Rheological properties of polypropylene during multiple extrusion

Costa, Helson M. da; Ramos, Valéria D.; Rocha, Marisa Cristina Guimarães

doi:10.1016/j.polymertesting.2004.06.006

Cited by 135 publications

(75 citation statements)

References 5 publications

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“…Although the 25° pin had a bigger weld thickness than the 15° pin ( Figure 6), a lower fracture load was obtained with it. The reason of this strength difference is due to the chain scission [40]. Chain scission lowers the strength of a thermoplastic material [41].…”

Section: Resultsmentioning

confidence: 99%

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Effect of tool geometry on friction stir spot welding of polypropylene sheets

Bilici

2012

Express Polym. Lett.

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Abstract. The effects of tool geometry and properties on friction stir spot welding properties of polypropylene sheets were studied. Four different tool pin geometries, with varying pin angles, pin lengths, shoulder diameters and shoulder angles were used for friction stir spot welding. All the welding operations were done at the room temperature. Lap-shear tensile tests were carried out to find the weld static strength. Weld cross section appearance observations were also done. From the experiments the effect of tool geometry on friction stir spot weld formation and weld strength were determined. The optimum tool geometry for 4 mm thick polypropylene sheets were determined. The tapered cylindrical pin gave the biggest and the straight cylindrical pin gave the lowest lap-shear fracture load.

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Section: Resultsmentioning

confidence: 99%

“…Chain scission lowers the strength of a thermoplastic material [41]. If a molten thermoplastic material is heated to a high temperature and then a high pressure is applied to it, a decrease in the molecular weight of the material occurs [40]. The mechanical properties of thermoplastics decrease with lowering the molecular weight [42].…”

Section: Resultsmentioning

confidence: 99%

Effect of tool geometry on friction stir spot welding of polypropylene sheets

Bilici

2012

Express Polym. Lett.

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“…For such purpose, it is used factorial design, that is a mathematical-statistic tool applied to infer the effect of parameters involved in plenty of experiments and studies, like blending [20] , hydrogels characterization [21] , mechanical properties [22] , residence time distribution during extrusion [23] , polymer functionalization [24] , and also polymer degradation [25,26] .…”

Section: Resultsmentioning

confidence: 99%

Influence of Reprocessing in the formation of functional groups during low density polyethylene aging

et al. 2012

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Abstract:In recent years, the interest in polymer recycling has increased. However, in every reprocessing step the material undergoes shear stress and is affected by temperature and oxygen. The aim of this paper is to investigate the influence of multiple extrusion in the generation of functional groups, namely hydroperoxide, carbonyl, and transvinylene. Low density polyethylene was reprocessed three times in a single screw extruder. In each recycling step hot pressed films were prepared. These films were submitted to a heat treatment in an oven with air circulation and renovation to proceed with aging tests at different times and temperatures. The results obtained showed that all functional groups had their concentration increased with the increase in number of reprocessing, the aging time and temperature of the heat treatment. The factorial design was applied to verify the influence of these parameters. All the parameters had significant effects, since their regression coefficients had the same order of magnitude, with the most influential parameter being the aging temperature, followed by the aging time and number of extrusions. Most of the interactions were influential, indicating that the formation of functional groups depends upon their interaction, and not only on their isolated effects.

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“…3 This thermal degradation can result on one hand in both cross-linking and chain scission of the polymer matrix and on the other hand in structural and chemical attrition of wood flour. [4][5][6][7][8][9][10][11][12][13] The literature review indicates that PP is significantly less stable than PE.…”

Section: Introductionmentioning

confidence: 99%

Effects of Multiple Extrusions on Structure-property Performance of Natural Fiber High-density Polyethylene Biocomposites

et al. 2018

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Detailed analysis of the effects of multiple extrusions on physical, mechanical, micro-structural as well as dynamic mechanical thermal properties of natural fiber high-density polyethylene (HDPE) composites is reported. Composite materials containing HDPE, wood flour, and Maleic Anhydride polyethylene (MAPE) were manufactured and subjected to a recycling process consisting of up to four times grinding and reprocessing under industrial conditions. A wide range of analytical methods including bending tests, modulus of elasticity, impact strength, Scanning electron microscopy (SEM), fiber length measurement, water absorption tests, and dynamic mechanical thermal analysis (DMTA) were employed to understand the effects of recycling on natural fiber-HDPE composites. The results revealed that the recycled composites had lower bending strength and modulus of elasticity values, as compared to the reference counterparts. Also, the once recycled composites showed higher impact strength. Results, as well, indicated that generally the recycled composites had lower water absorption values as compared to the reference ones. The results obtained from DMTA exhibited a decrease in storage modulus and an increase in mechanical loss factor (tan δ) for all composites subjected to recycling. Alterations in phase transition temperatures and intensities were also monitored and the possible reasons were analyzed.

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Rheological properties of polypropylene during multiple extrusion

Cited by 135 publications

References 5 publications

Effect of tool geometry on friction stir spot welding of polypropylene sheets

Effect of tool geometry on friction stir spot welding of polypropylene sheets

Influence of Reprocessing in the formation of functional groups during low density polyethylene aging

Effects of Multiple Extrusions on Structure-property Performance of Natural Fiber High-density Polyethylene Biocomposites

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