In the melt direct spinning polyester staple fiber production line, 1.33 dtex polyester staple fiber modified by graphene was produced by blending modification subsequent to adding graphene masterbatch to polyester melt through an on-line addition device. The effects of process conditions such as drying temperature, the addition amount of graphene masterbatch, and the spinning temperature, drawing, setting on fiber forming and product quality were investigated. Under the conditions of masterbatch drying temperature of 150 ℃, the 0.5% mass fraction of masterbatch added, spinning temperature of 288 ℃, ring blowing wind speed of 1.15 m/s, draw ratio of 3.58 times, and tension heat setting steam pressure of 0.8, 1.2, 1.8, 1.8 MPa, the titer of the graphene modified polyester staple fiber is 1.32 dtex. The breaking strength is 5.92 cN/dtex, the elongation at break is 23.8%, the defect content is 0.5 mg/100 g, the dry heat shrinkage rate at 180 ℃ is 6.2%, and the spinning and drawing production is in good condition. The performance indexes of fiber meet the requirements.

The thickness of three-dimensional carbon fiber preforms is a key factor in the design and processing of carbon fiber composites. However, there is no corresponding national standard for its measurement method, and there are significant differences among different testing methods. The existing thickness measurement methods of three-dimensional carbon fiber preforms are summarized and analyzed. The principle, advantages and disadvantages of non-destructive thickness measurement methods are mainly introduced. It is proposed that non-destructive testing should be taken as the research and development direction of thickness measurement methods for carbon fiber three-dimensional preforms.

To meet the demand for the coordinated treatment of multiple pollutants in industrial flue gas, a catalytic filtration material preparation process based on the composite of denitration catalyst and polytetrafluoroethylene (PTFE) fiber needle-punched felts was proposed to achieve the integration of efficient removal of nitrogen oxides in flue gas and dust filtration functions. The vanadium-titanium-based catalyst was loaded onto the surface of PTFE fiber needle-punched felts by impregnation method, and the influence of the ratio of catalyst, sodium silicate and surfactant in the impregnation solution on the chemical performance of the filter was systematically investigated. The tests show that when the mass fraction of sodium silicate in the impregnating liquid is increased from 0.5% to 7.5%, the catalyst loading in the filatration material is significantly improved, up to a maximum of 293 g/m2. However, excessive catalyst content can induce surface cracking, leading to structural discontinuity. The introduction of surfactants and sodium silicate effectively enhance the bonding strength between the catalyst and PTFE fibers, meeting the technical requirement of a conventional coating strength of≥0.1 MPa. However, the tape peeling test shows that the catalyst loss rate is 23.5% to 50.4%, which needs further optimization. Scanning electron microscopy analysis indicates that the catalyst is uniformly dispersed, but there are cracks at the microscopic interface. The manufacturing process of the catalytic filter material needs to be further optimized.

The base solution of poly(p-phenylenediamine)(PPTA) was prepared using p-phenylenediamine and p-phenylenediamine chloride as raw materials, and the coating solution containing alumina powder was made. It was coated on the polyethylene(PE) separator. The effects of PPTA with different characteristic viscosities on the appearance of the coating layer, the influence of moisture content on the polymerization reaction, the influence of the mass fraction of alumina powder on the Gurly value of PE separator were studied. The results show that when the intrinsic viscosity of PPTA for coating is about 2.0 dL/g, a coating layer with a good surface effect can be obtained. When preparing the PPTA base solution, controlling the water content of the system at about 0.05% is conducive to the stable preparation of the PPTA stock solution with an intrinsic viscosity of about 2.0 dL/g. When the mass fraction of alumina in the PPTA coating layer is around 60%, a coating layer with a lower Gurly value can be obtained.

Polyacrylonitrile with appropriate molecular weight was prepared by solution copolymerization in the solvent dimethyl sulfoxide using acrylonitrile, itaconic acid and methyl acrylate as copolymerizing monomers and azo disobutyronitrile as the initiator. The effects of polymerization reaction time, reaction temperature, monomer concentration and additive concentration on the quality of the polymerization solution were explored. The results show that the reaction time is 12 to 14 hours, the reaction temperature is 63 ℃ in the early stage and 69 ℃ in the later stage, the mass fraction of the monomer is 21%, the mass fraction of the initiator is 0.4%, and the mass fraction of the terminator is 0.1%, the rotational viscosity, conversion rate, relative molecular mass and its distribution in the obtained polymer solution are appropriate, meeting the production requirements of large-tow carbon fiber.

The research progress on the application of new functional fiber materials in the field of sports bras is systematically summarized, with a focus on the innovative achievements in five functional categories: antibacterial, health care, cooling sensation, skin care, and intelligent color-changing. The research indicates that by organically integrating high-performance fiber materials with the appearance design, both the wearing comfort and health protection performance of sports bras can be significantly enhanced. Finally, the trend of sports bras in terms of comfort, intelligence and sustainability is further looked forward to.

The process of DuPont's 900 t/d polyester production technology was introduced. The advantages of the production device were summarized, including reducing the area of infrastructure, saving investment costs, improving engineering stability, reducing single-line maintenance and accident losses, saving time costs, and reducing energy consumption per ton of product. The DuPont plant has improved the problems of the original plant, such as excessive entrainment, high solid content, excessive esterification reaction conditions, and poor uniformity of the melt. Through measures such as pressurizing the esterification reactor, moving the catalyst forward, and adding an online reactor on the esterification product pipeline to optimize the DuPont polyester plant, the goal of increasing production efficiency and ensuring stable production is achieved.

C-shaped beam sandwich structures with large length-to-diameter ratio were studied. Imported T 300 grade carbon fiber fabric prepreg was used to study the influencing factors of porosity of C-shaped beam sandwich structures, excluding the influence of curing system. The research mainly focused on the two processes of laying and packaging, and studied from the three influencing factors of pre-compaction parameters, auxiliary materials layout and air guide wire layout spacing. After setting different process parameters and testing the porosity of the manufactured C-shaped beam sandwich structure parts, the maximum porosity of the best process parameters is greatly reduced from 2.1% to 0.3%, which thereby improves the qualification rate of the parts.

Three density domestic PMI foam core were choosen as the research object to conduct pressure test of foam core, the effects of foam core density, foam core thickness and curing pressure on the curing shrinkage of PMI foam cores were explored. The effect of foam core density, glue-connected glue film layer, and molding process on the adhesive performance of PMI foam sandwich sample was researched through mechanical performance test. The test results show that the larger the foam core density and thickness, the smaller the curing pressure, the smaller the curing shrinkage, and the regression equation between the curing shrinkage and the foam core density, thickness and curing pressure was established. The mechanical performance test shows that the foam core density increases, which can significantly improve the adhesive strength between the panel and the core material. The adhesive strength of foam sandwich with 75 kg/m3 and 110 kg/m3are maximum increased by about 166% and 260% than that of the foam sandwich with 52 kg/m3, respectively. When the number of glue membrane layers increases from a single layer to two layers, the adhesive strength of foam sandwich sample is only up to about 40%, and the contribution to adhesive strength is not obvious.

An ultrasonic cutting machine was used to automatically net-dimension chamfer-cut prepreg laminate. A comparative study was conducted on the surface quality and contour dimensions of the laminate cut by different cutting paths, cutting angles, ‘normal-cutting’ and ‘contrary-cutting’, cutting rates, and thickness of prepreg. The results show that ‘pressing fiber’ cutting model can improve the surface quality of chamfer-cutting. 45° chamfer-cutting can provide a stabler cutting quality and profile accuracy, and be better for designer to distribute fasteners. To ensure the contour accuracy of the laminate during cutting, the normal-cutting model is used. Taking into account the cutting quality and cutting efficiency comprehensively, a cutting feed rate of 300 mm/min is more appropriate. Under different cutting feed rates, the 30° and 45° chamfer-cutting of laminate of different thicknesses exhibit their own rules.

Polymer asphalt mixture samples were fabricated using adhesives containing isocyanate groups, base asphalt and aggregates as raw materials. Their high-temperature stability, low-temperature crack resistance, skid resistance and water stability were studied through rutting tests, low-temperature bending tests and water immersion and fly-off tests. The research results show that the rutting depth increases monotonically and nonlinearly with the increase of the number of rolls. Under the same number of rolls, the rutting depth increases with the increase of the asphalt-aggregate ratio. The flexural tensile strength and maximum flexural tensile strain of asphalt mixtures made of polymer materials both show an increasing trend with the increase of the asphalt-aggregate ratio. With the increase of the asphalt-aggregate ratio, the stability of the high-molecular polymer asphalt mixture increases significantly after 30 minutes of immersion in water and then slightly decreases; the stability increases significantly after 48 hours of immersion in water and then slightly increases, while the residual stability shows a zigzag-shaped increasing trend.

To improve the lightning protection performance of carbon fiber-reinforced polymer (CFRP), matrix modified CFRP laminate specimens with a carbon fiber mass fraction of 0~40% were prepared by vacuum-assisted resin transfer molding technology. Through the lightning current impulse test, the damage behaviors of the traditional copper mesh protective laminate and the matrix modified laminate were systematically compared. The results show that the unmodified specimens exhibit warping and exposure of fiber, and the damage area significantly expands with the increase of the current. The copper mesh protective laminate specimen fails in protection when subjects to a current impact of more than 43 000 A, and the damaged area reaches 1 126 mm2. The surface of the matrix modified laminate specimens is not punctured, and the damaged area is only 1 023 mm2at a current of 59 000 A.

In order to improve the durability of concrete used in water conservancy engineering and meet the application requirements of concrete under complex working conditions, research on the application of polypropylene fiber concrete in water conservancy projects has been conducted through benchmark mix proportion design tests, single-factor tests of polypropylene fibers, and single-factor tests of polycarboxylate superplasticizer. The test results show that adding polypropylene fibers to concrete can improve the mechanical properties, impermeability and wear resistance of concrete, but it will reduce the fluidity of concrete. Based on the comprehensive test results, it is concluded that the optimal dosage of polypropylene fibers is 0.75 kg/m3. By increasing the dosage of polycarboxylate superplasticizer to counteract the reduction in the fluidity of concrete caused by the addition of polypropylene fibers and improve the workability of concrete, the experiment concluded that the optimal dosage of polycarboxylate superplasticizer is 0.55 kg/m3. The optimal mix ratio of polypropylene fiber concrete was applied to the gate slot working condition of water conservancy projects to test the performance. The test results show that the slump of polypropylene concrete is 140 mm, the 28-day compressive strength is 53.15 MPa, the average water seepage height is 55 mm, and the maximum water seepage pressure is 3.25 MPa. The wear per unit area is 0.50 kg/m2, which meets the requirements of engineering applications.

To improve the fluidity and mechanical properties of the face concrete used in rockfill dam, the influence law of steel/polypropylene fibers on its performance was analyzed through expansion tests, three-point bending tests and compressive tests. The results show that the addition of fibers reduces fluidity, and the influence of steel fibers is more severe. When the total volume fraction of blending exceeds 1%, the expansion degree decreases by 15.3%, and T500 increases by 98.5%. The addition of fibers enhances the compressive and flexural strength of concrete. The compressive strength of the mixed group increases by 30.0% compared with the reference group, and the flexural strength increases by 35.4%. The synergistic effect of the mixed group is significant. Compressive strength has a strong linear relationship with flexural strength. The strength and ductility of steel/polypropylene fibers are enhanced through bridging cracks, and the bending load-displacement curve of the blended group shows ductility. Based on the comprehensive test results, the overall volume fraction of steel/polypropylene fiber blending should be controlled within 1%, which can take into account the requirements of fluidity and mechanical property optimization.

The application of titanium-antimony composite catalysts in large-capacity polyester units was primarily investigated. In the early small-scale tests, by comparing the performance of ethylene glycol antimony catalysts and titanium-antimony composite catalysts in different ratios, it was found that the latter exhibited higher catalytic activity and better thermal stability during polyester synthesis. The use of titanium-antimony composite catalysts significantly shortened the esterification and polymerization reaction times. Additionally, the titanium-antimony composite catalysts demonstrated good adaptability and operability in large-capacity units. Compared to standalone ethylene glycol antimony catalysts or titanium-based catalysts, it reduced the content of heavy metal antimony in the fiber while ensuring the quality of the melt.

In order to solve the contradiction between high filtration efficiency and high airflow resistance of nanofiber membrane air filtration materials, PA6/PEO composite fiber membranes were prepared by solution jet spinning method, and the fiber diameter was changed by adjusting the molecular weight of PEO, the dual-scale layered structure was constructed by using double sprinklers to achieve high efficiency and low resistance filtration performance. The research found that increasing the molecular weight of PEO leads to an increase in fiber diameter and an improvement in porosity. The dual-scale layered fiber membrane prepared by the dual-nozzle spinning technology, through the synergistic effect of nanofibers (320 nm) and microfibers (1.6 m), forms a fiber membrane filter material with a fluffy interlaced three-dimensional structure, and the filtration efficiency of this material reaches over 99.5%.

The excellent filtration performance of electrospun polytetrafluoroethylene (PTFE) membranes stems from their outstanding properties such as fine fiber diameter, large specific surface area, small pore size, high porosity, good internal pore connectivity of the fiber membranes, and stable chemical performance. On the premise of summarizing the microstructure and properties of PTFE and analyzing the filtration mechanism of PTFE fiber membranes, the various technical researches on enhancing the filtration performance of PTFE fiber membranes guided by market demand are analyzed emphatically. Finally, the future technical research is prospected.

The thermal transmittance and electrostatic properties of viscose fabrics which treated with a certain amount of few-layer graphene, reduced graphene oxide, and graphene oxide, respectively. The thermal resistance value of the viscose fabric treated with few-layer graphene is 0.019 (m2·K)/W, the heat transfer coefficient is 52.6 W/(m2·K). The thermal resistance of fabrics treated with graphene oxide and reduced graphene oxide is reduced and the heat conductivity coefficient is increased. After being treated with few-layer graphene, the static voltage half-life of the viscose fiber fabric is reduced to 0.04 seconds. Few-layer graphene has excellent electrical conductivity, which can accelerate the dissipation of accumulated charges on the fabric surface and reduce the static voltage half-life of the fabric.

In order to solve the problems of soil pollution, air pollution and resource waste caused by the large-scale accumulation, burial and incineration of waste aramid fabrics, taking the research progress of high-value recycling and reuse of waste aramid fabrics as the topic, the recycling technology is introduced briefly, and the current recycling channels, recycling technology status and high-value utilization application fields of waste aramid fabrics are analyzed in detail. Finally, the challenges faced by waste aramid fabrics and their future development prospects are predicted. The research finds that the development of waste aramid technology is still not mature enough, although it is gradually applied to composite materials, construction, environmental protection energy, safety protection and innovation fields, but the overall recycling industry chain and application in practice is still very lacking, so the follow-up should establish and improve the relevant recycling policies to promote the aramid fabric recycling industry. In the future, with technological progress and policy support, this field will usher in greater space for development.

In order to investigate the influence of tow specifications and sectional pressure drop on cigarette physical indicators and routine cigarette smoke release, filter rods with different parameters were designed and cigarette tests were made. The tests results show that to achieve the same filter pressure drop, the low linear density of filament requires less tow filling, lower rod weight, and lower hardness. The segmented pressure drop design mainly affects the open draw resistance and ventilation rate of perforated cigarettes, and has little effect on the draw resistance of non-perforated cigarettes. Tow specifications have little effect on cigarette pressure drop and ventilation rate. With the close filter pressure drop, the release of TPM, nicotine and tar of the cigarette decreases with the decrease of linear density of filament. The filtration efficiency of the non-perforated cigarette filter increases with the increase of the sectional pressure drop, and the filtration efficiency of perforated cigarette filter increases with the increase of the pressure drop of the filter near the tobacco rod. The effects of different filter rod designs on the release of TPM, nicotine and tar of non-perforated cigarettes are 8.3%, 7.4% and 6.5%, and the effects on perforated cigarettes are 15.2%, 13.7% and 15.3%. When the filter rod pressure drop is fixed, through adjusting tow specifications and sectional pressure drop design can adjust the release of cigarette smoke.

In order to study the hygrothermal aging process and mechanism of carbon fiber reinforced polyphenylene sulfide (CF/PPS) composites, unidirectional CF/PPS composites were prepared for carrying out hygrothermal aging tests. The chemical structure, crystallization performance, mechanical properties, cross-sectional morphology, heat resistance of CF/PPS composites were tested and the service life was predicted under two humidity conditions: 90 ℃ and 100% RH (immersion and boiling), and 90 ℃ and 80% RH. The results show that the CF/PPS composites after hygrothermal aging do not undergo obvious chemical property changes. Only the plasticization of PPS during the hygrothermal aging process and the performance deterioration caused by moisture exist. The study of microscopic morphology further reveals microcracks, resin deterioration and the interfacial aging process between resin and fibers. The actual service life of CF/PPS composites when serving in an environment of 22 ℃ and a relative humidity of 75% is approximately (69.75 ± 39.05) years.