Effects Of Imidazolium Ionic Liquids On The Structure And Properties Of Polyolefin

In this study, imidazolium ionic liquids (imi-ILs), which were synthesized by ourLab, were incorporated into polypropylene (PP) and linear low density polyethylene(LLDPE) via melting blend, respectively. Meanwhile, the structure and propertiesof these blends were intensively determined and tested.Surface resistivity (ρ_s) and volume resistivity (ρ_v) of the blends were tested bythe ZC-36 megger. Lots of techniques have been employed into this study. Crystalstructure and morphology were investigated by polarized optical microscopy (POM)and X-ray diffraction (XRD), while the thermal properties of blends were studiedby differential scanning calorimetry (DSC) and the thermogravimetric analysis(TGA). The mechanical properties of blends were learned by dynamical mechanicalanalyses (DMA). Scanning electron microscopy (SEM) was used to reveal thecompatibility between imidazolium ionic liquids and PP or LLDPE.Testing results were shown as follows: The result of POM shows that[C₁₄mim]Br could have a nucleating effect in the PP matrix which made the crystalof PP smaller, and it can also help to form more crystal with a crystallization formin the PP resin. By adding ionic liquids and ordinary antistatic agents separatelyinto PP with the same share (3.0), [C₁₄mim]Br had turn out to be with the bestantistatic properties. In addition, the testing results of surface resistivity (ρ_s) andvolume resistivity (ρ_v) of neat PP and PP/ [C₁₄mim]Br blends implied that the[C₁₄mim]Br had excellent antistatic properties. When the weight ratio of[C₁₄mim]Br to PP was 3/100, the PP/ [C₁₄mim]Br blend had the best antistaticability in our experiment. The surface resistivity of PP/[C₁₄mim]Br decreased fromthe 6.25×10¹⁵ to 1.14 10⁹Ωand the volume resistivity of PP fell from 1.41×10¹⁶ to1.37×10⁹Ω·cm respectively. The adding of PP-g-MA to PP materials is not good forimproving antistatic properties of the PP/[C₁₄mim]Br blend. The surface resistivityof the PP/ [C₁₄mim]Br blend did not change distinctly after being scrubbed withdistilled water, indicating the good moving activity of [C₁₄mim]Br in PP resin.Scanning electron microscopy (SEM) studies reveal that the [C₁₄mim]Br had a gooddispersion in PP matrix. The thermogravimetric analysis (TGA) shows [C₁₄mim]Br can enhance the thermal stability of PP though its molecule is small. And it can alsoimprove the mechanical properties of PP, reduced the glass transition temperatureof PP as well, which can be regarded as plasticizers.The LLDPE/[C₁₄mim]Br blend can also achieve good antistatic properties,although the addition of ionic liquids was relatively low (0.5). When the weightratio of [C₁₄mim]Br to LLDPE was 2/100, the LLDPE/[C₁₄mim]Br blend had notonly the best antistatic properties, but also better antistatic persistence properties.The result of POM shows that [C₁₄mim]Br could have a nucleating effect in thematrix which made the crystal of LLDPE bigger. And the onset crystallizationtemperature of LLDPE/[C₁₄mim]Br blend was higher than that of neat LLDPE at the samecooling rates. Moreover, tensile strength had been reduced and impact strength ofLLDPE had been improved to certain degree since [C₁₄mim]Br incorporated intoLLDPE matrix. [C₁₄mim]Br also played a role as plasticizer in LLDPE matrix withadding [C₁₄mim]Br in excess of 2.5 shares, which result in the improvement of themelt index of LLDPE.