moderate sliding speed. Different wear mechanisms were observed on the worn surfaces. The wear performance depends on the mode of failure and correlates with the mechanical properties. Finally, the obtained abrasive wear results agree with the wear morphologies.

Polymer Composite with Enhanced Thermal Conductivity and Insulation Properties through Aligned Al2O3 Fiber.

Thermoplastic polyolefins, such as polyethylene (PE), are traditionally one of the most widely used polymer classes with applications in the electric industry, and their nanocomposites have caught the interest of researchers. The linear filler is shown to be beneficial in decreasing the charge injection and hindering the formation of charge packs. So, we demonstrate a novel composite with excellent properties. The low-density polyethylene (LDPE) composite with aligned aluminum oxide (Al2O3) fiber has been prepared in electric field conditions. The direction of the Al2O3 fiber was parallel to the thickness direction of the LDPE composite. The breakdown strength of the Al2O3/LDPE composite with 0.2% aligned Al2O3 fiber was 498 kV/mm, which is higher than other fillers induced. The aligned Al2O3 fiber has effect on preventing accumulation of space charge and reducing the amount of free electron in the material. In addition, the thermal conductivity of the LDPE composite (0.22 W/m·K) was increased to 0.85 W/m·K when doped with 0.5 wt% aligned Al2O3 fiber. The present structure provides a new possibility for mass new nanocomposites with excellent microstructures and remarkable functionality.