Effect of the presence of silica nanoparticles in the coefficient of thermal expansion of LDPE

作者：Olmos D; Martinez F; Gonzalez Gaitano G; Gonzalez Benito J^*

来源：European Polymer Journal, 2011, 47(8): 1495-1502.

DOI：10.1016/j.eurpolymj.2011.06.003

• Nano-composites
• LDPE (low density polyethylene)
• Coefficient of thermal expansion (CTE)
• AFM (atomic force microscopy)

The effect of the presence of alumina microparticles and silica nanoparticles on the coefficient of thermal expansion (CTE) of films of low density polyethylene (LOPE) based composites was investigated. A new method based on the use of an atomic force microscope (AFM) is proposed for measuring nano-thermal expansion of films to finally obtain the CTE in polymer based materials. Nanocomposites based on silica nanoparticles and LDPE were prepared by mixing those constituents by high energy ball milling (HEBM). Pure alumina microparticles come from the milling tools used to mix the components of the composites. When silica nanoparticles are used as nanofiller of LDPE the effectiveness on reducing the CTE (about a 40% of CTE reduction) is higher than that obtained when high amount of alumina microparticles are present in the LOPE. Only when high amount of silica nanoparticles and low amount of alumina microparticles are present, the reduction of CTE expected from the Levin model is in accordance with the experimental results. This effect was associated to the high surface to volume ratio of nanoparticles considering uniform dispersions of them within the polymer. The region of polymer between particles must be so thin (few nanometers) that constraint effects must play an important role on reducing the chain mobility and therefore the thermal expansion.

• 出版日期2011-8