| In recent years,natural fiber-reinforced composites have been generally used in engineering materials due to environmental and low cost.However,natural fiber-reinforced composites had advantages in terms of environmental impact and cost,their mechanical properties were not satisfactory,and various properties were generally lower than synthetic materials.Therefore,mixing with mineral fibers(basalt fibers)could broaden the industrial applications of natural fiber-reinforced composites.As a potential solution,research and preparation of basalt/hemp hybrid fiber reinforced composites,trying to obtain more excellent mechanical properties,while maintaining lower costs and significant environmental benefits.This paper conducts research from three aspects of hemp fiber degumming treatment,basalt fiber modification,and hybrid composites preparation:First,a natural freezing-mechanical treatment method was proposed for hemp fiber degumming,which aimed to reduce the VOCs,improve the interface performance and mechanical properties;Second,to promote the application of natural fiber-reinforced composites,it was considered to improve the mechanical properties by adding basalt fiber with surface modification treatment;Third,hybrid composites were prepared,and the effects of hemp fiber specific gravity,basalt fiber specifications,and basalt fiber surface modification treatment on the mechanical properties of the composite were explored.Research indicates:After the natural freezing-mechanical degumming treatment of hemp fiber,the content of lignin and hemicellulose was significantly reduced,and the obtained fiber had a rough surface and a larger surface area.And,the temperature corresponding to the maximum decomposition rate of hemp fiber was increased,and it had higher thermal stability.In addition,after degumming,the total VOCs of hemp fiber were reduced,and the content of formaldehyde,acetaldehyde and acrolein was significantly reduced.After cryogenic treatment of basalt fiber,the surface of the fiber was significantly improved,and there were some bulges.Different concentrations of KH550 silane coupling agent had different effects on fiber surface modification.As the concentration of KH550 solution increases,the basalt fiber surface bulges gradually increased,and the surface roughness gradually increased.Compared with U-BF,the tensile strength of C-BF was increased by10%.With the increase of the KH550 solution concentration,the tensile properties of the fiber prepreg increased first and then decreased.The tensile properties of K1.0-BF increased by more than 20%.The processed hemp fibers and polylactide fibers are made into felt,and then laminated with basalt fiber prepregs to prepare a hybrid composite.The molding process parameters were temperature 185~oC,pressure 9 MPa,and time 6 min.The mechanical properties of hybrid composites reinforced with basalt fibers have been significantly improved.As the specific gravity of hemp fiber increases,the mechanical properties of composites increased first and then decreased,reaching a maximum at a hemp fiber content of 40 wt%.CBF/HF/PLA compared with UBF/HF/PLA:tensile strength increased by 10.2?14.1%,up to 158.41 MPa,and flexural strength increased by 19.1?31.2%,up to159.02 MPa,and impact strength 17.4?53.1%,up to 33.15 k J/m~2.KBF/HF/PLA compared with UBF/HF/PLA:tensile strength increased by 14.7?28.5%,up to181.22 MPa,flexural strength increased by 35.4?44.6%,up to 180.58 MPa,and impact strength increased by148.1?192.1%,up to 61 k J/m~2.This showed that cryogenic treatment and silane coupling agent treatment had improved the interface properties of basalt fibers,thereby improving the mechanical properties of composites.Compared with UBF/HF/PLA,the mechanical properties of MBF/HF/PLA was not improved but greatly reduced.Analyzing the micromorphology of the composite,it explained the influence of hemp fiber specific gravity,basalt fiber specifications,and basalt fiber surface modification treatment on the mechanical properties of the composites. |
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