To compare the suitable working conditions of polypropylene(PP)and polycaprolactam(PA6)materials in actual use in automobiles,the effects of different temperature aging and different reagents on the mechanical propert...To compare the suitable working conditions of polypropylene(PP)and polycaprolactam(PA6)materials in actual use in automobiles,the effects of different temperature aging and different reagents on the mechanical properties of the two materials,such as tensile,bending,compression,and impact were studied.The results indicate that the short⁃term low⁃temperature environment had no much effect on the mechanical properties of PP and PA6.After long⁃term thermal aging at 80℃,the strength of PP and PA6 increased while their toughness decreased.After short⁃term thermal aging at 120℃,PP strength decreases and toughness increases,while PA6 strength increases and toughness decreases.The soaking of glass water and car shampoo had no much effect on the mechanical properties of PP,but had a significant impact on the mechanical properties of PA6.With the increase of soaking time,the strength of PA6 significantly decreases and the toughness significantly increases.The soaking of 95#gasoline had no much effect on the mechanical properties of PA6,but has a significant impact on the mechanical properties of PP.After 720 h of soaking,the retention rates of the tensile strength,bending strength,and compressive strength of PP were all less than 80%,while the retention rate of the impact strength of the cantilever beam was 160.4%.展开更多
This study focused on the production of polypropylene(PP)/silver(Ag)composites via additive manufacturing.This study aimed to enhance the quality of medical-grade PP in material extrusion(MEX)three-dimensional printin...This study focused on the production of polypropylene(PP)/silver(Ag)composites via additive manufacturing.This study aimed to enhance the quality of medical-grade PP in material extrusion(MEX)three-dimensional printing(3DP)by improving its mechanical properties while simultaneously adding antibacterial properties.The latter can find extremely important and versatile properties that are applicable in defense and security domains.PP/Ag nanocomposites were prepared using a novel method based on a reaction occurring while mixing appropriate quantities of the starting polymers and additives,namely polyvinylpyrrolidone(PVP)as the matrix material and silver nitrate(AgNO_(3))as the filler.This process produced three-dimensional(3D)printed filaments,which were then used to create specimens for a series of standardized tests.It was found that the mechanical properties of the nanocomposites were enhanced in relation to pristine PP,especially for the PP matrix with various loadings of AgNO_(3)and PVP,such as 5.0 wt%and 2.5 wt%,respectively.The voids,inclusions,and actual-to-nominal dimensions also showed improved results.The 3DP specimens exhibited a more effective biocidal performance against Staphylococcus aureus than Escherichia coli,which developed an inhibition zone only in the case of PP with filler loading percentages of AgNO_(3)and PVP at 10.0 wt%and 5.0 wt%,respectively Compounds possessing such properties can be beneficial for various applications requiring increased mechanical properties and biocidal capabilities,such as in the Defence or medical industries.展开更多
Polypropylene(PP) fibres have primarily used to control shrinkage cracks or mitigate explosive spalling in concrete structures exposed to fire or subjected to impact/blast loads, with limited investigations on capacit...Polypropylene(PP) fibres have primarily used to control shrinkage cracks or mitigate explosive spalling in concrete structures exposed to fire or subjected to impact/blast loads, with limited investigations on capacity improvement. This study unveils the possibility of using PP micro-fibres to improve the impact behaviour of fibre-reinforced ultra-high-performance concrete(FRUHPC) columns. Results show that the addition of fibres significantly improves the impact behaviour of FRUHPC columns by shifting the failure mechanism from brittle shear to favourable flexural failure. The addition of steel or PP fibres affected the impact responses differently. Steel fibres considerably increased the peak impact force(up to 18%) while PP micro-fibres slightly increased the peak(3%-4%). FRUHPC significantly reduced the maximum midheight displacement by up to 30%(under 20°impact) and substantially improved the displacement recovery by up to 100%(under 20° impact). FRUHPC with steel fibres significantly improved the energy absorption while those with PP micro-fibres reduced the energy absorption, which is different from the effect of PP-macro fibre reported in the literature. The optimal fibre content for micro-PP fibres is 1% due to its minimal fibre usage and low peak and residual displacement. This study highlights the potential of FRUHPC as a promising material for impact-resistant structures by creating a more favourable flexural failure mechanism, enhancing ductility and toughness under impact loading, and advancing the understanding of the role of fibres in structural performance.展开更多
Polypropylene was cracked thermally and catalytically in the presence of kaoline and silica alumina in a semi batch reactor in the temperature range 400℃～550℃ in order to obtain suitable liquid fuels.The dependenci...Polypropylene was cracked thermally and catalytically in the presence of kaoline and silica alumina in a semi batch reactor in the temperature range 400℃～550℃ in order to obtain suitable liquid fuels.The dependencies between process temperatures,types of catalyst,feed compositions and product yields of the obtained fuel fractions were found.It was observed that up to 450℃ thermal cracking temperature,the major product of pyrolysis was liquid oil and the major product at other higher temperatures(475℃～550℃) are viscous liquid or wax and the highest yield of pyrolysis product is 82.85% by weight at 500℃.Use of kaoline and silica alumina decreased the reaction time and increased the yield of liquid fraction.Again the major pyrolysis product in catalytic pyrolysis at all temperatures was low viscous liquid oil.Silica alumina was found better as compared to kaoline in liquid yield and in reducing the reaction temperature.The maximum oil yield using silica alumina and kaoline catalyst are 91% and 89.5% respectively.On the basis of the obtained results hypothetical continuous process of waste polypropylene plastics processing for engine fuel production can be presented.展开更多
Adding polypropylene(PP)fibers and coarse aggregates has become a popular way to enhance the strength and stability of the cemented tailings backfilling(CTB)body.It is essential to explore the influence of tailings-ag...Adding polypropylene(PP)fibers and coarse aggregates has become a popular way to enhance the strength and stability of the cemented tailings backfilling(CTB)body.It is essential to explore the influence of tailings-aggregate ratio and fiber content on the mechanical properties of CTB samples.The comprehensive tests of the unconfined compressive strength(UCS),slump and microstructure were designed,and the regression models were established to characterize the effect of the strength,ductility and fluidity.The results indicate that the tailings-aggregate ratio of 5:5 and PP fiber content of 0.5 kg/m^(3) are the optimum point considering the UCS,cracking strain,peak strain and post-peak ductility.The tailings-aggregate ratio is consistent with the unary quadratic to the UCS and a linear model with a negative slope to the slump.Microstructural analysis indicates that PP fiber tends to bridge the cracks and rod-mill sand to serve as the skeleton of the paste matrix,which can enhance the compactness and improve the ductility of the CTB.The results presented here are of great significance to the understanding and application of coarse aggregates and fibers to improve the mechanical properties of CTB.展开更多
To improve the environmental benefits and solve the problems of large shrinkage and high brittleness, the partial replacement of calcined kaolin by fly ash as a raw material for geopolymer synthesis and the influences...To improve the environmental benefits and solve the problems of large shrinkage and high brittleness, the partial replacement of calcined kaolin by fly ash as a raw material for geopolymer synthesis and the influences of polypropylene (PP) fiber on the mechanical properties and volume stability were investigated. The results show that compressive strength of the geopolymer containing 33.3%(mass fraction) fly ash by steam curing at 80 ℃ for 6 d is improved by 35.5%. The 3-day compressive strength, flexural strength and impacting energy of geopolymers containing 0.05%PP fiber increase by 67.8%, 36.1% and 6.25%, while the shrinkage and modulus of compressibility decrease by 38.6% and 31.3%, respectively. The results of scanning electron microscopy (SEM) and the appearances of crack growths confirm that PP fiber can offer a bridging effect over the harmful pores and defects and change the expanding ways of cracks, resulting in a great improvement of strength and toughness.展开更多
This paper investigates the effect of microwave irradiation on theβtoαphase transformation of theβ-nucleated isotactic polypropylene(iPP).Ten microwave irradiation cycles was applied to the iPP and iPP modified wit...This paper investigates the effect of microwave irradiation on theβtoαphase transformation of theβ-nucleated isotactic polypropylene(iPP).Ten microwave irradiation cycles was applied to the iPP and iPP modified with 0.3 wt%and 0.5 wt%β-NA,and the data at 2nd,4th,6th,8th and 10th irradiation were reported.As expected,the sample temperature was found to increase with the irradiation time,by more than 130°C,due to high frequency of microwave processing.This was the major factor that induced theβ-phase transformation and structural change.Both the differential scanning calorimetry(DSC)and X-ray diffraction(XRD)results indicated thatβ-phase was mainly transformed toα-phase and partially converted to the amorphous section.It was reflected as 1)the reduction of the enthalpy ofβ-crystal melting(ΔHmβ),2)the increased enthalpy ofα-crystal melting(ΔHmα),3)the decreasedβ-crystalline phase fraction(Kβ)and 4)the decrease of the overall degree of crystallinity(Xall).Under impact force,neat iPP showed a slight increase in the impact strength with the irradiation time,due to the increase of amorphous region.For theβ-iPP,it decreased due to the reduction of theβ-phase content.展开更多
The SDG-HAZOP(Signed Directed Graph,Hazard and Operability Analysis) is a qualitative safety assessment method,which is comprehensive,systematic and complete.However the result is tedious and large.Fault tree analysis...The SDG-HAZOP(Signed Directed Graph,Hazard and Operability Analysis) is a qualitative safety assessment method,which is comprehensive,systematic and complete.However the result is tedious and large.Fault tree analysis(FTA) is a logical and diagrammatic method,which is proved to be a useful quantitative analysis tool to evaluate the safety and reliability of complex systems.So a FTA based on SDG-HAZOP quantitative method was proposed in this paper.Firstly,the SDG-HAZOP and the FTA were established on the background of polypropylene production devices in the Sinopec Wuhan Branch.Secondly,the probability of top event was calculated by reliable data from the probability of basic events.Finally,the targeted measures were proposed to prevent fatal potential dangerous situations by probability calculation.展开更多
In order to explore the mechanism of improving the surface wettability of low-energy polytetrafluoroethylene(PTFE)by new extended surfactants,five kinds of extended anionic surfactants with different numbers of oxypro...In order to explore the mechanism of improving the surface wettability of low-energy polytetrafluoroethylene(PTFE)by new extended surfactants,five kinds of extended anionic surfactants with different numbers of oxypropylene(PO)and oxyethylene(EO),octadecyl-(PO)_(m)-(EO)_(n)-sodium carboxylate(C_(18)PO_(m)EO_(n)C,m=5,10,15,n=5,10,15),were studied.The surface tension and contact angle of C_(18)PO_(m)EO_(n)C solution with different concentrations were measured,and the adhesion tension,PTFE-water interfacial tension,and adhesion work were calculated.It was found that the extended surfactant molecules adsorb on the surface of the solution and the PTFE-liquid interface simultaneously when the concentration is lower than the critical micelle concentration(cmc),and there was a linear relationship between surface tension and adhesion tension.The adsorption amount of C_(18)PO_(m)EO_(n)C at the PTFE-water interface was significantly lower than that on the surface of the solution.As the concentration increases above cmc,semi-micelle aggregates on the surface of PTFE are formed by C_(18)PO_(m)EO_(n)C molecules through hydrophobic interaction,and the hydrophilic group faces the solution to modify the surface of PTFE with high efficiency.展开更多
The homogeneous dielectric barrier discharge(DBD) in atmospheric air is most favorable for polymer surface modification due to the low cost of operation and the ability of ambient on-line continuous uniform processing...The homogeneous dielectric barrier discharge(DBD) in atmospheric air is most favorable for polymer surface modification due to the low cost of operation and the ability of ambient on-line continuous uniform processing.In this paper,polypropylene(PP) films are treated using a homogeneous DBD plasma in atmospheric air.The surface properties of PP films are studied using contact angle and surface energy measurement,scanning electron microscopy (SEM) and Fourier transformed infrared spectroscopy(FTIR),and the aging effect after treatment when the treated materials are exposed to open air is also studied,with the modification mechanism being discussed.It is demonstrated that non-thermal plasmas generated by homogeneous DBD in atmospheric air is an effective way to enhance the surface properties of PP films.After the plasma treatment,the surface of PP film is etched,and oxygen-containing polar groups are introduced into the surface.These two processes can induce a remarkable decrease in water contact angle and a remarkable increase in surface energy,and the surface properties of PP films are improved accordingly.展开更多
文摘To compare the suitable working conditions of polypropylene(PP)and polycaprolactam(PA6)materials in actual use in automobiles,the effects of different temperature aging and different reagents on the mechanical properties of the two materials,such as tensile,bending,compression,and impact were studied.The results indicate that the short⁃term low⁃temperature environment had no much effect on the mechanical properties of PP and PA6.After long⁃term thermal aging at 80℃,the strength of PP and PA6 increased while their toughness decreased.After short⁃term thermal aging at 120℃,PP strength decreases and toughness increases,while PA6 strength increases and toughness decreases.The soaking of glass water and car shampoo had no much effect on the mechanical properties of PP,but had a significant impact on the mechanical properties of PA6.With the increase of soaking time,the strength of PA6 significantly decreases and the toughness significantly increases.The soaking of 95#gasoline had no much effect on the mechanical properties of PA6,but has a significant impact on the mechanical properties of PP.After 720 h of soaking,the retention rates of the tensile strength,bending strength,and compressive strength of PP were all less than 80%,while the retention rate of the impact strength of the cantilever beam was 160.4%.
文摘This study focused on the production of polypropylene(PP)/silver(Ag)composites via additive manufacturing.This study aimed to enhance the quality of medical-grade PP in material extrusion(MEX)three-dimensional printing(3DP)by improving its mechanical properties while simultaneously adding antibacterial properties.The latter can find extremely important and versatile properties that are applicable in defense and security domains.PP/Ag nanocomposites were prepared using a novel method based on a reaction occurring while mixing appropriate quantities of the starting polymers and additives,namely polyvinylpyrrolidone(PVP)as the matrix material and silver nitrate(AgNO_(3))as the filler.This process produced three-dimensional(3D)printed filaments,which were then used to create specimens for a series of standardized tests.It was found that the mechanical properties of the nanocomposites were enhanced in relation to pristine PP,especially for the PP matrix with various loadings of AgNO_(3)and PVP,such as 5.0 wt%and 2.5 wt%,respectively.The voids,inclusions,and actual-to-nominal dimensions also showed improved results.The 3DP specimens exhibited a more effective biocidal performance against Staphylococcus aureus than Escherichia coli,which developed an inhibition zone only in the case of PP with filler loading percentages of AgNO_(3)and PVP at 10.0 wt%and 5.0 wt%,respectively Compounds possessing such properties can be beneficial for various applications requiring increased mechanical properties and biocidal capabilities,such as in the Defence or medical industries.
基金the financial support from Australian Research Council(ARC)(Grant No.DP220100307).
文摘Polypropylene(PP) fibres have primarily used to control shrinkage cracks or mitigate explosive spalling in concrete structures exposed to fire or subjected to impact/blast loads, with limited investigations on capacity improvement. This study unveils the possibility of using PP micro-fibres to improve the impact behaviour of fibre-reinforced ultra-high-performance concrete(FRUHPC) columns. Results show that the addition of fibres significantly improves the impact behaviour of FRUHPC columns by shifting the failure mechanism from brittle shear to favourable flexural failure. The addition of steel or PP fibres affected the impact responses differently. Steel fibres considerably increased the peak impact force(up to 18%) while PP micro-fibres slightly increased the peak(3%-4%). FRUHPC significantly reduced the maximum midheight displacement by up to 30%(under 20°impact) and substantially improved the displacement recovery by up to 100%(under 20° impact). FRUHPC with steel fibres significantly improved the energy absorption while those with PP micro-fibres reduced the energy absorption, which is different from the effect of PP-macro fibre reported in the literature. The optimal fibre content for micro-PP fibres is 1% due to its minimal fibre usage and low peak and residual displacement. This study highlights the potential of FRUHPC as a promising material for impact-resistant structures by creating a more favourable flexural failure mechanism, enhancing ductility and toughness under impact loading, and advancing the understanding of the role of fibres in structural performance.
文摘Polypropylene was cracked thermally and catalytically in the presence of kaoline and silica alumina in a semi batch reactor in the temperature range 400℃～550℃ in order to obtain suitable liquid fuels.The dependencies between process temperatures,types of catalyst,feed compositions and product yields of the obtained fuel fractions were found.It was observed that up to 450℃ thermal cracking temperature,the major product of pyrolysis was liquid oil and the major product at other higher temperatures(475℃～550℃) are viscous liquid or wax and the highest yield of pyrolysis product is 82.85% by weight at 500℃.Use of kaoline and silica alumina decreased the reaction time and increased the yield of liquid fraction.Again the major pyrolysis product in catalytic pyrolysis at all temperatures was low viscous liquid oil.Silica alumina was found better as compared to kaoline in liquid yield and in reducing the reaction temperature.The maximum oil yield using silica alumina and kaoline catalyst are 91% and 89.5% respectively.On the basis of the obtained results hypothetical continuous process of waste polypropylene plastics processing for engine fuel production can be presented.
基金Project(51722401)supported by the National Science Foundation for Excellent Young Scholars of ChinaProject(51334001)supported by the Key Program of National Natural Science Foundation of ChinaProject(FRF-TP-18-003C1)supported by the Fundamental Research Funds for the Central Universities,China。
文摘Adding polypropylene(PP)fibers and coarse aggregates has become a popular way to enhance the strength and stability of the cemented tailings backfilling(CTB)body.It is essential to explore the influence of tailings-aggregate ratio and fiber content on the mechanical properties of CTB samples.The comprehensive tests of the unconfined compressive strength(UCS),slump and microstructure were designed,and the regression models were established to characterize the effect of the strength,ductility and fluidity.The results indicate that the tailings-aggregate ratio of 5:5 and PP fiber content of 0.5 kg/m^(3) are the optimum point considering the UCS,cracking strain,peak strain and post-peak ductility.The tailings-aggregate ratio is consistent with the unary quadratic to the UCS and a linear model with a negative slope to the slump.Microstructural analysis indicates that PP fiber tends to bridge the cracks and rod-mill sand to serve as the skeleton of the paste matrix,which can enhance the compactness and improve the ductility of the CTB.The results presented here are of great significance to the understanding and application of coarse aggregates and fibers to improve the mechanical properties of CTB.
基金Project(2006AA06Z225) supported by the National High-Tech Research and Development Program of China
文摘To improve the environmental benefits and solve the problems of large shrinkage and high brittleness, the partial replacement of calcined kaolin by fly ash as a raw material for geopolymer synthesis and the influences of polypropylene (PP) fiber on the mechanical properties and volume stability were investigated. The results show that compressive strength of the geopolymer containing 33.3%(mass fraction) fly ash by steam curing at 80 ℃ for 6 d is improved by 35.5%. The 3-day compressive strength, flexural strength and impacting energy of geopolymers containing 0.05%PP fiber increase by 67.8%, 36.1% and 6.25%, while the shrinkage and modulus of compressibility decrease by 38.6% and 31.3%, respectively. The results of scanning electron microscopy (SEM) and the appearances of crack growths confirm that PP fiber can offer a bridging effect over the harmful pores and defects and change the expanding ways of cracks, resulting in a great improvement of strength and toughness.
基金support of iPP resins at IRPC Public Company limited
文摘This paper investigates the effect of microwave irradiation on theβtoαphase transformation of theβ-nucleated isotactic polypropylene(iPP).Ten microwave irradiation cycles was applied to the iPP and iPP modified with 0.3 wt%and 0.5 wt%β-NA,and the data at 2nd,4th,6th,8th and 10th irradiation were reported.As expected,the sample temperature was found to increase with the irradiation time,by more than 130°C,due to high frequency of microwave processing.This was the major factor that induced theβ-phase transformation and structural change.Both the differential scanning calorimetry(DSC)and X-ray diffraction(XRD)results indicated thatβ-phase was mainly transformed toα-phase and partially converted to the amorphous section.It was reflected as 1)the reduction of the enthalpy ofβ-crystal melting(ΔHmβ),2)the increased enthalpy ofα-crystal melting(ΔHmα),3)the decreasedβ-crystalline phase fraction(Kβ)and 4)the decrease of the overall degree of crystallinity(Xall).Under impact force,neat iPP showed a slight increase in the impact strength with the irradiation time,due to the increase of amorphous region.For theβ-iPP,it decreased due to the reduction of theβ-phase content.
文摘The SDG-HAZOP(Signed Directed Graph,Hazard and Operability Analysis) is a qualitative safety assessment method,which is comprehensive,systematic and complete.However the result is tedious and large.Fault tree analysis(FTA) is a logical and diagrammatic method,which is proved to be a useful quantitative analysis tool to evaluate the safety and reliability of complex systems.So a FTA based on SDG-HAZOP quantitative method was proposed in this paper.Firstly,the SDG-HAZOP and the FTA were established on the background of polypropylene production devices in the Sinopec Wuhan Branch.Secondly,the probability of top event was calculated by reliable data from the probability of basic events.Finally,the targeted measures were proposed to prevent fatal potential dangerous situations by probability calculation.
文摘In order to explore the mechanism of improving the surface wettability of low-energy polytetrafluoroethylene(PTFE)by new extended surfactants,five kinds of extended anionic surfactants with different numbers of oxypropylene(PO)and oxyethylene(EO),octadecyl-(PO)_(m)-(EO)_(n)-sodium carboxylate(C_(18)PO_(m)EO_(n)C,m=5,10,15,n=5,10,15),were studied.The surface tension and contact angle of C_(18)PO_(m)EO_(n)C solution with different concentrations were measured,and the adhesion tension,PTFE-water interfacial tension,and adhesion work were calculated.It was found that the extended surfactant molecules adsorb on the surface of the solution and the PTFE-liquid interface simultaneously when the concentration is lower than the critical micelle concentration(cmc),and there was a linear relationship between surface tension and adhesion tension.The adsorption amount of C_(18)PO_(m)EO_(n)C at the PTFE-water interface was significantly lower than that on the surface of the solution.As the concentration increases above cmc,semi-micelle aggregates on the surface of PTFE are formed by C_(18)PO_(m)EO_(n)C molecules through hydrophobic interaction,and the hydrophilic group faces the solution to modify the surface of PTFE with high efficiency.
基金Supported by National Natural Science Foundation of China(50707012),State Key Laboratory of Electrical Insulation and Power Equipment(EIPE11205),"Qing Lan Project"in Jiangsu Province of China.
文摘The homogeneous dielectric barrier discharge(DBD) in atmospheric air is most favorable for polymer surface modification due to the low cost of operation and the ability of ambient on-line continuous uniform processing.In this paper,polypropylene(PP) films are treated using a homogeneous DBD plasma in atmospheric air.The surface properties of PP films are studied using contact angle and surface energy measurement,scanning electron microscopy (SEM) and Fourier transformed infrared spectroscopy(FTIR),and the aging effect after treatment when the treated materials are exposed to open air is also studied,with the modification mechanism being discussed.It is demonstrated that non-thermal plasmas generated by homogeneous DBD in atmospheric air is an effective way to enhance the surface properties of PP films.After the plasma treatment,the surface of PP film is etched,and oxygen-containing polar groups are introduced into the surface.These two processes can induce a remarkable decrease in water contact angle and a remarkable increase in surface energy,and the surface properties of PP films are improved accordingly.
