PA66 GF30

Nylon is widely used in automotive components, outdoor devices, electrical connectors, and industrial mechanisms due to its balance of strength, wear resistance, and cost. Under normal temperatures, PA6 and PA66 maintain stable toughness, but their performance deteriorates significantly in sub-zero environments. When the temperature drops to –20°C or lower, molecular mobility decreases sharply, causing brittleness, lower impact strength, and unstable dimensional behavior. Components intended for long-term outdoor exposure or cold-climate operation therefore require specially modified nylon to ensure reliability. The loss of toughness originates from the molecular freezing effect around the glass transition temperature. As temperature drops, chain mobility is restricted, and the material transitions from a ductile to a brittle response. Impact loads can no longer be dissipated through plastic deformation, resulting in rapid crack propagation. If a component contains thin ribs, sharp corners, snap-fits, or holes, these geometries intensify stress concentration and accelerate brittle failure. For devices such as drones, snow tools, cold-climate automotive parts, and polar monitoring equipment, the consequences are severe. Low-temperature toughness enhancement typically involves rubber toughening, block copolymer structures, nano-filler modification, and molecular chain-end adjustment. Rubber toughening systems such as POE, EPDM-g-MA, and ABS-g-MA disperse small rubber domains throughout the nylon matrix. During impact, these domains initiate shear banding and localized yielding that help dissipate energy. This approach must balance stiffness, flowability, and thermal stability to avoid excessive softening. Block copolymers provide a more intrinsic modification route. By integrating flexible segments into the polymer backbone, nylon retains chain mobility even at low temperatures. This method minimizes phase separation and maintains structural uniformity, improving durability in applications requiring high reliability. Nano-filler technology further enhances low-temperature behavior. Materials such as graphene, nano-silica, and nano-elastomers improve crack propagation resistance and interfacial strength without severely reducing stiffness. Additionally, nano-scale reinforcement improves dimensional stability by reducing internal stresses caused by uneven shrinkage at low temperatures. Design strategies are equally important. Fillet transitions, uniform wall thickness, fiber orientation control, and proper gate placement all play a role. In fiber-reinforced nylon, fiber alignment strongly influences low-temperature impact performance. Excessive orientation leads to directional brittleness. Optimizing melt flow paths or altering part geometry helps mitigate these effects. Low-temperature tough nylon is widely used in front-end automotive modules, sensor brackets, housings for exterior cameras, drone landing gears, and ski equipment connectors. These components must maintain integrity at temperatures reaching –30°C or –40°C without brittle failure. Future development will focus on highly efficient toughening systems, refined molecular engineering, and multi-scale composite structures. Emerging trends include nano-elastomer reinforcement, high-crystallinity controlled structures, and bio-based cold-resistant nylons. With the rising need for extreme-environment applications, low-temperature toughness becomes not just a material property but an engineering capability influencing design, tooling, and long-term reliability evaluation.

High-flow nylon materials have gained prominence as industries move toward lightweight structures and increasingly complex geometries. Automotive components, electrical devices, 3D-printed parts, and compact consumer products all require materials capable of filling thin-wall sections, micro-features, and extended flow paths. Conventional nylon grades, despite their balanced mechanical, thermal, and chemical resistance properties, often struggle with limited flow behavior during injection molding. Modern high-flow nylon grades, enabled by advances in molecular weight control, lubrication packages, and optimized reinforcement systems, form a unique class of materials that improves molding performance, aesthetic quality, and structural integrity. One of the strongest advantages of high-flow nylon is its ability to fill thin-wall regions with significantly lower injection pressure. For wall thicknesses below 0.6 mm, standard PA6 or PA66 grades tend to generate short shots, uneven filling, and visible weld lines. High-flow grades exhibit less sensitivity to shear, allowing the melt to maintain low viscosity even at high shear rates. As a result, thin-wall molds can be fully packed without excessive pressure or clamp force, reducing energy consumption and extending equipment life. Their enhanced front-flow stability ensures more complete filling in micro-ribs and elongated features, improving dimensional fidelity. High-flow nylon also improves the thermal balance of thin-wall molding. Because the melt fills the cavity more rapidly, solidification occurs more uniformly, minimizing internal stress and cold spots in regions with variable thickness. This contributes directly to improved fatigue resistance and long-term durability. Surface aesthetics benefit as well; reduced melt viscosity allows the polymer to replicate fine mold textures with superior clarity. For reinforced grades, glass or carbon fibers disperse more evenly, lowering the visibility of flow marks and fiber streaks. From a tooling perspective, high-flow nylon gives engineers greater design freedom. Fewer gate points are needed to achieve complete filling, reducing weld-line formation and enhancing overall appearance. The material’s reduced sensitivity to mold temperature allows stable molding even under moderate thermal conditions, shortening cycle times. Lower injection pressure also reduces mechanical stress on molds, extending their usable life. Industrial demand for high-flow nylons continues to grow. Electric vehicles rely on thin-wall connectors, compact motor housings, and complex structural components that benefit from extended flow capability. In 3D printing, high-flow nylon formulations help stabilize melt behavior in powder bed fusion, improving density and dimensional accuracy. Consumer electronics and smart devices increasingly utilize thin, lightweight enclosures and precision snap-fits, applications where high-flow nylon delivers enhanced durability and structural reliability. Future research will focus on balancing flow performance with mechanical strength and thermal stability. Advances in nano-reinforcement, interfacial chemistry, and polymer chain architecture will enable new high-flow compounds suitable for extreme environments and more integrated structural designs. As thin-wall structures continue to dominate product development, high-flow nylon will remain a key material driving innovation across multiple industries.

Global manufacturing is undergoing a rapid transition toward low-carbon and sustainability-oriented development, and nylon modification has also entered a stage where environmental indicators are as crucial as mechanical performance or processing stability. For many downstream industries, a material’s carbon footprint has become a decisive factor in supplier selection, especially in sectors such as automotive, electrical and electronic devices, household appliances, and industrial components. As international customers raise the requirements for lifecycle-based environmental transparency, nylon compounders must establish scientific, traceable, and auditable methodologies to calculate carbon footprints and align with ISO and European certification schemes. The methodological foundation for carbon footprint quantification is built upon ISO 14040 and ISO 14067, which define the framework of life-cycle assessment (LCA). For nylon compounds, the LCA boundary typically includes raw material acquisition, transportation, compounding processes, product usage, and end-of-life disposal. However, nylon modification is highly complex because each additive system—such as glass fiber reinforcement, flame retardants, impact modifiers, wear-resistant agents, and compatibilizers—can significantly alter the emission boundary. Since glass fiber production itself consumes large amounts of energy, and since recycled nylon materials have substantially lower carbon intensities than virgin resin, the precise selection of data inputs is critical. As more customers require Product Carbon Footprint (PCF) disclosures, nylon manufacturers must provide high-accuracy data that can withstand third-party verification. The most challenging aspect of carbon footprint calculation is data quality. Many material producers rely on generic industrial databases because they lack energy-monitoring systems capable of measuring consumption at the process level. In recent years, factories have begun installing energy-metering equipment to monitor extruder power consumption, drying system load, air-compression energy use, and other operational metrics. These values, recorded on a per-batch or per-hour basis, significantly improve the accuracy of PCF calculations. On the raw material side, suppliers must provide specific emission factors for PA6 and PA66 virgin resin, chemically recycled grades, mechanical recycled grades, glass fiber, flame retardants, elastomeric modifiers, and other additives. When these datasets are aggregated under a clearly defined system boundary, the resulting PCF becomes a reliable metric for comparing different formulations or optimizing development paths. As the European market progressively tightens its decarbonization regulations, international certification systems are playing an increasingly important role in the nylon modification sector. ISCC PLUS, one of the most widely adopted schemes in the materials industry, implements the mass-balance approach to assign sustainability attributes to certified feedstocks. This allows manufacturers to gradually replace fossil-based raw materials with bio-based or recycled alternatives while maintaining their existing equipment. In parallel, the upcoming Carbon Border Adjustment Mechanism (CBAM) in the European Union is pushing exporters to provide transparent emissions information for energy-intensive materials such as engineering plastics. For nylon producers with strong exposure to European markets, establishing a robust and auditable carbon-management system is no longer optional. Driven by these regulatory and market shifts, nylon compounders are increasingly adopting low-carbon design principles in their formulation strategies. In glass-fiber-reinforced systems, some developers are attempting to partially replace conventional high-content glass fiber with hybrid modulus-enhancing fillers, thereby reducing embodied emissions while maintaining stiffness and strength. Chemically recycled PA6/PA66 has become an important pathway to reduce the upstream carbon footprint of materials, as its carbon intensity can be significantly lower than virgin resin. Meanwhile, energy-efficient extrusion technologies, short-cycle drying systems, and optimized mixing processes are contributing to reductions in production-stage emissions. Digital carbon-management platforms allow enterprises to construct emission baselines for different customer segments, enabling them to provide tailored低-carbon solutions for automotive OEMs, appliance brands, and industrial equipment manufacturers. Overall, carbon footprint accounting is evolving from a peripheral marketing concept into a key competitive factor in the nylon modification industry. As policies tighten, customer expectations rise, and supply-chain transparency increases, companies that establish rigorous quantification systems, obtain internationally recognized certifications, and continuously improve low-carbon formulations will secure stronger positions in the global materials market.

In the home appliance industry, electrical insulation and thermal stability have always been central to material selection. As appliances move toward higher power density, compact design, and smarter functionality, traditional PA6 or PA66 resins no longer meet the insulation and thermal demands under high-voltage, long-duration operation. Thus, high-CTI and high-heat-resistant modified nylons have become the mainstream trend. High Comparative Tracking Index (CTI) nylon materials address the risks of tracking and dielectric breakdown, maintaining insulation performance even in humid, hot, and contaminated conditions. A higher CTI value indicates better resistance to electrical tracking. Components such as motor housings, relay sockets, connectors, and switches are exposed to long-term electrical stress and local heating, leading to potential surface tracking when moisture or contamination is present. Standard PA66 offers a CTI below 400 V, while modified grades can achieve 600 V or higher, providing a safer margin for high-voltage applications. The enhancement of CTI is achieved by incorporating anti-tracking fillers, halogen-free flame retardants, and dispersion control technology, which collectively reduce surface conductivity and ion migration. Thermal resistance is another key factor for appliance components operating near heat sources, such as coffee machines, air fryers, or power tool stator brackets. Standard nylons tend to lose strength and become brittle after prolonged thermal aging. To overcome this, aromatic structures, heat stabilizers, and reinforcement systems are integrated into the polymer chain. Common modification systems include PA66/PPA blends, PA6T copolymers, and high-crystallinity nylon matrices. These materials can reach heat deflection temperatures (HDT) above 240°C and glass transition temperatures (Tg) above 120°C while maintaining good mechanical and flow properties. In terms of flame retardancy, high-CTI nylons typically meet the UL94 V-0 rating without using halogen-based systems. Modern formulations rely on phosphorus-based or nitrogen–phosphorus synergistic flame retardants, forming a stable char layer that blocks flame propagation and suppresses smoke generation. This ensures compliance with IEC 60335 and RoHS standards while maintaining consistent appearance and performance reliability. From a processing perspective, high-CTI, heat-resistant nylons require balanced rheology. Their filled systems increase melt viscosity, so optimized molding conditions are needed: mold temperature between 90–110°C, extended holding pressure, and vacuum venting to prevent trapped gases. For thin-wall parts, PA66/PA6 blends or flow-enhanced formulations help maintain insulation with improved processability. A 30–35% glass fiber content is usually optimal for dimensional stability without sacrificing surface quality. Future development will emphasize sustainability and smarter material design. Bio-based nylons like PA610 and PA1010 combined with halogen-free, high-CTI systems represent eco-friendly alternatives. As appliances continue to evolve toward higher energy density, materials must ensure enhanced insulation, longer thermal aging resistance, and stable dielectric properties, driving the use of high-Tg nylons and PPA copolymers. The ultimate goal is to achieve a “high safety, high heat resistance, low environmental impact” material solution.    

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.