- 學位論文
碳黑導電纖維之製備及流變研究
Preparation and Rheological Study of Electrical Conductivity Carbon Black Fibers
摘要
一般高分子材料屬於良好的絕緣體，當我們將具有導電性質的材料(如金屬粉末、碳黑、奈米碳管)與高分子材料摻混後可以大幅的改進其導電性質，因為碳黑具有加工性質好、價格低、導電效果好等優點，所以本研究使用其作為導電填充物。首先利用Zeta potential觀察得到碳黑與分散劑以1:1之比例分散效果最好，因此我們將不同型號之碳黑(VXC72、300J、600JD)與分散劑以此比例均勻後再摻混入Nylon 6製成母粒，以便作為後續性質測試及抽絲加工之用。 經由電阻值測試得知Nylon6/CB-600JD此組母粒電阻值最低，在碳黑含量6%其表面電阻即可下降至4.46x103Ω/cm2，導電效果遠大於Nylon6/CB-VXC72、Nylon6/CB-300J；由母粒之流變性質可發現，Nylon6/CB-600JD在碳黑含量2%時已產生溶膠-凝膠轉移點(表示在此碳黑已形成網絡系統)，而Nylon6/CB-300J則是在6%碳黑含量才達到溶膠-凝膠轉換點，但Nylon6/CB-VXC72則一直都屬於溶膠狀態，此結果與電阻值測試結果一致。即使將碳黑含量6% 之Nylon6/CB-600JD母粒抽成絲後之比電阻值亦僅小幅上升到104Ω/cm2比外面市售之導電纖維106Ω/cm2來的好。接下來使用DSC觀察Nylon 6 R.V 2.4、2.7及3.4，以Nylon 6 R.V3.4結晶度最好，表示往後延伸過程中Nylon 6 R. V3.4纖維加工較容易。將絲線分別以加熱延伸以及熔融延伸探討延伸倍數與電阻值之關係，發現當將碳黑含量10% 之Nylon6/CB-600JD加熱延伸0.7倍，比電阻值就由4.2x104 Ω.cm急遽上升到8x108 Ω.cm，但使用熔融延伸即使延伸倍數達30倍，比電阻值只上升到1x105 Ω.cm，最後利用SEM及TEM觀察母粒與延伸絲之微結構，以了解其與電阻值變化的關係。由這些研究探討觀察使用Nylon6/CB-600JD導電效果最好，在抽絲加工方面建議在熔融態下將絲線延伸才不會造成電阻值急遽上升、纖維易斷裂等情形發生。
並列摘要
Generally, polymer materials is one kind of good insulators, and its electrical conductivity can be improved by mixing some conductive materials (like metal powder, carbon black or carbon nanotubes) with itself. In this research, carbon black is used as the conductive material because of its suitable processibility, cheapness and excellent electrical conductivity. First, we observed using Zata potential that carbon black combining with dispersant in a ratio of 1 to 1 achieved the best dispersion effects. Therefore, we used three carbon black which have different model number(VXC72, 300J, 600JD) to mix with dispersant in same-size ratio individually, then blended mixtures and Nylon 6 together to make matrices that will be used for following testing and spinning processes. By way of electric resistance tests, it was found that Nylon6/CB-600JD matrix had the lowest electric resistance which could decrease to 4.46x103Ω/cm2 as the proportion of carbon black was 6%, and the conductivity effects was much better than the two others. It was also found some similar results in the rheological properties of the matrices. Nylon6/CB-600JD reached the sol-gel transition point as blended with 2% carbon black content (it means that the carbon black started to form network systems), while Nylon6/CB-300J reached as blended with 6% carbon black contents, and Nylon6/CB-VXC72 was still in solution phase without getting up to the transition point. Even though we spinned the Nylon6/CB-600JD matrix mixed with 6% carbon black contents, its volume electrical resistance only a little increased to 104Ω.cm, still smaller than the resistance of commercial electrically conductive fiber(106Ω/cm2). Next, we used DSC to observe Nylon 6 R.V 2.4, 2.7 and 3.4 particularly. It was showed that Nylon 6 R.V 3.4 had the best crystallinity, and that means it is easier to investigate the relation between drawn mutiples and electrical resistance using Nylon 6 R.V 3.4 in fiber processing followed by solid-state drawing and melting-state drawing. It was found that Nylon6/CB-600JD combined with 10% carbon black content extended 0.7 times through solid-state drawing, as well as the volume electrical resistance extremely increased from 4.2x104 Ω.cm to 8x108 Ωcm. However, the same mixture extended 30 times throuth melting-state drawing, the volume electrical resistance just a bit increased to 1x105 Ω.cm. At last, we used SEM and TEM to look into the microstructure of the matrices and drawn fiber and tried to understand the correlations between their morphology and the variation of electrical resistance. Upon these experiments and observations, it seems that Nylon6/CB-600JD has favorable electrical conductivity, but it is suggested that it should be prevented from some undesirable situations such as dramatical decrease of electrical resistance and fiber break by drawing fiber under melting-state.