Polymer processing
Luisiana Morales-Zamudio; Francisco Rodriguez-Gonzalez; Minerva A.M Zamudio; Tomas Lozano; Juan Guillermo Martinez-Colunga; Saul Sanchez-Valdes; Luciano Da Silva; Erika Lopez-Martinez; Sergio Flores-Gallardo
Abstract
In this research we provide a practical guide to achieve the successful extrusion of LDPE tapes commercially used in mesh fences, with controlled dimensions, good mechanical properties and weather resistance. Here we share: 1) The die design dimensions and its specialized slotted manufacture to get the ...
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In this research we provide a practical guide to achieve the successful extrusion of LDPE tapes commercially used in mesh fences, with controlled dimensions, good mechanical properties and weather resistance. Here we share: 1) The die design dimensions and its specialized slotted manufacture to get the veins of tape, 2) Processing temperatures profile, 3) Cooling method, 4) Hot stretch ratio (HSR), and 5) The effect of colorant and ultraviolet rays’ protector, due to the outdoor use of polymer privacy tape. The formulated tape (0.8 wt. % UV protector and 5 wt. % colorant) showed the best performance under accelerated aging and reached good mechanical properties up to a time of 2000 hours compared to its initial values. The dye and the UV additive improved the mechanical properties. All these, led to obtain a LDPE tape to fulfill the expectative and characteristic of a commercial tape used for mesh fences.
Characterization
Reza Poorghasemi; Yousef Jahani
Abstract
In this work, the compatibility and crystallinity of low density polyethylene (LDPE) and polybutene-1 (PB-1) blends were studied. Various blends of LDPE/PB-1 containing 5, 10 and 20 wt.% PB-1 were prepared in a corotating twin-screw extruder and characterized by scanning electron microscopy (SEM), shear ...
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In this work, the compatibility and crystallinity of low density polyethylene (LDPE) and polybutene-1 (PB-1) blends were studied. Various blends of LDPE/PB-1 containing 5, 10 and 20 wt.% PB-1 were prepared in a corotating twin-screw extruder and characterized by scanning electron microscopy (SEM), shear oscillation rheology and wide-angle X-ray diffractometry (WAXD). A matrix-droplet morphology was observed in SEM images, indicating incompatibility of the two polymers in the solid state. Compared to neat LDPE, the relaxation spectra of the blends were broadened, and a slight increase in their relaxation times was observed. The relaxation time of the blends was enhanced by increasing PB-1 content, which was further proved by fitting rheological data in the Carreau-Yasuda model. Deviation of Cole-Cole diagrams from circular shape means that the blend samples were not miscible and the positive-deviation behavior of the complex viscosity and storage modulus from the mixing rule revealed the formation of strong interfacial interactions. The crystallinity of both LLDPE and PB-1 was decreased as a result of blending. The peaks attributed to the form II of PB-1 crystals were eliminated and the peaks related to LDPE were obviously weakened, suggesting to prevent crystallinity of polymers which is associated with a reduction in the total crystallinity percentage for the blend. The reduction of crystallinity was more pronounced in PB-1 phase.
Rezgar Hasanzadeh; Taher Azdast; Ali Doniavi; Richard Eungkee Lee
Abstract
The loss of energy especially in industrial and residential buildings is one of the main reasons of increased energy consumption. Improving the thermal insulation properties of materials is a fundamental method for reducing the energy losses. Polymeric foams are introduced as materials with excellent ...
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The loss of energy especially in industrial and residential buildings is one of the main reasons of increased energy consumption. Improving the thermal insulation properties of materials is a fundamental method for reducing the energy losses. Polymeric foams are introduced as materials with excellent thermal insulation properties for this purpose. In the present study, a deep theoretical investigation is performed on the overall thermal conductivity of low-density polyethylene (LDPE) foams. The thermal conductivity by radiation is predicted using two different methods. The most appropriate model is selected in comparison with experimental results. The results show that the theoretical model has an appropriate agreement with the experimental results. The effects of foam characteristics including foam density, cell size, and cell wall thickness on the overall thermal conductivity are investigated. The results indicate that by decreasing the cell size and increasing the cell wall thickness, the overall thermal conductivity is decreased significantly. Also, there is an optimum foam density in order to achieve the smallest thermal conductivity. The lowest overall thermal conductivity achieved in the studied ranges is 30 mW/mK at foam density of 37.5 kg.m-3, cell size of 100 μm, and cell wall thickness of 6 μm.
Polyolefin degradation
Mehrdad Seifali Abbas-Abadi; Mehdi Nekoomanesh Haghighi; Armando G. McDonald; Hamid Yeganeh
Abstract
Pyrolysis of low density polyethylene (LDPE) by equilibrium fluid catalytic cracking (FCC) was studied in a stirred reactor under different process parameters. In this work, the effect of process parameters such as degradation temperature (420-510°C), catalyst/polymer ratio (0-60%), carrier gas type ...
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Pyrolysis of low density polyethylene (LDPE) by equilibrium fluid catalytic cracking (FCC) was studied in a stirred reactor under different process parameters. In this work, the effect of process parameters such as degradation temperature (420-510°C), catalyst/polymer ratio (0-60%), carrier gas type (H2, N2, ethylene, propylene, Ar and He), residence time and agitator speed (0-300 rpm) on the condensate yield (liquid, gas and coke) and product composition were considered. Reaction products were determined by GC analysis and shown to contain naphthenes (cycloalkanes), paraffins (alkanes), olefins (alkenes) and aromatics. Higher temperature and more catalyst amount enhanced LDPE cracking. The maximum “fuel like” condensed product yield was attained at 450°C and 10% catalyst, respectively and gaseous products increased with increases in temperature. Hydrogen as a reactive carrier gas increased the condensed and paraffinic product yield. Appropriate heat transfer (by stirring) increased the catalyst efficiency in a stirred reactor.
