Structure and properties of polypropylene/low-density polyethylene blends grafted with itaconic acid in the course of reactive extrusion

• Published in: Journal of applied polymer science Vol. 102; no. 2; pp. 1746 - 1754
• Main Authors: Krivoguz, Y. M., Pesetskii, S. S., Jurkowski, B., Tomczyk, T.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 15.10.2006; Wiley
• Subjects: Applied sciences; Chemical modifications; Chemical reactions and properties; Exact sciences and technology; mechanical properties; Organic polymers; Physicochemistry of polymers; poly (propylene) (PP); polyethylene (PE); reactive processing; Viscoelasticity; Strengthening; Polymer blends; Thermal transition; Propylene polymer; polyethylene (PE); Mechanical properties; reactive processing; Tensile property; Experimental study; Property processing relationship; Functional polymer; Free radical reaction; Itaconic acid; Chemical modification; Low density ethylene polymer; Olefin polymer; Acid copolymer; Rheological properties; poly (propylene) (PP)
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.23998

This study was concerned with the structural features and mechanical properties of polypropylene (PP)/low‐density polyethylene (LDPE) blends, which after compounding were modified by the free‐radical grafting of itaconic acid (IA) to produce [PP/LDPE]‐g‐IA in the course of reactive extrusion. To analyze the structural features of the [PP/LDPE]‐g‐IA systems, differential scanning calorimetry and relaxation spectrometry techniques were used. The data were indicative of the incompatibility of PP and LDPE in the [PP/LDPE]‐g‐IA systems on the level of crystalline phases; however, favorable interactions were observed within the amorphous phases of the polymers. Because of these interactions, the crystallization temperature of PP increased by 5–11°C, and that of LDPE increased by 1.3–2.7°C. The rapprochement of their glass‐transition temperatures was observed. The single β‐relaxation peak for the [PP/LDPE]‐g‐IA systems showed that compatibility on the level of structural units was responsible for β relaxation in the homopolymers used. Variations in the ratios of the polymers in the [PP/LDPE]‐g‐IA systems led to both nonadditive and complex changes in the viscoelastic properties as well as mechanical characteristics for the composites. Additions of up to 5 wt % PP strengthened the [PP/LDPE]‐g‐IA blended systems between the glass‐transition temperatures of LDPE and PP. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1746–1754, 2006