Process Parameters Dependence Of Acrylonitrile Butadiene Styrene (ABS) Flow Patterns Inside A Capillary Rheometer Barrel

Abstract

Corak aliran leburan ABS di dalam barel rheometer kapilari tegasan-malar telah dikaji. Kesan perubahan parameter pemprosesan seperti suhu, tekanan dan sesaran penolak terhadap corak aliran diselidik. Suhu and sesaran penolak didapati mempunyai pengaruh yang ketara ke atas corak aliran. Ini diperhatikan melalui perubahan terhadap ketebalan lapisan berwarna dan kemunculan bentuk aliran yang kompleks. Tiada perubahan corak aliran yang besar dipamerkan apabila tekanan pengekstrudan ditingkatkan melebihi had tekanan bagi berlakunya rekahan leburan. Profil halaju diukur daripada corak aliran menggunakan penganalisis imej dan keputusan ujian menunjukkan bahawa terdapat sedikit penyimpangan antara profil halaju yang diukur melalui ujikaji dengan profil yang di perolehi secara pengiraan teori menggunakan persamaan aliran bendalir tak-Newtonan yang telah terbukti keberkesanan penggunaannya. Sisihan tersebut berkurangan sekiranya suhu pengekstrudan ditingkatkan namun menjadi agak rumit secara relatifnya apabila sesaran penolak yang lebih besar digunakan. Flow patterns of ABS melt inside a constant-stress capillary rheometer barrel was investigated. The effects of variations in process parameters such as temperature, pressure and plunger displacement towards the flow patterns were studied. Temperature and plunger displacements were found to have prominent influences on the flow patterns where changes in pigmented layer thickness and complex flow were observed respectively. No significant effect was displayed on the flow patterns when extrusion pressure was increased exceeding pressure limit of melt fracture occurrence. Velocity profiles were measured from the flow patterns using an image analyser and it was discovered that some deviations existed between experimental measured velocity profiles and that of theoretically calculated valves using an established non-Newtonian fluid flow equation. These deviations reduced with extrusion temperature but become relatively complicated when large plunger displacement was applied.