Linear Low-density Polyethylene Research Articles

МЕХАНИЧЕСКИЕ СВОЙСТВА БИОРАЗЛАГАЕМЫХ КОМПОЗИТОВ НА ОСНОВЕ ПОЛИЭТИЛЕНА И ЖЕЛАТИНА

As a result of this study, we have obtained polymer blends that are based on linear low-density polyethylene (LLDPE) and gelatin, and received data on biodegradation, mechanical properties, and amounts of compounds produced from blending of graft copolymer and free gelatin. It was found that as the amount of maleic groups in the polyethylene macromolecule increases, the amount of graft copolymer grows, and an increase in the content of gelatin in the blend leads to a noticeable rise in the elastic modulus, tensile strength, and a decrease in elongation at break. It was also found that the rate of biodegradability increases with a growth of the content of gelatin in the blend, biological degradation was observed in the first 10 days at 54 %, up to a maximum of 58 %. It was maintained that maximum degree of grafting LLDPE-g-MA and gelatin to each other depends on the amount of maleic anhydride in the graft copolymer; maximum degree of grafting appeared to be higher with increased amount of maleic anhydride in the composites.

Determination of Short Chain Branching in LLDPE by Rheology

AbstractThe relationship between the structure and the final properties of materials is an important issue in polymer science. In particular, the properties of polyolefins are impacted by their branching contents. A simple rheological method is presented to estimate the degree of short chain branching (SCB) in linear low‐density polyethylene (LLDPE). A range of ethylene‐1‐hexene copolymers is synthetized using a metallocene catalyst to obtain homogenous LLDPE models with various comonomer contents. The polymers are analyzed by size exclusion chromatography, 13C NMR, and crystallization elution fractionation to determine both their molar masses and their chemical composition distributions. Subsequently, they are measured by rheology to assess the impact of SCB. This work provides calibration curves for rheology and proves that it is possible to predict the SCB content in LLDPE from the melt viscosity analysis.

Design consideration of a novel polymeric transcatheter heart valve through computational modeling

Transcatheter heart valve replacement is becoming a more routine procedure, and this is further supported by positive outcomes from studies involving low-risk patients. Nevertheless, the lack of long-term transcatheter heart valve (TAV) durability is still one of the primary concerns. As a result, more research has been focused on improving durability through various methods such as valve design, computational modeling, and material selection. Recent advancements in polymeric valve fabrication showed that linear low-density polyethylene (LLDPE) could be used as leaflet material for transcatheter heart valves. In this paper, a parametric study of computational simulations showed stress distribution on the leaflets of LLDPE-TAV under diastolic load, and the results were used to improve the stent design. The in silico experiment also tested the effect of shock absorbers in terms of valve durability. The results demonstrated that altering specific stent angles can significantly lower peak stress on the leaflets (13.8 vs. 6.07 MPa). Implementing two layers of shock absorbers further reduces the stress value to 4.28 MPa. The pinwheeling index was assessed, which seems to correlate with peak stress. Overall, the parametric study and the computational method can be used to analyze and improve valve durability.

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.

Assessment of gas dispersion near an operating landfill treated by different intermediate covers with soil alone, low-density polyethylene (LLDPE), or ethylene vinyl alcohol (EVOH) geomembrane.

This study evaluated the impact area of odiferous gas (i.e., H2S) dispersion near an operating landfill installed with three different intermediate covers, including soil alone, linear low-density polyethylene (LLDPE), or ethylene vinyl alcohol (EVOH) geomembrane (GM). By using the finite element method employing Reynolds-averaged Navier-Stokes and Fick's Law coupled equations, the performance of the different cover cases for reducing odor dispersion was comparatively evaluated considering environmental factors, including topographic, meteorology, and gas emission. The odor dispersion patterns and the size of affected residents were analyzed for the twelve different scenarios varied with the cover type and seasonal variation. According to the results, it was found that the wind speed affected the time of odor dispersions more with the relatively flat terrain conditions around the landfill but barely affected the size of the dispersion area. Moreover, it was found that the higher concentration (100 ppb) of odor gas is mainly located within a 5.0-km distance from the landfill. Among four seasons, the odor covers the largest area in summer, which is mainly due to the landfill producing more odor gas and giving a higher source concentration in summer. The gas dispersion simulation for different covers showed that the type of covering layer significantly affects the impact area boundary of gas odor. The results showed that the odor area of the LLDPE GM cover case is 1.3% of soil alone case, and the case of EVOH GM is 14.5% of LLDPE GM case. At the same time, the number of residents that may be affected by the odor of the LLDPE GM case and EVOH GM case is 4.81% and 0.63% of soil alone case, respectively.

Assessing the Downstream Contamination of Chemically Recycled Ethylene Feed Streams on the Kinetic Behavior of Ziegler‐Natta Catalysts and Microstructural Properties of HDPE and LLDPE

AbstractThe sustainability of consumer materials, such as plastics, belongs to the most important aspect of eco‐efficiency analyses. Besides mechanical recycling, chemical recycling represents an interesting waste management pathway. In theory, this technique does not rely on single‐grade feedstock to maintain product quality. However, cross‐contamination of feedstocks potentially leads to above‐specification impurities in obtained pyrolysis oils. This study investigates the potential downstream poisoning of a fourth‐generation Ziegler‐Natta catalyst, using selected model poisons at high (worst‐case) concentrations. With experimental and computational analysis, economic feasibility factors such as catalyst activity and microstructural properties are evaluated during the synthesis of high‐density polyethylene (HDPE) and linear low‐density polyethylene (LLDPE). Noticeable effects on the catalyst activity can be observed when the poison interacts with the co‐catalyst, whereas a lower impact is observed for interactions with the activated catalyst‐co‐catalyst complex. Molecular weight distribution (MWD) and comonomer composition distribution (CCD) modeling highlighted marginal to no polymer property changes caused by contaminants. Combined with the applicability of pyrolysis post‐treatments, these observations show that chemical recycling can be a promising technique for post‐consumer plastic waste treatment.

Polyolefin-based electrospun fibrous matrices embedded with magnetic nanoparticles for effective removal of viscous oils.

In this work, we present a poly (ethylene-co-1-octene)-based fibrous matrix prepared via electrospinning for highly efficient removal of viscous oils. The sorbent consisting of linear low density polyethylene (LLDPE) allows selective absorption of crude oil spills at the water surface without the need for additional isolation of the matrix prior to the refining process. Moreover, the high specific pore volume of the LLDPE sorbent with uniform fibrous morphology was shown to enable the sorbent reach 81.5±5.9% of its equilibrium absorption capacity within 5min. Furthermore, magnetic nanoparticles (MNP) are incorporated into each fiber comprising the matrix to facilitate the recovery process via external magnetic field without altering the intrinsic absorption capacity. We envision that these sorbents offer a sustainable route for the quick and thorough clean-up of spilled oil due to their high absorption capacity, fast absorption rate, ease of recovery, and absence of secondary waste.

Effects of freeze–thaw cycles on the properties of polyethylene geomembranes

High-density polyethylene (HDPE) geomembranes (GMs) are frequently used as fluid barrier components of cover systems for mine site reclamation in regions that are prone to freeze–thaw cycles (FTCs). However, HDPE GMs are more susceptible to stress cracking than linear low-density polyethylene (LLDPE) GMs. Hence, LLDPE GMs are increasingly considered as alternatives to HDPE GMs in cover systems. Nevertheless, little information is available on LLDPE compared to HDPE GMs. Moreover, little is known about the changes in the fluid barrier properties (the equivalent hydraulic conductivity and the oxygen sorption and diffusion coefficients) for these two materials with FTCs. The purpose of this study is therefore to compare the effects of FTCs on the tensile, hydraulic, and oxygen sorption and diffusion properties of HDPE and LLDPE GMs. To do so, GM sheets were subjected up to 300 FTCs. Mechanically, both GMs got stiffer and their tensile break properties increased with increasing number of FTCs. However, although the GM fluid barrier properties changed with FTCs, the equivalent hydraulic conductivity and the oxygen permeation coefficient remained within an order of magnitude of 10−14 m/s and 10−13 m2/s, respectively. Up to 300 FTCs would therefore have no adverse effects on HDPE and LLDPE GMs.

The Effect of Carbon/Oxygen Ratio upon Structure-Property Relationships in Polymer/Graphene Nanocomposites

The oxygen functional group limits the performance of graphene oxide (GO). By raising the Carbon/Oxygen (C/O) ratio, reducing the oxygen functional group may enhance thermal stability. The effects of the (C/O) ratio of graphene derivatives on the structure-properties relationship in metallocene linear low-density polyethylene (PE), homo polypropylene (PP), and blends thereof were investigated in this research. Using reduced graphene oxide (rGO) and pristine graphene (G), the oxygen functional groups were reduced. The effect of raising the C/O ratio of GO, rGO, and G blending with PE and PP synthesized by solution blending is discussed. Solvent processing was used to synthesise these nanocomposites, with dimethylformamide) DMF (and o-xylene served as the solvents for graphene flakes and polymers, respectively, before the two components were combined to form a well-mixed initial state. Wide-angle X-ray diffraction was used to investigate the crystallisation of the nanocomposites (WAXD). X-ray photoelectron spectroscopy (XPS), ultraviolet visible spectroscopy (UVVS), and Raman spectroscopy were used to characterise the chemical structures, with the latter being used to calculate the intensity ratio of D and G band (ID/IG) value for pure graphene specimens. The C/O ratio was calculated as , 4.9 and 2.2 for the G, rGO and GO respectively. While the (ID/IG (increased with increasing the C/O ratio, the ID/IG values were calculated as 0.285, 1.137 and 1.726 for pure GO, rGO and G samples. Differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) were used to determine the melting temperature ( ), crystallization temperature ( ) as well as a range of degradation temperatures.

Research Trends in Carbon Chain Polymers and Their Derivatives: Highlighting the Decade-Long Research.

Polyolefins include low-density polyethylene (LDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), and polybutylene (PB). Polyolefins offer unique characteristics such as chemical resistance, smooth surface, re-shapability, and are lighter than glass and metal-based materials. The global plastics industry produces polyolefin as their major product and these polyolefins are mostly used as commercial commodity plastics. Moreover, the characteristics of polyolefin can be further improved by forming their blends and/or composites and incorporating fillers. This review highlights the role of various fillers such as titanium dioixde-based, nitride-based, and carbon-based nanomaterials, in influencing polyolefin composites. Moreover, the contribution of layered double hydroxide in olefin polymerization, and the impact of filler properties such as filler content, filler type, filler phase stability, and synergistic effect between the fillers and polymers on nanocomposites are discussed.

LLDPE-like Polymers Accessible via Ethylene Homopolymerization Using Nitro-Appended 2-(Arylimino)pyridine-nickel Catalysts

Four examples of para-nitro substituted 2-(arylimino)pyridine-nickel(II) bromide complexes of general formula, [2-{(2,6-R-4-NO2C6H2)N=CMe}C5H4N]NiBr2, but differentiable by the steric/electronic properties displayed by the ortho-groups [R = i-Pr (Ni1), Et (Ni2), CHPh2 (Ni3), CH(4-FPh)2 (Ni4)], have been prepared in good yield. For comparative purposes, the meta-nitro complex, [2-{(2,6-i-Pr2-3-NO2-4-(4-FPh)2C6H)N=CMe}C5H4N]NiBr2 (Ni5), has also been synthesized. The molecular structures of mononuclear Ni3·xH2O (x = 2, 3) and bromide-bridged dinuclear Ni4 and Ni5 are disclosed. Upon activation with either ethylaluminum dichloride (EtAlCl2) or modified methylaluminoxane (MMAO), all precatalysts displayed good catalytic performance at operating temperatures between 30 °C and 60 °C with higher activities generally seen using EtAlCl2 [up to 4.7 × 106 g PE (mol of Ni)−1 h−1]: Ni2 ~ Ni5 > Ni1 ~ Ni4 > Ni3. In terms of the resultant polyethylene (PE), Ni4/EtAlCl2 formed the highest molecular weight of the series (Mw up to 1.4 × 105 g mol−1) with dispersities (Mw/Mn) ranging from narrow to broad (Mw/Mn range: 2.2–24.4). Moreover, the melting temperatures (Tm) of the polymers generated via EtAlCl2 activation fell in a narrow range, 117.8–126.0 °C, which resembles that seen for industrial-grade linear-low density polyethylene (LLDPE). Indeed, their 13C NMR spectra revealed significant amounts of uniformly distributed long-chain branches (LCBs), while internal vinylene groups constituted the major type of chain unsaturation [vinylene:vinyl = 5.3:1 (EtAlCl2) and 9.9:1 (MMAO)].

Business Roundup

BUSINESS Business Roundup ShareShare onFacebookTwitterWechatLinked InRedditEmail C&EN, 2022, 100 (30), p 12August 29, 2022Cite this:C&EN 100, 30, 12AbstractArxada will spend about $20 million to expand production of niacin and other nutritional ingredients at its site in Visp, Switzerland. Arxada, formerly part of Lonza, supplies the ingredients to DSM under a long-term agreement. Sabic and SK Geo Centric will expand capacity at their joint venture in Ulsan, South Korea, by the second quarter of 2024. The venture uses SK’s Nexlene technology to makes linear low-density polyethylene, elastomers, and plastomers. Colonial Chemical has expanded ether carboxylate capacity at its plant in South Pittsburg, Tennessee. The surfactants are used in metalworking fluids, hydraulic fluids, personal care goods, oil and gas processing, and other applications. BASF will partner with Spain’s Multiverse Computing to develop quantum software for financial applications. In its initial phase, the project will focus on models for exchange trading optimization between euros and US dollars. The Good Face Project has raised $5.65 million in seed investment for itsView: PDF | Full Text HTML

Experiments and Modeling of Flow-Enhanced Nucleation in LLDPE.

A computational and experimental framework for quantifying flow-enhanced nucleation (FEN) in polymers is presented and demonstrated for an industrial-grade linear low-density polyethylene (LLDPE). Experimentally, kinetic measurements of isothermal crystallization were performed by using fast-scanning calorimetry (FSC) for melts that were presheared at various strain rates. The effect of shear on the average conformation tensor of the melt was modeled with the discrete slip-link model (DSM). The conformation tensor was then related to the acceleration in nucleation kinetics by using an expression previously validated with nonequilibrium molecular dynamics (NEMD). The expression is based on the nematic order tensor of Kuhn segments, which can be obtained from the conformation tensor of entanglement strands. The single adjustable parameter of the model was determined by fitting to the experimental FSC data. This expression accurately describes FEN for the LLDPE, representing a significant advancement toward the development of a fully integrated processing model for crystallizable polymers.

Microplastics can affect soil properties and chemical speciation of metals in yellow-brown soil

Although the influence of microplastics (MPs) in different soil environments has been investigated, their effects on the physiochemical properties and chemical speciation of heavy metals in yellow-brown soil remains unknown. This study aimed to determine the effects of various concentrations of linear low-density polyethylene (LLDPE), polyamide (PA), polyurethane (PU), polystyrene (PS), and low-density polyethylene (LDPE) MPs on the yellow-brown soil environment and chemical speciation of the heavy metals cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn). MPs influenced the physicochemical properties and chemical speciation of heavy metals in yellow-brown soil. The physicochemical properties of yellow-brown soil can be altered by changing the concentrations of LDPE MP. The relationship between changes in field capacity (FC) and LDPE concentrations was approximately linear. The physiochemical properties of yellow-brown soil containing added PA, PU, and LDPE MPs were substantially improved (control vs. MPs): FC, 39 % vs. 42.50 % for PU, cation exchange capacity (CEC) 45.77, 56.65, and 57.44 cmol.kg−1 for PA, PU, and LDPE respectively, and organic matter (OM) content, 40.16 vs. 51.68 g.kg−1 for PA. The LLDPE and PU MPs also simultaneously affected the chemical speciation of heavy metals in yellow-brown soil. The LLDPE MPs increased the acid-soluble (45.17–54.67 % (Cd-F1), 7.24–11.30 % (Cu-F1), 4.20–7.23 % (Pb-F1), 21.21–31.47 % (Zn-F1)) and reducible (24.02–29.41 % (Cd-F2), 25.69–34.95 % (Cu-F2), 74.29–81.07 % (Pb-F2), 28.77–34.19 % (Zn-F2)) fractions of heavy metals, which increased their bioavailability. However, PU MPs reduced the ecological risk of heavy metals in yellow-brown soil by increasing the content of the residual fraction (26.11–40.21 % (Cd-F4), 47.63–59.67 % (Cu-F4), 17.25–26.76 % (Pb-F4), 32.63–50.46 % (Zn-F4)). Changes in the properties of yellow-brown soil and the impact of MPs on heavy metals, might change the chemical speciation of heavy metals. The impact of MPs on heavy metals in yellow-brown soil requires further investigation.

Improvement of polyethylene fiber wettability and mechanical properties through an environmentally sustainable spinning process

Owing to its simple chain backbone and non-polar structure, polyethylene-based materials exhibit weak adhesion properties in both reinforcement and matrix form. Therefore, development of efficient production strategy is needed for polyethylene fibers with improved wettability and performance. Here, a novel single step modified melt spinning line (MMS) is investigated to obtain linear low-density (LLDPE) and medium density polyethylene (MDPE) fibers with high strength and improved wettability performance. The proposed cost-effective modified spinning system referred as MMS is able to manipulate fiber properties by using non-oily/non-toxic liquid baths, which are located between the melt spinneret and godets, during fiber spinning stage. The aim of this study is to examine the wetting behavior and mechanical properties of melt-spun PE fibers using non-oily/non-toxic liquid baths containing an organic additive. It is observed that higher drag force and interaction between fiber surface and non-oily/non-toxic liquid as ecological spinning liquid with higher dynamic viscosities provided enhanced mechanical properties of the fibers. Increasing the drag force to 0.138 N, resultant fibers exhibited modulus values of about 1 GPa and 1.3 GPa for MDPE and LLDPE, respectively at only 750 m/min take-up speed. Moreover, Arabic Gum (AG) as an organic additive into the liquid enhanced fiber wettability, i.e., water contact angle of 37.8° for MDPE samples. This versatile simple and ecological modified production line is capable of improving hydrophilicity and performance of PE fibers and can facilitate widespread use in composites for medical to defense applications at low manufacturing cost.

Melt flow ratio: A way to identify the type of polyethylene

Melt flow ratio (MFR or I21/I2) was measured for dozens of polyethylene (PE) in the melt index (MI or I2) range of 1–10 for various types of PE. I21/I2 for samples of linear low density polyethylene (LLD) polymerized by a Ziegler-Natta catalyst (ZN-LLD) lie near I21/I2 = 25, whereas those for specimens of metallocene linear low density polyethylene (m-LLD) scatter close to I21/I2 = 18. The plot of I21/I2 vs I2 for LLD showed that I21/I2 is almost independent on molecular weight and short chain branching (SCB), but strongly dependent on molecular weight distribution (MWD). The broader MWD, the larger I21/I2. This rule basically holds for both low density polyethylene (LDPE) and high density polyethylene (HDPE). However, at a certain I2 around 6 a discontinuous jump of I21/I2 for HDPE samples exits, where I21/I2 for samples of I2 less than 6 lie near those of LDPE and I21/I2 for ones having I2 bigger than 6 disperse close to those of ZN-LLD. In addition, bimodal PE or PE with long chain branching has a bigger I21/I2 in some case. Further, the relationship between the viscosity and melt index was discussed, indicating that I21/I2 as well as MWD is characteristic of all types of PE. Consequently, I21/I2 can be used as a convenient and efficient approach to identifying the type of PE.

The in situ synthesis of weakly entangled ultrahigh‐molecular‐weight polyethylene/polyethylene wax blends and its synergetic disentanglement effect on LLDPE reinforcement

AbstractHigh‐performance ultrahigh‐molecular‐weight polyethylene (UHMWPE)/low‐molecular‐weight polyethylene (PE) mixture additives were proven to be effective for enhancing commercial high‐density polyethylene (HDPE) resins, which were synthesized by the complicated dual‐site immobilized catalyst system. In this paper, PE wax components were preadded in the polymerization reactor for in situ synthesizing the UHMWPE/PE wax binary blends with just a single SiO2/MgCl2 supported Z–N catalyst modified by the active site isolators. The influence of PE wax addition on the catalytic activity, molecular weight, thermodynamic property, particle size, and entanglement density was systematically researched. It was evidenced that the catalytic activity and molecular weight exhibit a linear relationship with the ethylene solubility caused by the PE wax addition. Besides, the competition between chain propagation/crystallization balance and PE wax long chains entanglement effect arising from the PE wax addition leads to the minimum entanglement density (GNt = 0.59) of UHPE‐20%. The disbalance of chain propagation rate and chain crystallization rate can be broken by PE particle fragmentation, inducing rapidly increased entanglements. Furthermore, with the synergistic disentanglement influence of reduced entanglements for UHMWPE and the chain diffusion ability for PE wax, the LU‐30 sample with a mixture of UHPE‐30% and linear low‐density polyethylene (LLDPE) exhibits the optimum strength/stiffness/toughness properties. The tensile strength, Young's modulus, and impact strength of LU‐30 reach 18.2 MPa (+4%), 172.1 MPa (+53.8%), 60.5 kJ/m2 (+13.1%), respectively, compared with those of pure LLDPE. The overall enhanced mechanical properties are attributed to the intensive signal intensity and tightly stacked form of shish‐kebab structures, which were verified by the two‐dimensional small angle X‐ray scattering and two‐dimensional wide angle X‐ray diffraction patterns. In addition, the in situ polymerization method of UHMWPE/PE wax with SiO2/MgCl2 supported Z–N catalysts exhibits a great probability of efficient utilization of low‐molecular‐weight polyethylene by‐products (PE wax).

Compatibilized thermoplastic elastomers based on highly filled polyethylene with ground tire rubber

AbstractThermoplastic elastomers (TPE) based on ground tire rubber (GTR) are good strategies for the circular economy and sustainable development of waste tire rubber recycling. However, several parameters must be optimized to produce valuable TPE. The most important ones are GTR concentration and dispersion, as well as crosslinking degree, combined with interfacial interactions between the GTR and the thermoplastic matrix. In this work, TPE based on highly filled linear low‐density polyethylene (LLDPE) with GTR (50%–90%) was prepared via dynamic vulcanization. In particular, different reclaimed GTR (RR) was used alone or with a compatibilizer (maleic anhydride grafted polyethylene, PE‐g‐MAH) to prepare compatibilized TPE. The interactions between the rubber and plastic were quantified by a series of characterizations including mechanical tests, rheological measurements, differential scanning calorimetry, dynamic mechanical analysis and scanning electron microscopy. The results showed that the mechanical properties and processability decreased with increasing GTR content. Although the interfacial compatibility was improved with a higher GTR reclamation degree, the TPE mechanical properties were still gradually decreasing. To improve on these results, PE‐g‐MAH was added to increase the GTR‐LLDPE interfacial interactions. The results showed improvement in terms of mechanical properties and processability, especially for compatibilized TPE based on RR (tensile strength increased from 3.34 to 4.82 MPa and elongation at break from 91% to 101%).

Blown Composite Films of Low-Density/Linear-Low-Density Polyethylene and Silica Aerogel for Transparent Heat Retention Films and Influence of Silica Aerogel on Biaxial Properties.

Blown films based on low-density polyethylene (LDPE)/linear low-density polyethylene (LLDPE) and silica aerogel (SA; 0, 0.5, 1, and 1.5 wt.%) were obtained at the pilot scale. Good particle dispersion and distribution were achieved without thermo oxidative degradation. The effects of different SA contents (0.5–1.5 wt.%) were studied to prepare transparent-heat-retention LDPE/LLDPE films with improved material properties, while maintaining the optical performance. The optical characteristics of the composite films were analyzed using methods such as ultraviolet–visible spectroscopy and electron microscopy. Their mechanical characteristics were examined along the machine and transverse directions (MD and TD, respectively). The MD film performance was better, and the 0.5% composition exhibited the highest stress at break. The crystallization kinetics of the LDPE/LLDPE blends and their composites containing different SA loadings were investigated using differential scanning calorimetry, which revealed that the crystallinity of LDPE/LLDPE was increased by 0.5 wt.% of well-dispersed SA acting as a nucleating agent and decreased by agglomerated SA (1–1.5 wt.%). The LDPE/LLDPE/SA (0.5–1.5 wt.%) films exhibited improved infrared retention without compromising the visible light transmission, proving the potential of this method for producing next-generation heat retention films. Moreover, these films were biaxially drawn at 13.72 MPa, and the introduction of SA resulted in lower draw ratios in both the MD and TD. Most of the results were explained in terms of changes in the biaxial crystallization caused by the process or the influence of particles on the process after a systematic experimental investigation. The issues were strongly related to the development of blown nanocomposites films as materials for the packaging industry.

Developing an in-Line method to improve mechanical and flame retardancy performance of polyethylene fiber

Polyethylene (PE) has high flammability and can be quickly burned under atmospheric conditions without leaving any residues. This study presents PE fibers produced by a novel modified melt spinning line to enhance mechanical and flame retardancy properties. Scanning electron microscopy equipped with energy dispersive X-ray, thermogravimetric analysis, limiting oxygen index, micro combustion calorimeter and tensile tests were performed to reveal morphological, thermal and mechanical characteristics of the fibers. An organic phosphorus additive was used to provide flame retardancy in addition to mechanical performance in one-step production. Subsequently, the produced fibers were subjected to the hot drawing, increasing modulus values from 135 MPa to 2.8 GPa. In addition, phosphorus-treated fibers exhibited a limiting oxygen index (LOI) value of 21.5, leaving some residue at 600°C. Furthermore, a decrease in the peak heat release rate (pHRR) was observed in all samples compared to the control sample for the micro combustion calorimeter (MCC) test. Looking at the decrease in heat release (HR), the best result belongs to zone II with 50 and 95°C produced at 1000 m/min take-up speed for the samples. Moreover, about 23%, 23%, and 18% decreases were observed in HR capacity, pHRR, and total HR values, respectively. The modified spinning system is capable of continuous production of flame retardant linear low-density polyethylene (LLDPE) fibers, which can find widespread applications in aviation, automotive, and defense industries.