Erdem Koç

An analysis on air permeability of polyester/viscose blended needle-punched nonwovens

Air permeability is one of the important properties which affect the performance of nonwovens used for filtration, insulation and drainage applications. In this study, an analysis on the air permeability of the polyester/viscose blended needle-punched nonwovens has been carried out. In addition, a mixture-process crossed regression model with two mixture components (polyester and viscose blend ratios) and two process variables (fabric mass per unit area and needling density) is developed to analyze the air permeability of polyester/viscose blended needled nonwovens. For this purpose, five different blend ratios of polyester/viscose webs were produced, cross lapped and needled in four different mass per unit areas and three different punching densities. Air permeability of sixty nonwovens was determined by performing standard test method and the data obtained from tests were statistically analyzed with the Design Expert software. In conclusion, blend ratio of polyester-viscose fibers in web, fabric mass per unit area and needling density have major effects on the air permeability of nonwovens and the generated statistical model has given satisfactory predictions about air permeability.

The effect of sintering time, temperature, and graphene addition on the hardness and microstructure of aluminum composites

Currently, graphene is used in aluminum matrix composite manufacturing due to its superior mechanical properties. However, few detailed studies exist on the effect of the process conditions such as sintering temperature (TS), time (tS), and a number of graphene nanoplatelets. Therefore, the effects of different sintering times (tS = 60, 120, 180, 300 min), sintering temperatures (TS = 550, 600, 630℃), and graphene addition (0.1, 0.3, 0.5 wt%) on apparent density and hardness were reported in detail in this study. The crystal structure and microstructure of fabricated composites by powder metallurgy method were examined with X-ray diffractometer and scanning electron microscopy. Apparent density and mechanical properties were tested by density meter and micro Vickers hardness tester. The results indicated that the best sintering time, sintering temperature, and graphene addition were determined to be 180 min, 630℃, and 0.1 wt%, respectively, for the best hardness of composite. The hardness of composite increased from 38 to 57 HV when compared with pure aluminum under the best process conditions.

An analysis on abrasion resistance of polyester-/viscose-blended needle-punched nonwovens

In this study, the influence of fiber composition and process parameters such as mass per unit area and punching density on abrasion resistance of polyester-/viscose-blended needle-punched nonwovens has been investigated. For this purpose, five different blend ratios of polyester/viscose webs were produced, cross-lapped, and needled in four different mass per unit areas and three different needling/punching densities. The abrasion resistance and thickness of the nonwovens were determined by performing the standard test methods. The structural parameters such as fabric bulk density and fiber volume fraction were calculated and the data obtained from tests and calculations were analyzed in detail. It was concluded that abrasion resistance of the needle-punched nonwovens decreased with the increase of polyester proportion in the mixture and increased with the increase in mass per unit area. Also, an increase in punching density first caused to increase in abrasion resistance and then further increase in punching density decreased the abrasion resistance.

An investigation on bursting strength of polyester/viscose blended needle-punched nonwovens

The aim of this study is to analyze the bursting strength of polyester/viscose blended needle-punched nonwovens. For this purpose, five different blend ratios of polyester/viscose webs were produced, cross-lapped and needled in four different mass per unit areas and three different needling/punching densities. The bursting strength of 60 nonwovens was determined by performing the standard test method; the data obtained from tests were statistically analyzed in Design Expert software. In addition, a mixture process crossed-regression model with two mixture components (polyester and viscose blend ratios) and two process variables (fabric mass per unit area and needling density) was developed to analyze the bursting strength of polyester/viscose blended needled nonwovens. In conclusion, the regression model indicated that the bursting strength of the needle-punched nonwovens initially decreases and then increases with the increase of polyester fiber in the mixture and with the increase in mass per unit area. On the other hand, when the mass per unit area is kept constant, an increase in needling density causes decreases in bursting strength.

Optimization of the production cost and/or selected performance properties of towel fabrics

In this study, single and multi‐objective models have been developed aiming to optimize the cost and/or one or more defined performance properties of towel fabrics. For this purpose, the developed mathematical equations based on the physical and performance properties of a towel have been used as objective function and constraints in the designed models. With these models adopted, the physical properties, such as pile height, warp and weft densities, being used in real production conditions, have been attempted to predict under the conditions that the selected performance properties might take the best values for given constraints.

Mechanical and tribological behaviours of aluminium matrix composites reinforced by graphene nanoplatelets

ABSTRACT In the present study, the effects of graphene content (0.1, 0.3, 0.5 wt-%) on the mechanical and tribological properties of aluminium matrix composites were reported. The experimental results reveal that the best apparent density (2.58 ± 0.02 g cm−3), highest Vickers hardness (57 ± 2.5 HV), lowest mass loss (1.6 and 9.7 mg for 10 N and 40 N), and lowest wear rate (12 × 10−5 and 18 × 10−5 mm3/Nm for 10 N and 40 N) were obtained at aluminium–0.1% graphene composite when compared with pure aluminium. The ultimate compressive strength of composites increases from 106 ± 4 to 138 ± 4 MPa with increasing graphene nanoplatelet contents. All results showed that graphene has been a very effective reinforcement and solid-lubricant material for Al matrix composites.