Graft formation and chain scission in blends of polyamide-6 and -6.6 with maleic anhydride containing polymers

✍ Scribed by Martin Van Duin; Marcel Aussems; Rein J. M. Borggreve

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 189 KB
• Volume: 36
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/(sici)1099-0518(19980115)36:1<179::aid-pola22>3.0.co;2-f

✦ Synopsis

The in situ formation of a compatibilizer, consisting of a copolymer of PA grafted onto a maleic anhydride (MA) containing polymer, is essential for the morphology and properties of the corresponding PA blends. In this study four blends, containing PA-6 or PA-6.6 and EPDM-g-MA or poly(styrene-co-maleic anhydride) (SMA; 28 wt % MA), were prepared and characterized. Chemical analyses showed that the amount of PA graft is independent of the blend composition. Going from EPDM-g-MA to SMA the MA content of the original MA-containing polymer increases, which in the corresponding blends results in an increase in the number of PA grafts and a decrease in the length of the PA grafts. In the SMA blends the number averaged molecular weight of the grafted PA is only about 200 g/mol. It is postulated that the water molecule, released upon imide formation at the PA/(MA-containing polymer) interface, hydrolyses a PA amide group, resulting in a new amine end group, which in its turn reacts with the MA-containing polymer, etc. Differential scanning calorimetry shows that the degree of crystallinity of the PA phase is decreased only when the size of the PA phase between the MA-containing polymer domains approaches the PA crystalline lamellar thickness.