Processing Technology And Application Development Of Plastic Product With Micro Capillary Structure

Plastic product of micro capillary structure is a kind of polymer containing multi micron grade channels inside the material matrix,the features of which can be con-cluded as two aspects:multi channels and micron grade.Those products always show the properties of light-weight,large specific surface area,low-cost and easy manufac-ture,and they are widely applied in fields such microfluidics,biomedicine and envi-ronmental science.Micro capillary film(MCF)is a typical example of micro capillary structure products.In this thesis,a novel structure call micro capillary tube(MCT)is proposed based on the MCF,and relavant equipment is built for manufacturing MCT.Afterwards,the influences brought by processing parameters on sizes of MCT are re-searched;Besides,thermoplastic polyurethane(TPU)MCF is firstly produced and applied to fabricate microfluidics devices;What’s more,the MCF is innovatively adopted for fabricating testing strip for deteimination of hydrogen peroxide residue.The main research contents and results are detailed as following:1.Based on the old experimental platform,a novel specific experimental platform using to produce MCT is designed and set up.A special extrusion head including die exit,connecting rod,injector module,die box,and shunt is designed and man-ufactured according to requirements of producing MCT.Also the injection air system,coolant system and data acquisition system are specially improved and built to support the extrusion of MCT.2.MCT with a channel(0.9-3.0 mm in diameter)in the center surrounded by an ar-ray of microchannels(50-300 pm)using extrusion technology is first established.The draw ratio,injection air pressure and melt drawing length are demonstrated to significantly affect the cross-sectional parameters of MCT,which is consistent with theoretical analysis.It’s found the process parameters negligibly influence the relative proportions between cross-sectional parameters except changing the absolute value,but only the injection air pressure indeed affects the shape of cross section of MCT.Based on a simplified drawing model,a prediction function of high reliability(R-square>95%)for cross-sectional parameters is set up.The MCT are formed more uniformly compared with MCF because of the elimination of the sharp boundary effect.Drawing ratio is demonstrated to be dominating in affecting the forming of MCT when it goes above 10,and the prediction function works better with a higher drawing ratio.3.TPU-MCF,as a novel extruded product,inherently containing an array of circular micron-sized capillaries embedded inside the polymer matrixis first produced.With the aid of simple laser cutting and conventional sealing technologies,a rapid prototyping method for microfluidic devices is proposed based on the ready-made micro structure of MCFs.Two functionalized microfluidic devices:serpentine mi-cro mixer and two multi droplet generators(T-crossing and flow focus-ing)arerapidly fabricated to demonstrate the advantages and potential of employ-ing this new method.The whole proof-of-concept fabrication process can be com-pleted in 8-10 minutes in a simple way;each procedure is repeatable with stable performance control of microfluidic devices.The ratio of inflow rates and size of discret droplet generated are in a highly linear relationship(ε’=-0.678+3.15s)ex-hibited by T-crossing droplet generator;and the flow focusing droplet generator can produce droplet with diameter from 50μm to 650μm,and the ratio of inflow rates and ratio of droplet diameter to droplet interval distance are in a first order exponential model(ε’-0.8(1-e0.9ε)).The TPU-MCF and this novel method are ex-pected to provide a new perspective and alternative in microfluidic community with particular requirements.4.A novel idea for the determination of hydrogen peroxide in routine applications is proposed in this part.The method is based on the reaction of hydrogen peroxide with potassium Iodide to liberate iodine,which is used as chromogenic reagents together with starch.MCFs are firstly employed as reaction platform instead of conventional paper.Two cost-effective types of MCF test strip for semi-quantitative determination of hydrogen peroxide are fabricated in the present investigation:colorimetric strip and four-section grading test strip.Colorimetric strip worked based on the principle of colorimetric method.Standard colorimetric strip was made as reference for hydrogen peroxide with concentration from 0 to 0.1 wt.%with 0.5 wt.%KI under 120s testing time;Four-section grading test strip realized its function in a grading method rather than colorimetric method.Con-centration of hydrogen peroxide was rapidly graded into certain scale by simply judging the number of colored sections with naked eye.Concentration of hydro-gen peroxide from 0 to 0.12 wt.%could be subdivided into five grades in this work by testing strip filled with 0.1 wt.%,0.2 wt.%,0.5 wt.%and 1.0%wt.%KI under 45s testing time.Compared to traditional colorimetric method,results of grading method are more intuitive and understandable for observers.Besides,it provides a new perspective to help people of color weakness or blindness to play roles in relevant research community.