| Ethylene-tetrafluoroethylene(ETFE) is a kind of crystal thermoplastic,with tetrafluoroethylene and ethylene monomeric units arrange in the chain alternately. ETFE has an excellent integrated performance just as the combination of PE and PTFE.It’s melting temperature is about 260℃,while it’s decomposition temperature is over than 330℃, so it can be molded and processed by different kinds of thermoplastic methods.ETFE injection units can be used in chemical engineering and bio-pharmaceuticals field as antiseptic parts,ETFE film has a higher light transmittance than glass and an outstanding self-cleaning performance,wildly used in huge building structure and photovoltaic field,ETFE wire capping layer has excellent insulating property and anti-radiation property,with a lower density than common wire capping layer,is wildly used in airplane and spacecraft. ETFE has a low yield sthength,so it’s easy to deformation when bearing load, this is mainly because the amorphous in it’s aggregation.meanwhile,it’s hard to joint the ETFE film because the splice used in common polymer film is inoperative.This paper has study the crystal modification of ETFE,by the two methods of adding nano particles as nucleating agent and draw orientation we can change the intrinsic properity of ETFE. According to introduce fluorine-containing monomer to SiO2,it’s agglomerates can be eliminated,and the particles size both in aggregation morphology and DMF can be reduced to less than 100nm.The SiO2 particles can be dispersed in ETFE by mixed in the torque rheometer(haake internal mixer),with particles size about 50nm,so we made the nano-composite based in ETFE matrix successfully.By DSC and XRD we can test the change of crystalline of ETFE with different SiO2 content, the crystalline test by two methods were raise 20.5% and 30% at the most extent.Tensile curves show that the yield strength of ETFE increased mostly when the SiO2 content is 1%. After drawing put the ETFE splines under 120℃ with 30min,by DSC and XRD we find that when draw ratio is between 30%-50%,the effect of tensile crystal is best. The crystalline test by two methods were raise 24.6%and 35% at the most extent. At this time,yield strength of ETFE is evidently higher than before drawing.The fluoride hydroxyl polymer and PU prepolymer made in the experiment can be used as adhesive after mixed,IR test shows that the curing reaction can occur successfully. When we use this adhesive to splice ETFE film, fluorine content shows a influence to bonding strength, which achieve the best when F% is 2.7%. The influence factors of ETFE film hot welding are temperature、pressure and time, the best welding effect can be achieved when these three factors are suitably. Beside, the fitting mode can also influence the welding strength. The welding strength of ETFE film can be obtained above 80% of ETFE bulk material. When test the fatigue property of welding spline by DMTA, we find that the welding strength can still keeps at the conditions of high temperature(100℃) and high frequence(15-60Hz). To contrast the two joint modes have merits and demerits respectively:the operation of spline is simple,has no damage to the bulk material and repairable,bue the spline strength is quite low, which can just reach the yield strength of ETFE, so only can be used in structures that bear low strength; hot welding can got a high welding strength, which fit the operating requirements in building field, but external factors influence the welding effect observably, also the operation is complex and unrepairable. |
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