Vinylester-glass fiber composite for water pipe: Processing and effect of fiber direction

Vinylester-glass fiber composites have a wide scale of applications, however the combination between multiple fillers can cause some disadvantages due to complicated processing, high cost and incompatibility. This paper presents a novel trial for filling commercial vinylester (VE) resin with glass fiber (GF), as one filler component, in dual directions to prepare water pipe composite using the continuous winding technique, for the first time. 10% to 25% VE-GF composites were prepared with distributing GF in axial and hoop directions. The composites were cured via in-situ polymerization; the crosslinked network is occurred between catalyst and unsaturation sites in prepolymer. All concentrations show stability in all stages of thermal degradation, compared with blank VE; the more stable composite is 25% VE-GF. GF filled in axial and hoop directions enhanced the mechanical strength of both axes. The improved concentration (20% VE-GF composite) increased axial tensile strength and hoop tensile strength respectively to 32 MPa and 51 MPa, compared with 22 MPa and 42 MPa for blank VE. Furthermore, this concentration enhanced the strengths of surface harness and pull off from 39 BHC and 2.2 MPa to 46 BHC and 5.3 MPa, respectively. The 25% VE-GF composite decreased these values, but still higher than blank. GF improved the resistance of vinylester toward water absorption in different immersion conditions, especially the 25% VE-GF composites. The filling direction doesn’t affect the composite stability. As a key issue for sustainable applied polymer composites, the proposed technique presents stable and low cost composite with one filler type, as physically, thermally and mechanically stable water pipe system.