Query: polyamide material AND injection molding

title: Quasi Static Characterization of Polyamide Based Discontinuous CFRP Manufactured by Additive Manufacturing and Injection Molding
abstract: Generating serial components via additive manufacturing (AM) a deep understanding of process related characteristics is necessary. The extrusion based AM called fused layer manufacturing (FLM) also known as fused deposition modeling (FDM(tm) or fused filament fabrication (FFF) is an AM process for producing serial components. Improving mechanical properties of AM parts is done by adding fibers in the raw material to reinforce the polymer. The study aims to create a more detailed comprehension of FLM and process related characteristics with their influence on the composite.Thereby, a short carbon fiber reinforced polyamide (CarbonX(tm) Nylon, 3DXTECH, USA) with 12.5 wt. fiber content, 7 mm fiber diameter, and 150 to 400 um fiber length distribution was investigated. To separate process related characteristics of FLM, reference specimens were fabricated via injection molding (IM) with single batch material. For the mechanical characterization, quasi static tensile tests were carried out in accordance to DIN 527 2. Quality assessment including void content and void distribution was performed via micro computed tomography (CT).The mechanical characterization clarifies effects on mechanical properties depending on process related characteristics of FLM. CT scans show higher void contents of FLM specimens compared to IM specimens and void orientation dependent on printing direction. FLM shows process related characteristics which generally strengthen mechanical properties of polymers. Nevertheless, tensile strength of FLM specimens decrease by more than 28% compared to quasi homogenous IM specimens.

title: Reinforced polyamide molding material using flat glass fibers and injection molded parts made with polyamide molding material

title: Comparison of mechanical properties for polyamide 12 composite based biomaterials fabricated by fused filament fabrication and injection molding
abstract: The emergence of 3D printing technology known as fused filament fabrication (FFF) has offered the possibility of producing an anatomically accurate, patient specific implant with more affordable prices. The only weakness of this technology is related to incompatibility and lack of properties of current material to be applied in biomedical. Therefore, this study aims to develop a new, polymer composite based biomaterial that exhibits a high processability using FFF technique, strong enough and shows acceptable biocompatibility, and safe for biomedical use. Polyamide 12 (PA12) which meets all these requirements was incorporated with two bioceramic fillers, zirconia and hydroxyapatite in order to improve the mechanical and bioactivity properties. The obtained mechanical properties were compared with injection molded specimens and also a commercial biomedical product, HAPEXTM which is composed of hydroxyapatite and polyethylene. The yield strength and modulus of the PA12 composites increased steadily with in.

title: On the difference in material structure and fatigue properties of nylon specimens produced by injection molding and selective laser sintering
abstract: This paper describes the influence of dynamic tension/compression loading on notched and unnotched nylon specimens fabricated by Injection Molding (IM) and Selective Laser Sintering (SLS) The main objective of this work is to analyze and describe the differences in material structure and fatigue properties of as built nylon parts produced by IM and SLM from the same polyamide 12 powder. The differences in dimensional quality, density, surface roughness, crystal structure and crystallinity are systematically measured and linked to the mechanical fatigue properties. The fatigue properties of the unnotched SLS specimens are found to be equal to those of the unnotched IM specimens. The presence of pores in the sintered samples does not lead to rapid failure, and the microvoid coalescence failure mechanism is delayed. The notched specimens show more brittle failure and increased fatigue resistance which is caused by local notch strengthening. The results enable improved understanding of the difference in material structure and fatigue behavior of selective laser sintered and injection molded polyamide.

title: MECHANICAL AND MORPHOLOGICAL PROPERTIES OF POLYAMIDE 12 COMPOSITE FOR POTENTIAL BIOMEDICAL IMPLANT: INJECTION MOLDING AND DESKTOP 3D PRINTER
abstract: Fused filament fabrication is a filament based rapid prototyping process, which offers the possibility of new polymer material for invention of biomedical implant. This study represents an investigation on a preparation and characterization of new polyamide 12 reinforced with 20 wt% of zirconium dioxide and hydroxyapatite by desktop 3D printer in comparison with conventional manufacturing method, injection molding. Polyamide 12 composite was compounded, pelletized and filament extruded prior to apply to a 3D printer. Sample prototypes from the new polyamide composite have been successfully made and tested. Mechanical (flexural and impact) and morphological properties were evaluated and compared. From the results, the printed polyamide composite exhibited lower mechanical properties than injection molded due to the formation of porosity, laminate weakness and low pressure during printing. Although the mechanical properties of printed parts were lower than molded parts, but the capability of 3D printer to fabricate any customized 3D object could lead to the bright future and great contribution in this area, while at the same time many improvements can be made for the future works.

title: Experimental and simulation study on the warpage of polyamide 6 based on thermo mechanical behavior of material using uniaxial tensile test
abstract: This research focuses on investigating the time dependent behavior of polyamide 6 and using the generalized Maxwell model for prediction of this behavior. To achieve this goal, tensile specimens are manufactured via injection molding process and then are tested based on stress relaxation trials. Moreover, two specimens manufactured with different mold temperatures are tested to investigate the effect of the mold temperature on the time dependent behavior of this kind of polymer. Finally, to evaluate the ability of generalized Maxwell model to predict the time dependent behavior of polyamide 6 correctly, a finite element simulation is carried out via link between Moldflow and Abaqus software. In these simulations, the amount of warpage occurring in the specimen obtained from this model is compared with experimental finding. The results show that the mold temperature has a negligible effect on the time dependent behavior of this polymer and also, there is a good agreement between simulation and experimental results of warpage with mean error of 13% Therefore, the generalized Maxwell model is good enough to predict the time dependent behavior of polyamide 6. On the other hand, this methodology can be used prior to making real parts to prevent the high cost of manufacturing.

title: Laser structured surfaces for metal plastic hybrid joined by injection molding
abstract: The aim of this work is to investigate the influence of surface structures on the adhesion strength of metal plastic hybrids. Aluminum substrates were structured with continuous wave and picosecond pulsed laser systems and overmolded with a thermoplastic polyamide material. The materials were examined in terms of structure topography, molding accuracy, and a tensile shear test. It was found that the surface pretreatment by laser structuring with continuous wave laser enhances the effective joining surface, creates a mechanical interlocking, and increases the adhesion strength of the hybrid compared to the untreated condition significantly. A shear strength of 11.9 MPa was achieved, which exploits 90% of the pure polyamide properties.The aim of this work is to investigate the influence of surface structures on the adhesion strength of metal plastic hybrids. Aluminum substrates were structured with continuous wave and picosecond pulsed laser systems and overmolded with a thermoplastic polyamide material. The materials were examined in terms of structure topography, molding accuracy, and a tensile shear test. It was found that the surface pretreatment by laser structuring with continuous wave laser enhances the effective joining surface, creates a mechanical interlocking, and increases the adhesion strength of the hybrid compared to the untreated condition significantly. A shear strength of 11.9 MPa was achieved, which exploits 90% of the pure polyamide properties.

title: Thermogravimetric Characterization of the Microstructui Composition of Polyamide Injection Molded Denture Base Material vs Conventional Compression Molded Heat cured Denture Base Material.
abstract: Thermoplastic resin polymers are widely used in medicine due to their biostability and hypoallergenic properties, making them a possible alternative to poly methylmethacrylate (PMMA) The current research examined the microstructure of a rapid injection molding system thermoplastic resin for construction of flexible denture compared with that of heat cured PMMA.  A total of 40 disk shaped specimens (25 mm in diameter and 3 mm in thickness) were prepared and divided into two groups of 20 disks each (group I samples were of thermoplastic acrylic resin while group II was heat cured PMMA resin)  In group I, thermogravimetric analyzer showed that increasing the temperature up to 169degC resulted in about 1.3% of the material loss, and after that the material remains thermally stable up to 200degC. Group 11 showed 2.24% weight loss at 171degC, and further weight loss (12.025% was observed on heating to 230degC. Fourier transform infrared (FTIR) spectrophotometer analysis in the range of 400 4000 cm( 1) detected the presence of an amine group (N H) in group I samples and the presence of methylene group attached to inorganic Si as reinforcement filler (Si CH3) CONCLUSION Thermoplastic resin displayed excellent thermal stability and the absence of residual monomer within the polymerized material, suggesting its suitability for the fabrication dentures.

title: Influence of the mold temperature on the material properties and the vibration welding process of crosslinked polyamide 66
abstract: Radiation cross linking of polyamide 66 with electron beams alters the material characteristics. This leads to a varied relationship between the process, the structure, and properties for vibration welding cross linked polyamide 66. A three dimensional network of covalent bonds in the amorphous areas results in an impeded melt flow and altered welding characteristics. A possible way to influence this three dimensional network is to change the mold temperature during the injection molding process. At higher mold temperatures, the degree of crystallinity increases and leads to a decrease in the resulting covalent bonds in the amorphous area. The altered degree of covalent bonds influences the vibration welding process. Higher temperatures during the process can be achieved. The scope of this article is to show how the mold temperature influences the material characteristics and, by extension, the resulting processing and welding characteristics of radiation cross linked polyamide 66. Optical, thermal, mechanical and chemical investigations serve to highlight the influence of the mold temperature on the material and the welding process of radiation cross linked polyamide 66.

title: Selecting Optimal Molding and Material Conditions of Reinforced Polymeric Nanocomposites with MWCNT Using a Multi Criteria Decision Making Model
abstract: In order to solve conflicting decision problems, multi criteria decision making (MCDM) methods are used to make the best choice among many criteria. In this research, sixteen different samples of melt compounded polyamide 6 (PA6) and multi walled carbon nanotubes (MWCNTs) were studied. The raw materials were compounded using a twin screw extruder and the samples were chosen based on an L16 orthogonal array of Taguchi approach. The alternatives of the problem were samples produced under different injection parameters including holding pressure, injection temperature, and with various weight percentages of MWCNTs. The chosen criteria were tensile strength, elastic modulus, Charpy impact strength, Rockwell hardness, and cost. Analytical hierarchy process (AHP) was used to weight the criteria and due to the results, tensile properties were the most important criteria with the weight of 0.319. In the next step, a technique for order preference by similarity to an ideal solution (TOPSIS) and the multi objective optimization on the basis of ratio analysis (MOORA) were implemented to rank the alternatives. Based on the considered criteria the samples containing 1 wt% of MWCNTs was selected as the best alternatives.