scholarly journals The Low Breaking Fiber Mechanism and Its Effect on the Behavior of the Melt Flow of Injection Molded Ultra-Long Glass Fiber Reinforced Polypropylene Composites

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2492
Author(s):  
Po-Wei Huang ◽  
Hsin-Shu Peng ◽  
Sheng-Jye Hwang ◽  
Chao-Tsai Huang
Keyword(s):  
Injection Molding ◽  
Glass Fiber ◽  
Fiber Length ◽  
Mold Cavity ◽  
Fiber Breakage ◽  
Melt Flow ◽  
Molding Machine ◽  
Glass Fiber Reinforced ◽  
Long Glass Fiber ◽  
Long Fibers

In this study, fiber breaking behavior, fiber orientation, length variation, and changes in melt flow ability of long glass fiber reinforced polypropylene (L-FRP) composites under different mold cavity geometry, melt fill path, and plasticization parameters were investigated. The matrix material used was polypropylene and the reinforcement fibers were 25 mm long. An ultra-long-fiber composite injection molding machine (with a three-stage plunger and injection mechanism design) was used with different mold cavity geometry and plasticization parameters. Different screw speeds were used to explore the changes in fiber length and to provide a reference for setting fiber length and parameter combinations. Flow-length specimen molds with different specimen thickness, melt fill path, and gate design were used to observe the effect of plasticizing properties on the flow ability of the L-FRP composite materials. The experimental results showed that the use of an injection molding machine with a mechanism that reduced the amount of fiber breakage was advantageous. It was also found that an increase in screw speed increased fiber breakage, and 25 mm long fibers were shortened by an average of 50% (to 10 mm). Long fibers were more resistant to melt filling than short fibers. In addition, the thickness of the specimen and the gate design were also found to affect the filling process. The rounded angle gate and thick wall product decreased the flow resistance and assisted the flow ability and fiber distribution of the L-FRP injection molding.

Influence of low-fracture-fiber mechanism on fiber/melt-flow behavior and tensile properties of ultra-long-glass-fiber-reinforced polypropylene composites injection molding

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Po-Wei Huang ◽  
Hsin-Shu Peng ◽  
Sheng-Jye Hwang ◽  
Chao-Tsai Huang
Keyword(s):  
Injection Molding ◽  
Glass Fiber ◽  
Fiber Length ◽  
Glass Fibers ◽  
Melt Flow ◽  
Molding Machine ◽  
Injection Molding Machine ◽  
Glass Fiber Reinforced ◽  
Flow Length ◽  
Long Glass Fiber

AbstractIn this study, an injection molding machine with a low-fracture-fiber mechanism was designed with three stages: a plasticizing stage, an injection stage, and a packing stage. The fiber-fracture behavior is observed under the screw (plasticizing stage) of low-compression/shear ratio for the ultra-long fiber during the molding process. The molding material employed in this study was 25-mm-ultra-long-glass-fiber-reinforced polypropylene (PP/U-LGF). In addition, a thickness of 3 mm and a width of 12 mm spiral-flow-mold were constructed for studying the melt flow length and flow-length ratio through an experiment. The experimental results showed that the use of an injection molding machine with a three-stage mechanism decreased the fiber length when the screw speed was increased. On average, each fiber was shortened by 50% (>15 mm on average) from its original length of 25 mm. Longer glass fibers were more resistant to melt filling, and as the fiber length was reduced, the mixing between the melt and glass fibers was improved. Thus, the melt fluidity and fiber ratios were increased. In addition, the mixing/flow direction of the melt had an impact on the dispersion and arrangement of glass fibers, thus the tensile strength of PP/U-LGF increased.

INJECTION MOLDING OF FLAT GLASS FIBER REINFORCED THERMOPLASTICS

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2555-2560 ◽  
Author(s):  
KAZUTO TANAKA ◽  
TSUTAO KATAYAMA ◽  
TATSUYA TANAKA ◽  
AKIHIRO ANGURI
Keyword(s):  
Mechanical Properties ◽  
Injection Molding ◽  
Glass Fiber ◽  
Cross Section ◽  
Fiber Length ◽  
Flat Glass ◽  
Circular Cross Section ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced ◽  
Fiber Attrition

During an injection molding of composite materials, fiber attrition occurs and the average fiber length is reduced. In order to control the breakage of fibers and degradation of mechanical properties during processing, Flat glass Fiber (FF), that has oval cross-section shape, has been developed to use for glass fiber reinforced thermoplastic (GFRTP). Using FF as reinforcement of GFRTP has advantages as following: (1) Fluidity of FF is better than conventional Normal glass Fiber (NF) with 'circular' cross-section; (2) Fiber breakage during the injection molding process using FF is smaller than that using NF. In this study, the mechanical properties of FF and NF were compared for reinforcement of long fiber thermoplastics pellets (LFT pellets). We have also investigated the effect of screw design on fiber damage and the mechanical properties. The mechanical properties of specimens molded by FF reinforcement LFT (FF-LFT) pellets were superior to these of NF reinforcement LFT (NF-LFT) pellets. The former could give composites with higher fluidity and longer residual fiber length. Moreover, FF was able to strengthen injection-molded samples with higher fiber content than NF. Low shear type screw was effective to prevent the fiber attrition during plasticization process, hence leads to better mechanical properties of GFRTP

Fracture and Orientation of Long‐Glass‐Fiber‐Reinforced Polypropylene During Injection Molding

2019 ◽  
Vol 60 (1) ◽  
pp. 13-21 ◽  
Author(s):  
Xu‐Qin Hou ◽  
Xing‐Yuan Chen ◽  
Bao‐Chen Liu ◽  
Sheng‐Chao Chen ◽  
Hai‐Mei Li ◽  
...  
Keyword(s):  
Injection Molding ◽  
Glass Fiber ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced ◽  
Long Glass Fiber

scholarly journals The Effects of Strain Rates on Mechanical Properties and Failure Behavior of Long Glass Fiber Reinforced Thermoplastic Composites

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2019 ◽  
Author(s):  
Junjia Cui ◽  
Shaoluo Wang ◽  
Shuhao Wang ◽  
Guangyao Li ◽  
Peilin Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Glass Fiber ◽  
Ultimate Strength ◽  
Fracture Strain ◽  
Thermoplastic Composites ◽  
Strain Rates ◽  
Fiber Breakage ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced ◽  
Long Glass Fiber

Long glass fiber reinforced thermoplastic composites have been increasingly used in automotive parts due to their excellent mechanical properties and recyclability. However, the effects of strain rates on the mechanical properties and failure mechanisms of long glass fiber reinforced polypropylene composites (LGFRPPs) have not been studied systematically. In this study, the effects of strain rates (from 0.001 s−1 to 400 s−1) on the mechanical properties and failure mechanism of LGFRPPs were investigated. The results showed that ultimate strength and fracture strain of the LGFRPPs increased obviously, whereas the stiffness remained essentially unchanged with the strain rates from low to high. The micro-failure modes mainly consisted of fibers pulled out, fiber breakage, interfacial debonding, matrix cracking, and ductile to brittle (ductile pulling of fibrils/micro-fibrils) fracture behavior of the matrix. As the strain rates increased, the interfacial bonding properties of LGFRPPs increased, resulting in a gradual increase of fiber breakage at the fracture surface of the specimen and the gradual decrease of pull-out. In this process, more failure energy was absorbed, thus, the ultimate strength and fracture strain of LGFRPPs were improved.

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