Shanghai Electric Cable Research Institute

In view of the problem that epoxy resin (EP) cannot achieve effective flame retardancy, smoke and toxic gas suppression functions in fire, and poor interface compatibility with flame retardants, a core-shell structure with SiO 2 as the nucleus was designed, and a new multicomponent flame retardant was prepared by introducing Ni and phytic acid using metal-organic frameworks (MOFs) as precursors. After mixing and curing with EP, the SiO 2 /CoNi-DH-PA/EP was obtained. With only 5% SiO 2 /CoNi-DH-PA added, the peak heat release, total smoke production and total CO production of EP composites are reduced by 63.72%, 31.88% and 63.74%, respectively, and the residue yield increased from 15.05% to 24.40%. It has been verified that SiO 2 , Co–Ni bimetallic ions and phytic acid have synergistic effects, which can induce and catalyze the formation of a complete and dense carbon layer. This significantly reduces the heat release, smoke and toxic gas production, thereby reducing the fire hazard of EP. Additionally, the SiO 2 /CoNi-DH-PA/EP ensures good mechanical properties.

This paper proposes a current table for realizing Environmental and Economical Conductor Size Optimization (ECSO) design for photovoltaic systems. A simple method for calculating the energy saving and CO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> reduction based on the power conditioning system capacity is also proposed. The method is demonstrated using an ECSO design. The proposed table and method are applied to three case studies.

Polypropylene (PP) as an environmentally friendly cable insulation material has become an emerging research topic in recent years. To improve the long-term operational stability of PP cables, this study aims to enhance the electrical aging life of PP by incorporating TiO 2 nanoparticles through melt blending, both before and after surface treatment. The dispersion behavior of TiO 2 in the PP matrix, the associated functional groups, and the crystallization characteristics of PP were characterized. In addition, polarization depolarization current (PDC) measurements were used to examine the effects of TiO 2 on trap depth and density in the polymer. Accelerated electrical aging tests based on the inverse power law were conducted to predict the aging lifespan of TiO 2 /PP composites and to investigate how the surface treatment of TiO 2 influences insulation performance through its effects on particle dispersion and trap distribution. The results indicate that the incorporation of nano-TiO 2 effectively enhances the electrical aging lifespan of PP. However, high concentrations of untreated TiO 2 lead to particle agglomeration, which reduces performance. Surface modification improves the dispersion of TiO 2 in the PP matrix. Notably, adding 0.5wt% surface-treated TiO 2 to PP results in the greatest improvement in electrical aging lifespan, as evidenced by a 17.02% increase in the electrical aging lifetime index compared to pure PP and a 14.32% increase compared to TiO 2 /PP composites containing the same concentration of untreated TiO 2 . • A high-performance eco-friendly cable insulation material was developed by melt blending TiO 2 and PP insulation material. • Accelerated electrical aging tests were conducted to predict the aging lifespan of TiO 2 /PP composites. • The effects of TiO 2 on the electrical aging life of PP insulation materials were analyzed. • TiO 2 surface-treated with trimethoxy (2-methylpropyl) silane introduces oxygen vacancies, acting as deep traps to enhance the electrical aging life of PP. • Hydrophobic surface-treated TiO 2 improves nanoparticle dispersion, significantly enhancing the electrical aging life of PP insulation materials.

Long-distance offshore power transmission requires longer cables, and cross-linked polyethylene (XLPE) has become the primary insulation material for high voltage direct current (HVDC) cables due to its excellent electrical insulation properties. However, antioxidants may degrade during thermal-oxidative aging, thereby affecting the mechanical properties of XLPE. Consequently, optimizing the antioxidant system to enhance resistance to thermal-oxidative aging of XLPE has become a key research focus in the industry. This study investigates the effects of different antioxidants on the mechanical properties of XLPE under thermal-oxidative aging conditions, providing theoretical and experimental support for developing insulation materials for long-distance cables. Four antioxidants (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{3 0 0} \boldsymbol{,} \mathbf{1 0 1 0} \boldsymbol{,} \mathbf{1 0 3 5} \boldsymbol{,} \mathbf{1 0 7 6}$</tex>) were used to prepare XLPE sheets via low-density polyethylene (LDPE) melt blending, dicumyl peroxide (DCP) impregnation, and hotpress cross-linking. Subsequently, yellowness index(YI) of samples was measured before and after thermal-oxidative aging, revealing varying degrees of yellowing in XLPE with different antioxidant formulations. The effects of different antioxidants and DCP content on the mechanical tensile properties of XLPE before and after thermal-oxidative aging were then analyzed. Finally, the gel content of the insulation materials was measured to explore the mechanism by which antioxidants influence thermal-oxidative aging resistance of XLPE. The results indicate that: (1) After thermal-oxidative aging, XLPE with different antioxidant formulations exhibited varying YI, with antioxidant 1076 showing the least discoloration. This indicates that fewer hydroxyl groups in antioxidant 1076 were oxidized to form chromophores (such as <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{C}=\mathrm{O}$</tex>), demonstrating superior thermal-oxidative aging resistance. (2) Thermal-oxidative aging reduced the crosslinking degree in all XLPE samples, primarily due to oxidative degradation causing cross-link breakage and main-chain scission. (3) Both elongation at break and tensile strength of XLPE increased after thermal-oxidative aging, while the relative performance trends among different antioxidants remained consistent.This study provides experimental evidence for optimizing the thermal-oxidative aging resistance of XLPE insulation materials and offers guidance for material design and application in HVDC cable.

ABSTRACTIn this study, three kinds of surface‐modified silica were synthesized to improve their compatibility with silicone rubber and the flame‐retardant effect. The introduction of modified silica not only enhanced the mechanical properties of silicone rubber, especially the tensile strength and elongation at break, but also improved its electrical insulation properties significantly, including increased volume resistivity and breakdown strength. The tensile strength and elongation at break of SR/SBM‐1 (10.8 MPa, 431%) are 8.0% and 4.4% higher than those of SR/SB (10.0 MPa, 413%), respectively. In addition, the modified silicone rubber showed excellent flame retardancy, with an increased limiting oxygen index (LOI) of 34.7% and V‐1 rating in the UL‐94 vertical flame test of SR/SBM‐2, while the LOI of SR/SB was only 31.3%. The phosphorus‐containing polysilazane‐modified silica also provided the silicone rubber with excellent resistance to thermal and radiation aging, which ensures the stability of the physical and chemical properties during long‐term use. The phosphorus‐containing polysilazane‐modified silica significantly improved the overall performance of silicone rubber, making it more reliable and high‐performance material for high‐end applications such as aerospace, power systems and electronic devices.

Switching-induced stress waves (SSW) are recognized as a promising non-invasive technology for real-time monitoring of power module packaging failures, though limited by the lack of a comprehensive understanding of their characteristics and propagation mechanisms. In this study, a dedicated SSW detection platform was developed for SiC MOSFET power modules, where the mechanical wave nature was verified through time-delay analysis. Dominant frequency components at 150 kHz and 270 kHz were identified using both piezoelectric ceramic and PVDF sensors. Experimental investigations further demonstrated that the time-domain parameters of SSW were predominantly influenced by bus voltage (UDC), followed by load current (IR), whereas principal frequency components remained stable across operational conditions. Propagation effects through the module were systematically analyzed via finite element modeling, revealing a 5.82% increase in signal amplitude and 5.88% spectral bandwidth expansion after transmission. These results confirm that sensor-captured signals can be effectively equated to original chip vibrations in defect-free propagation paths.

The study on the preparation of a styrene-free unsaturated polyester using diallyl phthalate as a cross-linking agent, and the cross-linking reaction conditions for the preparation of unsaturated polyester through cross-linking and curing reaction of this cross-linking agent were studied. In this paper, the effects of the amount of initiator, curing temperature and curing time on the properties of unsaturated polyesters under two initiator systems, benzoyl peroxide (BPO) and tert-butyl peroxybenzoate (TBPB), were studied. Through research, it is found that under the two initiator systems, appropriately increasing the amount of initiator, increasing the curing temperature and prolonging the curing time are all beneficial to improve the tensile strength, flexural strength and thermal deformation temperature of unsaturated polyester, but unsaturated polyester The toughness of the ester is also deteriorated and the impact resistance is reduced. When the amount of initiator, curing temperature and curing time exceed a certain value, the change trend of these properties becomes slower. The initiation temperature required for the BPO initiated system is slightly lower than that of the TBPB initiated system. This study focuses on the preparation of a styrene-free unsaturated polyester using diallyl phthalate (DAP) as a cross-linking agent and systematically investigates the cross-linking reaction conditions. The effects of initiator type (benzoyl peroxide, BPO, and tert-butyl peroxybenzoate, TBPB), initiator content (1%–5%), curing temperature (100–140°C), and curing time (2–6 h) on the mechanical and thermal properties of the unsaturated polyester were evaluated. Experimental results indicate that increasing initiator content, curing temperature, and curing time within optimal ranges significantly enhances tensile strength, flexural strength, and heat deflection temperature (HDT). 本文开展了以邻苯二甲酸二烯丙酯为交联剂制备无苯乙烯不饱和聚酯的研究，并对这种交联剂进行交联固化反应制备不饱和聚酯的交联反应条件进行了研究。本文研究了过氧化苯甲酰（BPO）和过氧化苯甲酸叔丁酯（TBPB）两种引发体系下引发剂的用量、固化的温度和固化的时间等因素对不饱和聚酯性能的影响。通过研究发现，两种引发体系下，适当增 加引发剂的用量、提升固化温度和延长固化时间的，都有利于提升不饱和聚酯的拉伸强度、弯曲强度与热变形温度，但不饱和聚酯的韧性也因此变差，抗冲击性能下降。当引发剂用量、固化温度及固化时间超过一定数值后这些性能的变化趋势变缓。BPO引发体系比TBPB引发体系所需的引发温度略低。