The motor shell is generally made by injection molding,which protects the motor.The Moldflow analysis of the part forming process was carried out by Moldflow software.The response surface model was established with the mold temperature,melt temperature,holding pressure and cooling time as the response variables,and the warpage deformation of the part as the response target.The regression equation and variance analysis were used to optimize the forming process parameters of the part.The results show that when the mold temperature is 70℃,the melt temperature is 220℃,the holding pressure is 120 MPa and the cooling time is 15 s,the minimum warpage deformation of the part is 2.386 0 mm,which is 1.732 3 mm lower than that before optimization.The influence of various factors on the warpage deformation of the parts is as follows:cooling time>holding pressure>melt temperature>mold temperature.The response surface method can effectively reduce the warpage deformation of the part,which provides a reference for the optimization of similar warpage deformation process parameters.
HM4560UA,a special polyethylene material for IBC barrel,was successfully trial-produced in the 300,000 t/a slurry double-loop polyethylene plant of Zhejiang Petrochemical Company.The structure and properties of DMDB4506,TR580M and HM4560UA for IBC barrels were compared and analyzed by high temperature gel permeation chromatography(GPC),capillary rheometer and melt flow rate meter.The results show that HM4560UA(7001G,7001E,7001B)has better environmental stress cracking resistance compared with other two kinds of materials.Weight average molecular weight,melt strength and oxidation induction period are also high,and the difference in mechanical properties is small.Under the same processing conditions,the products have strong environmental durability and antioxidant capacity,which is more suitable for the needs of the application fields of products.However,its melt flow rate is low,and when γ is the same,ηa is high,so its processability is poor.
In order to improve the flame retardancy of polyvinyl chloride(PVC)used for wires and cables,zinc borate(ZB)was added to PVC to prepare PVC composites,and its flame retardancy and mechanical properties were studied.The mechanical properties test showed that with the increase of ZB content,the tensile properties of PVC composites decrease dgradually.However,when the ZB content was less than 6%,the tensile properties of PVC composites decreased slightly,which still met the requirements of relevant standards.The flame retardant test showed that the flame retardant of PVC composites increased with the increase of ZB content.When the content of ZB was 6%,the comprehensive properties of PVC composite(4#)were excellent.Compared with the composite without ZB,the flame retardancy of the 4#sample was significantly improved,the oxygen index reached 40.1%,the vertical combustion grade reached FV-0,the smoke density decreased to 72,the HCl release decreased to 41 mg/g,the peak heat release rate(PHRR)was decrease by 19.9%,the total heat release(THR)was decreased by 36.5%,and the total smoke production(TSP600 s)was decreased by 69.7%.The tensile strength of the composite was decreased by 10.8%,and the elongation at break was decreased by 12.7%.
Aiming at the problem of warpage deformation in injection molding of automobile interior panel,the molding process was analyzed by Moldflow software.The mold temperature,melt temperature,holding pressure and cooling time were taken as process variables,and the response surface model was established with the warpage deformation of the product as the target,and the best combination of molding process parameters was obtained.The results show that when the mold temperature of the part is 56℃,the melt temperature is 250℃,the holding pressure is 120 MPa and the cooling time is 21 s,the maximum warpage deformation of the part is 2.305 mm,which is 1.105 mm lower than that before optimization.The influence of factors is as follows:cooling time>holding pressure>mold temperature>melt temperature.Under the condition of the optimal process parameters,the quality of the parts essentially meets the industrial requirements,and the overall forming quality of the parts is better.
Polyetheretherketone/polytetrafluoroethylene(PEEK/PTFE)composite spline was prepared by injection molding with carbon fiber(CF)as reinforcing phase and nano boron nitride(h-BN)with different contents.Tensile test was carried out by mechanical testing machine,surface friction test was carried out by friction testing machine,wear mark data and three-dimensional morphology were observed by a white light instrument,and wear mark was observed and analyzed by SEM.The results show that with the increase of h-BN content,the maximum spline stress of PEEK/PTFE composites first increases and then decreases;When h-BN content is 3%and 6%,the maximum stress of PEEK/PTFE composite spline is 174 MPa and 165 MPa,respectively.Compared with PEEK/PTFE,the friction coefficient of the sample with CF alone decreased to 0.23.When CF and h-BN are added at the same time,the friction coefficient of composite spline decreases.When the content of h-BN is 3%and 6%,the friction coefficients of composite splines are 0.06 and 0.09,respectively.With the increase of h-BN content,the wear of PEEK/PTFE/CF/h-BN composites first decreased and then increased.When the content of h-BN is 3%,the wear rate of composite spline is the lowest.
The curing kinetics of pure epoxy resin(EP),epoxy resin/carbon nanotubes composites(EP/MWCNTs),epoxy resin/hyperbranched polyester modified carbon nanotubes composites(EP/MWCNTs-H204)and epoxy resin/hyperbranched polyamide modified carbon nanotubes composites(EP/MWCNTs-N103)were studied by differential scanning calorimetry(DSC).The activation energy of each system was calculated based on Kissinger's method and Ozawa's method,respectively.The results show that the EP/MWCNTS-H204 and EP/MWCNTS-N103 systems modified by hyperbranched polymer have lower apparent activation energy than the other two systems without modification,which indicates that the introduction of hyperbranched polymer has a significant promotion on the curing reaction of epoxy resin composites.The automatic catalytic model(Sesták-Berggren)is obtained by Málek method.The kinetic parameters and equations describing the curing process are proposed by using Sesták-Berggren to theoretically calculate each system.The similarity between the theoretical calculation results and the experimental results is high,indicating that the Sesták-Berggren model can well describe the curing kinetic behavior of four different epoxy resin systems.
2,6-monosubstituted aromatic phenolic resin(IPD-BPA-TPD)was prepared by microwave-assisted method using bisphenol A(BPA),terephthalaldehyde(TPD)and isophthalaldehyde(IPD)as co-condensation monomers based on an open system and solution polycondensation method.A reversible thermochromic nickel-based butadiene rubber film was prepared using resin as a chromogenic agent.The resin was tested by a gel permeation chromatograph,a nuclear magnetic resonance hydrogen spectrometer,a nuclear magnetic resonance carbon spectrometer,a thermogravimetric analyzer and a thermal analyzer.The composite film was tested by a thermogravimetric analyzer,a thermal analyzer,a spectrophotometer and a polarizing microscope.The thermochromic properties,thermal stability,thermal cycle stability and microstructure of the film were studied.The results show that the Mˉn of IPD-BPA-TPD is 1.133×103 g/mol,the PDI is 1.005.The total color difference ΔE of the composite film reaches about 90 in the low temperature section(12～38℃)of the constant-rate cooling phase transition,and the absorption/scattering color depth difference Δ(K/S)reach about 15 and 40 in the visible regions of 480～600 nm and 600～660 nm,and film has good thermal stability and thermal cycle stability.
Polylactic acid(PLA)has the advantages of degradability,good biocompatibility and low energy consumption.However,PLA has the characteristics of poor toughness,slow degradation rate,hydrophobicity and lack of reaction side chain groups,which limits the application range of PLA.Rubber-based materials have excellent elasticity and toughness,which can be used as materials to improve the performance of PLA.The effects of different rubber types such as natural rubber(NR),nitrile rubber(NBR),acrylate rubber(ACM),silicone rubber(SI)and other rubbers on the properties of PLA are summarized.The research progress of rubber modified PLA under different processing technologies in recent years is reviewed,and the difficulties faced by rubber modified PLA are discussed.It is pointed out that improving the interfacial compatibility between rubber and PLA is the focus of future research.
To inhibit the epoxy resin combustion,a novel flame retardant containing silicon and phosphorous(DOPO-Si)was synthesized using silane coupling agent and 9,10-dihydrogen-9-oxygen-10-phosphorus-10-oxide(DOPO)as reactants to improve the flame retardancy of epoxy resin.DOPO-Si can be mixed with epoxy resin or grafted on the epoxy chain to improve the flame-retardancy of the epoxy resin.When 5%DOPO-Si is introduced into the epoxy resin,the cured epoxy resin can pass the vertically combustion(UL-94)and reach V-0 grade,the limiting oxygen index(LOI)is up to 34.8%.Meanwhile,the tensile strength of epoxy resin is 70.5 MPa,which is 22.6%higher than that of pure epoxy resin.When the grafting rate of DOPO-Si is up to 5%,the cured epoxy resin also can pass the UL-94 vertical combustion test and get V-0 grade and the LOI is 35.1%,but the mechanical properties just increase a little.This new flame retardant DOPO-Si,whether it is blended with epoxy resin or grafted onto the main chain of epoxy resin,can significantly improve the flame retardancy of epoxy resin,and the mechanical properties are also improved to varying degrees.However,compared with pure epoxy resin,the glass transition temperature has decreased to varying degrees,and the decrease of blending method is greater than that of grafting method.Therefore,it can be flexibly selected according to actual needs in practical applications.
The injection molding process of a polyphthalamide(PPA)controller wire holder was simulated by using simulation technology and the flatness of its copper contact surface was calculated and analyzed.The optimal gate position was obtained based on the gate positioning algorithm and the construction of the runner system was completed.The maximum flatness of the copper contact surface under the initial process is 0.155 9 mm,which does not meet the design requirements.Therefore,an orthogonal test is designed to optimize the flatness.The range and variance analysis show that the influence of the cavity temperature on the flatness is extremely significant,the holding time and the injection time are significant,the melt temperature is not significant,and the optimized process is A4B1C3D4.The maximum flatness of the part under the optimized process is 0.089 8 mm,the optimization rate reaches 42.4%,which meets the design requirements,and the filling state is good.The actual test results also verify the feasibility of the optimized process.
Poly(12-hydroxystearate)was prepared by polycondensation.Palmitic acid,3-dimethylaminopropylamine and poly(12-hydroxystearate)were reacted to form a terminated polyhydroxystearate aliphatic amine(HTPF)hyperdispersant.The structure of the product was characterized by IR and 1H NMR.The dispersion effect of HTPF on carbon black was analyzed by sedimentation experiment and scanning electron microscope.HTPF was added into ABS/carbon black masterbatch,and the effects of the amount of HTPF on the rheological and mechanical properties of ABS/carbon black masterbatch were studied.The results show that the loss modulus and storage modulus of the composites decrease gradually with the increase of HTPF content compared with the pure masterbatch,and the composites appear shear thinning behavior.With the increase of HTPF content,the mechanical properties of the composites gradually improved.When the content of HTPF is 40%,the tensile strength and impact strength of the composite reach the maximum of 45.9 MPa and 8.54 kJ/m2;When the content of HTPF is 50%,the flexural strength of the composites reaches 80.22 MPa.
The injection molding process of an automobile front-end frame was simulated,and the optimization of process parameter combination was explored with the goal of maximizing all effects deformation.Aiming at the problem of large deformation of the maximum all effects under the initial process,the orthogonal test was designed and the range and variance analysis were carried out.The results show that the injection time has the greatest influence on the deformation of the part,which is extremely significant.The influence of the surface temperature of the die cavity and the barrel temperature on the deformation of the part is significant.The influence of the filling volume percentage of the speed pressure switching on the deformation of the part is not significant,and the optimal process parameter combination is A2B2C2D3.The simulation results of the optimized process show that the maximum deformation of all effects is reduced to 2.949 mm,and the optimization range is large and meets the index requirements.The optimized process is used to test the mold.The trial sample is in good condition and the deformation amount meets the requirements,which verifies the rationality of the optimization scheme.
In order to meet the application of epoxy resin in the fields of high strength and high toughness,it is necessary to toughen and modify it.However,common toughening agents are synthesized from non-degradable and non-renewable petroleum-based raw materials,which are harmful to human health and living environment.Hyperbranched structural polymers prepared by bio-based raw materials have gradually become a research hotspot.Hyperbranched structural polymers introduce green,environmentally friendly and renewable biomaterials into polymers,while meeting the needs of epoxy resin enhancement and toughening.It can also reduce the viscosity of the modified system and is easy to process.The toughening mechanism of epoxy-terminated hyperbranched polymers is expounded.The existing research results on bio-based epoxy-terminated hyperbranched polymers are summarized,and the existing problems are prospected.
PZS@ATP nano-composite flame retardant was successfully prepared by in-situ polymerization using natural nano-mineral attapulgite(ATP),hexachlorocyclotriphosphazene(HCCP)and 4,4'-dihydroxydiphenyl sulfone(BPS)as raw materials,and the composite flame retardant was applied to epoxy resin(EP).The structure of PZS@ATP nanocomposite flame retardant was characterized by Fourier transform infrared spectroscopy,X-ray diffraction,scanning electron microscopy and transmission electron microscopy.The mechanical properties and thermal stability of the composites were tested by electronic universal testing machine and thermogravimetric analyzer.The results show that the addition of PZS@ATP can effectively improve the mechanical properties of the composites.When the addition amount of PZS@ATP is 2%,the impact strength of the composite increases to 12.768 kJ/m2,which is 162%higher than that of pure EP.When the addition amount of PZS@ATP is 3%,the impact strength and tensile strength of the composite increase to 6.379 kJ/m2 and 63.31 MPa,respectively,which are 30.9%and 0.2%higher than those of pure EP.The addition of 3%PZS@ATP can improve the mechanical properties and thermal stability of pure EP.
Microplastics have the characteristics of strong stability,large variety and small size,which affect the safety and stability of the marine environment.The source,type and distribution characteristics of microplastics are summarized.The toxic effects of microplastics on algae,zooplankton,fish and other marine organisms are discussed,and the relevant experimental methods and key conclusions are listed.The effects of non-biological conditions such as photocatalysis and thermal degradation on the degradation of microplastics are summarized.The degradation effect of microplastics under the action of microorganisms is analyzed.It is pointed out that in the future,we should strengthen the exploration of the potential harm of microplastics to organisms and find suitable degradation conditions to deal with microplastics.
Biodegradable material is a kind of polymer material which has no pollution to the environment.It has been used in food packaging,medical treatment,agriculture and other industries.However,the production cost of biodegradable materials is high and the physical properties are defective,which affects their wide application in various fields.The types and properties of biodegradable materials are reviewed.The advantages and disadvantages of spectroscopy,nuclear magnetic resonance and chromatography and mass spectrometry in the identification of biodegradable materials are compared.It is pointed out that the material characterization of biodegradable materials and the analysis methods of impurities are the key research contents,so as to provide reference for the material analysis of biodegradable materials.
Binary copolymerized semi-aromatic polyamide(PA6T/66)is a kind of polymer material with low cost,high rigidity and mature process,but it has poor toughness and certain water absorption.PA6T/10T/66 resin was prepared by melt polymerization and micro-negative pressure viscosity enhancement by introducing high temperature resistant polyterephthaloyl decanediamine(PA10T)segment of aliphatic long carbon chain with low water absorption into PA6T/66 resin.The results show that the optimum amount of PA10T salt is 5%when preparing PA6T/10T/66 resin.Infrared spectra shows that PA6T/10T/66(45/5/50)resin is completely polymerized.The melting point of PA6T/10T/66(45/5/50)resin is 300℃by differential scanning calorimeter(DSC).When the viscosity of the resin is 2.5,the tensile strength is 50 MPa and the flexural strength is 54 MPa.When the polymerization pressure is 2.35 MPa and the amount of end capping agent is 1.5%of the total salt mass,the viscosity of the resin meets the application requirements.This process has low cost and simple preparation process,and the obtained ternary copolymer resin is suitable for glass fiber modification,color matching,injection molding and other applications.
In order to investigate the effect of recycled plastic content on the processability and physical properties of blended modified recycled materials,recycled polypropylene rubber head masterbatch(recycled material)was blended with pure polypropylene to prepare blend samples,and their rheological properties,crystallization properties and mechanical properties were characterized.The results show that the viscosity of blend samples decreases and the relaxation peak at 0.1 s shifts to lower frequency when the recycled material content increases from 0 to 50%.Relaxation peaks also appeared in the blend melt at 1 s due to the presence of higher molecular weight parts in the recycled material.The peak temperature of the main crystallization peak increases from 118.2℃to 120℃when the recycled material content increases from 0 to 50%,but the crystallization behavior at low temperature also appears.When the recycled material content increases from 10%to 50%,the crystallinity of the sample decreases from 40%to 35%,and a crystalline structure with lower melting point also appears.The impact strength,tensile strength,flexural strength and flexural modulus of the blend decrease by 35%,7%,10%and 9%,respectively,when the recycled material content is 50%,which indicates that the mechanical properties of the blend decrease with the increase of recycled material.
The current electromagnetic environment exhibits a growing demand for efficient microwave-absorbing materials. Developing multifunctional and efficient wave-absorbing materials poses a challenging research hotspot. Numerous researchers have dedicated their efforts to developing high-performance broadband wave-absorbing materials with outstanding mechanical properties. Utilizing carbon fiber-reinforced polymer composites (CFRP) for electromagnetic wave absorption (EMA) is a rapidly evolving field. Carbon fiber-based EMA composites are characterized by high dielectric loss, high thermal stability, and low density, enabling them to achieve EMA properties while meeting mechanical property requirements. This review summarizes the principles of electromagnetic EMA, focusing on dielectric and magnetic losses, the preparation methods of CFRP, such as organic polymer synthesis, chemical vapor deposition, and vacuum forming processes, as well as their underlying principles. It also evaluates the research progress on the EMA properties of CFRP composites, particularly highlighting CFRP matrix modification and coating treatment. Finally, the challenges of CFRP EMA and potential future development directions are discussed. This analysis offers multiple recommendations for future researchers. This paper provides a comprehensive overview of recent advancements in preparation, modification, and coating technologies employed for CFRP composites. It delves into several preparation stage processes, including organic polymer synthesis, chemical vapor deposition (CVD), and vacuum forming, underscoring the significance of each process. It also discusses the integration of metallic, nano, and ceramic materials, highlighting their roles in improving electromagnetic absorption (EMA) properties and mechanical strength. Additionally, it examines the impacts of structural modifications, including the integration of specialized structures like 3D porous and honeycomb designs, on EMA capabilities and mechanical properties. MXene, a promising 2D material, has garnered significant attention for its potential to facilitate the development of lightweight, high-strength EMA materials. Furthermore, the paper explores the role of coating technologies, including absorbers and composite coatings, in extending microwave absorption capabilities. Finally, the paper highlights the substantial progress and prospects in researching CFRP composites' mechanical and microwave properties. image
Polyacrylonitrile/polyethersulfone(PAN/PES)composite ultrafiltration membrane was prepared by immersion precipitation process,and the surface of PAN/PES ultrafiltration membrane was hydrophilically modified by soaking in alkali solution.The surface structure of UF membrane before and after modification was studied by scanning electron microscope,the chemical composition of UF membrane was analyzed by infrared spectrometer,the surface hydrophilicity of UF membrane before and after modification was compared by contact angle measuring instrument,and the pure water flux and anti-pollution of UF membrane were tested by membrane performance evaluating instrument.The results show that the optimum hydrolysis time is 1.0 h,and the pure water flux of PAN/PES-1.0 h modified ultrafiltration membrane is 541.9 L/(h·m2),which is increased by 75%compared with the original unmodified ultrafiltration membrane.Compared with the original ultrafiltration membrane,the water contact angle of the modified ultrafiltration membrane decreases from 79.3° to 62.9° after 1.0 h hydrolysis,indicating that the surface hydrophilicity of the modified ultrafiltration membrane is improved.At the same time,the anti-fouling ability of the hydrolysis membrane is also improved obviously,and the membrane fouling coefficient decreases from 0.846 2 to 0.217 4.
