Hybrid polymer membrane(TA-APTES),synthesized by tannic acid(TA)and aminopropyl trethoxysilane(APTES)based on the Schif’s base and Michael addition reaction,is deposited on the surface of poly(p-phenylene-2,6-benzobi...Hybrid polymer membrane(TA-APTES),synthesized by tannic acid(TA)and aminopropyl trethoxysilane(APTES)based on the Schif’s base and Michael addition reaction,is deposited on the surface of poly(p-phenylene-2,6-benzobisoxazole)(PBO)fbers,and then grafted with epoxy-terminated polysesquisiloxane(POSS)to obtain POSS-g-PBO@TA-APTES fbers.The POSS-g-PBO@TA-APTES fbers reinforced bisphenol A dicyanate ester(BADCy)resins(POSS-g-PBO@TAAPTES fbers/BADCy)wave-transparent laminated composites are prepared.The interlaminar shear strength and fexural strength of POSS-g-PBO@TA-APTES fbers/BADCy composites are respectively enhanced from 36.7 and 587.4 MPa to 42.8 and 645.8 MPa,increased by 16.6%and 9.9%compared with those of PBO fbers/BADCy composites.At 1 MHz,the corresponding dielectric constant and dielectric loss are reduced to 2.85 and 0.0047,respectively,lower than those of PBO fbers/BADCy(3.06 and 0.006)composites.Meanwhile,the simulated wave transmittance rate of POSS-g-PBO@TA-APTES fbers/BADCy composites with the thicknesses of 1.5–3.5 mm is higher than 86.2%at 0.3–40 GHz.The volume resistivity and breakdown strength of POSS-g-PBO@TA-APTES fbers/BADCy composites are 2.8×10^(15)Ω·cm and 19.80 kV/mm,higher than PBO fbers/BADCy composites(2.2×10^(15)Ω·cm and 17.69 kV/mm),respectively.And the corresponding heat resistant index is 221.5℃,lower than PBO fbers/BADCy composites(229.6℃).展开更多
The backfilling mining technology is a type of high-efficiency coal mining technology that is used to address the environmental issues caused by the caving mining technology.In this paper,the mechanical model of symme...The backfilling mining technology is a type of high-efficiency coal mining technology that is used to address the environmental issues caused by the caving mining technology.In this paper,the mechanical model of symmetrical laminated plate representing the overburden movement caused by the backfilling mining technology is established,and the governing differential equation of the motion of the overburden is derived.The boundary conditions of the mechanical model are put forward,and the analytical solution of the overburden movement and surface subsidence is obtained.The numerical model of the overburden movement and surface subsidence,under mining with backfilling,is established by means of the FLAC3D numerical software,which aims to systematically study the influence of backfilling compactness,mining thickness,and mining depth on the overburden movement and surface subsidence in backfilling mining.When the compactnessηis less than 70%,the overburden movement and surface subsidence is greater,while whenηis greater than 70%,the overburden movement and surface subsidence is reduced significantly.On this basis,the control mechanism of surface subsidence and overburden movement in backfilling mining is obtained.The suitable backfilling compactness is the key to controlling surface subsidence and overburden movement in backfilling mining.展开更多
为了研究不同叠合面对超高性能混凝土(UHPC)叠合板延性与抗弯刚度的影响,用3块不同叠合面UHPC叠合板进行了抗弯试验。试验结果表明:人工粗糙叠合面能满足UHPC叠合板叠合面的抗剪要求。设置叠合面抗剪钢筋会降低UHPC叠合板的位移延性与...为了研究不同叠合面对超高性能混凝土(UHPC)叠合板延性与抗弯刚度的影响,用3块不同叠合面UHPC叠合板进行了抗弯试验。试验结果表明:人工粗糙叠合面能满足UHPC叠合板叠合面的抗剪要求。设置叠合面抗剪钢筋会降低UHPC叠合板的位移延性与耗能延性,马镫钢筋较桁架钢筋的影响作用更大,同时能有效提高UHPC叠合板加载前期的抗弯刚度,但对加载中后期的抗弯刚度影响不大。UHPC叠合板使用阶段(0.5 M u^0.7 M u)的短期刚度,与钢纤维混凝土叠合板的计算短期刚度吻合良好,建议可按钢纤维混凝土叠合板短期刚度计算公式进行计算。展开更多
Jute/epoxy hybrid laminated biocomposites were manufactured by using Illite clay particles at various content （5 wt.% - 20 wt.%）. The effects of hybridization on the morphology, structure, and mechanical properties ...Jute/epoxy hybrid laminated biocomposites were manufactured by using Illite clay particles at various content （5 wt.% - 20 wt.%）. The effects of hybridization on the morphology, structure, and mechanical properties were investigated. The properties of the biocomposites reinforced with jute fibers were mainly influenced by the interfacial adhesion between the jute fibers and the epoxy matrix. An alkali treatment was applied to improve the interfacial fiber-matrix adhesion and thus obtaining better mechanical properties. Besides the chemical treatment, epoxy hybridization using clay particles also had a strong effect on the overall properties of laminated biocomposites. The mechanical properties of the jute/epoxy biocomposites reinforced with Illite clay increased with clay content, up to an optimum value at 15 wt.%. The average technique and the laminates theory were performed to validate the coherence of the elastic moduli between the calculated and experimental values. A difference between the experimental and predicted data was observed, which was attributed to the simplifying assumptions made in both models. The laminates theory gave better overall predictions.展开更多
Landscape designers increasingly prefer to use wood/bamboo-based composites for outdoor hydrophilic platforms owing to their natural surface texture,high performance,and sustainability to facilitate extensive interact...Landscape designers increasingly prefer to use wood/bamboo-based composites for outdoor hydrophilic platforms owing to their natural surface texture,high performance,and sustainability to facilitate extensive interaction between people and water and enable the full range of ecological functions of water resources.In this study,four laminated composite(LC)structures were designed and manufactured using fluffed bamboo and wood veneers.Their surface textures,profile densities,water resistances,and mechanical properties were then evaluated.The type of fluffed veneer of the surface layer determined the texture of the LC surface.The specific structures of fluffed bamboo and wood veneer laminations were found to affect the LC profile density variability,water resistance,and mechanical properties owing to the differences in the strength and interfacial properties of bamboo and wood fibers.Finally,the water resistance and mechanical properties of all four LCs were found to be much higher than the highest level specified in GB/T 20241-2006 for“laminated veneer lumber”and GB/T 30364-2013 for“bamboo scrimber flooring”,indicating that they are promising materials for structures and flooring,particularly for outdoor hydrophilic platforms.展开更多
基金The authors are grateful for the support and funding from National Scientifc Research Project(Basis Strengthening Plan)China Postdoctoral Science Foundation(2019M653735)+3 种基金State Key Laboratory for Modifcation of Chemical Fibers and Polymer Materials from Donghua University(KF2001)State Key Laboratory of Solidifcation Processing in NWPU(SKLSP202103)L.Tang thanks for the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX2021036)This work is also fnancially supported by Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars.
文摘Hybrid polymer membrane(TA-APTES),synthesized by tannic acid(TA)and aminopropyl trethoxysilane(APTES)based on the Schif’s base and Michael addition reaction,is deposited on the surface of poly(p-phenylene-2,6-benzobisoxazole)(PBO)fbers,and then grafted with epoxy-terminated polysesquisiloxane(POSS)to obtain POSS-g-PBO@TA-APTES fbers.The POSS-g-PBO@TA-APTES fbers reinforced bisphenol A dicyanate ester(BADCy)resins(POSS-g-PBO@TAAPTES fbers/BADCy)wave-transparent laminated composites are prepared.The interlaminar shear strength and fexural strength of POSS-g-PBO@TA-APTES fbers/BADCy composites are respectively enhanced from 36.7 and 587.4 MPa to 42.8 and 645.8 MPa,increased by 16.6%and 9.9%compared with those of PBO fbers/BADCy composites.At 1 MHz,the corresponding dielectric constant and dielectric loss are reduced to 2.85 and 0.0047,respectively,lower than those of PBO fbers/BADCy(3.06 and 0.006)composites.Meanwhile,the simulated wave transmittance rate of POSS-g-PBO@TA-APTES fbers/BADCy composites with the thicknesses of 1.5–3.5 mm is higher than 86.2%at 0.3–40 GHz.The volume resistivity and breakdown strength of POSS-g-PBO@TA-APTES fbers/BADCy composites are 2.8×10^(15)Ω·cm and 19.80 kV/mm,higher than PBO fbers/BADCy composites(2.2×10^(15)Ω·cm and 17.69 kV/mm),respectively.And the corresponding heat resistant index is 221.5℃,lower than PBO fbers/BADCy composites(229.6℃).
基金supported by the National Natural Science Foundation of China(51504081,51704095,51374201)the National Key Research and Development Program of China(2017YFC0805202)+3 种基金the Scientific Research Key Project Fund of Education Department of Henan Province(18A440012,14A440001)the Research Fund of Henan Key Laboratory for Green and Efficient Mining and Comprehensive Utilization of Mineral Resources(S201619)the Research Fund of the State Key Laboratory of Coal Resources and Safe Mining(13KF02)the Ph.D.Programs Foundation of Henan Polytechnic University(B2014-50,B2016-67).
文摘The backfilling mining technology is a type of high-efficiency coal mining technology that is used to address the environmental issues caused by the caving mining technology.In this paper,the mechanical model of symmetrical laminated plate representing the overburden movement caused by the backfilling mining technology is established,and the governing differential equation of the motion of the overburden is derived.The boundary conditions of the mechanical model are put forward,and the analytical solution of the overburden movement and surface subsidence is obtained.The numerical model of the overburden movement and surface subsidence,under mining with backfilling,is established by means of the FLAC3D numerical software,which aims to systematically study the influence of backfilling compactness,mining thickness,and mining depth on the overburden movement and surface subsidence in backfilling mining.When the compactnessηis less than 70%,the overburden movement and surface subsidence is greater,while whenηis greater than 70%,the overburden movement and surface subsidence is reduced significantly.On this basis,the control mechanism of surface subsidence and overburden movement in backfilling mining is obtained.The suitable backfilling compactness is the key to controlling surface subsidence and overburden movement in backfilling mining.
文摘为了研究不同叠合面对超高性能混凝土(UHPC)叠合板延性与抗弯刚度的影响,用3块不同叠合面UHPC叠合板进行了抗弯试验。试验结果表明:人工粗糙叠合面能满足UHPC叠合板叠合面的抗剪要求。设置叠合面抗剪钢筋会降低UHPC叠合板的位移延性与耗能延性,马镫钢筋较桁架钢筋的影响作用更大,同时能有效提高UHPC叠合板加载前期的抗弯刚度,但对加载中后期的抗弯刚度影响不大。UHPC叠合板使用阶段(0.5 M u^0.7 M u)的短期刚度,与钢纤维混凝土叠合板的计算短期刚度吻合良好,建议可按钢纤维混凝土叠合板短期刚度计算公式进行计算。
文摘Jute/epoxy hybrid laminated biocomposites were manufactured by using Illite clay particles at various content （5 wt.% - 20 wt.%）. The effects of hybridization on the morphology, structure, and mechanical properties were investigated. The properties of the biocomposites reinforced with jute fibers were mainly influenced by the interfacial adhesion between the jute fibers and the epoxy matrix. An alkali treatment was applied to improve the interfacial fiber-matrix adhesion and thus obtaining better mechanical properties. Besides the chemical treatment, epoxy hybridization using clay particles also had a strong effect on the overall properties of laminated biocomposites. The mechanical properties of the jute/epoxy biocomposites reinforced with Illite clay increased with clay content, up to an optimum value at 15 wt.%. The average technique and the laminates theory were performed to validate the coherence of the elastic moduli between the calculated and experimental values. A difference between the experimental and predicted data was observed, which was attributed to the simplifying assumptions made in both models. The laminates theory gave better overall predictions.
基金the Science and Technology Project of Zhejiang Province(2021C02012)the Science Foundation of Zhejiang Provincial Department of Education(113429A4F21070)the Science Foundation of Zhejiang Sci-Tech University(11340031282014 and 11343132612052).
文摘Landscape designers increasingly prefer to use wood/bamboo-based composites for outdoor hydrophilic platforms owing to their natural surface texture,high performance,and sustainability to facilitate extensive interaction between people and water and enable the full range of ecological functions of water resources.In this study,four laminated composite(LC)structures were designed and manufactured using fluffed bamboo and wood veneers.Their surface textures,profile densities,water resistances,and mechanical properties were then evaluated.The type of fluffed veneer of the surface layer determined the texture of the LC surface.The specific structures of fluffed bamboo and wood veneer laminations were found to affect the LC profile density variability,water resistance,and mechanical properties owing to the differences in the strength and interfacial properties of bamboo and wood fibers.Finally,the water resistance and mechanical properties of all four LCs were found to be much higher than the highest level specified in GB/T 20241-2006 for“laminated veneer lumber”and GB/T 30364-2013 for“bamboo scrimber flooring”,indicating that they are promising materials for structures and flooring,particularly for outdoor hydrophilic platforms.
