The effects of selected printing parameters on the fire properties of additively produced composites from neat polylactic acid(PLA)and wood/PLA filaments were investigated.The reaction to fire of the 3D-printed specim...The effects of selected printing parameters on the fire properties of additively produced composites from neat polylactic acid(PLA)and wood/PLA filaments were investigated.The reaction to fire of the 3D-printed specimens was tested according to the ISO 5660-1 cone calorimeter test method.The results showed that the properties of the specimens when exposed to fire were significantly affected by the incorporation of wood flour into the PLA filament.It was also interesting that PLA specimens had much better reactions to fire than the wood/PLA specimens.Time to ignition was found to be much longer in the 3D-printed PLA specimens.Although the maximal heat release rate was a little higher in the PLA than the wood/PLA specimens,the duration of HRR was longer for the wood/PLA specimens.The initial mass of the specimens was smaller in the wood/PLA composites,but during the radiant heat exposure the mass typically decreased slower than in the PLA specimens.展开更多
In the present work,polyester composites reinforced with a newly identified Cyperus pangorei fiber(CPF)were developed by compression moulding technique.The effects of varying fiber content and fiber length on the mech...In the present work,polyester composites reinforced with a newly identified Cyperus pangorei fiber(CPF)were developed by compression moulding technique.The effects of varying fiber content and fiber length on the mechanical properties of the Cyperus pangorei fiber reinforced polyester composites(CPFCs)such as tensile,flexural,and impact properties were studied.Mechanical strength of the CPFCs increased with fiber length up to 40 mm beyond which a reverse trend was observed.Based on the test results,it was concluded that the critical fiber length and the optimum fiber weight percentage were 40 mm and 40 wt%respectively.The maximum increase of 164%and 117%were found for the tensile and flexural strength of the composite with 40 mm fiber length and 40 wt%fiber content,respectively.On the other hand,a 64%increase in impact strength was noticed for the optimum case.The increasing contact surface between the fiber and the polyester matrix in optimum condition can restrict the probability of fiber pullout and in turn can make the composite carry more load.The chemical structure of CPF was also analyzed using Fourier-Transform Infrared Spectroscopy(FTIR)spectrum.The morphological analysis of fractured samples was performed using Scanning Electron Microscopy(SEM)to understand the interfacial bonding between CPFs and polyester matrix.The optimal composite can be a suitable alternative in the field of structural applications in construction and automobile industries.展开更多
Potential use of condensate generated by cooling the steam obtained during high-frequency/vacuum drying step of hardwood lumber was investigated.The liquid condensates were obtained from oak,beech and walnut wood.This...Potential use of condensate generated by cooling the steam obtained during high-frequency/vacuum drying step of hardwood lumber was investigated.The liquid condensates were obtained from oak,beech and walnut wood.This liquid condensate was then used as a replacement for deionized water in the synthesis of Urea-Formaldehyde(UF)resin(5 wt%of total resin)using a laboratory scale reactor.Medium Density Fibreboards(MDFs)were produced using control and modified resins.Emissions of Volatile Organic Compounds(VOCs)from the MDFs were determined by Micro Chamber method.The bonding properties of the MDFs were determined according to European standards.The main VOC emissions from MDFs produced using UF resin containing the condensate were a-Pinene,b-Pinene,careen,and acetic acid,which were lower than those of the control MDF,except for the acetic acid emission of MDF with oak condensate.In the tree species,the beech wood condensate gave the lowest VOC emissions(732μg·m^-3)from the MDFs,followed by the MDFs containing walnut wood condensate(852μg·m^-3),oak wood condensate(998μg·m^-3),and control MDF(3529μg·m^-3),respectively.However,the internal bond strength of MDFs containing the condensate was negatively impacted by the condensate(0.70 N·mm^-2 to 0.54 N·mm^-2 depending on the tree species).The results showed that the liquid wood-drying condensate which generally released to the ground could be efficiently used as an alternative to expensive VOCs scavenger used in the production of UF resin bonded MDF.This may be one of the most efficient uses of the condensate in high value-added materials.展开更多
基金would like to thank the Slovenian Research Agency for financial support within the scope of the program P4-0015,as well as BI-CN/18-20-016:Study on the functional properties and thermal safety performance of wood materials and adhesives for 3D printing technology.
文摘The effects of selected printing parameters on the fire properties of additively produced composites from neat polylactic acid(PLA)and wood/PLA filaments were investigated.The reaction to fire of the 3D-printed specimens was tested according to the ISO 5660-1 cone calorimeter test method.The results showed that the properties of the specimens when exposed to fire were significantly affected by the incorporation of wood flour into the PLA filament.It was also interesting that PLA specimens had much better reactions to fire than the wood/PLA specimens.Time to ignition was found to be much longer in the 3D-printed PLA specimens.Although the maximal heat release rate was a little higher in the PLA than the wood/PLA specimens,the duration of HRR was longer for the wood/PLA specimens.The initial mass of the specimens was smaller in the wood/PLA composites,but during the radiant heat exposure the mass typically decreased slower than in the PLA specimens.
文摘In the present work,polyester composites reinforced with a newly identified Cyperus pangorei fiber(CPF)were developed by compression moulding technique.The effects of varying fiber content and fiber length on the mechanical properties of the Cyperus pangorei fiber reinforced polyester composites(CPFCs)such as tensile,flexural,and impact properties were studied.Mechanical strength of the CPFCs increased with fiber length up to 40 mm beyond which a reverse trend was observed.Based on the test results,it was concluded that the critical fiber length and the optimum fiber weight percentage were 40 mm and 40 wt%respectively.The maximum increase of 164%and 117%were found for the tensile and flexural strength of the composite with 40 mm fiber length and 40 wt%fiber content,respectively.On the other hand,a 64%increase in impact strength was noticed for the optimum case.The increasing contact surface between the fiber and the polyester matrix in optimum condition can restrict the probability of fiber pullout and in turn can make the composite carry more load.The chemical structure of CPF was also analyzed using Fourier-Transform Infrared Spectroscopy(FTIR)spectrum.The morphological analysis of fractured samples was performed using Scanning Electron Microscopy(SEM)to understand the interfacial bonding between CPFs and polyester matrix.The optimal composite can be a suitable alternative in the field of structural applications in construction and automobile industries.
基金supported by the Research Fund of Istanbul University-Cerrahpasa(No:BEK-2017-26341)。
文摘Potential use of condensate generated by cooling the steam obtained during high-frequency/vacuum drying step of hardwood lumber was investigated.The liquid condensates were obtained from oak,beech and walnut wood.This liquid condensate was then used as a replacement for deionized water in the synthesis of Urea-Formaldehyde(UF)resin(5 wt%of total resin)using a laboratory scale reactor.Medium Density Fibreboards(MDFs)were produced using control and modified resins.Emissions of Volatile Organic Compounds(VOCs)from the MDFs were determined by Micro Chamber method.The bonding properties of the MDFs were determined according to European standards.The main VOC emissions from MDFs produced using UF resin containing the condensate were a-Pinene,b-Pinene,careen,and acetic acid,which were lower than those of the control MDF,except for the acetic acid emission of MDF with oak condensate.In the tree species,the beech wood condensate gave the lowest VOC emissions(732μg·m^-3)from the MDFs,followed by the MDFs containing walnut wood condensate(852μg·m^-3),oak wood condensate(998μg·m^-3),and control MDF(3529μg·m^-3),respectively.However,the internal bond strength of MDFs containing the condensate was negatively impacted by the condensate(0.70 N·mm^-2 to 0.54 N·mm^-2 depending on the tree species).The results showed that the liquid wood-drying condensate which generally released to the ground could be efficiently used as an alternative to expensive VOCs scavenger used in the production of UF resin bonded MDF.This may be one of the most efficient uses of the condensate in high value-added materials.
