Ayfer Dönmez Çavdar

Tea mill waste fibers filled thermoplastic composites: the effects of plastic type and fiber loading

The objective of this study was to investigate the utilization of tea mill waste fibers (TMWF) in thermoplastic composites. For this purpose, two plastic types: polypropylene (PP) and high density polyethylene (HDPE), were used as thermoplastic material while TMWF was utilized as a lignocellulosic filler. HDPE or PP and up to 50% TMWF were compounded in the single screw extruder and extrudates were compression molded into thermoplastic composite panels. The effects of plastic type and fiber loading rate on mechanical (flexural, tensile, and impact properties), physical (water absorption and thickness swelling), thermal properties, and morphological of the produced composites were determined. Tensile modulus, flexural modulus, water absorption, and thickness swelling of the produced composites were increased with the rise of the TMWF amount in the thermoplastic matrix. On the other hand, TMWF increase in the thermoplastic matrix reduced the tensile strength, flexural strength, and impact strength of the produced composites. It should also be noted that both flexural strength and flexural modulus have satisfied the requirements of ASTM D 6662. In the case of thermal properties, addition of TMWF into the thermoplastic matrix did not change the initial degradation significantly. However, the char rate of the composites increased. It appears that tea mill waste fibers may have a potential usage as filler in the PP- and HDPE-based thermoplastic composites.

Technological properties of thermoplastic composites filled with fire retardant and tea mill waste fiber

In this study, physical, mechanical, thermal, fire and biological properties of thermoplastic composites filled with fire retardant and tea mill waste fiber were investigated. The composites produced with the extrusion method were accomplished by using tea mill waste fiber as lignocellulosic materials and high-density polyethylene and polypropylene as thermoplastic polymer. Aluminum trihydrate and zinc borate were incorporated with different contents into polymer matrix for improving fire properties of the composites, and their effects on technological properties of the composites were evaluated. Aluminum trihydrate had a positive effect on the tensile modulus of the composites whilst zinc borate had adverse effect on that of the composites. The strength properties of the composites slightly decreased with usage of fire retardant. In the light of obtained results, it was specified that use of fire retardants improved physical, biological, thermal and fire properties of tea mill waste fiber-filled thermoplastic composites.

Long-Term Leaching Effect on Decay Resistance of Wood-Plastic Composites Treated with Boron Compounds

In this study, water absorption, thickness swelling and decay resistance of thermoplastic composites treated with three types of boron compounds was investigated. Spruce wood flour was treated with boric acid (BA), borax (BX) and mixture of BA–BX, and then was reinforced at two loading rate (20 and 40 wt%) in polymer matrix. Decay test of the composites was performed using with a brown rot fungus Coniophora puteana and a white rot fungus Trametes versicolor both for leached and unleached samples. The morphologic evaluations of decayed samples were done by scanning electron microscopy. Composites containing higher wood flour loading resulted in increased water absorption, thickness swelling, weight loss and moisture content. Fungal decay susceptibility of WPCs was influenced by leaching test for 60 days. Boron compound treated composites showed higher weight loss and moisture content than controls in decay test. All tested performance parameters were considerably increased in BX containing composites.

Mechanical and Physical Properties of Cement-Bonded Perticleboard Made from Tea Residues and Hardboards

The residues of tea factory and waste hardboards are generally incinerated without utilizing their heat performances. The first objective of this study was to manufacture cement bonded particleboard using residues of tea factory (Camellia sinenses L.) and waste hardboards. The second objective was to evaluate modulus of rupture (MOR), modulus of elasticity (MOE), internal bonding strength (IB), water absorption (WA) and thickness swelling (TS) properties of the boards produced. The boards were produced at two density levels of 800 and 1200 kg/m3 and at five lignocellulosic mixture ratios of poplar chips/hardboards/tea residues (1/0/0; 1/1/0; 1/0/1; 0/1/0; 0/0/1, based on weigth). All the boards were produced at lignocellulosic material/cement ratio of 1:2.75 on a weight to weight basis. As cement curing accelerators, Al2(SO4)3 and Na2SiO3 were used at ratios of 1.5% and 3.5%, based on cement weight, respectively. The MOR values ranged from 0.8 to 10.99 MPa and MOE values ranged from 254 to 2979 MPa. The mean values of WA and TS after 24 h of water soaking of the cemen bonded particleboards ranged from 28% to 43.5% and 1.3% to 8.08%, respectively.

Fire evacuation route determination based on particle swarm optimization

Fire may cause people in the building to be scared, distracted. In that case, some evacuation systems may help people to leave the building safely. This paper proposes a technique to explore a wayfinding during fire. Wayfinding depends on building type. We also investigated the possible influence of smoke, light and distance on route determination for fire evacuation. When the fire occurs, the system provides evacuation route guidance to people for them to be able to avoid hazard. It is important to optimize the evacuation route for minimum effects of dangerous conditions. Fire evacuation system can recommend the shortest and safety route. Here, Particle Swarm Optimization is used to optimize the evacuation route. On the other advantage of Particle Swarm Optimization is that it is easy to implement and has very few parameters.