Halloysite Nanotubes and Silane-Treated Alumina Trihydrate Hybrid Flame Retardant System for High-Performance Cable Insulation

Quantification of aluminium trihydrate flame retardant in polyolefins via in-line hyperspectral imaging and machine learning for safe sorting

The extensive use of aluminium trihydrate (ATH) flame retardant in plastics poses challenges and hazards in plastic waste recycling, thus it is crucial to accurately identify ATH. This study demonstrates the effectiveness of an industrial in-line shortwave infrared (SWIR) hyperspectral imaging system and principal component analysis (PCA) for detecting and quantifying ATH in low-density polyethylene (LDPE) and polypropylene (PP). The samples were characterized by elemental analysis, ATR-FTIR, DSC, and TGA. A quantitative estimation model was developed by analysing spectra with varying ATH concentrations. PCA and SWIR band area ratio were fitted to estimate the ATH concentration. The PCA model outperformed the SWIR band area ratio model and achieved good predictions between measured and predicted ATH concentrations ranging from 22.9 to 1.6 wt% (R2LDPE = 0.95) in LDPE and from 24.0 to 2.5 wt% in PP (R2PP = 0.94). The obtained in-line control tool is relevant to the recycling industries, enabling real-time assessment of additives.

Recent remediation strategies for flame retardancy via nanoparticles

This review article delves into the application of nanoparticles (NPs) in fire prevention, aiming to elucidate their specific contribution within the broader context of various fire prevention methods. While acknowledging established approaches such as fire safety principles, fire suppression systems, fire alarm systems, and the use of fire-retardant chemicals and safety equipment, this review focuses on the distinctive properties of NPs. The findings underscore the remarkable potential of NPs in controlling and mitigating fire propagation within both architectural structures and vehicles. Specifically, the primary emphasis lies in the impact of NPs on reducing oxygen levels, as assessed through the limiting oxygen index , a subject explored by various researchers. Furthermore, this review delves into the examination of combustion reduction rates facilitated by NPs, utilizing assessments of ignition time, heat release rate (HRR), and flammability tests (UL-94) on plastic materials. Beyond these aspects, the review evaluates the multifaceted role of NPs in achieving weight reduction and establishing fire-retardant properties. Additionally, it discusses the reduction of smoke, a significant contributor to environmental pollution and health risks. Among the nanoparticles investigated in this study, SiO2, MgAl, and nano hydrotalcite have demonstrated the best results in weight reduction, smoke reduction, and HRR, respectively. Meanwhile, Al2O3 has been identified as one of the least effective treated nanoparticles. Collectively, these findings significantly contribute to improving safety measures and reducing fire risks across a range of industries.

Synergistic Improvement of Flame Retardancy and Mechanical Properties of Epoxy/Benzoxazine/Aluminum Trihydrate Adhesive Composites

Epoxy resin was mixed with benzoxazine resin and an aluminum trihydrate (ATH) additive to provide flame retardancy and good mechanical properties. The ATH was modified using three different silane coupling agents and then incorporated into a 60/40 epoxy/benzoxazine mixture. The effect of blending compositions and surface modification on the flame-retardant and mechanical properties of the composites was investigated by performing UL94, tensile, and single-lap shear tests. Additional measurements were conducted including thermal stability, storage modulus, and coefficient of thermal expansion (CTE) assessments. The mixtures containing more than 40 wt% benzoxazine revealed a UL94 V-1 rating with high thermal stability and low CTE. Mechanical properties including storage modulus, and tensile and shear strength, also increased in proportion to the benzoxazine content. Upon the addition of ATH to the 60/40 epoxy/benzoxazine mixture, a V-0 rating was achieved at 20 wt% ATH. The pure epoxy passed a V-0 rating by the addition of 50 wt% ATH. The lower mechanical properties at high ATH loading could have been improved by introducing a silane coupling agent to the ATH surface. The composites containing surface-modified ATH with epoxy silane revealed about three times higher tensile strength and one and a half times higher shear strength compared to the untreated ATH. The enhanced compatibility between the surface-modified ATH and the resin was confirmed by observing the fracture surface of the composites.

Polymer Hybrid Nanocomposites Based on Homo and Copolymer Xlpe Containing Mineral Nanofillers with Improved Functional Properties Intended for Insulation of Submarine Cables

Cross-linked polyethylene (XLPE) is one of the most popular insulation materials used in the production of medium and high voltage cables (MV, HV). This article presents the results of research carried out on two types of commercially used insulation materials, modified with the addition of organophilic phyllosilicate (CLOISITE C20A)and halloysite nanotubes (HNTs). The influence of fillers on the mechanical properties of insulating materials is discussed as a potential mechanism for increasing their resistance to the phenomenon of water-tree. SEM and XRD analyses were performed to investigate the morphology and DSC for comparing phase transitions. Mechanical and functional properties for different concentrations of nanofillers, such as their hybrids, were also investigated.

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.