Effect of flow-induced crystallization on the distribution of spherulite dimensions along cross section of injection molded parts

Shear heating effect that occurs in melted polymers can cause serious quality problems with production of injection molded parts. The source of this effect is high viscosity of polymers and low thermal conductivity what leads to significant temperature gradients at the cross section of runners. In this work the influence of processing parameters on this phenomenon for difference runner diameters and lengths was presented for two polymers that have different thermal sensitivity.

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Micro and Macro Injection Molded Parts of Isotactic Polypropylene/Polyethylene Blends: Shear-Induced Crystallization Behaviors and Morphological Characteristics

Journal of Macromolecular Science Part B ◽

10.1080/00222348.2013.763700 ◽

2013 ◽

Vol 53 (1) ◽

pp. 24-39 ◽

Cited By ~ 7

Author(s):

Peng Deng ◽

Kejun Liu ◽

Lei Zhang ◽

Hong Liu ◽

Tao Wang ◽

...

Keyword(s):

Isotactic Polypropylene ◽

Morphological Characteristics ◽

Crystallization Behaviors ◽

Polyethylene Blends ◽

Molded Parts ◽

Injection Molded ◽

Induced Crystallization

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Porosity distribution in metal injection molded parts

Advanced Technologies & Materials ◽

10.24867/atm-2021-1-002 ◽

2021 ◽

Vol 46 (1) ◽

pp. 7-10

Author(s):

Samir Butković ◽

Emir Šarić ◽

Muhamed Mehmedović

Keyword(s):

Injection Molding ◽

Cross Section ◽

Density Variation ◽

Residual Porosity ◽

Metal Injection Molding ◽

Green Density ◽

Shaped Part ◽

Molded Parts ◽

Injection Molded ◽

Complex Parts

Metal injection molding technology is commonly used in production of small and very complex parts. Residual porosity is unavoidable characteristic of P/M parts, affecting their final properties. During injection molding phase powder-binder separation can occur, causing green density variation through cross section of the part. This behaviour is particularly pronounced as complexity of the parts increases. As a consequence, zones with different density and residual porosity can be seen after sintering. In this regard, porosity and hardness distribution of the sintered ring-shaped part is analysed and presented in the paper.

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A Study on the Birefringence Measurement in Injection Molded Parts Using Two Different Laser Sources and R-G-B Separation of White Light

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.326-328.187 ◽

2006 ◽

Vol 326-328 ◽

pp. 187-190

Author(s):

Jong Sun Kim ◽

Chul Jin Hwang ◽

Kyung Hwan Yoon

Keyword(s):

White Light ◽

Low Cost ◽

Main Idea ◽

Injection Molding Process ◽

Molding Process ◽

Laser Method ◽

High Productivity ◽

Molded Parts ◽

Injection Molded ◽

Plastic Parts

Recently, injection molded plastic optical products are widely used in many fields, because injection molding process has advantages of low cost and high productivity. However, there remains residual birefringence and residual stresses originated from flow history and differential cooling. The present study focused on developing a technique to measure the birefringence in transparent injection-molded optical plastic parts using two methods as follows: (i) the two colored laser method, (ii) the R-G-B separation method of white light. The main idea of both methods came from the fact that more information can be obtained from the distribution of retardation caused by different wavelengths. The comparison between two methods is demonstrated for the same sample of which retardation is up to 850 nm.

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Are We Able to Print Components as Strong as Injection Molded?—Comparing the Properties of 3D Printed and Injection Molded Components Made from ABS Thermoplastic

Applied Sciences ◽

10.3390/app11156946 ◽

2021 ◽

Vol 11 (15) ◽

pp. 6946

Author(s):

Bartłomiej Podsiadły ◽

Andrzej Skalski ◽

Wiktor Rozpiórski ◽

Marcin Słoma

Keyword(s):

Tensile Strength ◽

Injection Molding ◽

Mechanical Strength ◽

Cross Section ◽

Fused Deposition Modeling ◽

High Strength ◽

Large Cross Section ◽

Fused Deposition ◽

Injection Molded ◽

The Cross

In this paper, we are focusing on comparing results obtained for polymer elements manufactured with injection molding and additive manufacturing techniques. The analysis was performed for fused deposition modeling (FDM) and single screw injection molding with regards to the standards used in thermoplastics processing technology. We argue that the cross-section structure of the sample obtained via FDM is the key factor in the fabrication of high-strength components and that the dimensions of the samples have a strong influence on the mechanical properties. Large cross-section samples, 4 × 10 mm2, with three perimeter layers and 50% infill, have lower mechanical strength than injection molded reference samples—less than 60% of the strength. However, if we reduce the cross-section dimensions down to 2 × 4 mm2, the samples will be more durable, reaching up to 110% of the tensile strength observed for the injection molded samples. In the case of large cross-section samples, strength increases with the number of contour layers, leading to an increase of up to 97% of the tensile strength value for 11 perimeter layer samples. The mechanical strength of the printed components can also be improved by using lower values of the thickness of the deposited layers.

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A novel approach to the study of extensional flow-induced crystallization

Polymer Testing ◽

10.1016/j.polymertesting.2021.107060 ◽

2021 ◽

Vol 96 ◽

pp. 107060

Author(s):

Juliana Amirdine ◽

Thouaïba Htira ◽

Nicolas Lefevre ◽

René Fulchiron ◽

Nathalie Mathieu ◽

...

Keyword(s):

Extensional Flow ◽

Novel Approach ◽

Induced Crystallization ◽

Flow Induced Crystallization

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Silane-Functionalized Sheep Wool Fibers from Dairy Industry Waste for the Development of Plasticized PLA Composites with Maleinized Linseed Oil for Injection-Molded Parts

Polymers ◽

10.3390/polym12112523 ◽

2020 ◽

Vol 12 (11) ◽

pp. 2523

Author(s):

Franciszek Pawlak ◽

Miguel Aldas ◽

Francisco Parres ◽

Juan López-Martínez ◽

Marina Patricia Arrieta

Keyword(s):

Linseed Oil ◽

Microstructural Analysis ◽

Dairy Industry ◽

Poly Lactic Acid ◽

Industry Waste ◽

Wool Fibers ◽

Molded Parts ◽

Silane Modification ◽

Injection Molded ◽

Sheep Wool

Poly(lactic acid) (PLA) was plasticized with maleinized linseed oil (MLO) and further reinforced with sheep wool fibers recovered from the dairy industry. The wool fibers were firstly functionalized with 1 and 2.5 phr of tris(2-methoxyethoxy)(vinyl) (TVS) silane coupling agent and were further used in 1, 5, and 10 phr to reinforce the PLA/MLO matrix. Then, the composite materials were processed by extrusion, followed by injection-molding processes. The mechanical, thermal, microstructural, and surface properties were assessed. While the addition of untreated wool fibers to the plasticized PLA/MLO matrix caused a general decrease in the mechanical properties, the TVS treatment was able to slightly compensate for such mechanical losses. Additionally, a shift in cold crystallization and a decrease in the degree of crystallization were observed due to the fiber silane modification. The microstructural analysis confirmed enhanced interaction between silane-modified fibers and the polymeric matrix. The inclusion of the fiber into the PLA/MLO matrix made the obtained material more hydrophobic, while the yellowish color of the material increased with the fiber content.

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