本文選題：熔融紡絲法 + 非溶劑致相分離法　； 參考：《天津工業(yè)大學(xué)》2017年碩士論文

【摘要】：中空纖維膜因其較多的優(yōu)點廣泛應(yīng)用于超微濾、膜蒸餾等過程中。但在規(guī)�；瘧�(yīng)用過程中發(fā)現(xiàn),膜強度是影響膜系統(tǒng)穩(wěn)定運行的主要問題。中空纖維膜在氣流和水流的沖擊下容易出現(xiàn)斷絲的現(xiàn)象,膜組件使用壽命縮短,因此開發(fā)高強度的中空纖維膜具有很大的應(yīng)用價值。為此,本文首先研究了熔融紡絲工藝與纖維結(jié)構(gòu)和性能的關(guān)系,得到了高拉伸斷裂強度PVDF纖維;其次將PVDF纖維與三孔中空纖維進行復(fù)合,制備高拉伸斷裂強度的復(fù)合增強中空纖維膜。為得到高拉伸強度的聚偏氟乙烯(PVDF)纖維,通過正交實驗和單因素實驗,研究了熔融紡絲法制備PVDF纖維的工藝條件,并利用熱分析(DSC)、紅外光譜法(FTIR)、X-射線衍射(XRD)和拉伸實驗研究了纖維的晶體結(jié)構(gòu)、晶區(qū)取向和力學(xué)性能。研究結(jié)果表明,紡絲過程中影響纖維拉伸強度的因素主次順序為:卷繞速率噴頭溫度入水距離;纖維拉伸強度隨著冷拉伸倍數(shù)的增大而提高。利用熔紡PVDF纖維拉伸過程中產(chǎn)生的殘余應(yīng)力對其進行定長后處理,并對后處理過程中的最優(yōu)工藝條件進行探索,從而得到拉伸強度優(yōu)異的聚偏氟乙烯(PVDF)纖維。利用紅外光譜(FTIR)、X-射線衍射(XRD)、差示掃描量熱(DSC)分析了纖維的晶體結(jié)構(gòu)、晶區(qū)取向和力學(xué)性能。研究結(jié)果表明,在殘余應(yīng)力作用下的后處理過程中纖維進一步發(fā)生了 α晶型向β晶型的轉(zhuǎn)變,結(jié)晶度和晶區(qū)取向均有所提高,斷裂強度提高明顯,PVDF纖維在60 ℃的水浴下處理3小時可使斷裂強度達到633 MPa,相比未處理前提高了 70 MPa。在三孔PVDF中空纖維膜的紡制工藝的基礎(chǔ)上,通過對噴絲頭的改造,將高拉伸斷裂強度的聚偏氟乙烯(PVDF)熔紡纖維與三孔中空纖維膜進行復(fù)合,從而利用纖維的力學(xué)增強作用制備出高拉伸斷裂強力的復(fù)合三孔中空纖維膜。通過對復(fù)合膜的超濾水通量、最大孔徑、破裂壓力、膜蒸餾通量等一系列基本性能測試,證明PVDF熔紡纖維在增強膜拉伸斷裂強力的同時并未對膜的其他性能造成影響。
[Abstract]:Hollow fiber membrane is widely used in ultrafiltration and membrane distillation because of its advantages.However, in the process of large-scale application, it is found that the membrane strength is the main problem affecting the stable operation of the membrane system.The hollow fiber membrane is easy to break under the impact of air flow and water flow, and the service life of the membrane module is shortened. Therefore, the development of high strength hollow fiber membrane has great application value.Therefore, the relationship between the melt spinning process and the structure and properties of the fibers was studied, and the high tensile breaking strength PVDF fiber was obtained, and the PVDF fiber was combined with the three-pore hollow fiber.Composite reinforced hollow fiber membranes with high tensile fracture strength were prepared.In order to obtain high tensile strength polyvinylidene fluoride (PVDF) fiber, the technological conditions of preparing PVDF fiber by melt spinning method were studied by orthogonal experiment and single factor experiment.The crystal structure, crystal orientation and mechanical properties of the fiber were studied by thermal analysis, FTIR and X-ray diffraction (XRD) and tensile tests.The results show that the main and secondary factors affecting the tensile strength of the fiber during spinning are as follows: winding rate nozzle temperature inlet water distance, and the fiber tensile strength increases with the increase of cold drawing ratio.The polyvinylidene fluoride polyvinylidene fluoride (PVDF) fiber with excellent tensile strength was obtained by using the residual stress produced in the tensile process of melt-spun PVDF fiber to carry out the fixed length post-treatment and to explore the optimum process conditions in the post-treatment process.The crystal structure, crystal orientation and mechanical properties of the fiber were analyzed by FTIR X-ray diffraction (XRD) and differential scanning calorimetry (DSCS).The results show that during the post-treatment under residual stress, the transformation of 偽 -crystalline form to 尾 -crystalline form occurs further, and the crystallinity and orientation of the crystal zone are improved.The fracture strength of PVDF fiber increased obviously when treated in water bath at 60 鈩，

本文編號：1751362