Residual orientation in injection micro-molded samples

✍ Scribed by John Healy; Graham H. Edward; Robert B. Knott

• Publisher: Elsevier Science
• Year: 2006
• Tongue: English
• Weight: 208 KB
• Volume: 385-386
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2006.06.116

✦ Synopsis

The orientation of polymer chains after injection molding is usually studied using techniques that measure the average orientation of molecular segments. Small-angle neutron scattering (SANS) is a technique for measuring the overall chain orientation and is very sensitive to molecular anisotropy. In this study, a blend of a commercial general-purpose polystyrene and deuterated polystyrene was injection micro-molded under a variety of molding conditions. SANS was then used to measure the residual orientation of the deuterated chains. As expected, the molecular orientation decreased with increasing mold temperature and increased with decreasing mold thickness. However, for these micro-moldings, the residual orientation decreased with increasing injection velocity. The measured orientation also appears to be Q-dependent indicating that the average residual orientation of short-chain segments may not necessarily reflect the overall chain conformation.