A method to improve dimensional accuracy and mechanical properties of injection molded polypropylene parts
-
Shuai Li
and
Jiachang Wang
Abstract
Gas counter pressure (GCP) technology can impose a reverse pressure to melt and thereby effectively increase the pressure acting on the melt at flow front. Theoretically, it has a potential to solve some defects often occurring in conventional injection molding (CIM) process. This paper designed and manufactured a GCP injection mold. GCP injection molding experiments were conducted. Effects of GCP process on melt flow and density, dimensional accuracy, and mechanical properties of molded samples were investigated. The results showed that GCP process can effectively inhibit the “fountain effect” in melt filling process, decrease the dimensional shrinkage of molded samples, increase dimensional accuracy of samples, and effectively improve impact property of samples. For the samples without weld line, tensile strength and flexural strength of GCP injection molded samples are slightly increased in comparison with those of CIM samples, but for the samples with weld line, GCP process can greatly improve the tensile strength and flexural strength of molded samples. When GCP is 9 MPa and GCP holding time is 10 s, the dimensional accuracy of molded samples without weld line, the tensile strength and flexural strength of the molded samples with weld line all increase up to maximum values. In comparison with CIM samples, the dimensional shrinkage of samples without weld line decreases by 17.2%, the tensile strength and flexural strength of samples with weld line increase by 30.51% and 23.69%, respectively. The impact value of the samples molded by process parameter combination of GCP 9 MPa and GCP holding time 20 s is the highest, and the impact value increases by 18.65%.
Acknowledgments
This research work is supported by the Research Award Fund for Shandong Province Excellent Innovation Team (No. 2012-136).
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Articles in the same Issue
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- Original articles
- A method to improve dimensional accuracy and mechanical properties of injection molded polypropylene parts
- Effect of banana fibers and plasticizer on melt processing of poly(vinyl alcohol)
- Improved thermal and mechanical properties of carbon fiber filled polyamide 46 composites
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- Influence of micron size aluminum particles on the aging properties and wear resistance of epoxy resin coatings
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- Investigating the in-plane mechanical behavior of single-ply quasi-unidirectional glass fiber/polypropylene composites
- Characterization of layer built-up and inter-layer boundaries in rotational molding of multi-material parts in dependency of the filling strategy
- Experimental and numerical determination of compressive mechanical properties of multi-walled carbon nanotube reinforced polymer
Articles in the same Issue
- Frontmatter
- Original articles
- A method to improve dimensional accuracy and mechanical properties of injection molded polypropylene parts
- Effect of banana fibers and plasticizer on melt processing of poly(vinyl alcohol)
- Improved thermal and mechanical properties of carbon fiber filled polyamide 46 composites
- Preparation and characterization of carbon fiber/polylactic acid/thermoplastic polyurethane (CF/PLA/TPU) composites prepared by a vane mixer
- Influence of micron size aluminum particles on the aging properties and wear resistance of epoxy resin coatings
- The effect of casting solution composition on surface structure and performance of poly(vinylidene fluoride)/multi-walled carbon nanotubes (PVDF/MWCNTs) hybrid membranes prepared via vapor induced phase separation
- Mechanical and thermal properties of PLA/halloysite bio-nanocomposite films: effect of halloysite nanoclay concentration and addition of glycerol
- Preparation and characterization of core-shell oil absorption materials stabilized by modified fumed silica
- Investigating the in-plane mechanical behavior of single-ply quasi-unidirectional glass fiber/polypropylene composites
- Characterization of layer built-up and inter-layer boundaries in rotational molding of multi-material parts in dependency of the filling strategy
- Experimental and numerical determination of compressive mechanical properties of multi-walled carbon nanotube reinforced polymer
