Abstract:

Objective The glass fiber belongs to non-metallic insulation materials, and carbon nanomaterials have excellent electrical conductivity. In order to study the influence of carbon nanocoating on glass fiber with common plastics as carbon source and to further expand the application fields of carbon nanomaterials and glass fiber, glass fiber and carbon nanomaterials were combined to obtain carbon nanocoated glass fibers.

Method Polyethylene terephthalate(PET) or polyvinyl chloride(PVC) polymer was used as a solid carbon source to prepare carbon nanocoating on glass fiber by chemical vapor deposition. Carbon nanocoated glass fibers were prepared at 700, 750, 800, 850, 900 and 950 ℃. Scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermal shock experiment, single fiber strength instrument and resistivity instrument were adopted to characterize the fiber properties.

Results The surface of glass fiber was obviously observed at 700 ℃ but carbon nanocoating was not obvious. The black carbon nanocoating with metallic luster became more obvious and the preparation effect became better with the increase of preparation temperature (Fig. 2). SEM characterization further confirmed that the carbon nanocoating was successfully prepared and the coating surface was smooth and tightly coated on the surface of glass fiber (Fig. 3). For the carbon nanocoating on glass fiber prepared from PET and PVC, the intensity ratios of D peak to G peak were 0.942 6 and 0.904 6, respectively. The carbon nanocoating had a multilayer graphene-like structure with a tendency to pile up, and the defect density of carbon nanocoating prepared from PVC was smaller in Raman spectra (Fig. 4). The ratios of sp² C=C to sp³ C—C were 6.428 1 and 6.821 3, respectively, further indicating that the carbon nanocoating prepared from PVC had fewer defects in XPS (Fig. 5 and Tab. 1). In the thermal shock experiment, no structural defect appeared in 10 cycles, the carbon nanocoating prepared from PET began to show structural defects after 15 cycles. The carbon nanocoating prepared from PET and PVC showed the whole sheet spalling, lamellar structure adhesion and granular debris after 20 cycles. It was also found that the defect structure of the carbon nanocoating prepared by PET was more obvious (Fig. 6). The fracture stresses of the raw glass fiber and the glass fiber with carbon nanocoating prepared by PET and PVC were 929.29, 649.00 and 719.73 MPa, respectively, and the fracture stresses were reduced by 30.17% and 22.55%, respectively. The glass fiber with carbon nanocoating prepared from PVC had slightly better mechanical property than that prepared from PET, and no significant difference was found in mechanical property between the two types of fibers in practical application (Fig. 7). The resistance of the initial glass fiber was 7.485×10⁸ Ω/cm, and the resistance of glass fiber with carbon nanocoating prepared from PET and PVC at 950 ℃ was 602.10 and 181.65 Ω/cm, respectively (Fig. 8).

Conclusion PET and PVC are adopted to prepare carbon nanocoating on the glass fiber successfully. The coating can be closely coated on the glass fiber without cracks and faults. The two types of carbon nanocoating show good bonding performance within 10-15 thermal shock cycles and the bonding property of carbon nanocoating prepared from PVC is better than that prepared from PET. No significant difference exists in the mechanical property of fibers. The coating quality improves with the increase of preparation temperature in the range of 700-950 ℃. The carbon nanocoating has a sp² hybrid multilayer graphene-like structure with certain defects, and the carbon nanocoating prepared from PVC has fewer defects. The glass fiber with carbon nanocoating has excellent electrical conductivity, and the resistance decreases significantly with the increase of temperature in the range of 700-950 ℃. Finally, PET, PVC and other polymers are used as solid carbon sources for carbon nanocoating on glass fiber, which is of great significance for the achieving of electrical conductivity of the glass fiber and other functional applications, and for high value recycling of waste plastics.

Key words: polymer, solid carbon source, glass fiber, carbon nanocoating, chemical vapor deposition, polyethylene terephthalate, polyvinyl chloride