38 results about "Relative viscosity" patented technology

The invention belongs to the technical field of high polymer materials, and particularly relates to nylon powder as well as a preparation method and application thereof. The nylon powder comprises high-viscosity nylon resin, low-viscosity nylon resin and an auxiliary agent, the relative viscosity of the high-viscosity nylon resin is 1.75-1.85, and the relative viscosity of the low-viscosity nylon resin is 1.55-1.65; the mass ratio of the high-viscosity nylon resin to the low-viscosity nylon resin is 10: (1-3); the auxiliary agent comprises an antioxidant. The high-viscosity nylon resin with specific viscosity and the low-viscosity nylon resin with specific viscosity are compounded in proportion for use, the high-viscosity nylon resin serves as a framework of a hydrogen storage bottle inner container and provides mechanical property support, and the low-viscosity nylon resin provides fluidity and ensures that a finished bottle has few defects. The mechanical property of the hydrogen storage cylinder liner and the integrity of the liner structure are improved, and the nylon IV type hydrogen storage cylinder liner with high stability and few defects is prepared.

The invention relates to the technical field of bio-based polyamide modification, and discloses a bio-based polyamide modified raw material composition for improving the surface hairiness distribution of bunchy yarn, which comprises the following components in percentage by mass: 2.5-6.0% of bio-based polyamide 1010 resin, 0.5-2.0% of maleic anhydride grafted castor oil polyether with the weight-average molecular weight of 3500-5500g / mol, 0.5-2.0% of maleic anhydride grafted castor oil polyether with the weight-average molecular weight of 3,500-5,500 g / mol, 0.5-2.0% of maleic anhydride grafted castor oil polyether with the weight-average molecular weight of 3,500-5,500 g / mol, the functional components are driven to migrate to a surface layer and generate interface secondary bonding by utilizing reaction activity and temperature drop rate coupling among the components and a temperature drop rate difference generated corresponding to an axial variable cross section of the slub yarn, and a thickness heterogeneous interface layer is spontaneously constructed at slubs and details; the technical contradiction that a homogeneous modified material cannot be matched with a non-uniform thermal field is solved, and the physical integrity of the fiber surface is improved.

The application belongs to the technical field of polymer materials, and particularly relates to a nylon powder and a preparation method and application thereof. The nylon powder comprises high-viscosity nylon resin, low-viscosity nylon resin and an additive, wherein the relative viscosity of the high-viscosity nylon resin is 1.75-1.85, the relative viscosity of the low-viscosity nylon resin is 1.55-1.65, the mass ratio of the high-viscosity nylon resin to the low-viscosity nylon resin is 10:1-3, and the additive comprises an antioxidant. The high-viscosity nylon resin and the low-viscosity nylon resin with specific viscosities are compounded and used in proportion, the high-viscosity nylon resin serves as a skeleton of a hydrogen storage bottle inner container and provides mechanical property support, and the low-viscosity nylon resin provides fluidity and ensures few defects in bottle forming. The use of the nylon powder of the application improves the mechanical property of the hydrogen storage bottle inner container and the integrity of the inner container structure, and a stable and defect-free type IV nylon hydrogen storage bottle inner container is prepared.

This invention relates to a renewable polyamide 56 fiber, its preparation method, and its application. The raw materials for its production include at least a tackifying renewable polyamide 56 resin. The relative viscosity of the tackifying renewable polyamide 56 resin is 2.4-2.9, and its crystallization temperature is 180-210℃. This invention uses a tackifying renewable polyamide 56 resin obtained by tackifying a recycled polyamide 56 resin produced from recycled polyamide waste fibers and waste fabrics as a raw material. This not only enables the production of fibers with mechanical and dyeing properties comparable to conventional polyamide 56 fibers but also achieves the goal of recycling polyamide waste.

The invention discloses a PP / PA composite material as well as a preparation method and application thereof. The PP / PA composite material comprises the following components in parts by weight: 50-80 parts of PA resin; 20 to 50 parts of PP resin; 10 to 30 parts of modified carbon fiber; wherein the relative viscosity of the PA resin is 2.38-2.8, and the melt flow rate of the PP resin under the conditions of 230 DEG C and 2.16 kg is 40-85 g / 10 min; the molar content of silicon on the surface of the modified carbon fiber is greater than or equal to 7%. According to the PP / PA composite material and the preparation method thereof, the modified carbon fibers with the surface silicon element content larger than or equal to 7% are added into a PP / PA system, the melt flow rate of PP resin and the relative viscosity of PA resin are adjusted, so that the system is easier to build a perfect network, and the prepared PP / PA composite material has good electromagnetic shielding effectiveness and meanwhile has good dry and wet mechanical properties.

The invention provides a method for slicing anionic polymerization fiber-grade nylon 6, and belongs to the technical field of chemical preparation. The method comprises the following steps: respectively pouring materials into corresponding reactors, heating, carrying out vacuum dehydration, feeding into a mixing reactor, heating, melting, stirring and devolatilizing after the reaction is completed, and drafting the melt to prepare slices. The technological process is simple, the product quality is stable, the relative viscosity of the obtained nylon 6 slices is 2.8-3.1, the molecular weight distribution is 1.8-2.0, the conversion rate is 98%, and the nylon 6 slices can be directly used for melt spinning without aftertreatment, so that the anionic polymerization nylon 6 breaks through the traditional casting molding field and can be applied to various melt processing environments.

This invention belongs to the field of nylon polymers and discloses a low-temperature preparation method for high-temperature resistant semi-aromatic polyamide, including the following steps: (1) Weigh diacid, diamine, antioxidant, catalyst and deionized water according to the designed molar number, add the raw materials to a high-temperature and high-pressure polymerization reactor, the predetermined temperature of the polymerization reactor is 190-230℃, the pressure is raised to the first predetermined pressure of 1.2-2.6MPa, and the temperature and pressure are maintained for 0.5-3h. The pressure inside the reactor is gradually reduced to the second predetermined pressure of 0.5-1.0MPa by venting, and the venting time is 0.5-3h. Finally, the prepolymer is sprayed out from the bottom of the polymerization reactor to obtain a loose porous dry powder / small particle prepolymer, and there is no prepolymer residue in the reactor; (2) The prepolymer obtained above is subjected to solid-phase post-polymerization in a solid-phase post-polymerization reactor to obtain a high-temperature resistant semi-aromatic polyamide final polymer with a relative viscosity of 2.0-5.0. The method of this invention is suitable for preparing high-temperature resistant semi-aromatic polyamides with different compositions. The resulting prepolymer has a loose and porous powder / small particle structure, which provides a favorable channel for the discharge of water molecules, a byproduct of the solid-state polymerization reaction. This can significantly improve the efficiency of solid-state polymerization, shorten the polymerization time, and reduce energy consumption.

The application belongs to the technical field of polyamides, and particularly relates to a solid-phase viscosity-increasing method for semi-aromatic polyamides. The method comprises the following steps: (1) mixing dicarboxylic acid monomers, diamine monomers, water, a catalyst and a metal compound to perform a salt formation reaction, and then heating to 200-270 DEG C to perform a polymerization reaction, so as to obtain a polyamide resin melt with a relative viscosity of 1.9-2.55; and (2) adding an ester of dicarboxylic acid to the polyamide resin melt, uniformly mixing, and then heating to 175-235 DEG C to perform a solid-phase viscosity-increasing treatment, until the relative viscosity reaches 2.9-3.8, so as to obtain the semi-aromatic polyamide. According to the method, the ester of dicarboxylic acid and the metal compound are introduced, the occurrence of a gel side reaction is significantly inhibited, the solid-phase viscosity-increasing reaction is ensured to maintain a high efficiency, and thus the semi-aromatic polyamide resin with a high relative viscosity and without gel is obtained.

The invention relates to the technical field of textile chemical fiber production, in particular to a production method of chinlon 66 industrial yarn and the chinlon 66 industrial yarn, and the production method comprises the following steps: step 1, performing tackifying treatment on chinlon 66 raw material slices to obtain high-viscosity chinlon 66 slices with formic acid relative viscosity of 75-93; step 2, carrying out humidifying treatment on the high-viscosity chinlon 66 slices obtained in the step 1; 3, the high-viscosity chinlon 66 slices obtained in the step 2 are subjected to melt compression, and chinlon 66 melt is prepared; 4, quantitatively feeding the chinlon 66 melt into a spinning assembly, spraying the chinlon 66 melt through the spinning assembly to form chinlon 66 nascent fibers, and then cooling the chinlon 66 nascent fibers; 5, the cooled nylon-66 nascent fiber is sequentially subjected to oiling, stretching, sizing and winding, and then the nylon-66 industrial yarn is obtained. The invention aims to solve the problem that the industrial yarn produced by the existing production method of the chinlon 66 industrial yarn has higher broken filaments and wool balls.

The invention discloses a polyamide composition as well as a preparation method and application thereof, and relates to the technical field of high polymer materials. The polyamide composition is prepared from the following components in parts by weight: 38 to 52 parts of polyterephthalamide resin; 13 to 56 parts of long carbon chain polyamide resin; 8-22 parts of a flame retardant; 10 to 45 parts of glass fiber; 8-42 parts of a flaky filler; the long carbon chain polyamide resin comprises at least one of PA610 (polyamide 610), PA612 (polyamide 612), PA1010 (polyamide 1010) and PA1012 (polyamide 1012); the relative viscosity of the poly-terephthalamide resin is less than 3.0, and the relative viscosity of the long carbon chain polyamide resin is less than 3.0. The polyamide composition disclosed by the invention has the characteristics of low CLTE, ultrahigh flatness and excellent impact cracking resistance.

The invention discloses a polyamide 12 draw-textured yarn with both high resilience and excellent dimensional stability and a preparation method thereof, polyamide 12 slices with the relative viscosity of 2.0-3.5 are dried until the water content is lower than 700 ppm, melt spinning is performed at the temperature of 210-245 DEG C, and winding is performed at the spinning speed of 1000-4500 m / min to prepare a pre-oriented yarn; then the pre-oriented yarn subjected to hot stretching is subjected to false twisting deformation, the draw ratio is 1.20-1.80, the D / Y ratio is 1.5-2.4, the temperature of a deformation hot box is 100-170 DEG C, the temperature of a microwave-assisted shaping hot box is 120-160 DEG C, and therefore the polyamide 12 stretch-textured yarn is obtained. According to the scheme, by optimizing the pre-oriented yarn structure of the polyamide 12 and precisely controlling the texturing process of deformation and heat setting, the problems of narrow processing window and poor stability of the polyamide 12 in high-speed false twist deformation are solved; the prepared polyamide 12 draw-textured yarn not only retains the characteristics of low water absorption and light weight of the original polyamide 12, but also has high elasticity and excellent dimensional stability, and is suitable for the fields of high-end sportswear, swimwear, medical textiles and the like.

The present application relates to the field of film, particularly to a kind of biaxially oriented polypropylene matt film and its preparation method, matt film includes the matt layer, core layer and light layer arranged in sequence, matt layer includes random copolymer polypropylene and 40~55wt% high density polyethylene;Core layer includes homopolymer polypropylene and 10~15wt% relative viscosity is 2.2~3.5 m-xylylenediamine-adipic acid copolymer;Light layer includes homopolymer polypropylene and 5~10wt% 2,2,6,6-tetramethyl-4-piperidinol graft polyethylene.The present application is through 2,2,6,6-tetramethyl-4-piperidinol graft polyethylene capture polypropylene radical generated by ultraviolet light initiation;Also through m-xylylenediamine-adipic acid copolymer improves the dimensional stability of film under temperature change, and inhibits oxygen from core layer to light layer migration, synergistic inhibition chain degradation, reduce light layer powder, improve the problem of uneven transfer of coating liquid, meet the demand of high-speed production.

The invention discloses a linear easy-to-tear polyamide matt film as well as a preparation method and application thereof, the preparation method comprises the following steps: taking binary acid, 1, 5-pentamethylene diamine and 2-methyl pentamethylene diamine as raw materials, and providing parity polyamide with the relative viscosity of 2-3.2; the odd-even polyamide is subjected to drying, melt extrusion and chilling cooling, and a casting piece is obtained; and carrying out uniaxial stretching treatment on the cast sheet to obtain the linear easy-to-tear polyamide matt film. Compared with a traditional matt polyamide film, the polyamide matt film prepared through the method has double rough surfaces and has the advantages of being high in matt effect and good in matt uniformity.

The application discloses a kind of polyamide composite material and its preparation method and application, it is related to the technical field of plastic.A kind of polyamide composite material includes the following weight parts of component: first PA resin 48-72 parts;Nylon composition 9-26 parts;Nylon composition includes second PA resin and glass fiber, the number ratio of glass fiber in nylon composition is 90-100% in the distribution of the retained length of 500 μm below, the number ratio of glass fiber retained length is 0-10% in the distribution of 500 μm above;The relative viscosity of first PA resin is not less than 2.7, and the relative viscosity of nylon composition is not less than 2.4.The polyamide composite material with excellent surface treatment performance and mechanical properties is prepared by adding nylon composition in first PA resin in the application, is suitable for being used for preparing automobile parts, especially suitable for functional parts needing surface treatment or using special appearance requirements.

The invention discloses a preparation method of a nylon 6 anti-counterfeiting master batch and a fiber thereof, and belongs to the field of high polymer material anti-counterfeiting. Aiming at the defects that the existing fiber anti-counterfeiting technology is easy to imitate, short in anti-counterfeiting service life and complex in identification, the method comprises the following steps: firstly, preparing a yellow polymolybdenum acid crystal by taking polymolybdenum acid (H3 [PMo12O40]. XH2O) as a characteristic substance through a diethyl ether extraction method; carrying out twin-screw extrusion granulation on the master batch, nylon 6 glazed slices, a dispersing agent and a coupling agent, and reducing the master batch at a high temperature by using molybdenum polyacid so that the master batch is green; finally, the anti-fake master batch and nylon 6 slices are dried and then subjected to melt spinning, and the green nylon 6 anti-fake fiber is prepared. The green color of the fiber is derived from a specific in-situ reaction of a process and is difficult to imitate; and the polymolybdenum acid is an inorganic cluster compound, and is durable and stable in washing resistance, illumination resistance and anti-counterfeiting property. The relative viscosity of the prepared anti-fake master batch is 1.8-1.9, the breaking strength of anti-fake fiber (FDY 70D / 24F) is larger than or equal to 3.5 cN / dtex, the performance of the anti-fake fiber is close to that of conventional fiber, and the anti-fake master batch can be widely applied to the high-end textile anti-fake field.

The invention provides an injection speed determination method and device, an injection molding method and device and electronic equipment, and belongs to the field of intelligent manufacturing, and the method comprises the steps that an injection molding machine is controlled to conduct injection according to multiple different set injection speeds, the actual filling time and the actual injection pressure peak value at each set injection speed are obtained, and a relative viscosity index is obtained through calculation; and determining the change trend characteristics of the relative viscosity index along with the set injection speed based on the relative viscosity index, and determining the target injection speed of the injection molding machine. The physical principle that the injection pressure and the filling time represent the viscosity under the constant volume is utilized, a rheology curve can be constructed without an external rheometer, the optimal process point is automatically locked by identifying the stable trend of the curve, the problems that traditional injection molding depends on empirical machine adjustment, and the flowability cannot be objectively quantified are solved, and the production efficiency is improved. And accurate and automatic setting of scientific mold testing and process parameters is realized.

A resin composition including from 10 to 300 parts by mass of reinforcing fibers with respect to 100 parts by mass of a xylylenediamine-based polyamide resin, the xylylenediamine-based polyamide resin containing a diamine unit and a dicarboxylic acid unit, the diamine unit containing 70 mol % or more of a structural unit derived from a xylylenediamine, the dicarboxylic acid unit containing 70 mol % or more of a structural unit derived from an α,ω-linear aliphatic dicarboxylic acid having from 11 to 20 carbon atoms, and the xylylenediamine-based polyamide resin having a relative viscosity of from 1.6 to 2.4.

The invention provides a continuous polymerization preparation method and a preparation system of polyamide, and belongs to the technical field of preparation of compounds. The continuous polymerization preparation method of the polyamide comprises the following steps: carrying out salt forming reaction on metered binary acid and diamine, and carrying out pH regulation to obtain a polyamide salt solution; evaporating and concentrating the polyamide salt solution to obtain a polyamide salt concentrated product; pre-polymerizing the polyamide concentrated product in the first reactor to obtain a polyamide prepolymer; performing condensation polymerization on the prepolymer of the polyamide in a second reactor to obtain a polycondensate of the polyamide; pelletizing the polycondensate of the polyamide to obtain wet slices of the polyamide; the wet slices of polyamide are sequentially dehydrated and dried to obtain polyamide slices, and the value range of the relative viscosity of the polyamide slices is 2.4-3.6. The continuous polymerization preparation system of polyamide can be used for realizing the method. The method has the characteristics of energy conservation, high efficiency and simple process flow.

This invention discloses a method for preparing high-strength, low-shrinkage PA6 industrial yarn, comprising: premixing PA6A (relative viscosity 2.4-2.8, mass fraction 80-99%) and PA6B (relative viscosity 3.4-4.0, mass fraction 1-20%) at high speed with stirring; drying to remove moisture to obtain PA6 spinning particles; adding a high-temperature antioxidant to the PA6 spinning particles; preparing PA6 nascent fibers using a melt spinning machine; coating the fiber surface with an antioxidant oil; and then preparing high-strength, low-shrinkage PA6 industrial yarn using a subsequent drawing system with multi-stage drawing and high-temperature tension setting technology. This invention utilizes a small amount of high-molecular-weight PA6B molecular chains as binding chains to induce crystallization and orientation of conventional molecular weight PA6A molecules, improving the condensed-state structure of the fiber and enhancing the mechanical properties of the PA6 industrial yarn.

The present application relates to the technical field of power equipment fault diagnosis, and discloses a kind of oil-immersed transformer fault diagnosis method, including synchronous acquisition transformer's operating phase voltage discrete sequence, load current discrete sequence, top oil temperature discrete sequence and box wall acceleration sequence;In light load steady state condition, identify transfer function parameter matrix, reconstruct core vibration reference component in dynamic condition and difference extraction winding vibration component;Relative viscosity coefficient is calculated using top oil temperature to dampen winding vibration component;In load transient time window, extract excitation force characteristics, macroscopic displacement characteristics and high-frequency distortion rate characteristics, map to three-dimensional state space, calculate space distortion volume and compare with reference threshold, output diagnosis result.The present application reduces the damping influence of core background vibration interference and oil temperature fluctuation, quantifies multi-source nonlinear degradation characteristics into volume index, and improves the recognition ability of early micro loose state of transformer winding.

The invention discloses a polyamide composition as well as a preparation method and application thereof. The polyamide composition comprises the following components in parts by weight: 25-65 parts of polyamide resin, 15-55 parts of polyphenyl ether resin, 4-18 parts of an organic phosphorus halogen-free flame retardant, 0.05-3 parts of an electrochemical stabilizer and 10-50 parts of glass fibers. The electrochemical stabilizer comprises mesoporous silica and vermiculite; the polyamide resin comprises PA6 resin and MXD6 resin; the relative viscosity of the MXD6 resin is less than that of the PA6 resin. The polyamide composition disclosed by the invention has strong electrochemical corrosion resistance in a working environment with high temperature (greater than or equal to 40 DEG C) and high humidity (greater than or equal to 80% RH).

It has a relative viscosity (RV) of approximately 90 to approximately 200 and a molecular weight distribution (M) of ≥1.40 and ≤1.50±0.03. z / M w A stretched polyamide (preferably PA66) high-tenacity yarn containing PA66 characterized by ). The yarn finds useful in a variety of end applications, including tire cords. The yarn provides improved fatigue resistance and / or cured rubber strength.

The application discloses a preparation method of high-strength fine denier large-brightness nylon 66 fully-drawing fiber. Firstly, nylon 66 spinning grade chips with a relative viscosity of 2.4-2.6 are solid-phase increased in viscosity to obtain nylon 66 medium-high viscosity chips with water content of less than or equal to 300 ppm and a relative viscosity of 3.0-3.2; then the chips are sent to a screw extruder for melt extrusion; the extruded melt is sent into a spinning box and is pressed into a spinning assembly by a metering pump; the melt is sprayed from a spinneret plate of the spinning assembly to form a fiber bundle; the sprayed melt is cooled to form a nascent fiber bundle; the obtained nascent fiber bundle is oiled by an oil nozzle crude oil; the oiled fiber bundle is subjected to three-stage hot drawing and two-stage relaxation heat setting; and finally, the fiber bundle is wound to obtain the high-strength fine denier large-brightness nylon 66 fully-drawing fiber. According to the application, the high-strength fine denier fiber with more stable structure and higher orientation degree can be prepared, the physical properties of the obtained high-strength fine denier fiber are more uniform, and the breaking strength and the breaking strength retention rate are higher, so that the continuous and stable production of the high-strength fine denier nylon 66 fiber is realized.

The invention provides high-fluidity nylon 66 resin as well as a preparation method and application thereof, and the high-fluidity nylon 66 resin is prepared from the following raw materials: hexamethylenediamine, adipic acid, a hyperbranched oligomer / polymer, a catalyst and a solvent, wherein the hyperbranched oligomer / polymer is any one or a combination of at least two of a polyamide-amine dendritic polymer, four-arm polyethylene glycol and a star polyethylene oxide polymer. The hyperbranched oligomer / polymer is introduced into the molecular structure design of the high-fluidity nylon 66 resin, the microstructure is improved, and the interaction force between polymer macromolecules can be weakened, so that the fluidity of the resin is greatly improved and the application range is expanded under the condition of keeping the high molecular weight of the resin, namely the same level of the relative viscosity of the resin; and moreover, excessive crosslinking is avoided, better mechanical properties are still kept under high fluidity, mobility caused by adding excessive lubricant and other flow improving auxiliaries is avoided, and the long-term stability is improved.

The invention provides anti-ultraviolet regenerated polyamide resin and a preparation method and application thereof, and the preparation method comprises the following steps: collecting polyamide waste silk and grouping the collected polyamide waste silk to obtain M groups of polyamide waste silk; in the M groups of polyamide waste filaments, the range of the relative viscosity of each unit group in each group of polyamide waste filaments is less than or equal to 0.05; cleaning the M group of polyamide waste filaments to obtain M group of oil-free polyamide waste filaments; respectively melting and extruding the M groups of oil-free polyamide waste filaments and an anti-ultraviolet material to obtain M groups of first anti-ultraviolet polyamide resin; respectively tackifying the M groups of first anti-ultraviolet polyamide resins to obtain M groups of second anti-ultraviolet polyamide resins; and mixing the M groups of second anti-ultraviolet polyamide resins, extracting, and drying to obtain the anti-ultraviolet regenerated polyamide resin. The anti-ultraviolet regenerated polyamide resin has proper relative viscosity, low yellow index, excellent spinnability, dyeing uniformity and weather resistance.

This invention relates to a low-odor glass fiber reinforced nylon modified material, mainly prepared from the following raw materials in weight fractions: 60-80% PA6 chips, 20-40% glass fiber, 0.1-0.2% additives, and 1.0-2.0% carbon powder. The carbon powder serves as a black masterbatch and odor adsorbent; preferably, it is carbon powder used in inks, which has a finer particle size and a larger specific surface area. The relative viscosity of the PA6 chips in the raw materials is 2.37-2.47, and the moisture content is 0.25-0.5%. The length of the glass fiber in the raw materials is 3.0±1.0 mm. This invention, on the one hand, utilizes the large specific surface area of ​​carbon powder as an adsorbent by adding it to the composition for physical adsorption of odors; on the other hand, it considers reducing residual monomers and oligomers in the preparation method.

The application relates to a PA / ABS alloy material and a preparation method and application thereof, and belongs to the technical field of polymer materials. The PA / ABS alloy material provided by the application comprises the following components in proportion by weight: 39-71 parts of PA6 resin, 29-56 parts of ABS resin, 4-31 parts of polyimide fiber and 0.05-5.5 parts of processing aid; the relative viscosity of the PA6 resin is 2.0-3.0. The polyimide fiber is introduced into the PA / ABS alloy material, so that the tensile strength and the bending strength of the material can be improved, the affinity of the inorganic fiber with the resin matrix is stronger, and the impact resistance of the material can be improved. The polyimide fiber is compounded with the PA6 resin with the relative viscosity of 2.0-3.0, so that the mechanical properties and the appearance of the material are effectively improved, and the application range of the PA / ABS alloy material is widened.

This invention provides a polyamide resin, its preparation method, and its applications. The polyamide resin has a carboxyl content ≤35 mol / t and an amino content ≤50 mol / t. The polyamide resin exhibits good thermal retention stability and resistance to yellowing. Furthermore, it possesses high relative viscosity and good flowability, enabling it to be used in high-temperature molding processes and meeting the resin requirements of the automotive parts, electrical and electronic parts, and sliding parts industries.

This invention relates to fiber-reinforced polyamide resin compositions and molded articles. The invention provides a fiber-reinforced polyamide resin composition that imparts sufficient mechanical properties and reduces property variations. A fiber-reinforced polyamide resin composition comprising crystalline polyamide (A) and glass fiber (B), characterized in that the formic acid relative viscosity of the soluble component of the fiber-reinforced polyamide resin composition is 90 or higher, and the boron concentration of the glass fiber (B) is 1000 ppm or lower.

This invention discloses a melamine standard substance based on a polyamide substrate, its preparation method, and its application, belonging to the field of standard substance preparation technology. The melamine standard substance provided by this invention comprises the following components in parts by weight: 89-99 parts polyamide resin, 1-10 parts melamine cyanurate, 0.05-0.35 parts antioxidant, and 0.1-1.1 parts lubricant; the relative viscosity of the polyamide resin is ≤2.55; the antioxidant is at least one of phosphite antioxidants and hindered phenolic antioxidants; the lubricant is polyethylene wax; the apparent viscosity of the polyethylene wax at 140°C is 550-660 cps. The melamine standard substance provided by this invention exhibits excellent stability when the melamine content is in the range of 300-1000 mg / kg, and there are no significant differences within and between samples of the obtained standard substance.