TY - JOUR
T1 - Understanding competing mechanisms for glass transition changes in filled elastomers
AU - Wood, Charles D.
AU - Ajdari, Amin
AU - Burkhart, Craig W.
AU - Putz, Karl W.
AU - Brinson, L. Catherine
N1 - Funding Information:
Support for this project was provided by Goodyear Tire and Rubber Company (Akron, OH) ( 4507401163 ). Differential Scanning Calorimetry (DSC) data was collected at the Integrated Molecular Science and Education Center (IMSERC) at Northwestern University. The authors would also like to thank Charlotte Stern and Stephen Marrou for assistance with collecting DSC data. Appendix A
PY - 2016/4/28
Y1 - 2016/4/28
N2 - In polymeric nanocomposites, shifts in the glass transition temperature (Tg) that increase monotonically with particle loading have been attributed to the interphase, in ideally dispersed, attractive systems. However, in elastomeric composites a trend has emerged that shows Tg shifts first towards higher and then towards lower temperatures with increasing filler volume fraction, when measured via mechanical methods (DMA). At high filler loadings (>10 vol%), glass transition temperatures have been recorded below that of the base polymer, even for systems with attractive interactions between polymer and filler. One-dimensional analytical models and three-dimensional finite elements models were used to investigate the source of a mechanically-induced negative Tg shift in highly filled systems. The results attribute the origin of the shift towards higher temperatures as an effect of the interphase, while the subsequent shift to lower temperatures as an apparent relaxation time shift that arises solely due to the addition of stiff elastic particles. These replicated shifts explain a consistent trend across the literature and provide some considerations for those designing elastomeric composites with high filler loading.
AB - In polymeric nanocomposites, shifts in the glass transition temperature (Tg) that increase monotonically with particle loading have been attributed to the interphase, in ideally dispersed, attractive systems. However, in elastomeric composites a trend has emerged that shows Tg shifts first towards higher and then towards lower temperatures with increasing filler volume fraction, when measured via mechanical methods (DMA). At high filler loadings (>10 vol%), glass transition temperatures have been recorded below that of the base polymer, even for systems with attractive interactions between polymer and filler. One-dimensional analytical models and three-dimensional finite elements models were used to investigate the source of a mechanically-induced negative Tg shift in highly filled systems. The results attribute the origin of the shift towards higher temperatures as an effect of the interphase, while the subsequent shift to lower temperatures as an apparent relaxation time shift that arises solely due to the addition of stiff elastic particles. These replicated shifts explain a consistent trend across the literature and provide some considerations for those designing elastomeric composites with high filler loading.
KW - Dynamic mechanical thermal analysis (DMTA)
KW - Finite element analysis (FEA)
KW - Interphase
KW - Nano composites
KW - Thermomechanical properties
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U2 - 10.1016/j.compscitech.2016.02.027
DO - 10.1016/j.compscitech.2016.02.027
M3 - Article
AN - SCOPUS:84960499860
SN - 0266-3538
VL - 127
SP - 88
EP - 94
JO - Composites Science and Technology
JF - Composites Science and Technology
ER -