scholarly journals Fiber Orientation and Concentration in an Injection-Molded Ethylene-Propylene Copolymer Reinforced by Hemp

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2771
Author(s):  
Antoine Dupuis ◽  
Jean-Jacques Pesce ◽  
Paulo Ferreira ◽  
Gilles Régnier
Keyword(s):  
Injection Molding ◽  
Fiber Orientation ◽  
Glass Fibers ◽  
Thermomechanical Properties ◽  
Fiber Content ◽  
Hemp Fibers ◽  
Shear Rates ◽  
High Shear Rates ◽  
Injection Molded ◽  
The One

This paper characterizes and analyzes the microstructures of injection-molded polypropylene parts reinforced with 20 wt% of hemp fibers in order to understand the process induced variations in thermomechanical properties. In-thickness fiber orientation and fiber content were determined by X-ray tomography along the flow. The fiber content along the flow path was also determined by direct fiber content measurements after matrix dissolution, showing an increase of 2%/100 mm for a 2.2 mm-thick plate due to fiber migration during the filling stage. A typical shell/core structure for fiber orientation in injection molding was observed, but with a very clear transition between the layer solidified under high shear rates and the core in which the fiber content was reduced by more than 50%. The orientation of hemp fibers is lower than the one of glass fibers, especially in thickness direction. However, the overall fiber orientation in the injection direction induces significant anisotropic thermomechanical properties, which cannot be explained by simple micromechanical models that consider isotropic mechanical properties for hemp fibers. These phenomena must be taken into account in process simulation codes for injection molding to better predict thermomechanical properties as well as part shrinkage and warpage to design molds.

Process Development for the Ceramic Injection Molding of Oxide Chopped Fiber Reinforced Aluminum Oxide

2017 ◽  
Vol 742 ◽  
pp. 231-237 ◽  
Author(s):  
Metin Tülümen ◽  
Thomas Hanemann ◽  
Michael J. Hoffmann ◽  
Rainer Oberacker ◽  
Volker Piotter
Keyword(s):  
Injection Molding ◽  
Fiber Orientation ◽  
Average Length ◽  
Flow Behavior ◽  
Fiber Content ◽  
Oxide Ceramic ◽  
Fiber Reinforced ◽  
Mechanical Reinforcement ◽  
Ceramic Injection Molding ◽  
Fiber Orientation Distribution

In this study, it was tried to develop a process chain for ceramic injection molding of Al2O3-chopped-fiber reinforced oxide-ceramic-matrix-composite. The feedstocks are compounded at 50 Vol. % filling degree of solid (Al2O3 μ-powder (Taimei Chemicals Co. Ltd.) and 3,2 mm chopped fibers (3M)), in which fiber content varies from 0 Vol. % to 100 Vol. %. As binder system, PE + Paraffin Wax + Stearic Acid are used. The ingredients are compounded in a kneader (Brabender) at 125°C and after the viscosity measurement in the high pressure capillary rheometer at 160°C and certain shear rates, the feedstock is injection molded (Battenfeld) at 160°C, which is followed by debinding process, including chemical (in n-Hexane) and thermal steps, and 2h sintering at different temperatures. Flow paths in the machinery parts, rheological properties of binding system, fiber content and the fiber orientation have significant effect on the flow behavior of the feedstock, fiber -orientation, -distribution & -length, which are crucial to understand the properties of end-parts like mechanical reinforcement of the fibers. The fibers in the sintered parts are ca. 200 μm in average length. The fibers in the feedstock show different orientations depending on the part-geometry and the green bodies have different densities depending on sintering temperature, amount of dispersant and fiber orientation.

Electrical Contact Properties of Micro-Injection Molded Polypropylene/CNT/CB-Composites on Metallic Electrodes

2015 ◽  
Vol 1103 ◽  
pp. 77-83 ◽  
Author(s):  
Michael Heinrich ◽  
Ricardo Decker ◽  
Joerg Schaufuss ◽  
Juergen Troeltzsch ◽  
Jan Mehner ◽  
...  
Keyword(s):  
Injection Molding ◽  
Large Scale ◽  
Electrical Contact ◽  
Influential Factors ◽  
Scale Production ◽  
Micro Injection Molding ◽  
Micro Electro Mechanical Systems ◽  
Aspect Ratios ◽  
Injection Molded ◽  
The One

The investigations carried out under this work dealing with a new field of application for large-scale production of electric contacting processes for micro-electro-mechanical systems (MEMS) using the micro-injection molding technology. The focus of this article is the analysis of process-related influential factors of micro-injection molding that determines both the electrical resistivity and the flowability of polymer nanocomposites filled with carbon nanotubes (CNT) and carbon black (CB). For that, the viscosity and the electrical conductivity as a function of different CNT-and CB-contents and their combination were investigated in a manufacturing study for Polypropylene. The results of the investigations answered questions regarding material science and technical processes. By this, optimal rheological properties for formation of micro injection molded conductive patterns with high aspect ratios on the one side and with the best possible conductivity of the nanocomposites on the other side can be set.

scholarly journals On short glass fiber reinforced thermoplastics with high fiber orientation and the influence of surface roughness on mechanical parameters

2021 ◽  
pp. 073168442110517
Author(s):  
Tamara van Roo ◽  
Stefan Kolling ◽  
Felix B Dillenberger ◽  
Joachim Amberg
Keyword(s):  
Fiber Orientation ◽  
Glass Fibers ◽  
Fiber Direction ◽  
Fiber Reinforced ◽  
Polybutylene Terephthalate ◽  
Structural Simulation ◽  
Fiber Reinforced Materials ◽  
Molded Parts ◽  
Injection Molded ◽  
Short Glass

Injection molding is a common process for manufacturing thermoplastic polymers. Preconnected to fabrication, mechanically loaded parts are examined in structural simulation. A crucial prerequisite for a valid structural simulation for any material is the underlying material data. To determine this data, different phenomena must be considered such as influences of load type, strain rate, environmental conditions and in case of fiber reinforced materials the fiber orientation (FO) in the considered area. Because of rheological effects, injection molded parts often possess a non-homogeneous FO distribution. This makes it challenging to create testing plates for specimen extraction with a well-defined FO over thickness and width in the considered area. In this paper, a novel testing part is introduced with an unidirectionally oriented testable area. It shows a FO degree of more than 0.75, which has been validated with μ-CT measurement and two thermoplastic materials: polyamide and polybutylene terephthalate, both reinforced with 30 weight percent of short glass fibers. In order to resolve influences of the already addressed FO distribution in injection molded parts, tensile test specimens need to be extracted out of specially designed plates via milling and cannot be injection molded directly. Experiments were carried out to study possible effects of preparation on the mechanical properties of specimens with both materials and two milling parameter sets. The first milling parameter set creates reproducible surface roughnesses, whereas the second parameter set shows a correlation between FO and roughness value: when milling perpendicularly to the main FO lower roughnesses are reached than milling in fiber direction. Uncertainties of the normalized rupture strain from orthogonally extracted specimens seem to be larger than the values from those extracted in fiber direction.

Correlation between fiber orientation distribution and mechanical anisotropy in glass-fiber-reinforced composite materials

2019 ◽  
Vol 39 (7) ◽  
pp. 653-660 ◽  
Author(s):  
Senji Hamanaka ◽  
Chisato Nonomura ◽  
Thanh Binh Nguyen Thi ◽  
Atsushi Yokoyama
Keyword(s):  
Glass Fiber ◽  
Fiber Orientation ◽  
Flexural Modulus ◽  
Orientation Distribution ◽  
Fiber Content ◽  
Mechanical Anisotropy ◽  
Bending Test ◽  
Flat Plates ◽  
Fiber Orientation Distribution ◽  
Injection Molded

Abstract This study investigates the correlation between the fiber orientation distribution along the thickness and mechanical anisotropy in injection-molded products using a thermoplastic resin reinforced by short fibers. To this end, polyamide-6 samples containing 15, 30, 50, and 65 wt% of short fiberglass were compounded, and flat plates with side gates were injection-molded. The fiber orientation distribution near the center of the plates was observed via X-ray computed tomography and that along the thickness was quantified via a fiber orientation tensor. Coupon test pieces were cut from the plates along the machine and transverse directions, and a three-point bending test was performed. Mechanical anisotropy was evaluated from the ratio of the flexural modulus in each direction. Evaluation results of the fiber orientation distribution and mechanical anisotropy were compared. As a result of the above investigation, a clear correlation was found between the fiber orientation distribution and mechanical anisotropy when the glass fiber content was 15–50 wt%. In the anisotropic expression under the condition of high glass fiber content (65 wt%), contributions of parameters other than the fiber orientation distribution became evident.

Effect of Atmospheric Pressure Plasma Treatment of Glass Fibers on the Composite Strength of Endless Fiber-Reinforced Injection Molded Components

2019 ◽  
Vol 801 ◽  
pp. 251-257
Author(s):  
Tobias Gebken ◽  
Rüdiger Sachs ◽  
Markus Kühn ◽  
Jörg Ihde ◽  
Klaus Dröder ◽  
...  
Keyword(s):  
Injection Molding ◽  
Glass Fibers ◽  
Injection Molding Process ◽  
Fiber Reinforced ◽  
Molding Process ◽  
Plasma Parameters ◽  
Flow Process ◽  
Adhesion Properties ◽  
Surface Pretreatment ◽  
Injection Molded

Injection molding is an efficient manufacturing process for short-fiber reinforced plastic components and is used for the production of semi-structural or geometrically complex components. To improve stiffness and strength, continuous fibers can be locally integrated inside the part during manufacturing. A local integration of fibers is not feasible for high output manufacturing processes but can be achieved by direct impregnation of endless fibers in the injection molding process. It is a challenging option to integrate endless fibers in injection molded parts in means of fiber position and infiltration. Thereby, the knowledge of the flow process of the injected melt must be precisely understood in means of orientation of the fibers to achieve a correct position. In previous works the process parameters for the impregnation of fibers and the composite behavior of untreated fibers were investigated. As a result, the surface pretreatment of the fibers can have an important effect on the composite and the direct impregnation of fibers. An important focus of this work is the pretreatment of glass fibers by plasma. The influence of the plasma parameters resulting on the adhesion properties between fiber and matrix and thus the bond strength of the composite are evaluated and measures for further adhesive property improvement are shown.

The Effect of Oil and Black on the Injection Molding of EPDM Compounds. I.

1969 ◽  
Vol 42 (5) ◽  
pp. 1321-1335
Author(s):  
William G. DePierri ◽  
J. R. Hopper
Keyword(s):  
Pressure Drop ◽  
Injection Molding ◽  
Flow Behavior ◽  
Injection Pressure ◽  
Flow Properties ◽  
Pressure Drops ◽  
Factors Affecting ◽  
Shear Rates ◽  
Divergent Flow ◽  
High Shear Rates

Abstract Factors affecting the flow properties of EPDM compounds have been studied and the findings of the study applied to the injection molding of these compounds. The level of oil and of black were found to change the flow properties of EPDM compounds. Higher levels of oil decreased the compound viscosity while higher levels of black increased the compound viscosity. The viscosity of the oil influenced compound viscosities. Compounds made with the more viscous (at 210° F) oil had slightly higher viscosities. However, changing from an aromatic to a naphthenic oil of similar viscosity had little effect on the compound viscosity. Compounds made from two different polymers of similar Mooney viscosity were found to have widely divergent flow behavior at high shear rates. Injection molding of EPDM compounds was studied with a molding assembly which had a capillary rheometer as barrel and plunger. Injection pressure data from the molding experiments was found to parallel closely the rheological data. An analysis of the pressure drops in passing through different parts of the mold assembly was made. The total calculated pressure drop agreed closely with the measured pressure drop. The viscous generation of heat was found to be proportional to pressure drop, and an equation is presented which relates the temperature increase to the pressure drop.

Predictions of fiber concentration in injection molding simulation of fiber-reinforced composites

2017 ◽  
Vol 31 (11) ◽  
pp. 1529-1544 ◽  
Author(s):  
Huan-Chang Tseng ◽  
Rong-Yeu Chang ◽  
Chia-Hsiang Hsu
Keyword(s):  
Injection Molding ◽  
Fiber Orientation ◽  
Short Fiber ◽  
Core Structure ◽  
Particle Migration ◽  
Migration Behavior ◽  
Fiber Concentration ◽  
Numerical Predictions ◽  
Injection Molding Simulation ◽  
Injection Molded

The microstructures of injection-molded short fiber composites, involving fiber orientation and fiber concentration, strikingly influence flow behaviors and mechanical properties. Through the use of certain commercial software, reported numerical predictions of fiber orientation for the shell–core structure have been obtained to date. However, no work has been done on fiber concentration prediction available in processing simulations. In the theoretical field of suspension rheology, the suspension balance (SB) model has proven successful in capturing particle migration behavior under the simple Couette shear flow of “spherical” particle suspension, hence the attempt to verify the SB model applied in the “like-rod” suspensions. To predict flow-induced variations of fiber concentration, the SB model is implemented in 3-D-injection molding simulation with more general flows. It is remarkable for the shell–core structure is explored to reflect the relationship between fiber orientation and fiber concentration.

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