A processing method with high efficiency for low density polyethylene nanofibers reinforced by aligned carbon nanotubes via nanolayer coextrusion

Aramid textile with near-infrared laser-induced graphene for efficient adsorption materials

Porous carbon materials show great application potential in the field of adsorption. However, the preparation process of carbon adsorption materials relies on high temperature, high energy consumption, many steps, and long time. Most of them exist in the form of powder or block, and the practical application scenarios are limited and difficult to recycle. In this study, based on in-situ carbonization of polymer precursor, we directly generated laser-induced graphene (LIG) on the surface of commercial aramid textile using a low-energy near-infrared laser in air, and prospected the application prospect of the prepared aramid/graphene textile in the field of adsorption. Under a certain laser energy, the photothermal reaction promotes the breaking of the CO and CN bonds in the surface layer of the aramid fiber, and reorganizes into a graphene structure at an instantaneous high temperature, while the overall flexible structure of the textile was not destroyed. Further, adsorption materials based on the as-prepared aramid/graphene textiles were also designed, including VOC-adsorbing textile in air and dye-adsorbing textile in water. Using low-energy near-infrared laser to directly achieve LIG writing in commercial textiles under air condition will provide an efficient, environmentally friendly, and designable direction for the large-scale fabrication of textile adsorption products.

Laser irradiation method to prepare polyethylene porous fiber membrane with ultrahigh xylene gas filtration capacity

In recent years, volatile organic compound (VOC) gases have caused potential harm to people's health. This study reveals the preparation of polyethylene porous fiber membrane with excellent low-concentration VOCs filtration performance via laser irradiation technology. A neodymium-doped yttrium aluminum garnet (Nd:YAG) pulsed laser beam was used to scan the laser-sensitive low-density polyethylene/carbon black (LDPE/CB) fibers prepared by nanolayer coextrusion in the air. The controllable thermal energy generated by laser irradiation makes the surface of the fiber membrane to produce a porous carbon layer in situ. Laser power and scanning speed are important parameters for controlling laser-induced carbonization. The results indicate that the rich "fluffy" carbon structures on the surface of the porous fiber membrane can efficiently adsorb xylene gas. This study can provide a positive reference for the large-scale preparation of polyolefin porous fiber membrane with VOCs filtration by simple and efficient laser irradiation method.

Non-Isothermal Crystallization Kinetic of Polyethylene/Carbon Nanotubes Nanocomposites Using an Isoconversional Method

Behavior studies of thermoplastic polymers during non-isothermal crystallization are extremely important since most of their properties are influenced by degree of crystallinity and the crystallization process. In general, an approach based on a model-fitting method is used to perform crystallization kinetic studies. Due to their inability to uniquely determine the reaction mode, many studies have used the isoconversional method, where it is not necessary to assume a crystallization model to obtain the kinetic parameters. Therefore, in this work, the influence of acid and octadecylamine functionalized carbon nanotubes (CNTs) in the crystallization kinetic of polyethylene (PE) was studied using an isoconversional method with differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The kinetic parameters and the crystallization model were determined. The incorporation of functionalized and non-functionalized CNTs into PE did not change the Johnson-Mehl-Avrami crystallization model. However, the CNTs increased the crystallization temperature and reduced the activation energy for crystallization. In addition, the Avrami coefficient values were lower for the nanocomposites when compared to pure PE. The incorporation of CNTs accelerated the crystallization of PE, reducing the crystallite sizes and modifying their morphology.

Nanolayer coextrusion: An efficient and environmentally friendly micro/nanofiber fabrication technique

Researchers have developed many types of nanoscale materials with different properties. Among them, nanofibers have recently attracted increasing interest and attention due to their functional versatility and potential applications in diverse industries, including tapes, filtration, energy generation, and biomedical technologies. Nanolayer coextrusion, a novel polymer melt fiber processing technology, has gradually received attention due to its environmental friendliness, efficiency, simplicity and ability to be mass-produced. Compared with conventional techniques, nanolayer coextruded non-woven nanofibrous mats offer advantages such as a tunable fiber diameter, high porosity, high surface area to volume ratio, and the potential to manufacture composite nanofibers with different components to achieve desired structures and properties. Dozens of thermoplastic polymers have been coextruded for various applications, and the variety of polymers has gradually continued to increase. This review presents an overview of the nanolayer coextrusion technique and its promising advantages and potential applications. We discuss nanolayer coextrusion theory and the parameters (polymer and processing) that significantly affect the fiber morphology and properties. We focus on varied applications of nanolayer coextruded fibers in different fields and conclude by describing the future potential of this novel technology.

A review of the interfacial characteristics of polymer nanocomposites containing carbon nanotubes

This paper provides an overview of recent advances in research on the interfacial characteristics of carbon nanotube–polymer nanocomposites. The state of knowledge about the chemical functionalization of carbon nanotubes as well as the interaction at the interface between the carbon nanotube and the polymer matrix is presented. The primary focus of this paper is on identifying the fundamental relationship between nanocomposite properties and interfacial characteristics. The progress, remaining challenges, and future directions of research are discussed. The latest developments of both microscopy and scattering techniques are reviewed, and their respective strengths and limitations are briefly discussed. The main methods available for the chemical functionalization of carbon nanotubes are summarized, and particular interest is given to evaluation of their advantages and disadvantages. The critical issues related to the interaction at the interface are discussed, and the important techniques for improving the properties of carbon nanotube–polymer nanocomposites are introduced. Additionally, the mechanism responsible for the interfacial interaction at the molecular level is briefly described. Furthermore, the mechanical, electrical, and thermal properties of the nanocomposites are discussed separately, and their influencing factors are briefly introduced. Finally, the current challenges and opportunities for efficiently translating the remarkable properties of carbon nanotubes to polymer matrices are summarized in the hopes of facilitating the development of this emerging area. Potential topics of oncoming focus are highlighted, and several suggestions concerning future research needs are also presented.

The state of research on the characteristics at the interface in polymer nanocomposites is reviewed. Special emphasis is placed on the recent advances in the fundamental relationship between interfacial characteristics and nanocomposite properties.