Submitted to: Journal of Applied Polymer Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/27/2008
Publication Date: 12/5/2008
Citation: Biresaw, G., Mohamed, A., Gordon, S.H., Harry O Kuru, R.E., Carriere, C.C. 2008. Compatibility Study in Poly(tetramethyleneadipate-co-terephthalate)/Polystyrene Bioblends. Journal of Applied Polymer Science. 110(5):2932-2941.
Interpretive Summary: One way of increasing demand for ag-based raw materials is by developing new consumer and industrial products through blending. Blends of agricultural products with other natural or synthetic materials can be used to develop new materials or replace existing materials based on petroleum feedstock. However, successful development of ag-based blends requires that the blend components be compatible. Compatibility affects a number of blend characteristics, including thermal stability. Thermal properties affect the manufacturability of blends as well as the application of products manufactured from the blends. In this work, the thermal properties of blends containing biodegradable polyesters are investigated. The results showed that blend thermal properties are highly dependent on the properties of the biodegradable polyesters as well as its composition in the blend. The result indicates that, blends with improved thermal stability can be obtained through careful selection of the chemistry of the biodegradable polyester to be used in the blend, as well as its concentration in the blend.
Technical Abstract: The thermal properties of blends of polystyrene (PS) with each of the biodegradable synthetic polyesters polylactic acid (PLA), polycaprolacone (PCL), poly(tetramethyleneadipate-co-terephthalate) also known under the trade name Eastar Bio Ultra® (EBU), were investigated using thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) methods. TGA studies indicate that incorporation of PS in biodegradable polyesters will result in the thermal stabilization of EBU, and thermal destabilization of PLA and PCL blends. From DSC measurements, melting (Tm), crystallization (Tc), and glass transition (Tg) temperatures, and the corresponding heats (deltaHf, deltaHc, deltaCp) were analyzed as a function of blend composition. DSC results seem to indicate that PS might be acting as a nucleating agent for PLA in PLA/PS blends. However, examination of all the parameters from the DSC studies showed contradictory results regarding the miscibility of PS with the biodegradable polyesters. Some parameters favored partial miscibility while others favored immiscibility in all three blend systems.