Effect of mold opening on the properties of PLA samples obtained by foam injection molding

Volpe, Valentina; Filitto, Martina De; Klofacova, Vera; Santis, Felice De; Pantani, Roberto

doi:10.1002/pen.24730

Cited by 36 publications

(26 citation statements)

References 35 publications

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“…Volpe et al [70] concluded that longer flow paths and faster cycle times can be obtained compared to usual injection molding due to the plasticization effect induced by the added supercritical blowing agent (i.e., the glass transition and melting temperature are decreased and the melt viscosity is reduced). Guanghong et al [135] reviewed microcellular foams having uniform cell diameters of 1 to 100 µm, and Xu et al [133] reviewed cell densities of 10 5 to 10 9 cells per cubic centimeter for foams produced by this technique.…”

Section: Foam Injection Moldingmentioning

confidence: 99%

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Foaming of PLA Composites by Supercritical Fluid-Assisted Processes: A Review

et al. 2020

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Polylactic acid (PLA) is a well-known and commercially available biopolymer that can be produced from different sources. Its different characteristics generated a great deal of interest in various industrial fields. Besides, its use as a polymer matrix for foam production has increased in recent years. With the rise of technologies that seek to reduce the negative environmental impact of processes, chemical foaming agents are being substituted by physical agents, primarily supercritical fluids (SCFs). Currently, the mass production of low-density PLA foams with a uniform cell morphology using SCFs as blowing agents is a challenge. This is mainly due to the low melt strength of PLA and its slow crystallization kinetics. Among the different options to improve the PLA characteristics, compounding it with different types of fillers has great potential. This strategy does not only have foaming advantages, but can also improve the performances of the final composites, regardless of the implemented foaming process, i.e., batch, injection molding, and extrusion. In addition, the operating conditions and the characteristics of the fillers, such as their size, shape factor, and surface chemistry, play an important role in the final foam morphology. This article proposes a critical review on the different SCF-assisted processes and effects of operating conditions and fillers on foaming of PLA composites.

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Section: Foam Injection Moldingmentioning

confidence: 99%

“…Different works have reported the use of SFCs as foaming agents for PLA. Nitrogen was used for injection molding [ 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 ] and batch foaming [ 72 ]. However, Li et al [ 73 ] showed that the solubility of CO 2 in PLA is approximately ten times that of N 2 .…”

Section: Introductionmentioning

confidence: 99%

Foaming of PLA Composites by Supercritical Fluid-Assisted Processes: A Review

et al. 2020

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“…Core-back foaming was realized to be an effective way to improve the cellular density of samples produced via FIM. [21][22][23][24][25][26][27] In the typical method of combining FIM with core-back technology, a movable mold is retracted for a short distance immediately or slightly after the gas-laden polymer melt is either fully or partially injected into the mold cavity, leading to the mold cavity being partially opened. There are generally two benefits to this operation: the core-back allows the foamed components more space and the pressure drop rate of the mold cavity increases, resulting in possible improvements in the foaming ratio and cellular density.…”

Section: Introductionmentioning

confidence: 99%

Combining foam injection molding with batch foaming to improve cell density and control cellular orientation via multiple gas dissolution and desorption processes

Zhou

Chen

2020

Polymers for Advanced Techs

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In contrast to solid parts fabricated through conventional injection molding (CIM), foamed parts manufactured via foam injection molding (FIM) exhibit substantial variations in mechanical properties, which are attributed to differences in the cellular structure. In this study, parts with different cellular structures are fabricated via FIM, during which the gas dissolution and desorption processes are controlled by subjecting the gas‐laden melt to reciprocating compression and expansion operations. The results suggest that the cell density can be drastically improved by rapidly decreasing the pressure caused by the mold opening and that the cell orientation obviously occurs in the direction perpendicular to the mold‐opening direction. Moreover, the cell density and cellular orientation can be adjusted by utilizing appropriate mold opening and closing operations, leading to improvements in the resultant ultimate mechanical properties. In particular, the foamed samples fabricated with controlled mold opening‐closing operations exhibit excellent tensile strength and strain‐at‐break, indicating that samples containing a high density of cells oriented along the tensile test direction facilitate the formation of superductility and an increase in tensile strength. Hence, a method that combines FIM with batch foaming has been proposed for improving the cellular structure and controlling the cellular orientation.

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“…To save raw materials and provide sound absorption and shock resistance, polymer foaming has gradually become a common processing technology with a wide application range from industrial and agricultural production to the national defense industry [16][17][18][19][20]. PP is no exception and therefore has been the focus of research in recent years [21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Improvement of the dispersity of micro‐nano particles for PP/PVC composites using gas‐assisted dispersion in a controlled foaming process

Zhou

Zhao

Dong

et al. 2019

Polymer Engineering & Sci

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Polyvinyl chloride (PVC) and nanosilicon dioxide (nano‐SiO2) were blended with neat polypropylene (PP) to improve its flame retardancy and cellular foam structure, and the dispersal effects of PVC and nano‐SiO2 and the foaming effect of the PP/PVC composites were investigated. PP/PVC samples with different compositions and foaming degrees were first fabricated by conventional injection molding with and without a blowing agent. Tensile testing, differential scanning calorimetry, scanning electron microscopy, limiting oxygen index testing, and vertical burn testing were used to study the mechanical properties, thermal features, microstructures, and flame‐retardant properties of the molded samples, and the samples with different degrees of foaming were compared. The results suggest that the foaming process facilitates the dispersion of PVC and nano‐SiO2, while the presence of PVC and nano‐SiO2 improves the foamability of PP. A method for a gas‐assisted dispersion technology to control the foaming process was hence proposed. Considering that the mechanical properties of PP/PVC could be retained with satisfactory flame retardancy and weight loss, convenient processing, and low‐cost materials; the technology presented can be directly applied for lightweight engineering and the manufacture of fire‐resistant material and can act as a reference for other micro‐nano processing involving the dispersion of particles. POLYM. ENG. SCI., 60:524–534, 2020. © 2019 Society of Plastics Engineers

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Effect of mold opening on the properties of PLA samples obtained by foam injection molding

Cited by 36 publications

References 35 publications

Foaming of PLA Composites by Supercritical Fluid-Assisted Processes: A Review

Foaming of PLA Composites by Supercritical Fluid-Assisted Processes: A Review

Combining foam injection molding with batch foaming to improve cell density and control cellular orientation via multiple gas dissolution and desorption processes

Improvement of the dispersity of micro‐nano particles for PP/PVC composites using gas‐assisted dispersion in a controlled foaming process

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