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Exploring the effect of cooling rate on non-isothermal crystallization of copolymer polypropylene by fast scanning calorimetry
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作者 Yang Liao Ye-yuan Hu +4 位作者 Kosuke Ikeda Ryoji Okabe Rui-fen Wu Ryota Ozaki Qing-yan Xu 《China Foundry》 SCIE EI CAS CSCD 2024年第4期379-386,共8页
Polypropylene is commonly used as a binder for ceramic injection molding,and rapid cooling is often encountered during processing.However,the crystallization behavior of polypropylene shows a strong dependence on cool... Polypropylene is commonly used as a binder for ceramic injection molding,and rapid cooling is often encountered during processing.However,the crystallization behavior of polypropylene shows a strong dependence on cooling rate due to its semi-crystalline characteristics.Therefore,the influence of cooling rate on the quality of final product cannot be ignored.In this study,the fast differential scanning calorimetry(FSC)test was performed to study the influence of cooling rate on the non-isothermal crystallization behavior and non-isothermal crystallization kinetics of a copolymer polypropylene(PP BC03B).The results show that the crystallization temperatures and crystallinity decrease as the cooling rate increases.In addition,two exothermic peaks occur when cooling rate ranges from 30 to 300 K·s^(-1),indicating the formation of another crystal phase.Avrami,Ozawa and Mo equations were used to explore the non-isothermal crystallization kinetics,and it can be concluded that the Mo method is suitable for this study. 展开更多
关键词 cooling rate crystallization temperature CRYSTALLINITY non-isothermal crystallization kinetics FSC copolymer polypropylene
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Characterization and Modeling of Mechanical Properties of Additively Manufactured Coconut Fiber-Reinforced Polypropylene Composites
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作者 George Mosi Bernard W. Ikua +1 位作者 Samuel K. Kabini James W. Mwangi 《Advances in Materials Physics and Chemistry》 CAS 2024年第6期95-112,共18页
In the face of the increased global campaign to minimize the emission of greenhouse gases and the need for sustainability in manufacturing, there is a great deal of research focusing on environmentally benign and rene... In the face of the increased global campaign to minimize the emission of greenhouse gases and the need for sustainability in manufacturing, there is a great deal of research focusing on environmentally benign and renewable materials as a substitute for synthetic and petroleum-based products. Natural fiber-reinforced polymeric composites have recently been proposed as a viable alternative to synthetic materials. The current work investigates the suitability of coconut fiber-reinforced polypropylene as a structural material. The coconut fiber-reinforced polypropylene composites were developed. Samples of coconut fiber/polypropylene (PP) composites were prepared using Fused Filament Fabrication (FFF). Tests were then conducted on the mechanical properties of the composites for different proportions of coconut fibers. The results obtained indicate that the composites loaded with 2 wt% exhibited the highest tensile and flexural strength, while the ones loaded with 3 wt% had the highest compression strength. The ultimate tensile and flexural strength at 2 wt% were determined to be 34.13 MPa and 70.47 MPa respectively. The compression strength at 3 wt% was found to be 37.88 MPa. Compared to pure polypropylene, the addition of coconut fibers increased the tensile, flexural, and compression strength of the composite. In the study, an artificial neural network model was proposed to predict the mechanical properties of polymeric composites based on the proportion of fibers. The model was found to predict data with high accuracy. 展开更多
关键词 Additive Manufacturing Artificial Neural Network Mechanical Properties Natural Fibers POLYPROPYLENE
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Comparative impact behaviours of ultra high performance concrete columns reinforced with polypropylene vs steel fibres
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作者 Thong M.Pham Harrison Hyde +4 位作者 Maw K.Kaung Yan Zhuge Duong T.Tran Des Vlietstra Tung M.Tran 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第10期138-153,共16页
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
关键词 Ultra high-performance concrete Steel fibre Polypropylene micro-fibre Fibre volume fraction Impact loading Pendulum tests COLUMNS
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Efficient and selective removal of Pb(Ⅱ) from landfill leachate using L-serine-modified polyethylene/polypropylene nonwoven fabric synthesized via radiation grafting technique
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作者 Xin-Xin Feng Cheng Li +6 位作者 Xuan-Zhi Mao Wan-Ning Ren Yang Gao Yu-Long He Zhe Xing Rong Li Guo-Zhong Wu 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2024年第4期144-155,共12页
In this study,to efficiently remove Pb(Ⅱ) from aqueous environments,a novel L-serine-modified polyethylene/polypropylene nonwoven fabric sorbent(NWF-serine)was fabricated through the radiation grafting of glycidyl me... In this study,to efficiently remove Pb(Ⅱ) from aqueous environments,a novel L-serine-modified polyethylene/polypropylene nonwoven fabric sorbent(NWF-serine)was fabricated through the radiation grafting of glycidyl methacrylate and subsequent L-serine modification.The effect of the absorbed dose was investigated in the range of 5–50 kGy.NWF-serine was characterized by Fourier transform infrared spectroscopy,thermogravimetric analysis,and scanning electron microscopy.Batch adsorption tests were conducted to investigate the influences of pH,adsorption time,temperature,initial concentration,and sorbent dosage on the Pb(Ⅱ) adsorption performance of NWF-serine.The results indicated that Pb(Ⅱ) adsorption onto NWF-serine was an endothermic process,following the pseudo-second-order kinetic model and Langmuir isotherm model.The saturated adsorption capacity was 198.1 mg/g.NWF-serine exhibited Pb(Ⅱ) removal rates of 99.8% for aqueous solutions with initial concentrations of 100 mg/L and 82.1% for landfill leachate containing competitive metal ions such as Cd,Cu,Ni,Mn,and Zn.Furthermore,NWF-serine maintained 86% of its Pb(Ⅱ) uptake after five use cycles.The coordination of the carboxyl and amino groups with Pb(Ⅱ) was confirmed using X-ray photoelectron spectroscopy and extended X-ray absorption fine structure analysis. 展开更多
关键词 Landfill leachate Radiation grafting Polyethylene/polypropylene nonwoven fabric Pb(Ⅱ)removal
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Effects of cement content, polypropylene fiber length and dosage on fluidity and mechanical properties of fiber-toughened cemented aeolian sand backfill
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作者 Shushuai Wang Renshu Yang +1 位作者 Yongliang Li Zhongwen Yue 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2024年第11期2404-2416,共13页
Using aeolian sand(AS)for goaf backfilling allows coordination of green mining and AS control.Cemented AS backfill(CASB)exhibits brittle fracture.Polypropylene(PP)fibers are good toughening materials.When the tougheni... Using aeolian sand(AS)for goaf backfilling allows coordination of green mining and AS control.Cemented AS backfill(CASB)exhibits brittle fracture.Polypropylene(PP)fibers are good toughening materials.When the toughening effect of fibers is analyzed,their influence on the slurry conveying performance should also be considered.Additionally,cement affects the interactions among the hydration products,fibers,and aggregates.In this study,the effects of cement content(8wt%,9wt%,and 10wt%)and PP fiber length(6,9,and 12 mm)and dosage(0.05wt%,0.1wt%,0.15wt%,0.2wt%,and 0.25wt%)on fluidity and mechanical properties of the fibertoughened CASB(FCASB)were analyzed.The results indicated that with increases in the three aforementioned factors,the slump flow decreased,while the rheological parameters increased.Uniaxial compressive strength(UCS)increased with the increase of cement content and fiber length,and with an increase in fiber dosage,it first increased and then decreased.The strain increased with the increase of fiber dosage and length.The effect of PP fibers became more pronounced with the increase of cement content.Digital image correlation(DIC)test results showed that the addition of fibers can restrain the peeling of blocks and the expansion of fissure,and reduce the stress concentration of the FCASB.Scanning electron microscopy(SEM)test indicated that the functional mechanisms of fibers mainly involved the interactions of fibers with the hydration products and matrix and the spatial distribution of fibers.On the basis of single-factor analysis,the response surface method(RSM)was used to analyze the effects of the three aforementioned factors and their interaction terms on the UCS.The influence surface of the two-factor interaction terms and the three-dimensional scatter plot of the three-factor coupling were established.In conclusion,the response law of the FCASB properties under the effects of cement and PP fibers were obtained,which provides theoretical and engineering guidance for FCASB filling. 展开更多
关键词 polypropylene fibers fiber-toughened cemented aeolian sand backfill digital image correlation scanning electron microscopy response surface method
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Influence ofβ-nucleating Compound Agents on the Mechanical Properties and Crystallization Behavior of Polypropylene Random Copolymer 被引量:2
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作者 谷亚新 LIU Yunxue +3 位作者 FAN Zhaorong GUI Jianfeng 刘鹏 WANG Hongmei 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2023年第1期237-243,共7页
A novel polypropylene random(PPR)composite materials with optimized properties was developed by addingβ-nucleating compound agents(rare earth complex WBG-2 and aryl amide derivative TMB-5)and ternary compound modifie... A novel polypropylene random(PPR)composite materials with optimized properties was developed by addingβ-nucleating compound agents(rare earth complex WBG-2 and aryl amide derivative TMB-5)and ternary compound modifier(TPE/WBG-2/CaCO_(3)).The effects of differentβ-nucleating agents and ternary compound modifier on the mechanical properties and crystallization behavior of PPR were analyzed.The results show that,compared with pure PPR materials,both WBG-2 and TMB-5 could significantly improve the impact strength of PPR.The crystallization temperature of PPR increased with the addition ofβ-nucleating agent.The modified PPR prepared with ternary compound modifier showed the most excellent comprehensive properties. 展开更多
关键词 polypropylene random copolymer β-nucleating agent impact strength crystallization behavior
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Effect of Polypropylene Fiber on the Unconfined Compressive Strength of Loess with Different Water Content 被引量:1
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作者 Wankui Ni Jiaxin Zhong Haiman Wang 《Journal of Renewable Materials》 SCIE EI 2023年第4期1699-1714,共16页
Fiber-reinforced soils have been of great interest to experimenters for building foundations’strength performance,time,and economy.This paper investigates the effects of water content and polypropylene fiber dosage a... Fiber-reinforced soils have been of great interest to experimenters for building foundations’strength performance,time,and economy.This paper investigates the effects of water content and polypropylene fiber dosage and length on loess’s unconfined compressive strength(UCS)according to the central composite response surface design test procedure.The water content is 11%–25%,the mass ratio of fiber to soil is 0.1%–0.9%,and the fiber length ranges from 6–18 mm.The response surface method(RSM)developed full quadratic models of different variables with response values.After analysis of variance(ANOVA),the mathematical model developed in this study was statistically significant(p≤0.05)and applicable to the optimization process.The optimization results showed that the optimal water content values,fiber amount,and fiber length were 16.41%,0.579%,and 14.90 mm,respectively.The unconfined compressive strength of the optimized specimens was increased by 288.017 kPa.The research results can reference the design and construction of fiber-reinforced soil in practical projects such as road base engineering and foundation engineering. 展开更多
关键词 LOESS polypropylene fiber response surface method water content
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DYNAMIC RHEOLOGICAL BEHAVIOR OF POLYPROPYLENE FILLED WITH ULTRA-FINE POWDERED RUBBER PARTICLES 被引量:7
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作者 郑强 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2004年第4期363-367,共5页
Dynamic rheological characteristics of polypropylene (PP) filled with ultra-fine full-vulcanized powdered rubber (UFPR) composed of styrene-butadiene copolymer were studied through dynamic rheological measurements on ... Dynamic rheological characteristics of polypropylene (PP) filled with ultra-fine full-vulcanized powdered rubber (UFPR) composed of styrene-butadiene copolymer were studied through dynamic rheological measurements on an Advanced Rheometric Expansion System (ARES). A specific viscoelastic phenomenon, i.e. 'the second plateau', appeared at low frequencies, and exhibits a certain dependence on the amount of rubber particles and the dispersion state in the matrix. This phenomenon is attributed to the formation of aggregation structure of rubber particles. The analyses of Cole-Cole diagrams of the dynamic viscoelastic functions suggest that the heterogeneity of the composites is enhanced on increasing both particle content and temperature. 展开更多
关键词 POLYPROPYLENE Ultra-fine powdered rubber Filled polymers Dynamic rheological behavior Aggregation of fillers
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Rotator cuff repair with an interposition polypropylene mesh:A biomechanical ovine study 被引量:1
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作者 Winston Shang Rong Lim Andy Khye Soon Yew +2 位作者 Hannah Lie Siaw Meng Chou Denny Tijauw Tjoen Lie 《World Journal of Orthopedics》 2023年第5期319-327,共9页
BACKGROUND Chronic large to massive rotator cuff tears are difficult to treat and re-tears are common even after surgical repair.We propose using a synthetic polypropylene mesh to increase the tensile strength of rota... BACKGROUND Chronic large to massive rotator cuff tears are difficult to treat and re-tears are common even after surgical repair.We propose using a synthetic polypropylene mesh to increase the tensile strength of rotator cuff repairs.We hypothesize that using a polypropylene mesh to bridge the repair of large rotator cuff tears will increase the ultimate failure load of the repair.AIM To investigate the mechanical properties of rotator cuff tears repaired with a polypropylene interposition graft in an ovine ex-vivo model.METHODS A 20 mm length of infraspinatus tendon was resected from fifteen fresh sheep shoulders to simulate a large tear.We used a polypropylene mesh as an interposition graft between the ends of the tendon for repair.In seven specimens,the mesh was secured to remnant tendon by continuous stitching while mattress stitches were used for eight specimens.Five specimens with an intact tendon were tested.The specimens underwent cyclic loading to determine the ultimate failure load and gap formation.RESULTS The mean gap formation after 3000 cycles was 1.67 mm in the continuous group,and 4.16 mm in the mattress group(P=0.001).The mean ultimate failure load was significantly higher at 549.2 N in the continuous group,426.4 N in the mattress group and 370 N in the intact group(P=0.003).CONCLUSION The use of a polypropylene mesh is biomechanically suitable as an interposition graft for large irreparable rotator cuff tears. 展开更多
关键词 Rotator cuff repair Massive tear Interposition graft BIOMECHANICS Polypropylene mesh
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Characterization, preparation, and reuse of metallic powders for laser powder bed fusion: a review 被引量:1
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作者 Xiaoyu Sun Minan Chen +4 位作者 Tingting Liu Kai Zhang Huiliang Wei Zhiguang Zhu Wenhe Liao 《International Journal of Extreme Manufacturing》 SCIE EI CAS CSCD 2024年第1期52-91,共40页
Laser powder bed fusion(L-PBF) has attracted significant attention in both the industry and academic fields since its inception, providing unprecedented advantages to fabricate complex-shaped metallic components. The ... Laser powder bed fusion(L-PBF) has attracted significant attention in both the industry and academic fields since its inception, providing unprecedented advantages to fabricate complex-shaped metallic components. The printing quality and performance of L-PBF alloys are infuenced by numerous variables consisting of feedstock powders, manufacturing process,and post-treatment. As the starting materials, metallic powders play a critical role in infuencing the fabrication cost, printing consistency, and properties. Given their deterministic roles, the present review aims to retrospect the recent progress on metallic powders for L-PBF including characterization, preparation, and reuse. The powder characterization mainly serves for printing consistency while powder preparation and reuse are introduced to reduce the fabrication costs.Various powder characterization and preparation methods are presented in the beginning by analyzing the measurement principles, advantages, and limitations. Subsequently, the effect of powder reuse on the powder characteristics and mechanical performance of L-PBF parts is analyzed, focusing on steels, nickel-based superalloys, titanium and titanium alloys, and aluminum alloys. The evolution trends of powders and L-PBF parts vary depending on specific alloy systems, which makes the proposal of a unified reuse protocol infeasible. Finally,perspectives are presented to cater to the increased applications of L-PBF technologies for future investigations. The present state-of-the-art work can pave the way for the broad industrial applications of L-PBF by enhancing printing consistency and reducing the total costs from the perspective of powders. 展开更多
关键词 laser powder bed fusion powder characterization powder preparation powder reuse
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Surface Treatment of Polypropylene Powders Using a Plasma Reactor with a Stirrer 被引量:1
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作者 方世东 孟月东 +1 位作者 沈洁 丛杰 《Plasma Science and Technology》 SCIE EI CAS CSCD 2011年第2期217-222,共6页
A radio frequency argon plasma reactor with a stirrer was employed for the surface treatment of polypropylene (PP) powders. The changes in the superficial contact angle and the superficial composition of the un-trea... A radio frequency argon plasma reactor with a stirrer was employed for the surface treatment of polypropylene (PP) powders. The changes in the superficial contact angle and the superficial composition of the un-treated and treated PP powders were analyzed by means of water contact angle (WCA) measurement, X-ray photoelectron spectroscopy (XPS) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). The water contact angle changed from the original value of 130.2° before plasma treatment to the value of 73.6° after treatment for 5 minutes. With the increase in plasma treating time, there were a decrease in the water contact angle and an increase in the content of oxygen containing polar functional groups (i.e., C-O, C=O and O-C=O). Both XPS and ATR-FTIR results indicated that the plasma treatment led to the formation of oxygen containing polar functional groups due to oxidation on the surface of the PP powders, and the trend of variation of the water contact angle with plasma treating time was related to the concentration of oxygen atom on the treated PP powders surface. Furthermore, the aging of the plasma-treated PP powders was investigated. 展开更多
关键词 PLASMA polypropylene powders surface treatment
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Influence of heat treatment on microstructure,mechanical and corrosion behavior of WE43 alloy fabricated by laser-beam powder bed fusion 被引量:5
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作者 Chenrong Ling Qiang Li +6 位作者 Zhe Zhang Youwen Yang Wenhao Zhou Wenlong Chen Zhi Dong Chunrong Pan Cijun Shuai 《International Journal of Extreme Manufacturing》 SCIE EI CAS CSCD 2024年第1期258-275,共18页
Magnesium(Mg)alloys are considered to be a new generation of revolutionary medical metals.Laser-beam powder bed fusion(PBF-LB)is suitable for fabricating metal implants withpersonalized and complicated structures.Howe... Magnesium(Mg)alloys are considered to be a new generation of revolutionary medical metals.Laser-beam powder bed fusion(PBF-LB)is suitable for fabricating metal implants withpersonalized and complicated structures.However,the as-built part usually exhibits undesirable microstructure and unsatisfactory performance.In this work,WE43 parts were firstly fabricated by PBF-LB and then subjected to heat treatment.Although a high densification rate of 99.91%was achieved using suitable processes,the as-built parts exhibited anisotropic and layeredmicrostructure with heterogeneously precipitated Nd-rich intermetallic.After heat treatment,fine and nano-scaled Mg24Y5particles were precipitated.Meanwhile,theα-Mg grainsunderwent recrystallization and turned coarsened slightly,which effectively weakened thetexture intensity and reduced the anisotropy.As a consequence,the yield strength and ultimate tensile strength were significantly improved to(250.2±3.5)MPa and(312±3.7)MPa,respectively,while the elongation was still maintained at a high level of 15.2%.Furthermore,the homogenized microstructure reduced the tendency of localized corrosion and favoredthe development of uniform passivation film.Thus,the degradation rate of WE43 parts was decreased by an order of magnitude.Besides,in-vitro cell experiments proved their favorable biocompatibility. 展开更多
关键词 laser-beam powder bed fusion WE43 alloys heat treatment mechanical performance biodegradation behavior
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Influence of layer thickness on formation quality,microstructure,mechanical properties,and corrosion resistance of WE43 magnesium alloy fabricated by laser powder bed fusion 被引量:2
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作者 Bangzhao Yin Jinge Liu +7 位作者 Bo Peng Mengran Zhou Bingchuan Liu Xiaolin Ma Caimei Wang Peng Wen Yun Tian Yufeng Zheng 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2024年第4期1367-1385,共19页
Laser powder bed fusion(L-PBF)of Mg alloys has provided tremendous opportunities for customized production of aeronautical and medical parts.Layer thickness(LT)is of great significance to the L-PBF process but has not... Laser powder bed fusion(L-PBF)of Mg alloys has provided tremendous opportunities for customized production of aeronautical and medical parts.Layer thickness(LT)is of great significance to the L-PBF process but has not been studied for Mg alloys.In this study,WE43 Mg alloy bulk cubes,porous scaffolds,and thin walls with layer thicknesses of 10,20,30,and 40μm were fabricated.The required laser energy input increased with increasing layer thickness and was different for the bulk cubes and porous scaffolds.Porosity tended to occur at the connection joints in porous scaffolds for LT40 and could be eliminated by reducing the laser energy input.For thin wall parts,a large overhang angle or a small wall thickness resulted in porosity when a large layer thicknesses was used,and the porosity disappeared by reducing the layer thickness or laser energy input.A deeper keyhole penetration was found in all occasions with porosity,explaining the influence of layer thickness,geometrical structure,and laser energy input on the porosity.All the samples achieved a high fusion quality with a relative density of over 99.5%using the optimized laser energy input.The increased layer thickness resulted to more precipitation phases,finer grain sizes and decreased grain texture.With the similar high fusion quality,the tensile strength and elongation of bulk samples were significantly improved from 257 MPa and 1.41%with the 10μm layer to 287 MPa and 15.12%with the 40μm layer,in accordance with the microstructural change.The effect of layer thickness on the compressive properties of porous scaffolds was limited.However,the corrosion rate of bulk samples accelerated with increasing the layer thickness,mainly attributed to the increased number of precipitation phases. 展开更多
关键词 Magnesium alloy WE43 Laser powder bed fusion Layer thickness Process optimization
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Alloy design for laser powder bed fusion additive manufacturing:a critical review 被引量:1
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作者 Zhuangzhuang Liu Qihang Zhou +4 位作者 Xiaokang Liang Xiebin Wang Guichuan Li Kim Vanmeensel Jianxin Xie 《International Journal of Extreme Manufacturing》 SCIE EI CAS CSCD 2024年第2期29-63,共35页
Metal additive manufacturing(AM)has been extensively studied in recent decades.Despite the significant progress achieved in manufacturing complex shapes and structures,challenges such as severe cracking when using exi... Metal additive manufacturing(AM)has been extensively studied in recent decades.Despite the significant progress achieved in manufacturing complex shapes and structures,challenges such as severe cracking when using existing alloys for laser powder bed fusion(L-PBF)AM have persisted.These challenges arise because commercial alloys are primarily designed for conventional casting or forging processes,overlooking the fast cooling rates,steep temperature gradients and multiple thermal cycles of L-PBF.To address this,there is an urgent need to develop novel alloys specifically tailored for L-PBF technologies.This review provides a comprehensive summary of the strategies employed in alloy design for L-PBF.It aims to guide future research on designing novel alloys dedicated to L-PBF instead of adapting existing alloys.The review begins by discussing the features of the L-PBF processes,focusing on rapid solidification and intrinsic heat treatment.Next,the printability of the four main existing alloys(Fe-,Ni-,Al-and Ti-based alloys)is critically assessed,with a comparison of their conventional weldability.It was found that the weldability criteria are not always applicable in estimating printability.Furthermore,the review presents recent advances in alloy development and associated strategies,categorizing them into crack mitigation-oriented,microstructure manipulation-oriented and machine learning-assisted approaches.Lastly,an outlook and suggestions are given to highlight the issues that need to be addressed in future work. 展开更多
关键词 laser powder bed fusion alloy design PRINTABILITY crack mitigation
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The effect of pulse voltage rise rate on the polypropylene surface hydrophilic modification by ns pulsed nitrogen DBD
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作者 刘峰 李舒豪 +3 位作者 赵昱雷 Shakeel AKRAM 张丽 方志 《Plasma Science and Technology》 SCIE EI CAS CSCD 2023年第10期6-14,共9页
The nanosecond(ns) pulsed nitrogen dielectric barrier discharge(DBD) is employed to enhance the hydrophilicity of polypropylene(PP) surface and improve its application effect.The discharge characteristics of the ns pu... The nanosecond(ns) pulsed nitrogen dielectric barrier discharge(DBD) is employed to enhance the hydrophilicity of polypropylene(PP) surface and improve its application effect.The discharge characteristics of the ns pulsed nitrogen DBD with different pulse rise times(from 50to 500 ns) are investigated by electrical and optical diagnostic methods and the discharge uniformity is quantitatively analyzed by image processing method.To characterize the surface hydrophilicity,the water contact angle(WCA) is measured,and the physical morphology and chemical composition of PP before and after modification are analyzed to explore the effect of plasma on PP surface.It is found that with increasing pulse rise time from 50 to 500 ns,DBD uniformity becomes worse,energy efficiency decreases from 20% to 10.8%,and electron density decrease from 6.6 × 10^(11)to 5.5 × 10^(11)cm^(-3).The tendency of electron temperature is characterized with the intensity ratio of N_(2)/N_(2)^(+)emission spectrum,which decreases from 17.4 to15.9 indicating the decreasing of T_(e) with increasing pulse rise time from 50 to 500 ns.The PP surface treated with 50 ns pulse rise time DBD has a lower WCA(~47°),while the WCA of PP treated with 100 to 500 ns pulse rise time DBD expands gradually(~50°–57°).According to the study of the fixed-point WCA values,the DBD-treated PP surface has superior uniformity under50 ns pulse rise time(3° variation) than under 300 ns pulse rise time(8° variation).After DBD treatment,the increased surface roughness from 2.0 to 9.8 nm and hydrophilic oxygencontaining groups on the surface,i.e.hydroxyl(-OH) and carbonyl(C=O) have played the significant role to improve the sample’s surface hydrophilicity.The short pulse voltage rise time enhances the reduced electric field strength(E/n) in the discharge space and improves the discharge uniformity,which makes relatively sufficient physical and chemical reactions have taken place on the PP surface,resulting in better treatment uniformity. 展开更多
关键词 dielectric barrier discharge pulse rise time material surface modification POLYPROPYLENE UNIFORMITY
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Role of heterogenous microstructure and deformation behavior in achieving superior strength-ductility synergy in zinc fabricated via laser powder bed fusion 被引量:1
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作者 Zhi Dong Changjun Han +7 位作者 Yanzhe Zhao Jinmiao Huang Chenrong Ling Gaoling Hu Yunhui Wang Di Wang Changhui Song Yongqiang Yang 《International Journal of Extreme Manufacturing》 SCIE EI CAS CSCD 2024年第4期225-245,共21页
Zinc(Zn)is considered a promising biodegradable metal for implant applications due to its appropriate degradability and favorable osteogenesis properties.In this work,laser powder bed fusion(LPBF)additive manufacturin... Zinc(Zn)is considered a promising biodegradable metal for implant applications due to its appropriate degradability and favorable osteogenesis properties.In this work,laser powder bed fusion(LPBF)additive manufacturing was employed to fabricate pure Zn with a heterogeneous microstructure and exceptional strength-ductility synergy.An optimized processing window of LPBF was established for printing Zn samples with relative densities greater than 99%using a laser power range of 80∼90 W and a scanning speed of 900 mm s−1.The Zn sample printed with a power of 80 W at a speed of 900 mm s−1 exhibited a hierarchical heterogeneous microstructure consisting of millimeter-scale molten pool boundaries,micrometer-scale bimodal grains,and nanometer-scale pre-existing dislocations,due to rapid cooling rates and significant thermal gradients formed in the molten pools.The printed sample exhibited the highest ductility of∼12.1%among all reported LPBF-printed pure Zn to date with appreciable ultimate tensile strength(∼128.7 MPa).Such superior strength-ductility synergy can be attributed to the presence of multiple deformation mechanisms that are primarily governed by heterogeneous deformation-induced hardening resulting from the alternative arrangement of bimodal Zn grains with pre-existing dislocations.Additionally,continuous strain hardening was facilitated through the interactions between deformation twins,grains and dislocations as strain accumulated,further contributing to the superior strength-ductility synergy.These findings provide valuable insights into the deformation behavior and mechanisms underlying exceptional mechanical properties of LPBF-printed Zn and its alloys for implant applications. 展开更多
关键词 laser powder bed fusion ZINC heterogeneous microstructure bimodal grains strength-ductility synergy
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Effect of Synthetic Conditions and Thickener Formulation on the Rheological and Tribological Properties of Polypropylene Grease
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作者 He Boyang 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS CSCD 2023年第4期164-174,共11页
Polypropylene(PP)grease holds great potential for special industrial applications.In this study,synthetic conditions,thickener content,and the ratio of two different molecular weight PPs were investigated systematical... Polypropylene(PP)grease holds great potential for special industrial applications.In this study,synthetic conditions,thickener content,and the ratio of two different molecular weight PPs were investigated systematically using a rheometer,scanning electron microscope,X-ray diffraction,Fourier transform infrared spectrometer,oscillating tribometer,and 3D surface profiler measurements.The results showed that suitable synthetic conditions are two quenching cycles,and the synthetic temperature and time is 240℃for 12 h.The rheological analysis showed that thickener content and different proportions of the two PP molecular weights have a significant influence on the rheological properties of PP grease.High molecular weight PP(H-PP)has a stronger thickening ability than low molecular weight PP(L-PP).The higher the amount of H-PP in the fixed thickener content or the higher the thickener content with a specific proportion,the higher the viscoelasticity of PP grease.The tribological performance is related to the rheological properties.The proportion of two different molecular weight PPs in the thickener content should be appropriate;excessive H-PP content leads to lubrication failure. 展开更多
关键词 polypropylene grease synthetic conditions thickener formulation rheological properties tribological properties
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A Circular Economy Use of Post-Consumer Polypropylene Packaging for Low Thermal Conductive and Fire-Retardant Building Material Applications
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作者 Jakkid Sanetuntikul Borwon Narupai Nawadon Petchwattana 《Journal of Renewable Materials》 EI 2023年第9期3567-3582,共16页
Wastes from polypropylene(PP)packages are accumulating every year because it is one of the most widely consumed and short lifecycle products.This paper aims to develop low thermal conductive and fire-retardant materia... Wastes from polypropylene(PP)packages are accumulating every year because it is one of the most widely consumed and short lifecycle products.This paper aims to develop low thermal conductive and fire-retardant materials from post-consumer PP(pPP)packages.Ammonium polyphosphate(APP)and hollow glass microsphere(HGM)were further added to improve the fire retardancy and thermal conductivity of pPP.The influence of APP and HGM on the mechanical and thermal properties,fire retardancy and thermal conductivity of pPP were investigated and compared with that of virgin PP(vPP).HGM was constantly added at 5 wt%while the content of APP was varied from 5 to 20 wt%.Experimental results showed that the tensile and flexural strengths were reduced with increasing APP concentrations.A morphological study confirmed the poor interfacial adhesion and debonding of each component during the applied load.Formulations containing APP less than 10 wt%did not show a satisfying fire retardancy rating due to the long self-extinguishing time.Further flame dipping and cotton ignition were observed for these formulations.With 15 and 20 wt%APP,the fire rating was significantly improved from no rating to V-0.The conductive heat transfer coefficient(k)was reduced by the presence of HGM.Based on these results,the formulation with 15 and 20 wt%could be used as a low k,fire-retardant building material. 展开更多
关键词 Post-consumer polypropylene RECYCLING hollow glass microsphere thermal conductivity fire retardancy
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Experimental study on mechanical and frost heave behaviors of silty clay improved by polyvinyl alcohol and polypropylene fiber
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作者 JianKun Liu Sergey Tsaybel +3 位作者 XiaoQiang Liu Li Liu XiaoKang Li Xu Li 《Research in Cold and Arid Regions》 CSCD 2023年第2期57-65,共9页
Silty clay is widely used as subgrade filler in cold regions,which suffer from frost heave in winter and mud pumping in spring.In this study,polyvinyl alcohol(PVA)and polypropylene(PP)fiber were used to improve the me... Silty clay is widely used as subgrade filler in cold regions,which suffer from frost heave in winter and mud pumping in spring.In this study,polyvinyl alcohol(PVA)and polypropylene(PP)fiber were used to improve the mechanical and frost heave behavior of silty clay in cold regions,and the direct shear test and one-dimensional frost heave test were employed in studying improvement effects.Moreover,improvement mechanisms of PVA and PP fiber were analyzed based on test results.The main findings are as follows.(1)Both PP and PVA can heighten the strength of silty clay and suppress frost heave,but the PVA solution has a more decisive influence on improving mechanical properties than PP fiber.(2)The improvement mechanism of the PVA solution is cementing.The improvement effect of 2%PVA solution is the best,which can increase the shear strength by approximately 40%–60%at different stress levels and decrease the frost heave ratio from 0.89%to 0.16%at optimal water content.(3)For 2%PVA improved samples,0.25%PP fiber can further increase soil cohesion by approximately 20–30 kPa at different stress levels and further decrease the frost heave ratio from 0.16%to 0.07%at optimal water content.The improvement effect is neglectable when the PP fiber content exceeds 0.25%.Overall,2%PVA with 0.25%PP fiber is the optimum combination to improve silty clay in cold regions. 展开更多
关键词 Frost heave Improved soil Subgrade fillers Polyvinyl alcohol Polypropylene fiber
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Microstructure and thermal properties of dissimilar M300–CuCr1Zr alloys by multi-material laser-based powder bed fusion 被引量:1
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作者 Xiaoshuang Li Dmitry Sukhomlinov Zaiqing Que 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CSCD 2024年第1期118-128,共11页
Multi-material laser-based powder bed fusion (PBF-LB) allows manufacturing of parts with 3-dimensional gradient and additional functionality in a single step. This research focuses on the combination of thermally-cond... Multi-material laser-based powder bed fusion (PBF-LB) allows manufacturing of parts with 3-dimensional gradient and additional functionality in a single step. This research focuses on the combination of thermally-conductive CuCr1Zr with hard M300 tool steel.Two interface configurations of M300 on CuCr1Zr and CuCr1Zr on M300 were investigated. Ultra-fine grains form at the interface due to the low mutual solubility of Cu and steel. The material mixing zone size is dependent on the configurations and tunable in the range of0.1–0.3 mm by introducing a separate set of parameters for the interface layers. Microcracks and pores mainly occur in the transition zone.Regardless of these defects, the thermal diffusivity of bimetallic parts with 50vol% of CuCr1Zr significantly increases by 70%–150%compared to pure M300. The thermal diffusivity of CuCr1Zr and the hardness of M300 steel can be enhanced simultaneously by applying the aging heat treatment. 展开更多
关键词 multi-material additive manufacturing laser-based powder bed fusion thermal diffusivity dissimilar metals copper alloy
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