Study On The Preparation And Its Defects Of Glass Fiber Reinforced Thermoplastic Resin Matrix Composite

The hot spot in the development of global oil and gas resources have been gradually transferred from the land to the ocean.In recent years,as a new type of submarine pipeline products,the development of marine flexible pipe used in the offshore oil field has been paid more and more attention at home and abroad.For the marine flexible pipe prepared by glass fiber reinforced thermoplastic bonded flexible pipe of composite material,in the same stiffness and strength,compared with the non bonded flexible pipe,the glass fiber winding layers were significantly reduced,only about half the material needs of,and processing the characteristics of an excellent corrosion resistance,easy to form poly gas,and relatively simple manufacturing process.In this paper,using glass fiber reinforced polypropylene prepreg tape as the raw material,the composite of were prepared under different process conditions.The defect status was analyzed by ultrasonic nondestructive testing.Based on the test results of mechanical properties,the relationship between technological parameters,defects and properties was studied.A porosity measurement model based on acoustic impedance and a better process system for glass fiber reinforced thermoplastic composites are established.By the comparison and analysis of ultrasonic nondestructive testing systems,the defects of glass fiber reinforced polypropylene composites were tested by ultrasonic scanning microscope system.Based on the analysis of C scanning results of composite materials containing preformed inclusions,the better ultrasonic nondestructive testing parameters of glass fiber reinforced polypropylene composites are determined:transducer frequency 15 MHz,gain value 20 dB,scanning speed 1000 mm/s.Under better testing parameters,the quality and defect of glass fiber reinforced polypropylene composites were analyzed.The C scan results show that,with the increase of the temperature,the quality of the fusion state firstly increases and then decreases,and reaches the optimum at 200?,and then there exists fiber bending defects when the temperature higher than 210?.With the increase of the fusion pressure,the quality of the fusion state firstly increases and then decreases,and reaches the optimum at 0.3 MPa.At0.5 MPa,poor resin defects begin to appear.With the increase of the fusion time,the quality of the fusion is improved gradually,and the optimum effect is achieved at 450 s,after then,the time has little effect on the fusion quality.The A scan results show that,the surface echo and bottom echo can only be observed when there is no apparent defect in the composite.When layered defects are observed,surface echo and defect echo can be observed.Surface echo,defect echo and bottom echo can be observed when there are fiber bending and poor resin deficiency.Acoustic impedance test results show that,with the increase of fusion temperature and pressure,the acoustic impedance value firstly increases and then decreases,and reaches the maximum at 200 and 0.3 MPa,and the fusion quality is the best.With the increase of fusion time,the acoustic impedance value increases,the quality increases,and the acoustic impedance value has no obvious change after 450 s.The pore characteristics of the composite were observed by metallographic microscope,and the relationship between porosity and technological parameters was obtained.The result shows that the morphology of pores in composites is mainly with the characteristics of long,oval and round shapes.The relationship between the acoustic impedance and the porosity is established.Based on acoustic impedance,the porosity detection model is obtained when the porosity is in the 0.59%~5.59%range:Z=25.11P~2-527.46P+6335.43.The influence of defects on the properties of composites is studied,the results show that when the porosity is less than 1%,it has little influence on the flexural strength and interlaminar shear strength of composite plate,when the porosity is between 1%~5%,once the porosity increases by 1%,the flexural strength and interlaminar shear strength of the composite plate decrease by 2%and 8%respectively.The change of defects in composite materials is consistent with the change of mechanical properties,when there exist the fiber bending and poor resin defects,flexural strength and interlaminar shear strength of composite materials is low.In summary,a better molding process is obtained:the fusion temperature is 200?,the fusion pressure is 0.3 MPa,and the fusion time is 450 s.