Optimization Mechanism of Mechanical Properties of Basalt Fiber-Epoxy Resin Composites by Interfacially Enriched Distribution of Nano-Starch Crystals

Fibre reinforced polymer composites have become a new generation of structural materials due to their unique advantages such as high specific strength,designability,good dimensional stability and ease of large-area monolithic forming.However,the problem of interfacial bonding between the resin matrix and the fibres limits the direct use of reinforcing fibres and has become a central difficulty in the development of basalt fibre-epoxy composites.This paper proposes a solution for enhancing the strength of the fibre-resin interface using maize starch nanocrystals,which are highly yield and eco-friendly.Firstly,in this paper,corn starch nanocrystals(SNC)were prepared by hydrolysis,and were deposited on the surface of basalt fibers by electrostatic adsorption.After that,in order to maximize the modification effect of nano-starch crystals on the interface,the basalt fiber-epoxy resin composite samples were prepared by mixing in a pressureless molding method.The test results shown that the addition of basalt fibers alone led to a reduction in the strength of the sample.Deposition of 0.1 wt%SNC on the surface of basalt fibers can make the strength consistent with pure epoxy resin.When the adsorption amount of SNC reached 0.5 wt%,the tensile strength of the samples was 23.7%higher than that of pure epoxy resin.This is due to the formation of ether bond homopolymers between the SNC at the fibre-epoxy interface and the epoxy resin,which distorts the originally smooth interface,leading to increased stress concentration and the development of cracks.This enhances the binding of basalt fibers.The conclusions of this paper can provide an effective,simple,low-cost and non-polluting method of interfacial enhancement modification.

Design and test of the bilateral throwing soil-covering device for straw mulching machine in orchards

Aiming to lack the function of soil covering in the developed orchard straw mulching machine(OSM),a kind of bilateral counter-throwing soil-covering device was developed to eliminate the orchard fire risk caused by the straw layer.The soil-covering device was suspended at the rear of the OSM.Its core component was a pair of throwing wheels installed on both sides of a frame.Hydraulic motors drove the throwing wheels to take soil on-site and cover the straw layer.The adjustment range of the space between the throwing wheels on both sides was 1.4-2.1 m.Based on the analysis of soil-covering quantity,soil-covering width,thickness uniformity of soil layer,and power consumption,the key parameters such as the radius,the number of the vane,and the minimum rotation speed of the throwing wheels were determined.It was proved that the thickness uniformity of the soil layer by bilateral counter-throwing was better than by unilateral,and bottom throwing was better than top throwing.The blade of the soil cutter consisted of a straight blade and a curved blade,and the sliding-cutting angle was 14°-40°.The field test results showed the soil-covering device had good performance with a width of 1.4-2.2 m,a thickness of the soil-covering layer(TSL)of 23.2-40.7 mm,a standard deviation(SD)of 1.4-2.9 mm,width uniformity of 100%,and leakage rate of zero.The established model,between the thickness of soil-covering layer and trenching depth,throwing angle,and rotation speed of the throwing wheels,has a determination coefficient of 0.9757 and can be used to guide the operating parameters.The soil cutter reduced the power consumption and impact load of the throwing wheels by 64.77%and 60.88%,respectively.This work provides a type of new equipment for the mechanization technology of straw mulching in arid and semi-arid orchards.