Linear Low Density Polyethylene Modified By Two-Dimensional Nanomaterials

As a new type of two-dimensional layered inorganic compound,?-zirconium phosphate(ZrP)not only shares the common advantages of the traditional layered materials,but also has excellent characteristics such as controllable size,high crystallinity and purity,excellent mechanical and thermal properties and so on.Therefore,ZrP can be used in polymer composites to increase the strength,toughness and thermal stability.At the same time,the oxidation resistance,aging resistance,friction resistance and acid and alkali resistance of the composites can be improved.As a third-generation polyethylene,linear low-density polyethylene(LLDPE)has been increasingly favored.Due to its excellent environmental stress crack resistance,anti-aging performance,acid and alkali resistance,etc.,LLDPE has been applied to various industries.However,LLDPE has poor heat resistance and low strength,so it needs to be modified to improve strength and heat resistance.In this paper,the properties of LLDPE nanocomposites are improved by the ZrP.Meanwhile,the mechanical and thermal properties of LLDPE/ZrP nanocomposites have been characterized by various techniques.Firstly,the organophilic ?-zirconium phosphates(OZrP)is prepared by ultrasonic intercalated method which means the isooctyl amine is inserted into the interlayers and surface of ZrP.XRD and SEM characterization methods are used to prove that isooctyl amine has been inserted into ZrP successfully,and the interlayer spacing has been changed from 0.76 nm to 2.12 nm.Moreover,the structure of OZrP is still remained.The FT-IR results show the hydrogen bonding interaction between isooctyl amine amino and hydroxyl,which is happened between the interlayers of OZrP.In addition,the experimental results of thermogravimetric analysis show that OZrP still remain good thermal stability after the intercalation.Secondly,the LLDPE/ZrP nanocomposites with different concentration are prepared by the blending method and the injection molding.The tensile tests show that not only can ZrP improve modulus of nanocomposites,but also can boost elongation at break of nanocomposites.Moreover,the SEM images indicate that the ZrP could be well dispersed in LLDPE matrix.However,the agglomeration would be formed when the content of ZrP is more than 10 wt.%.The XRD patterns show that the crystal structure of ZrP is still maintained in LLDPE/ZrP composites and has not been intercalated or exfoliated by LLDPE molecular chain.However,the crystal structure and morphology of LLDPE matrix are influenced by ZrP.It indicates that ZrP has heterogeneous nucleation effect to increase the crystallinity of LLDPE matrix combined with data of DSC characterization.In addition,it can be seen from the DMA results that ZrP could improve the storage modulus of LLDPE nanocomposites,and these results are consistent with the mechanical properties mentioned above.Moreover,the thermal distortion temperature(HDT)is estimated through the DMA results,and it can be noted that ZrP could improve heat resistant properties of LLDPE.Finally,the LLDPE/OZrP nanocomposites with different concentration are prepared by the same processing method,and the LLDPE/OZrP nanocomposites are compared with LLDPE/ZrP nanocomposites.As shown from SEM pictures,the compatibility between LLDPE matrix and OZrP modified by the organic amine is better than inorganic ZrP.XRD patterns indicate that the nanoplatelets remained the same crystal structures before and after being incorporated into the LLDPE matrices by melt compounding.The above phenomenon also suggests that no exfoliation of the embedded nanoplatelets occur during the melt processing.The tensile properties show that OZrP can also improve the modulus and toughness of the LLDPE nanocomposites.The effect of OZrP on the modulus of the material is lower than that of ZrP,but the effect of OZrP on the toughness of the materials is higher than that of ZrP.Moreover,the results of DSC indicate that OZrP has little effect on the crystallinity of the nanomaterials,and DMA data shows that OZrP has less effect on the improvement of thermal distortion temperature.