Influence of preheating on the fracture behavior of over-molded short/continuous fiber reinforced polypropylene composites

Anandakumar, Paramasivam; Timmaraju, Mallina Venkata; Ramachandran, V.

doi:10.1177/00219983211038615

Cited by 4 publications

(4 citation statements)

References 28 publications

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“…The inserts were positioned in the die. The fabricated inserts were positioned on both cavities in the die and preheating was performed on inside surfaces of the inserts at 140°C using a heat gun 23 . Three sets of over‐molded specimens were prepared by injecting SGFPP between the two laminated composite inserts with a stacking sequence of [(0/90) (45/−45)/SGFPP core/ (45/−45) (0/90)] into the die at three different melt temperatures i.e., 190°C, 210°C, and 230°C.…”

Section: Methodsmentioning

confidence: 99%

“…The fabricated inserts were positioned on both cavities in the die and preheating was performed on inside surfaces of the inserts at 140 C using a heat gun. 23 Three sets of overmolded specimens were prepared by injecting SGFPP between the two laminated composite inserts with a stacking sequence of [(0/90) (45/À45)/SGFPP core/ (45/À45) (0/90)] into the die at three different melt temperatures i.e., 190 C, 210 C, and 230 C. Their respective interface temperatures are 165 C, 175 C, and 185 C approximately as the average of the injection over-molding melt temperature (T o ) and preheating temperature of the insert (T p ) turn out to be interface temperature (T i ), that is,…”

Section: Preparation Of Composite Inserts and Over-molded Couponsmentioning

confidence: 99%

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Effect of interface temperature on low‐velocity impact response of injection over‐molded short/continuous fiber reinforced polypropylene composites

Paramasivam,

Mallina,

Ramachandran

et al. 2023

Polymer Composites

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Injection over‐molded short/continuous fiber reinforced composites are a unique class of materials for fabricating lightweight components having complex geometries in automotive manufacturing due to their higher specific mechanical properties, lower assembly cost, and short production cycle time. The influence of interface temperature on the low‐velocity impact response of short/continuous fiber‐reinforced polypropylene was experimentally investigated by varying the melt temperature. The over‐molded specimens fabricated at an interface temperature considerably higher than the melting point of polypropylene exhibited a 12% enhanced peak load with less impact damage compared with specimens over‐molded at a lower interface temperature. Optical analysis of impacted specimens over‐molded at lower interface temperature revealed interface debonding and insert delamination. Whereas insert delamination alone was observed for the specimens fabricated at higher interface temperature. The specimens over‐molded at high interface temperature exhibited less impact energy absorption and high compression strength after impact because of their strong interfacial adhesion.Highlights Impact energy absorption is less if melt temperature is high in injection over‐molding. Higher melt temperature enhances interface bonding by raising interface temperature. Interface debonding and insert delamination are the dominant impact failure modes. The compression strength after impact has increased with higher melt temperature. Impact and compression strength after impact is governed by the interfacial strength.

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Section: Methodsmentioning

confidence: 99%

Section: Preparation Of Composite Inserts and Over-molded Couponsmentioning

confidence: 99%

Effect of interface temperature on low‐velocity impact response of injection over‐molded short/continuous fiber reinforced polypropylene composites

Paramasivam,

Mallina,

Ramachandran

et al. 2023

Polymer Composites

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“…Press and injection hybrid molded structural parts are now commercially available and displayed as prototypes at many exhibitions. On the other hand, academic papers are usually focused on the interfacial bond properties between the surface material and the injection material [16][17][18], which represent an issue in actual structural parts. Quantitatively evaluated mechanical properties (stiffness, strain distribution, etc.)…”

Section: Introductionmentioning

confidence: 99%

Effects of the Injection Material and Resin Layer on the Mechanical Properties of Carbon Fiber-Reinforced Thermoplastic (CFRTP) Press and Injection Hybrid Molded Parts

Tanaka,

Taniguchi

2024

J. Compos. Sci.

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In the press and injection hybrid molded parts of fiber-reinforced thermoplastics (FRTPs), failure at the interface between the surface material (the outer shell) and the ribs (the injection part) or that at the injection part has become an issue. Adding a resin layer to the rib roots at the same time that the ribs are molded through injection has been proposed, which may increase the mechanical properties and reduce the material cost. To prevent failure at the injection part, the use of fiber-reinforced resin as an injection material has been suggested. This approach contributes to a higher bond strength by lowering the molding shrinkage rate. In this study, the hat-shaped parts of carbon fiber-reinforced thermoplastics (CFRTPs) with fiber-reinforced and neat resin layers at the rib root were fabricated through press and injection hybrid molding, and their mechanical properties were evaluated through three-point bending tests. The effects of the resin layer at the rib root and the existence or nonexistence of fiber reinforcement on the mechanical properties, as well as the relationship between the material cost and the mechanical properties, were clarified through an experiment and FEM analysis. The bond strength was also evaluated through tensile tests that were undertaken at the rib root. Molded parts with neat PA6 and glass fiber-reinforced PA6 resin layers at the rib roots showed higher bond strength than those without resin layers. In a three-point bending test of a CFRTP hat-shaped part with a resin layer at the rib roots, the use of a 1 mm thick CFRTP laminate for the outer shell and glass fiber-reinforced PA6 resin as the injection material showed the same stiffness as a part that used a 2 mm thick CFRTP laminate for the outer shell. FEM analysis showed that the resin layer prevented the concentration of strain at the rib roots, and the model that used a 1 mm thick CFRTP laminate for the outer shell and glass fiber-reinforced PA6 resin as the injection material showed the best specific stiffness in this study. By adding a resin layer to the rib roots, the fabrication of molded parts with excellent specific stiffness was enabled at a small increase in cost.

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“…The fabrics can be directly inserted into the mold to save the prepregs preparation step [ 10 ], but the direct fabric insert injection molding generally cannot achieve quality standards required for consumer enclosures. In addition, the poor interfacial bonding between polymer and continuous fibers reduces the performance of the insert-molded composites [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

Fabric Insert Injection Molding for the Preparation of Ultra-High Molecular Weight Polyethylene/High-Density Polyethylene Two-Component Self-Reinforced Composites

et al. 2022

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The fabric insert injection molding approach can be applied to produce easily recyclable self-reinforced polymer composites (SrCs) whose reinforcement and matrix are from the same polymer. However, the mechanical properties of the SrCs are usually limited due to the poor impregnation of the inserted fabric. In this work, the ultra-high molecular weight polyethylene (UHMWPE) fabrics were used as the insert, and the high-density polyethylene (HDPE) melt was injected to fill the mold cavity and impregnate the fabrics. The UHMWPE/HDPE two-component SrCs were prepared. The large difference of melting temperatures between UHMWPE and HDPE can establish a wide processing temperature window, and thus the impregnation of the fabric can be improved by increasing temperature. The tensile strength and modulus of the UHMWPE/HDPE SrCs were up to 148 and 1132 MPa, respectively. The peel strength could be up to 35.2 N/cm. The influences of four main injection molding parameters, including the injection temperature, injection pressure/packing pressure, injection velocity, and packing time, were investigated. The temperature, pressure, viscosity, and density of the matrix in the mold cavity were calculated by the numerical simulation to indicate the impregnation process during the fabric insert injection molding process.

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Influence of preheating on the fracture behavior of over-molded short/continuous fiber reinforced polypropylene composites

Cited by 4 publications

References 28 publications

Effect of interface temperature on low‐velocity impact response of injection over‐molded short/continuous fiber reinforced polypropylene composites

Effect of interface temperature on low‐velocity impact response of injection over‐molded short/continuous fiber reinforced polypropylene composites

Effects of the Injection Material and Resin Layer on the Mechanical Properties of Carbon Fiber-Reinforced Thermoplastic (CFRTP) Press and Injection Hybrid Molded Parts

Fabric Insert Injection Molding for the Preparation of Ultra-High Molecular Weight Polyethylene/High-Density Polyethylene Two-Component Self-Reinforced Composites

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