Amorphous Polymer Blends Recent Developments

Rather than review the field historically, or provide a tutorial on amorphous polymers and their blends, we will update the reader on key progress in recent years in the area of amorphous polymer blends, with particular emphasis on areas 

EncydopaUa of Pdymor Blends,Volume 1 Fundamentals. Edited by Avraam I. Isayev Copyright 2010 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 978-3-527-31929-9 

Miscible Blend Dynamics and Length Scales of Mixing 

In total, the aforementioned experiments clearly show that the historical view, in which individual polymer components in a miscible amorphous blend should exhibit identical glass transition (and therefore a-relaxation chain dynamics) properties, is not always true. Qualitatively, these experimental results support the self-concentration idea, in that individual polymer chain dynamics for the blend constituents should depend on the relative concentrations of each of the components in the blend, as discussed in References [28, 37] in which concentration dependent results were obtained based on variations in the amounts of each 

---

Chapter 3 provides a brief review of recent developments in areas of amorphous polymer blends. Differential mixing, chain dynamics, and glass transition properties for individual polymer components in miscible binary blends, as well as new methods to experimentally acquire such information, are considered. Miscible blend dynamics and length scales of mixing of amorphous polymer blends are discussed. Amorphous biopolymer blends involving polymers obtained from renewable feedstocks is also briefly reviewed. 

Recent developments have been in the area of microthermal analysis using thermal conductivity with thermal diffiisivity signals or AFM to visualize specific areas or domains in the material and perform localized thermal analysis studies (183,184). Relaxational behavior over time and temperature is related to changes in free volume of the material. Positron annihilation lifetime spectroscopy (PALS) measurements of positron lifetimes and intensities are used to estimate both hole sizes and free volume within primarily amorphous phases of polymers. These data are used in measurement of thermal transitions (185,186) structural relaxation including molecular motions (187-189), and effects of additives (190), molecular weight variation (191), and degree of crystallinity (192). It has been used in combination with DSC to analyze the range of miscibility of polymethyl methacrylate poly(ethylene oxide) blends (193). 

ILs have been recently evaluated as non-volatile plasticizers and as external or internal lubricants in several polymers including PVC [3], PMMA [4] and polyamides [5]. In this article, an amorphous PL A (polylactide) polymer is blended with two phosphonium-based ILs at various ratios by melt-blending, solution casting and a microencapsulation technique in order to investigate polymer/IL miscibility and its role in the development of a modified polymer with novel rheological, mechanical and thermal characteristics. Results of thermogravimetric analysis, differential scanning calorimetry, capillary rheometry, batch mixer torque measurements and optical microscopy are discussed. 

---