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Influence of sulfur/chlorine-containing pesticides on the aging and heavy metal dynamics of PBAT and LDPE microplastics in soil

Yi Liu,Jiafei Xie,Yimiao Lin,Ruojia Li,Liang Zhu,Ying Zhou

Microplastics (MPs) pollution in soil has emerged as a significant environmental concern, particularly regarding the interactions between MPs and chemical contaminants such as pesticides. This study focused on the aging of biodegradable poly(butylene adipate-co-terephthalate) (PBAT) and low-density polyethylene (LDPE) films in the presence of five sulfur/chlorine (S/Cl)-containing pesticides (prothioconazole, myclobutanil, isazophos, harmony, and flumetsulam), selected for their common use in agricultural practices and potential environmental persistence. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and inductively coupled plasma mass spectrometry (ICP-MS) were employed to investigate the dynamics of heavy metal adsorption and release (specifically Ni, Cu, and Sn) during MPs aging, as indicated by changes in surface morphology and polymer functional groups. Results revealed that PBAT aged more rapidly than LDPE, irrespective of pesticide presence. All pesticides tested accelerated aging of MPs, with a notable enhancement in the adsorption of Ni and Cu and the release of Sn. Among the pesticides, prothioconazole and myclobutanil exhibited the most significant effects on aging of MPs and heavy metal interactions, while harmony and flumetsulam had minimal impact. These findings highlight the potential environmental risks associated with the combined exposure of MPs and pesticides, offering insights for future environmental risk assessments.

Application of Nanofibrillated Cellulose on BOPP/LDPE Film as Oxygen Barrier and Antimicrobial Coating Based on Cold Plasma Treatment

Peng Lu,Mengya Guo,Zhijun Xu,Min Wu

The application of nanofibrillated cellulose (NC) films in packaging industry has been hindered by its lack of heat-sealing ability. Incorporation of NC films with the biaxially oriented polypropylene/low density polyethylene (BOPP/LDPE) laminates can take advantage of each material and endow the films with novel functions for food packaging applications. In this study, a coating that consists of NC and nisin was applied onto a cold plasma treated BOPP/LDPE film to fabricate a novel active packaging with an improved oxygen barrier performance and an added antimicrobial effect. The results showed that cold plasma treatment improved the surface hydrophilicity of BOPP/LDPE films for better attachment of the coatings. NC coatings significantly enhanced oxygen barrier property of the BOPP/LDPE film, with an oxygen transmission rate as low as 24.02 cc/m2·day as compared to that of the non-coated one (67.03 cc/m2·day). The addition of nisin in the coating at a concentration of 5 mg/g caused no significant change in barrier properties but imparted the film excellent antimicrobial properties, with a growth inhibition ofL. monocytogenesby 94%. All films exhibit satisfying mechanical properties and transparency, and this new film has the potential to be used as antimicrobial and oxygen barrier packaging.Keywords:nanofibrillated cellulose;nisin;BOPP/LDPE film;oxygen barrier;cold plasma;active packaging

Migration of copper from nanocopper/LDPE composite films

Fang Liu,Chang-Ying Hu,Quan Zhao,Yu-Jie Shi,Huai-Ning Zhong

Three nanocopper/low-density polyethylene (LDPE) composite films were tested in food simulants (3% acetic acid and 10% ethanol) and real food matrices (rice vinegar, bottled water and Chinese liquor) to explore the behaviours of copper migration using ICP-OES and GFAAS. The effects of exposure time, temperature, nanocopper concentration and contact media on the release of copper from nanocopper/LDPE composite films were studied. It was shown that the migration of copper into 10% ethanol was much less than that into 3% acetic acid at the same conditions. With the increase of nanocopper concentration, exposure time and temperature, the release of copper increased. Copper migration does not appear to be significant in the case of bottled water and Chinese liquor compared with rice vinegar with a maximum value of 0.54 μg mL−1 for the CF-0.25# bags at 70°C for 2 h. The presence and morphology of copper nanoparticles in the films and the topographical changes of the films were confirmed by field emission scanning electron microscope (FE-SEM) and atomic force microscope (AFM). In this manner, copper nanoparticles of different morphologies, sizes and distribution were found, and samples with higher nanocopper concentration had a more irregular topography. In the case of Fourier transform infrared spectroscopy (FTIR), no chemical bonds formed between copper nanoparticles and LDPE. Copper nanoparticles were just as physically dispersed in LDPE.

A Polyethylene Base Moisture Activating Oxygen Scavenging Film Co-Extruded with Tea Polyphenols-β-Cyclodextrin Inclusion Complex

Liao Pan,Meiying Zhang,Lixin Lu,Bingxian Ou,Xi Chen

Antioxidant packaging is an effective method to protect oxygen-sensitive food from oxidation. In order to concurrently obtain a storage stability and excellent oxygen scavenging of antioxidant film for the high moisture food, a moisture activating oxygen scavenging film was prepared by using tea polyphenols as the oxygen scavenger. The moisture activating function was achieved by introducing the β-cyclodextrin embedding technology, and the tea polyphenols–β-cyclodextrin inclusion complex was co-extruded with low-density polyethylene (LDPE) to improve the storage stability. The results indicate that the tea polyphenols is well embedded by β-cyclodextrin according to the Fourier transform infrared spectra (FT-IR), and a relatively homogeneous dispersion of oxygen scavenger is observed while the oxygen scavenger content is less than 5%. The oxygen scavenging increases with the increase of oxygen scavenger from 1% to 5%, and a maximal oxygen absorption of 0.0150 mol/m2is exhibited at oxygen scavenger content value of 5%. Then, the oxygen scavenging significantly decrease under the oxygen scavenger content of 7% and 10%. Moreover, the oxygen scavenging amount sharply increase after steeping in water or storage in extremely high humidity of RH 84% while the oxygen scavenging is restrained under RH 32–75%, indicating that the moisture activating oxygen scavenging is functioning. The oxygen scavenging is obvious restrained under low temperature of 4 °C while the oxygen scavenging is activated at 23 °C and 50 °C with similar oxygen scavenging amount. Besides, both of the tensile and heat-sealing strength deteriorative with the increase of oxygen scavenger content, while they are acceptable at oxygen scavenger content of 5%. Finally, the prepared oxygen scavenging film was used for packaging orange juice and received a good antioxidant effect. Thus, the acquired moisture activating oxygen scavenging film has a good stability under regular storage condition, and shows a potentially application for oxygen-sensitive food with high moisture content.Keywords:moisture activating;oxygen scavenging film;tea polyphenols;β-cyclodextrin;low-density polyethylene (LDPE)

Quadruple-shape-memory effect of TPI/LDPE/HDPE composites

Jiayu Xian,Jieting Geng,Yan Wang,Lin Xia

Shape-memory polymers are important smart materials with potential applications in smart textiles, medical devices, and sensors. We prepared trans-1,4-polyisoprene, low-density polyethylene (LDPE), and high-density polyethylene (HDPE) shape-memory composites using a simple mechanical blend method. The mechanical, thermal, and shape-memory properties of the composites were studied. Our results showed that the shape-memory composites could memorize 3 temporary shapes, as revealed by the presence of broad melting transition peaks in the differential scanning calorimetry curves. In the trans-1,4-polyisoprene/LDPE/HDPE composites, the cross-linked network and the crystallization of the LDPE and HDPE portions can serve as fixed domains, and all crystallizations can act as reversible domains. We proposed a schematic diagram to explain the vital role of the cross-linked network and the crystallization in the shape-memory process.

Enhanced Thermal Conductivity and Dielectric Properties of h-BN/LDPE Composites

Lijuan He,Junji Zeng,Yuewu Huang,Xiong Yang,Dawei Li,Yu Chen,Xiangyu Yang,Dongbo Wang,Yunxiao Zhang,Zhendong Fu

Low-density polyethylene (LDPE), as an excellent dielectric insulating material, is widely used in electrical equipment insulation, whereas its low thermal conductivity limits its further development and application. Hexagonal boron nitride (h-BN) filler was introduced into LDPE to tailor the properties of LDPE to make it more suitable for high-voltage direct current (HVDC) cable insulation application. We employed melt blending to prepare h-BN/LDPE thermally conductive composite insulation materials with different contents. We focused on investigating the micromorphology and structure, thermal properties, and electrical properties of h-BN/LDPE composites, and explained the space charge characteristics. The scanning electron microscope (SEM) results indicate that the h-BN filler has good dispersibility in the LDPE at a low loading (less than 3 phr (3 g of micron h-BN particles filled in 100g of LDPE)), as well as no heterogeneous phase formation. The results of thermal conductivity analysis show that the introduction of h-BN filler can significantly improve the thermal conductivity of composites. The thermal conductivity of the composite samples with 10 phr h-BN particles is as high as 0.51 W/(m·K), which is 57% higher than that of pure LDPE. The electrical performance illustrates that h-BN filler doping can significantly inhibit space charge injection and reduce space charge accumulation in LDPE. The interface effect between h-BN and the substrate reduces the carrier mobility, thereby suppressing the injection of charges of the same polarity and increasing the direct-current (DC) breakdown strength. h-BN/LDPE composite doped with 3 phr h-BN particles has excellent space charge suppression effect and high DC breakdown strength, which is 14.3% higher than that of pure LDPE.

Heavy metal release from irradiated LDPE/nanometal composite films into food simulants

Shan Lu,Xia Gao,Chang-Ying Hu,Yining Xia

Low-density polyethylene (LDPE) films containing three types of nanometals (ZnO, Cu, or Ag) were prepared and characterized. A release experiment was carried out on the nanocomposite films subjected to three treatments: no irradiation, gamma irradiation with solvent contact (10 kGy), and gamma irradiation without solvent contact. The release of heavy metals from the nanocomposite films into three types of solvents (water, 95 % ethanol, and 3 % acetic acid) was recorded at room temperature. In general, gamma irradiation was likely to promote the release of heavy metals. The release amount of heavy metals depended on the type of nanometal and solvent. An increase in release amount of Zn and Cu was observed in 95 % ethanol and Ag in all types of solvents at the end of the experiment after the film samples were treated with gamma irradiation (with solvent contact during irradiation). The increase in heavy metal release was attributed to the accelerated surface oxidation of nanometals after irradiation, as confirmed by XPS analysis on the irradiated Ag powders.

Influence of polypyrrole nanospheres on the direct current dielectric properties of LDPE

Chengcheng Zhang,Qiang Ren,Dahu Cheng,Chunyang Li,Jiaming Yang,Hong Zhao

To study the effect of nano conducting materials on the direct current (DC) dielectric properties of low density polyethylene (LDPE), polypyrrole nanospheres are prepared by the soft template method and then melt-blended with LDPE to obtain LDPE/polypyrrole nanocomposites. The micro-structure, space charge distribution, thermally stimulated depolarization current, DC conductivity and DC breakdown strength of the nanocomposites are investigated. The results show there is interaction between polypyrrole nanospheres and LDPE, which will not affect the crystal structure of LDPE, but slightly increase the crystallinity of LDPE/polypyrrole nanocomposites. Polypyrrole nanospheres can introduce deep traps in LDPE to capture space charge carriers, which will suppress the accumulation of space charges in LDPE and reduce the DC conductivity. The DC breakdown strength of LDPE/polypyrrole nanocomposites is improved slightly by adding a small amount of polypyrrole nanospheres.

Low temperature catalytic oxidative aging of LDPE films in response to heat excitation

Xuegang Luo,Sizhao Zhang,Feng Ding,Xiaoyan Lin

The waste treatment of polymer materials is often conducted using the photocatalytic technique; however, complete decomposition is frequently inhibited owing to several shortcomings such as low quantum yield and the requirement of ultraviolet irradiation. Herein, we report a strategy to implement moderate management of polymeric films via thermocatalytic oxidative route, which is responsive to heat stimulus. Diverse LDPE-matrix films together with as-prepared thermal catalysts (TCs) or initiators were synthesized to further investigate heat-dependent-catalytic degradation effects. After artificial ageing, structural textures of the as-synthesized films could be chemically deteriorated, followed by a huge increase in surface roughness values, and appreciable loss was also found in the average molecular weights and mechanical parameters. We found an emergent phenomenon in which crystallization closely resembled two-dimensional (2D) growth, which displayed rod-like or disc-type crystal shapes. New chemical groups generated on film surfaces were monitored, and led to a higher limiting oxygen index because of strong catalytic oxidation, thus demonstrating the success of catalytic oxidative ageing by heat actuation. The underlying mechanism responsible for thermocatalytic oxidative pattern is also discussed. Accordingly, these findings may have important implications for better understanding the development of polymeric-matrix waste disposal.

Topology-controlled polymer brushes on LDPE for enhanced cellulase immobilization and lignocellulose conversion

Yuchong Liu,Guan Wang,Changwen Zhao,Wantai Yang

Visible-light graft polymerization enables topology-controlled polymer brushes. • Linear-bottlebrush brush achieves highest enzyme loading (0.25 mg/cm 2 ). • Immobilized cellulase retains 70 % activity after 8 reuse cycles. • LB-immobilized cellulase enables SSF with 0.6 g/L ethanol and 8-cycle reusability. By providing a flexible microenvironment, immobilization of cellulase on polymer brushes represents an effective strategy to improve the interactions of cellulase with the substrate in biomass conversion. However, manipulation of polymer brush morphology remains largely unexplored, owing to the lack of an effective synthesis strategy. Herein, we developed a versatile visible-light-induced graft polymerization strategy to precisely fabricate three types of polymer brushes with well-defined topologies on low-cost low-density polyethylene (LDPE) films. Benefiting from its unique three-dimensional high-density topology, linear-bottlebrush (LB) architecture exhibited a unique 3D high–density topology and achieved the highest enzyme loading capacity (0.25 mg/cm 2 ) and favorable enzymatic activity. The reusability was also demonstrated with 70 % of its initial activity remained after 8 reuse cycles for LB architecture. Furthermore, potential of LB brush-based immobilized cellulase in simultaneous saccharification and fermentation (SSF) of corncob for bioethanol production was demonstrated with its efficiency and reusability in practical biomass conversion processes. This study provides a synthetic methodology for constructing complex biointerfaces and establishes clear structure–property relationships, offering design principles for high-performance immobilized enzyme systems and advancing sustainable biomanufacturing. Download: Download high-res image (145KB) Download: Download full-size image

Space charge dynamics of acetophenone and cumyl alcohol and their synergistic effect in LDPE

Meng Chen,Hongliang Zhang,Yalin Wang,Jiandong Wu,Yi Yin

The mechanical properties of LDPE composite filled with CF coated by dimethylamine treated TiO2

Li Jian

In order to improve the surface wettability of carbon fiber and enhance its composite interface performance, dimethylamine treated TiO2 was coated on carbon fiber (CF). The surface morphology, surface chemical state, and surface wettability of CF were characterized by SEM, XPS, and TEM tests, and the interlaminar shear strength (ILSS) and cross-sectional morphology tests were used to test the performance of CF/Low density polyethylene (LDPE) composites. The interface bonding status was analyzed and characterized. The results show that after the surface treatment of CF by dimethylamine treated TiO2, the O/C (atomic ratio) of the surface of CF is increased, and a certain amount of nano-scale small convex micro-mechanical structure is given, which improves the surface wetting of CF. The surface of the CF modified by the TiO2 is rough; the contact area between modified CF and LDPE increases.