導電高分子複合材料的應用範圍日趨廣泛，其相關製程技術儼然成為科技研發的重點項目，其中在導磁纖維複合材料方面，由於纖維的配向與分佈會影響產品的電學性質與機械性能，因此如何控制纖維配向與分佈便成為技術關鍵之一。本研究採用外加磁場輔助射出成型來控制導磁纖維於熔膠充填時的配向行為，其中可分為兩部分，第一部分設計外加磁場輔助之特殊模具，模擬不同間隔塊的材料和厚度，並評估磁鐵在模具中最佳的配置，依據模擬結果開發相同配置之實際模具，並將實際量測的磁通量密度與模擬值比對，再探討磁場與流場耦合對於鍍鎳碳纖維配向的影響，計算充填過程中熔膠流經模穴各位置時纖維受磁場產生之磁矩大小，並預測纖維受磁場作用下的流動軌跡。 第二部分則為實際操作，將LDPE與鍍鎳碳纖維混和並重新抽粒，再將其置於外加磁場中進行射出製程，在本研究中依不同的製程參數(模溫、料溫、射速)及有無外加磁場來控制纖維的排向與分佈。在研究中可發現磁場可令纖維往左右兩側集中，並且使其纖維排向平行於磁場方向，另外改變纖維分佈與配向有助於提升成品導電度，故控制成型參數也可做為改良導電度的一種方式。 在實驗中可發現在有外加磁場時高模溫、高料溫時成品有較良好之導電度，提升射速也有助於提升導電度但效果較並不明顯。 ;Conductive polymer composite material is increasingly used in a variety of fields, and its related processing technology has been a focus of research and development. Regarding magnetic fiber, because the orientation and distribution of the fiber affect the electrical and mechanical properties of products, the control of fiber orientation and distribution has been regarded as a critical technology. This study used magnetic-assisted injection molding to control the orientation of magnetic fibers during the melt-polymer filling process. This study can be divided into two parts. In first part, a special mold containing a magnetic apparatus was simulated and designed. Its material and thickness of various spacing blocks as well as the optimal layout of magnets in the mold were determined. An actual mold with the same magnet layout was then manufactured accordingly, and the measured magnetic flux density was compared with simulated results. This study also examined the coupled effect of magnetic and flow fields on the orientation of nickel-coated carbon fibers, calculating the magnetic moment produced due to the influence of the magnetic field on the fibers when melt polymer flowed through different positions in the cavity during the filling process. The flow trajectories of the fibers, which were affected by the magnetic field, were also predicted. The second part was experimental procedures. The LDPE was mixed with the nickel-coated carbon to palletize plastic granules for magnetic-assisted injection molding. This study used different process parameters (melt temperature, mold temperature, injection speed, and external magnetic field) to control fiber orientation and distribution. In this study we found that external magnetic field can make the fiber concentrate on the left and right side, and make the fiber orientation parallel to the magnetic field direction. Moreover, altering fiber distribution and orientation affects the electrical conductivity of the products. Therefore, controlling the process parameters can be one way of improving electrical conductivity. To conclude, the experimental results show that the electrical conductivity was increased along with high mold temperature and high melt temperature under external magnetic field. In addition, the electrical conductivity was slightly increased when the injection speed is raised.
