Morphological comparison of isotactic polypropylene molded by water-assisted and conventional injection molding
(7830-7838) Journal of Materials Science 46 #23 (2011)
Liu et al of Zhengzhou University, China  water-assisted injection molding (WAIM) can be fulfilled based on the melt filling stage of conventional injection molding (CIM).  Polarized optical microscopy (POM) observations showed that the WAIM part exhibits a “skin–core–water channel” structure, while the CIM part shows a typical “skin–core” structure.  2D-WAXD results showed obvious arclike reflections in each position along thickness direction of the WAIM part, indicating a pronounced molecular orientation. Furthermore, a parent–daughter model (or branched shish-kebab structure) appears at 0 and 100 μm for both the parts, and the fraction of daughter lamellae for WAIM part is lower than that of CIM part.  As for the 1D-WAXD curves, it is noticed that there is a very tiny (300) reflection of β-form in the CIM part, while it is invisible in all positions of the WAIM part.  In addition, the crystallinity and crystalline size L of CIM part are found to be higher than that of WAIM part. Those results demonstrate that water penetration and rapid cooling rate have a significant effect on the morphological features of WAIM part.  (RDC 10/4/2011)

Morphological comparison of isotactic polypropylene molded by water-assisted and conventional injection molding
(7830-7838) Journal of Materials Science 46 #23 (2011)
Liu et al of Zhengzhou University, China  water-assisted injection molding (WAIM) can be fulfilled based on the melt filling stage of conventional injection molding (CIM).  Polarized optical microscopy (POM) observations showed that the WAIM part exhibits a “skin–core–water channel” structure, while the CIM part shows a typical “skin–core” structure.  2D-WAXD results showed obvious arclike reflections in each position along thickness direction of the WAIM part, indicating a pronounced molecular orientation. Furthermore, a parent–daughter model (or branched shish-kebab structure) appears at 0 and 100 μm for both the parts, and the fraction of daughter lamellae for WAIM part is lower than that of CIM part.  As for the 1D-WAXD curves, it is noticed that there is a very tiny (300) reflection of β-form in the CIM part, while it is invisible in all positions of the WAIM part.  In addition, the crystallinity and crystalline size L of CIM part are found to be higher than that of WAIM part. Those results demonstrate that water penetration and rapid cooling rate have a significant effect on the morphological features of WAIM part.  (RDC 10/4/2011)