Preparation And Properties Of Vinyl Polymers/Graphene Oxide Composites

Polypropylene is a widely used material,which has light weight and acid-alkali resistance.But its application is limited by its flamable property.Cement-based material is widely used in engineering projects,which is easy cracking and easy penetration.These defects seriously influence performance and durability of cement-based composite.So seeking for a way to overcome this issue becomes the research hotpot.The performance of polypropylene and cement material can be improved by adding suitable additive.Graphene oxide is a derivative of graphene,which has a huge specific surface area,superior mechanical properties and excellent thermal conductivity.The mechanical properties and thermal conductivity of composites might be improved by adding graphene oxide.Presently,the problem is the compatibility of graphene oxide between polypropylene and cement phase,and properties of composite are not ideal.Graphene oxide is hydrophilic material,whose basal plane and edges are decorated with functional groups,such as carboxylic,phenol hydroxyl and epoxide groups.It has different requirements when adding graphene oxide into the hydrophobic polypropylene or the hydrophilic cement-based material.The dispersibility of graphene oxide in composites can be improved by chemical modification.In this paper,graphite oxide was prepared by Hummers method and its nano-lamellae disperse liquid was obtained by ultrasonic.The dispersibility of graphene oxide in polypropylene was improved by chemical modified.The polycarboxylate superplasticizer was prepared by solution polymerization.The PCS/GO composite was prepared by ultrasonic.Graphene oxide and composite were studied.The main works are as follows:（1）Graphite oxide were prepared by improved Hummers method.And graphene oxide nano-lamellae disperse liquid was obtained by ultrasonic.Characterized GO with elemental analysis,Fourier transform infrared spectrometer（FT-IR）,atomic force microscope and so on.The results showed that oxygen content of graphite oxide has increased from 32.18 % to 35.83 % bypreoxidation.The optimum conditions for preparing graphite oxide were: m（KMnO₄）:m（graphite）= 6:1,low temperature reaction time 2 h,middle temperature reaction time 6 h,high temperature reaction time 20 min.The highest oxidation of graphite oxide could be reached 35.94 %.The graphene oxide lamellar size was 200 nm to 1200 nm and lamellar thickness was 0.83 nm to 1.23 nm when the GO was dispersed in solution.（2）Graphene oxide was reacted with silane coupling agent KH-550.PP/GO composites were prepared by melt blending method.The characterization and performance testing results showed that when polypropylene added with0.5 % graphene oxide,the T_c of composites was up to 120.4 ℃ and T_m was up to171.1 ℃.The λ（thermal conductivity）of composites was up to 0.435 W/（m·K）,raised 111.7 %.The LOI was up to 21.1 %.Tensile strength raised 11.96 % up to33.7 MPa,flexural strength was 42.7 MPa,impact strength reduced to 3.9 kJ/m².（3）A new type of polycarboxylate superplasticizer was synthesized in solution at room temperature with polyether monomer（HPEG）,acrylic acid（AA）,acrylamide（AM）by radical polymerization.The initiator was ammonium persulfate（APS）and sodium bisulfite（SHS）.The best experiment conditon was confirmed.The initiator mole ratio between APS and SHS was 2:1.The addition of chain transfer agent IPA was 2 %.Monomer mole ratio as follow: n（HPEG）:n（AA）:n（AM）=1:3:2.5.（4）Graphene oxide is uniformly dispersed into polycarboxylate superplasticizer by ultrasonic dispersion method.The mixing solution was added into cement phase.The testing results showed that the best addition of graphene oxide was 0.04 %.The fluidity decreased slowly,and cement microstructure became regularly.The flexural and compressive strength were 7.2 Mpa and 62.8Mpa at 7 days reaction.The innovation of this paper is: The preparing condition of graphene oxide by improved Hummers method was optimized.The method of improving the graphene oxide dispersibility in polypropylene was researched and found.And polycarboxylate/graphene oxide composites were prepared.