Correlative investigation of copper/low-density polyethylene nanocomposite on the endometrial angiogenesis in rats

The purpose of this study was to investigate the effects of copper/low-density polyethylene nanocomposite(nano-Cu/LDPE)on the endometrial angiogenesis in rats,and 100 sexual mature female SD rats were randomly divided into five groups:sham-operation groups(SO group,n=20),bulk copper groups(Cu group,n=20),LDPE groups(n=20),nano-Cu/LDPE groups I(n=20)and II(n=20).The levels of angiopoietin-2(Ang-2),its receptor(Tie-2)and CD34 of the rats’endometria in each group were examined by using the S-P method of the immunohistochemistry 30 and 180 days after insertion,respectively.Compared with those in the SO group,the expression of Ang-2 and Tie-2 in all the experimental groups was obviously increased 30 days after insertion,and these parameters in nano-Cu/LDPE groups,except for Ang-2 level in nano-Cu/LDPE group II,were significantly lower in comparison with those in Cu group(P<0.05).On the 180th day after insertion,Ang-2 and Tie-2 levels were still higher in Cu group and LDPE group,but there was no difference of Ang-2 and Tie-2 levels between nano-Cu/LDPE groups and the SO group(P>0.05).Com-pared with those in the SO group,the significant increases in microvessel density(MVD)were observed on the 30th and the 180th day after the insertion of the bulk copper(P<0.05).There was no significant difference in MVD counts before and after the insertion of nano-Cu/LDPE(P>0.05).The results show that Nano-Cu/LDPE have slighter influence on the endometrial angiogenesis than bulk copper.

Preparation of carbon nanotube-reinforced polyethylene nanocomposites with better antiscaling and corrosion-resistant properties

Anti-scaling technology for pipelines has always been a focus of oilfield industrial production.Compared with traditional metal pipes,polyethylene(PE)pipes have unique advantages in terms of corrosion resistance,surface friction resistance,and service life.In this paper,aiming at an enhancement of antiscaling and corrosion-resistant properties,as well as increased mechanical properties,PE nanocomposites have been prepared by the introduction of modified carbon nanotubes(m-CNTs)into the PE matrix.To improve the interface compatibility of the composites,the CNTs were treated with reactive tetrabutyl titanate after nitric acid oxidation,which brings about uniform dispersion of the CNTs and intimate interface interaction.As the m-CNT fraction increases,the PE crystallinity displays a slight increase.Polarized microscopy shows that the scaling on the surface of the composite material is obviously reduced compared with pure PE,because the surface free energy of the composite material decreases.Moreover,due to the good dispersion,the composites show enhanced mechanical properties.That is,by adding 1.10 wt%CNTs,the tensile stress and impact toughness of the composites are 20.76 MPa and 37.89 kJ m^(-2),respectively,increases of 15.0% and 11.9% compared with pure PE.This paper supports the idea that the crystallinity of the PE matrix can be improved by adding CNTs,thereby increasing the corrosion resistance and anti-scaling properties.This work can provide inspiration for using the methods of scale inhibition and corrosion resistance in polymer nanocomposites.

The Dynamic Viscoelasticity of Polyethylene Based Montmorillonite Intercalated Nanocomposites

The viscoelastic behavior of melts for two systems composed of intercalated nanocomposites based on low density polyethylene and 3 wt% loading of cetyltrimethyl- ammonium bromide modified montmorillonite was studied. The results obtained through examining the dynamic storage module G' and dynamic loss module G' values of the composite revealed that the dynamic viscoelastic properties of composite strongly depended on intercalation of polymer, and exhibited dramatically change with altering intercalation conditions. Only when modified montmorillonite content was about 3 wt%, the composite showed a trend of pseudo-solidlike at lower frequencies.

Rheological Behavior of the Melts for Polyethylene-based Montmorillonite Nanocomposites

The viscoelastic properties of melts of nanocomposites with partially exfoliated structures, which were composed of low-density polyethylene （LDPE）, ethylene vinyl acetate copolymer （EVA）, and montmofillonite and modified by cetyltrimethyl ammonium bromide and octadecyltrimethyl ammonium bromide, were studied. The results obtained through measurements of the dynamic storage modulus G′, the dynamic loss modulus G″, and the transiem stress relaxation modulus G（t） of the composites, reveal that the viscoelastic properties of the composites strongly depend on the amount of montmorillonite that is exfoliated into the composites. With the increase in montmoriUonite content, the composites show an obvious property of pseudo solid-like materials within the region of lower frequencies （ω）. The montmorillonite layers are aligned along the stress direction, and the dependence of dynamic modulus on ω, appears quite different for the composites before and after being exposed to a large amplitude oscillatory shears.

Emerging low-density polyethylene/paraffin wax/aluminum composite as a form-stable phase change thermal interface material

Thermal interface materials(TIMs) play a vital role in the thermal management of electronic devices and can significantly reduce thermal contact resistance(TCR). The TCR between the solid–liquid contact surface is much smaller than that of the solid–solid contact surface, but conventional solid–liquid phase change materials are likely to cause serious leakage. Therefore, this work has prepared a new formstable phase change thermal interface material. Through the melt blending of paraffin wax(PW) and low-density polyethylene(LDPE), the stability is improved and it has an excellent coating effect on PW. The addition of aluminum(Al) powder improves the low thermal conductivity of PW/LDPE, and the addition of 15wt% Al powder improves the thermal conductivity of the internal structure of the matrix by 67%. In addition, the influence of the addition of Al powder on the internal structure, thermal properties, and phase change behavior of the PW/LDPE matrix was systematically studied. The results confirmed that the addition of Al powder improved the thermal conductivity of the material without a significant impact on other properties, and the thermal conductivity increased with the increase of Al addition. Therefore, morphologically stable PW/LDPE/Al is an important development direction for TIMs.

Structure and Properties of Self-reinforced Material Made from Ultra-high Molecular Weight Polyethylene-montmorillonite Nanocomposite

High-strength and high-modulus ultra-high molecular weight polyethylene(UHMWPE), named self-reinforced material, was obtained by the elongation of UHMWPE-montmorillonite nanocomposite at melting temperature. According to the scanning electron microscope(SEM) analysis, a great deal of fibrillar texture formed in the direction of elongation, and the tensile fractured surface was similar to that of highly oriented fiber. The transmission electron microscope(TEM) and selective area electron diffraction(SAED) analyses reveal that the reinforced phase of the self-reinforced material is an extended chain crystal and its size is about 50_200 nm wide and several microns long, and the montmorillonite layers are broken up to pieces in the size from 100 to 10 nm. The broken layers which have a huge surface area interacting strongly with macromolecules reduces the entanglement density of UHMWPE and induces the chain orientation in flow field. It is supposed that the astriction of montmorillonite layers to polyethylene chains is not only end-tethered but also side-tethered. The differential scan calorimetry(DSC) analysis shows that there are two endothermal peaks for the self-reinforced material, of which the peak at a higher temperature(136.4 ℃) is ascribed to the melting of the reinforced phase.

LOW DENSITY POLYETHYLENE/CLAY NANOCOMPOSITES MODIFIED BY ETHYLENE COPOLYMERS: EFFECTS OF FUNCTIONALIZED SEGMENTS ON MORPHOLOGY

Melt extrusion was used to prepare binary nanocomposites of ethylene copolymers and organoclay and trinary nanocomposites of low-density polyethylene （LDPE）, ethylene copolymer and organoclay. X-ray diffraction （XRD） and transmission electron microscopy （TEM） were used to analyze the structure of the clay phase and the morphology of the nanocomposites. Influences of the comonomer in the copolymer and the content of the copolymer on the morphology of the resulting nanocomposites were discussed. The binary and the trinary composites may form intercalated or exfoliated structures depending on the interaction between the copolymer and the clay layers and the content of the copolymer.

Adsorption and Kinetic Study of Activated Carbon Produced from Post-Consumer Low-Density Polyethylene (LDPE) Wastes

Post-consumer polymeric wastes in form of low-density polyethylene (LDPE) can now be considered suitable as a precursor for the synthesis of low-cost activated carbon (AC). This study produced AC from LDPE using sulphuric acid (H2SO4) and potassium hydroxide (KOH) as the activating agent. The reaction conditions for pyrolysis were varied in the range of 0.50 - 2.00 M, 400°C - 500°C, and 45 - 60 minutes. Physico-chemical investigations reveal that AC yield is significantly dependent on both carbonization temperatures and time. The obtained optimum values of 446.50°C and 51.09 mins gave a yield of 24% for the base-activated carbon. The high iodine numbers obtained strongly indicate the presence of large surface area and pore volumes is further confirmed using the Scanning Electron Microscopy (SEM) analysis which reveals the presence of pores on the external surface of the carbons. Fourier Transform Infrared Technique (FTIR) analysis further shows that the synthesized compounds are purely carbon with rich oxy-gen-surface complexes on the surface which is as a result of the introduction of the chemical oxidizing agents. The produced carbons were found to have high adsorption affinity for selected inorganic ions which are: Mn7+, Co2+, and Cr6+. Adsorption isotherm results show the adsorption process to be favourable with the Langmuir isotherm parameter RL having values of <1, while the Freudlich adsorption model was found to perfectly fit the data at selected adsorbent dosages and adsorbate concentrations. The pseu-do-second-order model provides the best correlation for the kinetic analysis. The acid-activated carbon was found to have better adsorption capacities than the base-activated carbon.

PE/CaCO_3-nanocomposites synthesized by in-situ polymerization

Polyethylene-nanocomposites with CaCO3-weight fractions from 0 to 15 wt.% were prepared by in-situ polymerization with Me2Si（Ind）2ZrC12/MAO metallocene catalysts. A high activity especially in the presence of TIBA was observed. The morphology was investigated by using raster electron microscopy （REM） showing that the CaCO3-nanoparticles are uniformly distributed. The melting temperatures and the crystallization temperatures are not much influenced by increasing filler content.

Preparation and Properties of Poly(Ethylene Terephthalate)/Boehmite Nanocomposite

Colloidal boehmite particles have been included into a polyethylene terephthalate matrix by in situ polymerization. Boehmite nanoparticles were produced by the controlled hydrolysis of aluminium isopropylate. The nanoparticles were characterized using Transmitted Electronic Microscopy (TEM) and X-ray Diffraction (XRD), which revealed the particles of magnitude about 10 nm. The particles have been used without any surface modification. Characterization of the nanocomposite has been carried out using TEM and differential scanning calorimetry (DSC). TEM images indicate that the particles have been homogeneously dispersed in the polymer. DSC results show that the presence of boehmite affects the process of crystallization of polyethylene terephthalate.

Improving the Dielectric Properties of High Density Polyethylene by Incorporating Clay-Nanofiller

Polymer nanocomposites have been used for various important industrial applications. The preparation of high density polyethylene composed with Na-montmorillonite nanofiller using melt compounding method for different concentrations of clay-nanofiller of 0%, 2%, 6%, 10%, and 15% has been successfully done. The morphology of the obtained samples was optimized and characterized by scanning electron microscope showing the formation of the polymer nanocomposites. The thermal stability and dielectric properties were measured for the prepared samples. Thermal gravimetric analysis results show that thermal stability in polymer nanocomposites is more than that in the base polymer. It has been shown that the polymer nanocomposites exhibit some very different dielectric characteristics when compared to the base polymer. The dielectric breakdown strength is enhanced by the addition of clay-nanofiller. The dielectric constant (εr) and dissipation factor (Tan δ) have been studied in the frequency range 200 Hz to 2 MHz at room temperature indicating that enhancements have been occurred in εr and Tan δ by the addition of clay-nanofiller in the polymer material when compared with the pure material.

Electrically Conductive and Flame Retardant Graphene/Brominated Polystyrene/Maleic Anhydride Grafted High Density Polyethylene Nanocomposites with Satisfactory Mechanical Properties

Electrically conductive and flame-retardant maleic anhydride grafted high-density polyethylene(MA-HDPE) nanocomposites with satisfactory mechanical properties are fabricated by melt compounding MA-HDPE with polyethyleneimine(PEI)-modified reduced graphene oxide(PEI@RGO) as the conductive nanofiller and brominated polystyrene(BPS) as the flame retardant. The modification with PEI significantly improves the interfacial compatibility and dispersion of the RGO sheets in the MA-HDPE matrix, leading to electrically conductive nanocomposites with enhanced mechanical properties. Furthermore, the addition of 25 wt% of BPS makes the nanocomposite flame-retardant with a UL-94 V-0 rating. Thus, the multifunctional RGO/MA-HDPE nanocomposites with good electrical, flameretardant, and mechanical properties would have potential applications in construction and pipeline fields.

Supercritical CO2 Assisted Preparation of Open-cell Foams of Linear Low-density Polyethylene and Linear Low-density Polyethylene/Carbon Nanotube Composites

The open-cell structure foams of linear low-density polyethylene（LLDPE） and linear low-density polyethylene（LLDPE）/multi-wall carbon nanotubes（MWCNTs） composites are prepared by using supercritical carbon dioxide（sc-CO2）as a foaming agent. The effects of processing parameters（foaming temperature, saturation pressure, and depressurization rate） and the addition of MWCNTs on the evolution of cell opening are studied systematically. For LLDPE foaming, the foaming temperature and saturation pressure are two key factors for preparing open-cell foams. An increase in temperature and pressure promotes both the cell wall thinning and cell rupture, because a high temperature results in a decrease in the viscosity of the polymer, and a high pressure leads to a larger amount of cell nucleation. Moreover, for the given temperature and pressure, the high pressurization rate results in a high pressure gradient, favoring cell rupture. For LLDPE/MWCNTs foaming, the addition of MWCNTs not only promotes the cell heterogeneous nucleation, but also prevents the cell collapse during cell opening, which is critical to achieve the open-cell structures with small cell size and high cell density.

Infusing High-density Polyethylene with Graphene-Zinc Oxide to Produce Antibacterial Nanocomposites with Improved Properties

Nanocomposites of high-density polyethylene(HDPE)modified with 0.2 phr graphene-zinc oxide(GN-ZnO)exhibited optimal mechanical properties and thermal stability.Two other nano-materials—GN and nano-ZnO—were also used to compare them with GN-ZnO.increasing the content of GN-ZnO gradually enhanced the antibacterial and barrier properties,but the addition of 0.3 phr GN-ZnO led to agglomeration that caused defects in the nanocomposites.Herein,we investigated the antibacterial and barrier properties of HDPE nanocomposites infused with different nanoparticles(GN,ZnO,GN-ZnO)of varying concentrations.HDPE and the nanoparticles were meltblended together in a Haake-Buchler Rheomixer to produce a new environment-friendly nano-material with improved physical and chemical properties.The following characterizations were conducted:tensile test,thermogravimetric analysis,morphology,differential scanning calorimetry,X-ray diffraction,antibacterial test,and oxygen and water vapor permeation test.The results showed that the crystallinity of HDPE was affected with the addition of GN-ZnO,and the nanocomposites had effective antibacterial capacity,strong mechanical properties,high thermal stability,and excellent barrier performance.This type of HDPE nanocomposites reinforced with GN-ZnO would be attractive for packaging industries.

The structure and mechanical property of silane-graftedpolyethylene/SiO_(2) nanocomposite fiber rope

The effect of vinyltrimethoxysilane(VTMS)graft and SiO_(2) on the structure and mechanical properties of silane-grafted-polyethylene/SiO_(2)(VTMS-g-PE/SiO_(2))nanocomposite fibers and ropes was studied.Scanning electron microscopy(SEM),Fourier transfer infrared(FT-IR),differential scanning calorimetry analysis(DSC)and tensile mechanical tests were performed to characterize the morphology,thermal and mechanical properties of nanocomposite fibers and ropes.The results revealed that the SiO_(2) nanoparticles were well dispersed throughout the polymeric matrix.With increasing SiO_(2) content,T_(m),the melt peak width and X_(c),degree of crystallinity,of VTMS-g-PE/SiO_(2) nanocomposite fibers increased.The breaking load and breaking strength of the nanocomposite fiber ropes were remarkably improved compared to pure PE fiber ropes and elongation at break was also decreased.

Sorption kinetics of parent and substituted PAHs for low-density polyethylene（LDPE）:Determining their partition coefficients between LDPE and water(KLDPE) for passive sampling

Low-density polyethylene(LDPE)has been widely used as a sorbent for passive sampling of hydrophobic organic contaminants(HOCs)in aquatic environments.However,it has seen only limited application in passive sampling for measurement of freely dissolved concentrations of parent and substituted PAHs(SPAHs),which are known to be toxic,mutagenic and carcinogenic.Here,the 16 priority PAHs and some typical PAHs were selected as target compounds and were simultaneously determined by gas chromatography–mass spectrometer(GC–MS).Some batch experiments were conducted in the laboratory to explore the adsorption kinetics of the target compounds in LDPE membranes.The results showed that both PAHs and SPAHs could reach equilibrium status within19–38 days in sorption kinetic experiments.The coefficients of partitioning between LDPE film(50μm thickness)and water(KLDPE)for the 16 priority PAHs were in good agreement with previously reported values,and the values of KLDPEfor the 9 SPAHs are reported in this study for the first time.Significant linear relationships were observed,i.e.,log KLDPE=0.705×log KOW+1.534 for PAHs(R^2=0.8361,p<0.001)and log KLDPE=0.458×log KOW+3.092 for SPAHs(R^2=0.5609,p=0.0077).The selected LDPE film was also proven to meet the condition of"zero sink"for the selected target compounds.These results could provide basic support for the configuration and in situ application of passive samplers.

有机化蒙脱土对XLPE/OMMT纳米复合电介质微观形态及水树枝老化特性的影响

文中采用熔融共混法分别制备了交联聚乙烯/有机化蒙脱土(XLPE/OMMT)纳米复合电介质,研究有机化蒙脱土种类对纳米复合电介质微观形态和水树枝老化特性的影响。对试样进行力学性能测试发现,OMMT质量分数为0.5%时,综合力学性能达到最佳;利用差示扫描量热法和扫描电子显微镜研究了试样的微观形态,经双十八烷基苄基季铵盐有机化改性并细化的有机化蒙脱土(OMMT3)起到明显的异相成核作用,使晶体更加完善,结晶度高达25.3%,晶体平均尺寸仅为16.67μm;采用水针电极法对各试样进行加速水树枝老化试验,剥离分散的OMMT3片层形成了更加曲折的迷宫路径,其对水分子的阻隔效应与XLPE交联网状结构对分子链运动束缚的共同作用,有效抑制了XLPE/OMMT3试样中水树枝的生长,引发概率下降至23.4%;傅里叶变换红外光谱对水树枝老化前后的化学结构进行了表征,纳米复合电介质水树区的羰基指数增加、羟基振动峰增强,表明水树枝老化是电化学降解的作用;在水树枝生长过程中,XLPE/OMMT3试样老化断链较少,表现出较优的耐热氧老化性能。

维生素E聚乙二醇琥珀酸酯乳化α-生育酚琥珀酸酯纳米乳的制备及体外抗肿瘤细胞活性评价

目的探索以维生素E聚乙二醇琥珀酸酯(TPGS)做乳化剂,制备α-生育酚琥珀酸酯纳米乳(T-NE),对纳米乳进行处方优化、制备方法以及制剂学性质考察,并且评价其体外抗肿瘤细胞活性。方法自2022年1―4月,先后通过水滴定法绘制伪三元相图,根据纳米乳区域确定最优处方,再采用乳化蒸发法制备,并对其进行了理化性质评价,包括类型确定、形态学考察、粒径大小和分布、Zeta电位、载药量和稳定性,并通过细胞活力实验(MTT)进行体外抗肿瘤细胞活性评价。结果T-NE的最优处方为α-生育酚琥珀酸酯(α-TOS)、维生素E、TPGS、聚乙二醇400质量比1∶1∶2∶1;所制得T-NE为O/W型,外观呈类球形且无粘连;载药量为(20.15±1.91)g/L,粒径为(258.8±3.48)nm,多分散指数(PDI)为0.136±0.03,Zeta电位值为(-27.0±0.46)mV;4℃和25℃条件下放置稳定性良好,且适宜室温长期贮存;与游离的α-TOS药物溶液相比,T-NE对人乳腺癌细胞系(MCF-7)及人卵巢癌细胞系(A2780)细胞具有更强的抑制作用,IC50值分别为16.68μmol/L和7.50μmol/L,且空白纳米乳基本无毒性作用。结论该实验制备的T-NE外观均一呈类球形,粒径较小且分布均匀,载药量高稳定性好,同时表现出比游离α-TOS更为优异的抗肿瘤细胞活性作用,具有良好的开发前景。

Constructing the Al deficiency in Si-O(H)-Al units based on Pt/ZSM-5 for enhanced hydrocracking of polyethylene into high-quality liquid fuel

Hydrocracking catalysis is a controllable route to plastic waste upgrading. However, the mismatched acid site-driven C-C cleavage and C=C hydrogenation process on metal restrict the efficiency and selectivity in conventional metal/acid bi-functional catalyst. Herein, we introduce Al deficiency in Si-O(H)-Al structural units of Pt/zeolite socony mobil-5 (Pt/ZSM-5) through discharge driven reduction (DR) process to precisely control the ratio of metal to acid, achieving hydrocracking of low-density polyethylene (LDPE) waste at 270 °C with 87.7% conversion and liquid fuel (C5-C21) selectivity of 77.8%. Pair distribution function (PDF) and nuclear magnetic resonance (NMR) spectroscopy demonstrate the partial absent Al sites further resulting short-range local disorder Si-O(H)-Al. Upon pyridine infrared spectroscopy (Py-IR) and CO diffuse reflectance Fourier-transform infrared (CO DRIFT) analysis, the extraction of Al modulates Brønsted acid density of Pt/ZSM-5 with DR process (Pt/Z5DR), improves the interaction between Pt and ZSM-5 support, enhances the cationic of Pt. The metal-acid balance and electron-deficient Pt favor the matching speed of light olefins hydrogenation and the cracking of macromolecule intermediates. Moreover, density functional theory (DFT) calculations identify the thermodynamic stability of Pt/Z5DR and moderate adsorption capability towards light olefins. This work confirms the great potential of precisely controlled molar of metal to acid in metal/zeolite catalysts for LDPE upcycling, providing a viable path for dealing with PE plastic wastes.

Multilayer polyethylene separator with enhanced thermal properties for safe lithium-ion batteries Author links open overlay panel

The separator plays an important part in battery safety and performance.Polyolefin separators are widely used in commercial Lithium-ion batteries(LIBs),owing to their excellent properties,but they suffer from serious thermal shrinkage and poor electrolyte wettability.Thus,a multilayer separator(ASPESA)is developed by coating two thin layers of low-density polyethylene(LDPE)and Al_(2)O_(3)on both sides of a polyethylene membrane using a facile and environmentally friendly casting technique.The ASPESA separator demonstrates a shutdown function at 120℃and shows enhanced thermal stability under 185℃,with a small thermal shrinkage of 1%.Meanwhile,the LDPE and Al_(2)O_(3)layers can improve the electrolyte wettability and electrolyte uptake(407.23%).The multilayer ASPESA separator delivers an excellent cycle performance in LiFePO_(4)||Li cells with a discharge capacity of 144.5 mAh g^(-1)after 900 cycles,with a high-capacity retention of 98.9%(compared to the 5th cycle).Therefore,the multilayer ASPESA separator has great utilization potential as a high-safety separator in LIBs.