Research And Preparation Of Polytetrafluoroethylene Composite With High Adhesive Properties

Polytetrafluoroethylene(PTFE),a polymer which low dielectric constant,high temperature resistance, chemical corrosion resistance and other excellent performance.But its perfect symmetric molecular structure ?high crystallinity have led to low surface energy,poor infiltration and significant non-adhesive,which has a strong impact on the application of PTFE.In order to improve the surface adhesive performance of PTFE, the surface porous PTFE was prepared and the surface layer of PTFE was modified by adding metal,inorganic,organic,inorganic/organic composite,respectively. And the more systemic research on the adhesive and other properties of the composite material was studied.In this paper,firstly,the main factors influenced the sintering process of PTFE was discussed as following(sintering temperature ? rising rate ? holding time?molding pressure?dwell time) and so on.According to the analysis of the molecular structure and the bonding theory,then applied the methods of porous modification and filling modification to modify PTFE, thus PTFE composite material with high adhesive was prepared at the same time. Among them,adopting adding chemical foaming agent to prepare surface porous PTFE composite;adding metal,inorganic Si O2,organic,inorganic/organic composite to modify PTFE.Finally,the modified materials of lap tensile shear strength,surface morphology and thermal stability were analyzed and discussed by the analysis characterization methods such as SEM?TG?FT-IR and lap tensile shear strength.The experimental results showed that when selected azobisformamide(AC),sodium bicarbonate(Na HCO3) and oxalic acid(H2C2O4)as chemical foaming agent to modifity PTFE,respectively.We found that adding 20 w t% azobisformamide(CCR20A) foaming agent in the surface of PTFE,lap tensile shear strength was 4.08 MPa;the type of CCR20 A azobisformamide foaming agent had the excellent effect among the three kinds of different models of foaming agent;the surface of the sample was observed by SE M taken on the structure of uniform pore size and distribution;the surface of the composite material was porous owing to the decomposition of foa ming agent in the composite,which was advantageous to the adhesive infi ltration and improved lap tensile shear strength greatly,also the thermal st ability of PTFE was less influenced.In the method of filling modification,when the metal of Ni was 5 wt% in the surface,lap tensile shear strength was 1.06 MPa,which has obtained a better effect compared with other m etals;adding 6 wt% nano Si O2 to modify PTFE obtained the best effect,l ap tenslie shear strength value of the composite was 5.43 MPa;when sint ering 40 minutes and adding the same amount of hydroxy organic silicon(1500 cps)?vinyl organic silicon(1200 cps),lap tenslie shear strength of the composite was 5.74 MPa ?5.81 MPa,respectively.Applying nano Si O2 and organic silicon achieved the best modification effect among all the inorganic and organic materials involved in this paper;while adding 5 w t% nano Si O2 without surface modification?Si O2/organic silicone(1200 cp s),molding pressure is 23.52 MPa?sintering time is 40 min ?PTFE is 2g,lap tensile shear strength achieved the highest,up to 9.48 MPa,which obtained the best effect.High adhesive PTFE composite was prepared with the method mentioned,which was simple,low cost of materials and good long-term stability.