Synthesis Of Macromolecular Modifier And The Study Of Its Surface Hydrophilic Modification For HDPE

Polyethylene have been widely used because of it's many advantages such as high chemical stability and good mechanical strength. However, as a typical non polar crystalline polymer, the surface of polyethylene is chemically inert and hydrophobic because its low surface energy, so the surface wettability of its products is poor. For the polyethylene pipelines, during the process of oil transportation, it's easy to cause pipeline wax fouling when the temperature is lower than wax precipitation point because of the hydrophobic pipeline wall, sometimes even cause blockage of the pipeline. Therefore, it is necessary to improve the surface energy and the wettability of polyethylene, and reduce the probability of paraffin wax deposition. In this paper, we started with the design of molecular structure, prepared two kinds of new hydrophilic modification agent, and then studied it's surface modification effect for high density polyethylene (HDPE).Firstly, with methoxy polyethylene glycol (MPEG) as the hydrophilic chain, we prepared PEMA-g-MPEG and EAA-g-MPEG with MPEG grafted on the molecular chain of Poly(ethylene-alt-maleic anhydride) (PEMA) copolymer and ethylene-acrylic acid (EAA) copolymer. The MPEG molecular weight had a significant effect on the esterification reaction, the grafting rate decreased with the increase of molecular weight, and the grafting reaction also related to other reaction conditions such as the reactants ratio, reaction temperature, reaction time and dosage of catalyst. With the FT-IR characterization of the grafted product, the appearance of absorption peak of ester group indicated that the grafting was succeed. From the TG curve in N2, we could learn that the thermal stability of the product get worse after grafted with MPEG, and thermal stability of grafted product get more and more worse with the growth of side chain. By means of DSC curves of the product in N2, we found that MPEG have a certain degree of influence on the crystallization behavior of the grafted product, the increase of grafting ratio is conducive to the formation of more better crystal phase and the crystalline melting peak have the tendency to drift to a higher temperature.Secondly, the PEMA-g-MPEG and EAA-g-MPEG were blended with HDPE to prepare the modified films, and the water contact angle was measured to evaluate the effect of the grafted products on the hydrophilic modification of HDPE. The experimental results showed that both of modifiers have good hydrophilic modification effect on HDPE, the water contact angle of the modified films decreased from 105°o 60°ith the modifier content of 10 wt%. The effects of stainless steel, polypropylene film and polytetrafluoroethylene (PTFE) film on the surface properties of the blend films were studied. The surface properties of the modified films were studied after placed in the air and soaking in the water for a certain period of time. The mechanical properties of HDPE get worse after blending with modifiers, the tensile strength of modified HDPE dropped from 26.7 MPa to 21.2 MPa with 10 wt% of modifier.