Experiment Of Bubbled-root Emitter Shell Material Formula

As the most important part of the whole micro-irrigation system,the emitters have a direct impact on the uniformity of irrigation,anti-blocking capacity and system life.This article takes the bubbled-root emitter as the research object,and firstly uses the bubbled-root emitter made of ABS,HDPE,HDPE+EVA,LDPE+EVA,HDPE+LDPE+LLDPE+EVA,and five different shell materials at room temperature.In the hydraulic performance test,four kinds of material formulations that meet the design requirements except for ABS were preliminarily screened.At the same time,the characteristics of material flow to the emitter were studied from the aspects of mold shrinkage,modulus,and tensile deformation characteristics of the shell material.The influence of environmental temperature on the hydraulic performance of bubbled-root emitter of different materials,the mechanical properties of the shell material,and the microscopic components were studied.Finally,the aging was accelerated by the outdoor natural aging and the weather resistance test box of the Xenon lamp.The mechanical properties and changes of micro-components before and after the aging of the material in the bubbled-root emitter,and the correlation between artificial accelerated aging and natural aging.Through the research,the conclusion is as follows:(1)The shell material has a significant impact on the outflow characteristics of the bubbled-root emitter: the greater the mold shrinkage of the shell material,the smaller the flow rate of the emitter;the greater the rigidity of the shell material,the greater the emitter flow rate increases with pressure.The slower the trend is;the greater the natural resilience of the shell material,the smaller the manufacturing deviation of the emitter under the same manufacturing process.(2)In the low temperature frost heaving test,with the increase of the number of frost heaving cycles,the tensile strength and elongation at break of the emitter shell material and the natural rebound rate after breaking gradually decreased.After the freezing frost swell test,the main components of the emitter shell remained unchanged,but the crystallinity decreased.After the frost heaving,the surface of the emitter shell became powdered and expanded.With the increase of the number of freeze-thaw cycles,the flow rate of the bubbled-root emitters of four different materials gradually decreased,and it became more obvious when the working water pressure was higher.(3)Except for E4,the flow rate and manufacturing deviation of bubbled-root emitter under high temperature environment did not change significantly with increasing temperature.E4 As the temperature and working water pressure increase,the emitter flow rate increases gradually,and the manufacturing deviation of the emitter also increases with the temperature.The main components of E2 E3 and E5 shell materials are HDPE emitters,and the temperature has no significant effect on the emitter flow rate.After the high temperature test,the elastic modulus of the material of the bubbled-root emitters of four different materials increased,and the tensile strength,elongation at break,and natural rebound rate after breaking decreased.After the high temperature test,the main components of the emitter shell remained unchanged,but the crystallinity decreased.After the high-temperature test,the surface of the emitter shell was enlarged,and the surface of the shell material became rough and uneven.(4)After the aging test,the mechanical properties of the emitter shell materials decreased,and the material tensile strength,elongation at break,and natural rebound rate decreased.After aging,the main components of the emitter shell remained unchanged,but the degree of crystallinity decreased,the surface of the emitter shell became rough and non-uniform,and the surface of the emitter appeared powdery and expanded.Compared with the artificial accelerated aging test,the characteristic change of the material properties after natural aging is more obvious.(5)In order to obtain the bubbled-root emitter with good hydraulic performance,small manufacturing deviation,low temperature resistance and high temperature resistance,it is recommended to consider 40%HDPE+40%LDPE+10%LLDPE+10%EVA as the bubbled-root emitter`s shell material formula.