PA66 GF30

In the field of electronics and electrical appliances, high-CTI (Comparative Tracking Index) nylon materials are increasingly favoured by design engineers and materials scientists due to their excellent electrical corrosion resistance and insulation performance. Choosing the proper high-CTI nylon affects not only product safety, but also service life, reliability, and cost. Therefore, the selection strategy must consider multiple aspects comprehensively. It is crucial to understand the physical meaning of the CTI metric. The CTI value reflects a material’s ability to resist surface tracking or electrical discharge under conditions of high humidity and pollution. The higher the CTI, the less likely a material is to develop arcs or conductive paths on its surface when exposed to damp conditions. This is especially important for housings, switches, sockets, and other components exposed to air that may contain dirt or moisture. Generally, a CTI value of 400 V or above is considered high-grade, suitable for outdoor or high humidity environments; for indoor consumer electronics, CTI values between 175 V and 250 V are common and often sufficient. One must consider the material’s thermal performance and glass transition temperature (Tg). In electronics, the heating of circuit boards, components, and even the outer casing impose high temperature loads on materials. Although nylon (polyamide) naturally provides good heat resistance, its specifications vary greatly. You must examine both the continuous operating temperature and the transient peak temperature, and whether the CTI value degrades under high-temperature conditions. Also important is whether the material is modified with heat stabilizers or glass fibre reinforcements; these can enhance thermal performance, but may also affect electrical insulation (e.g. exposed fibres might alter surface corona propagation paths). The moisture absorption rate and its effect on electrical characteristics cannot be ignored. Nylon tends to absorb water; when hydrated, its insulating properties deteriorate, volume swells, mechanical strength drops, and the CTI value may fall significantly. In practice, inspect how the material behaves under saturated absorption: whether its tracking or arcing resistance in soaked state remains acceptable. If the environment involves high humidity or rapid temperature changes, also consider performance after repeated wet-dry cycles. Some high-CTI nylons are modified (with carbon black or other additives) to reduce water uptake; although more costly, these materials are often more reliable under harsh conditions. Processing behaviour and forming method requirements are important. Housings, pin seats, connectors, etc., are usually manufactured by injection moulding, extrusion, or other plastic forming processes. High-CTI nylon, particularly when filled (glass fibre, inorganic powders, carbon black) or weather-stabilised, may change melt flow behaviour, viscosity, melt flow index (MFI), and the melt temperature. These will affect mould design, wall thickness uniformity, demoulding difficulty, and surface finish quality. Poor flow may lead to short shots, weld lines, air bubbles, or sink marks. Thus, when selecting material, one must obtain from datasheets the melt index, melting temperature, processing temperature range, and ensure they match the equipment’s capability. Long-term reliability and environmental regulation must be considered. Products in this sector often require lifetimes of several years or more. The performance degradation over time under temperature, humidity, and electrical stress is expected. Key issues are whether high-CTI nylon will oxidise, yellow, embrittle, or crack. Also it must comply with regulations such as RoHS, REACH: using non-toxic flame retardants, not containing prohibited substances; additives should not compromise recyclability. Also one should check whether the supplier provides accelerated ageing test data (high temperature, high humidity, voltage cycling) and whether the material sample is certified under UL or IEC standards. Cost and supply chain stability should not be underestimated. High performance nylon often carries higher costs for raw materials, fillers, colorants, safety flame retardants than standard nylon. Design teams must balance performance requirements with cost budget. In mass-produced equipment like household appliances, power adapters, communication devices, material cost and processing efficiency directly influence the overall cost. Also, supplier lead time, batch-to-batch consistency (variation in performance between lots) can directly affect manufacturing reliability. Choosing a reputable high-CTI nylon brand, understanding its global or local inventory, and having alternative sources to cover supply disruptions are hallmarks of mature material selection strategy. Comprehensive testing and prototype validation are indispensable. Theoretical datasheets are instructive, but actual performance in end-use is influenced by environmental conditions, structural design, wall thickness distribution, surface finish and more. Design engineers should request material samples and conduct real assembly testing in expected environments, including extreme temperature/humidity cycling, dielectric withstand tests, surface tracking tests, thermal shock, mechanical strength tests, etc., to verify the material’s behaviour in specific applications. Also allow design margin to accommodate performance degradation. In summary, selecting high-CTI nylon materials in electronics and electrical appliances is a multi-factor trade-off: one must look beyond just insulation metrics to consider thermal resistance, moisture absorption, processability, reliability and regulatory compliance. Only when performance, cost, manufacture, and regulation are all balanced can the final product achieve safety, longevity, and market competitiveness.

Nylon as a high-performance engineering plastic, is widely used in automotive, electronics, electrical, and mechanical industries due to its excellent comprehensive properties. However, the presence of numerous amide groups in its molecular chain imparts strong polarity, making nylon prone to moisture absorption through hydrogen bonding. This inherent hygroscopicity affects not only dimensional stability but also alters mechanical properties and even degrades electrical performance, posing a potential risk for precision and long-term applications. Therefore, strict drying before processing is critical to ensuring product quality. Moisture influences nylon in two ways. First, water acts as a plasticizer, lowering the glass transition temperature, softening the material, accelerating creep, and reducing dimensional accuracy. Second, under high-temperature melt conditions, residual moisture causes hydrolysis, breaking polymer chains, reducing molecular weight, and significantly weakening mechanical performance. For injection molding, excessive moisture results in splay marks, bubbles, and poor surface gloss; for extrusion and fiber spinning, moisture compromises tensile strength and long-term reliability. Industry standards generally require moisture content below 0.12% before processing, and for precision parts, under 0.08%. Common drying technologies include hot-air ovens, desiccant dryers, vacuum dryers, and infrared drying, each with its own advantages and limitations. Traditional hot-air ovens heat the surrounding air to reduce humidity and evaporate moisture, offering low cost but slow drying speed and inconsistent results in humid environments, often causing reabsorption. Desiccant dryers use adsorbents or rotor systems to lower air dew point below -30°C, providing efficient and consistent drying, making them the most common industrial choice. Vacuum drying reduces pressure to lower the boiling point of water, enabling rapid moisture removal with thorough results, but higher equipment cost and limited suitability to small batches. Infrared drying uses high-energy radiation to penetrate and heat resin granules internally, offering the fastest drying speed and low energy consumption, though it requires careful process control to prevent local overheating or thermal degradation. The choice of drying process depends on production scale, cost, energy consumption, and product requirements. For large-scale injection molding, desiccant dryers are preferred for their stability and automation, while vacuum or infrared drying suits R&D, small batches, or time-critical operations. Regardless of method, strict moisture verification with infrared analyzers or Karl Fischer titration is essential. Additionally, dried nylon must be stored and transported in sealed containers and closed systems to prevent reabsorption. Controlling nylon moisture content is not only key to ensuring dimensional accuracy and mechanical strength but also critical for long-term stability and electrical performance. With the rise of smart manufacturing, future drying systems will incorporate real-time monitoring and closed-loop control, achieving higher precision and energy efficiency to meet stringent performance requirements of advanced engineering plastics.

Nylon is one of the most widely used engineering plastics, valued for its strength, toughness, and wear resistance in industries such as automotive, electronics, and consumer goods. However, its molecular structure contains a large number of amide groups, which have a strong affinity for water molecules. This intrinsic feature makes nylon highly hygroscopic, and when exposed to humid environments, it readily absorbs moisture. Such moisture absorption significantly affects both mechanical properties and dimensional stability, often leading to unexpected failures. When nylon absorbs moisture, water molecules penetrate the intermolecular spaces and form hydrogen bonds. This process weakens the original hydrogen bonding between chains and increases molecular mobility. In the short term, toughness and impact resistance may improve, but tensile strength decreases over time. In structural components, repeated cycles of swelling and shrinkage during humidity changes introduce residual stresses that can cause warpage, deformation, and cracking. In electronics, moisture-induced dimensional changes may compromise precision, disrupt assembly tolerances, and even cause electrical contact failure. In automotive applications, nylon parts such as gears and connectors may lose strength due to water absorption, resulting in reduced fatigue life or sudden failure. Under alternating hot and cold conditions, the freezing or evaporation of absorbed water further amplifies these destructive effects. Moisture absorption also lowers the glass transition temperature of nylon, causing it to shift from a rigid state to a softer, unstable one. For applications requiring long-term stiffness, this is highly detrimental. When the absorbed water eventually evaporates, the material becomes brittle again, concentrating stresses and promoting cracking. This alternating cycle of embrittlement and deformation makes nylon components prone to unpredictable failure in real-world conditions. Several solutions have been developed to address nylon’s hygroscopicity. Copolymerization, such as PA6/66 copolymers or the introduction of hydrophobic monomers, can reduce the number of polar groups. Reinforcement with glass or carbon fibers helps limit swelling and improve dimensional stability. Surface coatings or barrier layers can reduce water penetration. In manufacturing, thorough drying before molding is essential to maintain low moisture content. For demanding environments, high-performance modified nylons such as PA6T or PA9T offer significantly lower water absorption due to their denser molecular structures. Nylon’s moisture absorption issue is the combined result of its molecular structure and environmental factors. It may increase toughness in the short term but compromises strength and dimensional stability in the long run. Engineers must account for the dynamic impact of moisture and adopt suitable modification and design strategies. Only by understanding the mechanisms thoroughly can nylon components maintain reliable performance under complex operating conditions.

Nylon, as a key engineering plastic, has evolved from a general-purpose material to a variety of performance-adjustable modified products since its invention in the last century. Among them, PA6 and PA66 are the most common base types. Although their molecular structures are similar, their performance differs slightly. PA66 has advantages in crystallinity, heat resistance, and rigidity, while PA6 offers better toughness and different moisture absorption characteristics. In the early stage of industrialization, these materials were mainly used in their virgin form for fibers, gears, and bearings. However, as industrial demands increased, single-property nylon materials could no longer meet complex application requirements, leading to the emergence of modified nylon. Modified nylon is produced by physically or chemically adjusting the performance of base PA6 or PA66. Common modification methods include reinforcement, toughening, flame retardancy, wear resistance, and weather resistance. Reinforcement often involves adding glass fibers, carbon fibers, or mineral fillers to improve mechanical strength and dimensional stability. Toughening typically uses elastomeric rubbers to enhance low-temperature impact resistance. Flame retardant modification introduces phosphorus- or nitrogen-based systems into the polymer structure to meet safety standards in the electrical and electronics industries. These modifications not only alter physical properties but also expand nylon’s application boundaries in automotive, home appliances, electronics, and industrial machinery. The evolution of these materials is driven by application requirements. For example, components in automotive engine compartments must operate for long periods under high temperatures and exposure to oil, demanding excellent heat stability, chemical resistance, and mechanical strength. Traditional PA6 or PA66 would degrade under such conditions, while glass fiber-reinforced and heat-stabilized nylon maintains its performance. In the electronics sector, components such as sockets and switches require flame retardancy while maintaining electrical insulation and dimensional accuracy, which has driven the widespread adoption of flame-retardant reinforced nylon. The development of modified nylon is also closely tied to advances in processing technology. Modern modification processes go beyond traditional twin-screw compounding to include nano-filler dispersion technology, reactive extrusion, and intelligent formulation design, enabling balanced performance while maintaining uniformity and processability. This synergy between materials and processing allows modified nylon to be tailored precisely for specific applications rather than serving as a simple universal replacement. From the virgin forms of PA6 and PA66 to the wide variety of modification options available today, the evolution of these materials reflects the broader trend in the engineering plastics industry toward diversified performance and specialized applications. In the future, with the deepening focus on sustainability and the circular economy, modification technologies based on recycled nylon will become a research hotspot, achieving a balance between material performance and environmental requirements. This represents not only scientific progress in materials but also a shift of the entire value chain toward higher added value.

Nylon, as one of the most important engineering plastics, has been widely used in automotive, electrical and mechanical manufacturing fields due to its excellent mechanical strength, wear resistance and chemical corrosion resistance. However, the high water absorption characteristics of nylon materials have become a key bottleneck limiting its application in precision engineering. The saturated water absorption rates of nylon 6 and nylon 66 can reach 9.5% and 8.5% respectively, which originates from the hydrogen bonding between polar amide groups (-CONH-) in molecular chains and water molecules. When environmental humidity changes, nylon products will expand due to water absorption or shrink due to water loss, seriously affecting the assembly accuracy and service performance of parts. In engineering practice, the primary method to improve the dimensional stability of nylon is to add inorganic fillers for reinforced modification. Glass fiber is the most commonly used reinforcing material. Adding 30%-50% glass fiber can reduce the water absorption of nylon by 40%-60%, while significantly improving its mechanical strength and heat deflection temperature. Although carbon fiber is more expensive, it can not only reduce water absorption but also endow materials with conductivity and higher rigidity. In recent years, nano-scale fillers such as montmorillonite and talc have attracted widespread attention. These nano-fillers can significantly slow down the water absorption rate by prolonging the diffusion path of water molecules in materials. Studies show that adding 5% organically modified montmorillonite can reduce the water absorption of nylon 6 by more than 30%. Chemical modification is a fundamental method to solve the water absorption problem of nylon at the molecular structure level. Through end-capping technology, using reagents such as anhydride or isocyanate to react with amino or carboxyl groups at the end of nylon chains can effectively reduce active sites for hydrogen bonding with water molecules. Epoxy resin modification can introduce cross-linked structures between nylon molecular chains, which not only reduces water absorption but also improves the heat resistance and dimensional stability of materials. Radiation cross-linking is another effective chemical modification method. Through electron beam or γ-ray irradiation, a three-dimensional network structure is formed between nylon molecular chains, which can control water absorption below 3%. The cross-linked nylon material developed by Ube Industries is a typical case of successful application of this technology. Polymer blending is an important way to improve the dimensional stability of nylon. Blending nylon with hydrophobic polymers such as polyolefins (PP, PE) or polyphenylene sulfide (PPS) can significantly reduce the overall water absorption of composite materials. However, due to the poor compatibility between these polymers and nylon, compatibilizers are usually needed to improve interfacial bonding. Maleic anhydride grafted polyolefin is the most commonly used compatibilizer, which can react with the terminal amino groups of nylon to form chemical bonds at the interface. The Zytel series products developed by DuPont in the United States have achieved excellent dimensional stability through this technology and are widely used in precision components such as automotive fuel systems and electronic connectors. Surface treatment technology provides another solution to improve the dimensional stability of nylon. Plasma treatment can introduce hydrophobic groups on the material surface to form a water barrier. Fluorocarbon coating and silane coupling agent treatment can construct superhydrophobic structures on the nylon surface, making the water contact angle reach more than 150°. The fluorinated nylon material developed by Daikin Industries in Japan can reduce water absorption to 1/3 of ordinary nylon. These surface treatment technologies are particularly suitable for application scenarios that need to maintain substrate performance while requiring low water absorption, such as precision gears, bearings and other mechanical parts. In practical engineering applications, appropriate modification schemes need to be selected according to specific use environments and performance requirements. For the high temperature and humidity environment in automobile engine compartments, a comprehensive scheme combining glass fiber reinforcement and chemical cross-linking is usually adopted; electronic connectors are more often selected with a combination of mineral filling and surface treatment; while medical devices often need to adopt nano-composite materials with better biocompatibility. With the progress of materials science, new modification technologies such as in-situ polymerized nanocomposites and ionic liquid modification continue to emerge, providing more possibilities to solve the water absorption problem of nylon. Through continuous material innovation and process optimization, nylon materials will surely gain wider applications in more high-precision fields.

Nylon (polyamide) is a high-performance engineering plastic widely used in automotive components, electronics, textiles, sports equipment, and outdoor gear due to its excellent mechanical strength, wear resistance, and chemical stability. However, prolonged exposure to ultraviolet (UV) radiation can lead to photo-oxidative degradation, causing chain scission, yellowing, surface chalking, and deterioration of mechanical properties. This significantly impacts both the lifespan and appearance of nylon products, particularly in outdoor applications such as automotive exteriors, construction materials, and sporting goods. Therefore, enhancing the UV resistance of nylon through material modification has become a critical research focus in polymer science and engineering. Ultraviolet absorbers (UVAs) are one of the most effective additives for improving nylon’s UV stability. These compounds selectively absorb UV light (particularly in the 290-400 nm range, including UV-A and UV-B) and convert it into harmless thermal energy, thereby minimizing damage to the polymer matrix. Common UVAs include benzotriazoles (e.g., BASF’s Tinuvin 326, Tinuvin 328) and benzophenones (e.g., Clariant’s Chimassorb 81). To ensure optimal performance, UVAs must be uniformly dispersed in the nylon matrix, typically via melt blending or masterbatch incorporation. Studies show that adding 0.5%-2% UVA can significantly delay photoaging, extending the service life of nylon in outdoor environments.   Hindered amine light stabilizers (HALS) are another essential class of additives for UV protection. Unlike UVAs, HALS do not absorb UV radiation but instead scavenge free radicals generated during photo-oxidation, thereby inhibiting degradation. Notable commercial HALS products include Tinuvin 770 (BASF) and Cyasorb UV-3853 (Solvay). Due to their long-term stability, HALS are particularly suitable for high-durability applications. Importantly, UVAs and HALS exhibit a synergistic effect—combining them (e.g., Tinuvin 326 + Tinuvin 770) provides comprehensive UV shielding by both absorbing radiation and suppressing radical reactions, significantly enhancing nylon’s weatherability.   Incorporating inorganic nanoparticles is another effective strategy to improve UV resistance. Metal oxides such as titanium dioxide (TiO₂) and zinc oxide (ZnO) are widely used due to their ability to scatter and reflect UV light. Rutile TiO₂, with its high refractive index, offers excellent UV blocking while improving rigidity and thermal stability. Nano-ZnO not only shields UV but also provides antibacterial properties, making it suitable for medical and packaging applications. To ensure uniform dispersion, surface modification (e.g., silane coupling agents) is often applied to prevent agglomeration and enhance interfacial adhesion. Additionally, advanced nanomaterials like carbon nanotubes (CNTs) and graphene are being explored for UV protection, as they can absorb radiation while improving electrical conductivity and mechanical strength.   Polymer blending is another viable approach to enhance UV stability. By blending nylon with inherently UV-resistant polymers (e.g., polycarbonate (PC) or polyphenylene oxide (PPO)), its susceptibility to degradation can be reduced. However, due to poor compatibility, compatibilizers (e.g., maleic anhydride-grafted polyethylene) are often required to improve interfacial adhesion. Chemical modifications, such as grafting or crosslinking, can also improve UV resistance. For instance, introducing acrylate or styrene monomers onto nylon chains can reduce photo-oxidation, enhancing long-term stability.   In practical applications, the choice of UV stabilization strategy depends on cost, processing requirements, and end-use conditions. Automotive exterior parts (e.g., door handles, mirror housings) require high-load UVA/HALS combinations with glass fiber reinforcement for dimensional stability. In contrast, electronic components (e.g., connectors, housings) may use lower stabilizer doses due to milder environments. For optically clear applications (e.g., films), low-molecular-weight benzotriazoles are preferred to maintain transparency.   Future trends include developing eco-friendly UV stabilizers (e.g., lignin derivatives, polyphenols) and smart materials (e.g., photochromic additives) for advanced applications. Through continuous innovation, nylon’s UV resistance will further improve, enabling its use in even harsher environments.