Study On The Preparation And Properties Of Hybrid Fibers/cement-base Lightweight Thermal Materials

Currently, cement-based wall thermal insulation materials have many defects, such as low strength, fire resistance is poor, high water absorption, poor durability, which seriously restricts the further application of wall insulation materials. Fibers incorporated in insulation materials as a reinforcing material are mainly a single fiber. Although they can a certain level enhance a variety of wall materials properties, the rate and intensity of enhancement are limited. At the same time, with heavy use of a variety of ad vanced electronics and communications products, electromagnetic radiation can produce irreversible harm on the human body directly or indirectly, howerer, the current insulation materials used have hardly any electromagnetic protection. To solve the above problems, glazed hollow beads and polystyrene particles were used as a complex aggregate, cement, slag and latex powder were used as cementitious materials, and hybrid fibers and carbon nanotubes were added as reinforcing materials and electromagnetic shielding materials to prepare excellent wall thermal insulation, which were taken the way of chemical foaming. The main research contents and results are as follows:(1) Related test equipments for testing slag composition, particle size and morphology were used to analyzed, and the effects of the content of slag replacing cement on the performance of inorganic composite material samples composed of cement and slag were studied. Besides, the potential cementitious activity incentives of slag were explored. The results showed that: the main chemical components of slag test were CaO, SiO2, Al2O3, MgO, SO3, TiO2, Na2 O, K2 O and so on, with its average particle size of only 4.470μm, and the specific surface area of up to 42096cm2/ml; the content of slag replacing cement was 30%; the ratio for complex activator were 1.5% NaOH, 1.5% CaO and 2.0% desulfurization gypsum, then the 3d flexural and compressive strength and 28 d flexural and compressive strength of the samples prepared were respectively 5.21 MPa, 35.32 MPa and 7.72 MPa, 64.43 MPa.(2) The effect of preparation process technology, mass ratio of polystyrene particles and cementitious materials, the alternative volume of glazed hollow beads, water-cement ratio and the content of foam stabilizer on the performance o f the samples were studied. And the preparation process and basic ratio of the samples were determined: foaming agent was added into the slurry first, then the foam slurry was mixed with aggregate was the ideal preparation process; mass ratio of polystyrene particles and cementitious materials was 11.84, the alternative volume of glazed hollow beads was 20%, water-cement ratio was 0.62 and the content of foam stabilizer was 6%; At the ratio, the density was 229kg/m3, the 3d flexural strength was 0.31 MPa, the compressive strength was 0.52 MPa, the softening coefficient was 0.65, and the thermal conductivity was 0.0583 W/(m·K).(3) In an experimental study of fiber reinforced the properties of lightweight insulation material, the single- factor test was used to study the effect of the optimum fibers adding ways and fiber-modifying treatment on the performance of the samples. Meanwhile, the dosages of latex powders and hybrid fibers comprised of polypropylene fibers and carbon fibers were explored by means of orthogonal test. Through experiments mixing method three was the best: firstly fibers were dispersed into water, then ultrasonic dispersion and mechanical dispersion were used at the same time, lastly the solid and the dispersion system composed of fibers and water was mixtured uniformity; Polypropylene fibers coated exterior improvements improved the interface link status, and the appropriate amount of polypropylene fibers was elected 1.2%; Carbon fibers externally generated active groups, which went through chemical oxidation, then the ideal amount of fibers was 1.2 ‰; The ideal ratio of hybrid fibers and latex powders was: the amount of modified polypropylene fibers was 1.2%, the amount of modified carbon fibers was 0.8 ‰, the amount of latex powders was 1%.(4) In the test of carbon nanotube reinforce ment, the role of the dispersing method and content of carbon nanotubes on the properties of the lightweight insulation materials was studied. The results showed that: the mechanical of the samples prepared by first ultrasonic dispersion then magnetic stirring; appropriate amount of carbon nanotubes significantly improved the mechanical properties and water resistance of the samples, when the amount of carbon nanotubes was 0.02%, the 3d and 28 d flexural strength, compressive strength, softening coefficient reached the peak 0.56 MPa, 0.80 MPa, 0.81 and 0.68 MPa, 0.97 MPa, 0.86 respectively; Appropriate amount of carbon nanotubes significantly improved the electromagnetic shielding effectiveness of the samples, when the frequency was between 2GHz and 18 GHz, the shielding effectiveness upgraded from 0.6dB-8.7dB to 30.3dB-44.7dB.