scholarly journals Mechanical Properties Distribution within Polypropylene Injection Molded Samples: Effect of Mold Temperature under Uneven Thermal Conditions

Polymers ◽  
2017 ◽  
Vol 9 (11) ◽  
pp. 585 ◽  
Author(s):  
Sara Liparoti ◽  
Vito Speranza ◽  
Andrea Sorrentino ◽  
Giuseppe Titomanlio
Keyword(s):  
Mechanical Properties ◽  
Thermal Conditions ◽  
Mold Temperature ◽  
Injection Molded

scholarly journals Post-Processing Time Dependence of Shrinkage and Mechanical Properties of Injection-Molded Polypropylene

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 22
Author(s):  
Artur Kościuszko ◽  
Dawid Marciniak ◽  
Dariusz Sykutera
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Injection Molding ◽  
Accelerated Aging ◽  
Mold Temperature ◽  
Degree Of Crystallinity ◽  
Injection Mold ◽  
Secondary Crystallization ◽  
Scanning Calorimetry ◽  
Injection Molded

Dimensions of the injection-molded semi-crystalline materials (polymeric products) decrease with the time that elapses from their formation. The post-molding shrinkage is an effect of secondary crystallization; the increase in the degree of polymer crystallinity leads to an increase in stiffness and decrease in impact strength of the polymer material. The aim of this study was to assess the changes in the values of post-molding shrinkage of polypropylene produced by injection molding at two different temperatures of the mold (20 °C and 80 °C), and conditioned for 504 h at 23 °C. Subsequently, the samples were annealed for 24 h at 140 °C in order to conduct their accelerated aging. The results of shrinkage tests were related to the changes of mechanical properties that accompany the secondary crystallization. The degree of crystallinity of the conditioned samples was determined by means of density measurements and differential scanning calorimetry. It was found that the changes in the length of the moldings that took place after removal from the injection mold were accompanied by an increase of 20% in the modulus of elasticity, regardless of the conditions under which the samples were made. The differences in the shrinkage and mechanical properties of the samples resulting from mold temperature, as determined by tensile test, were removed by annealing. However, the samples made at two different injection mold temperature values still significantly differed in impact strength, the values of which were clearly higher for the annealed samples compared to the results determined for the samples immediately after the injection molding.

Effect of mold temperature on the structures and mechanical properties of micro-injection molded polypropylene

2015 ◽  
Vol 88 ◽  
pp. 245-251 ◽  
Author(s):  
Jing Jiang ◽  
Shiwei Wang ◽  
Bo Sun ◽  
Shuaijiang Ma ◽  
Jianming Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mold Temperature ◽  
Injection Molded

scholarly journals Production and Processing of a Spherical Polybutylene Terephthalate Powder for Laser Sintering

2019 ◽  
Vol 9 (7) ◽  
pp. 1308 ◽  
Author(s):  
Rob Kleijnen ◽  
Manfred Schmid ◽  
Konrad Wegener
Keyword(s):  
Mechanical Properties ◽  
Thermal Processing ◽  
Selective Laser Sintering ◽  
Spherical Shape ◽  
Laser Sintering ◽  
Polybutylene Terephthalate ◽  
Powder Production ◽  
Injection Molded ◽  
Continuous Extrusion ◽  
Matrix Powder

This work describes the production of a spherical polybutylene terephthalate (PBT) powder and its processing with selective laser sintering (SLS). The powder was produced via melt emulsification, a continuous extrusion-based process. PBT was melt blended with polyethylene glycol (PEG), creating an emulsion of spherical PBT droplets in a PEG matrix. Powder could be extracted after dissolving the PEG matrix phase in water. The extrusion settings were adjusted to optimize the size and yield of PBT particles. After classification, 79 vol. % of particles fell within a range of 10–100 µm. Owing to its spherical shape, the powder exhibited excellent flowability and packing properties. After powder production, the width of the thermal processing (sintering) window was reduced by 7.6 °C. Processing of the powder on a laser sintering machine was only possible with difficulties. The parts exhibited mechanical properties inferior to injection-molded specimens. The main reason lied in the PBT being prone to thermal degradation and hydrolysis during the powder production process. Melt emulsification in general is a process well suited to produce a large variety of SLS powders with exceptional flowability.

Micro-Injection Molding of Polymer Nanocomposites Composition-Process-Properties Relationship

2021 ◽  
Vol 36 (3) ◽  
pp. 276-286
Author(s):  
Z. Dekel ◽  
S. Kenig
Keyword(s):  
Mechanical Properties ◽  
Plug Flow ◽  
Volume Resistivity ◽  
Process Conditions ◽  
Polyamide 66 ◽  
Fountain Flow ◽  
Microinjection Molding ◽  
Injection Molded ◽  
Composition Process ◽  
Rheological Percolation

Abstract The mechanical, electrical, thermal, and rheological properties of micro injection molded nanocomposites comprising 2% and 5% carbon nanotubes (CNTs) incorporated in polycarbonate (PC), and polyamide 66 (PA) were studied. The design of experiments method was used to investigate the composition-process – properties relationship. Results indicated that the process variables significantly affected the flow patterns and resulting morphology during the filling stage of the microinjection molding (lIM) process, using 0.45 mm diameter lIM samples. Two distinct flow regimes have been identified in lIM using the low cross-section samples. The first was a conventional “fountain flow,” which resulted in a skin/core structure and reduced volume resistivity up to 10 X cm in the case of 5% CNTs and up to 100 X cm in 2% CNTs, in both polymers, respectively. In addition, inferior mechanical properties were obtained, attributed to polymer degradation under high shear rate conditions, when practicing high injection speeds, high mold temperatures, and high screw rotation velocities. The second was a “plug flow” due to wall slippage, obtained under low injection speeds, low mold temperatures, and low rotation velocities, leading to a substantial increase in modulus of elasticity (60%) with increased electrical resistivity up to 103 X cm for 5% CNTs and 105 X cm for 2% CNTs, respectively. The rheological percolation threshold was obtained at 2% CNTs while the electrical threshold was attained at 0.4% CNTs, in both polymers. It was concluded that in lIM, the process conditions should be closely monitored. In the case of high viscous heating, degradation of mechanical properties was obtained, while skin- core morphology formation enhanced electrical conductivity.

Mechanical Properties of Injection Molded Rubber Testing Samples

2015 ◽  
Vol 752-753 ◽  
pp. 308-311
Author(s):  
Adam Skrobak ◽  
Michal Stanek ◽  
David Manas ◽  
Martin Ovsik ◽  
Vojtech Senkerik ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Injection Molding ◽  
Standardized Testing ◽  
Rubber Compound ◽  
Testing Sample ◽  
Synthetic Rubber ◽  
Injection Molded

The aim of this article is to demonstrate and asses to what extent there is an impact on the mechanical properties of a standardized testing sample made of rubber compound based on synthetic rubber EPDM and produced by injection molding in comparison with a sample produced by classic preparation (cutting off a compression molded plate) according to the standard ISO 23529.

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