Effect of water on the properties of some polymeric composites

:- The effect of water was studied on some physical and mechanical properties including (Roughness, Hardness, Compression Strength), and diffusion coefficient was calculated using Ficks’ 2 nd law for a polymeric composite materials PVC+carbon black, Epoxy+Al powder, Epoxy + E-glass (chapped)), with volume fraction Vf=30% reinforcement for all specimens, results showed the negative effect of water on these properties which is differed between one specimen and other, PVC+CB was affected more than Epoxy+E-glass then Epoxy+Al powder and the diffusion coefficient (D) was less for Epoxy+Al then PVC+CB and the less value was for Epoxy + E-glass .


Introduction
Although particulated fillers reinforcement were used in awide range industry but still more of their properties were unknown, so the replacement of fillers can simplify the manufacturing process, while using of fibers can also improve anisotropic performance, the main objective of this paper is to show how the water effects the properties [1].
Metal and ceramic fillers were used as a reinforcement to enhance the electrical and thermal properties of the composite in addition to improve the mechanical properties, as example (SiO 2 ) Silica was used with thermoplastic polymers to reduce the thermal conductivity and thermal expansion of polymers, mechanism of reinforcing with powders give a high viscosity and good adhesion, depending on grain size of particles used, [2].Fillers used randomly in rubbers then phenolic resin was used recently with woodflour and celleluse to improve physical properties due to aspect ratio.Many types of reinforcements were knows such as: 1. Fiber reinforced composites.2. Particulated reinforced composites 3. Laminated reinforced composites.

Flakes reinforced composites.
All these types affected by solutions (especially water).Degradation may occur including (aggressive liquids), especially particulated composites due to porosity occurs and in the interface region (between matrix and fillers), [3].Some fillers work on improving mechanical bonds like carbon black with polyethylene and polyunylechloride in a pipes industry.

Ideal fillers own physical properties including:-[4]
1. Good strength to weight ratio.

Good diffusion properties.
Aim of this project is to study the effect of water on some physical properties on polymeric composites mentioned above.

Experimental
Epoxy resin used produced from (FORSOC) Co. types Ep10, with density 1.2g/cm 3 with amino hardener used with 1:4 of resin, chapped fiber (E-glass) was used in addition to Al powder 5µ m as a reinforcement with Epoxy, using hand lay up method (square mold), PVC with carbon black was delivered from industrial company (saudi regime)) using extruder to produce a water pipe, E-glass used with density 2.5 g/cm 3 and modulus 130 GPa [5,6], all specimens were with volume fraction Vf 30% using the weight method.Specimens were cut for tests according to ASTM D695, ISO 179, DIN 8062 standards, Brinell hardness was used and hydraulic press used to evaluate compression strength for all specimens.While assessment of surface roughness was done by using Talysurf-4 apparatus product by English Taylor-Hobson Company.For each specimen take the average of three measurements reading directly from the apparatus, by automatic scanning with fine needle and take the average for all areas with magnification X500 for the first and second specimens, while the magnification for the third specimen X1000.

Results and discussion
Results from the current study are discussed to other in table shown below, Eng.&Tech., Vol.26,No.5,2008Effect of water on the properties of some polymeric composites 528 Ficks' 2 nd law was used to calculate the diffusion coefficient (D) after 6 weeks immersed in water [7------Ficks' 2 nd law where b: thickness of the sample (2 mm).k: weight gain per unit time.∞ µ : max weight absorbed.
Fig(4): Hardness difference for samples before and after immersion in water