Tailor-Made High Density PLA Foam Sheets - Strategies to Improve the Mechanical Properties

Geissler, Bernd; Feuchter, Michael; Laske, Stephan; Walluch, Matthias; Holzer, Clemens; Langecker, Guenter Ruediger

doi:10.1177/026248931403300502

Cited by 5 publications

(6 citation statements)

References 11 publications

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“…Consequently, only a few reports were done, mainly with azodicarbonamide (ADC) [ 43 , 59 , 60 , 84 , 99 , 110 ]. Also, nitrogen is rarely applied as a blowing agent for PLA and rather less expansion was achieved [ 61 ]. Another work reports the use of a combination of CO 2 and nitrogen resulting in foamed sheets with densities down to 350 kg/m 3 [ 54 ].…”

Section: Processesmentioning

confidence: 99%

Chemical Modification and Foam Processing of Polylactide (PLA)

et al. 2019

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Polylactide (PLA) is known as one of the most promising biopolymers as it is derived from renewable feedstock and can be biodegraded. During the last two decades, it moved more and more into the focus of scientific research and industrial use. It is even considered as a suitable replacement for standard petroleum-based polymers, such as polystyrene (PS), which can be found in a wide range of applications—amongst others in foams for packaging and insulation applications—but cause strong environmental issues. PLA has comparable mechanical properties to PS. However, the lack of melt strength is often referred to as a drawback for most foaming processes. One way to overcome this issue is the incorporation of chemical modifiers which can induce chain extension, branching, or cross-linking. As such, a wide variety of substances were studied in the literature. This work should give an overview of the most commonly used chemical modifiers and their effects on rheological, thermal, and foaming behavior. Therefore, this review article summarizes the research conducted on neat and chemically modified PLA foamed with the conventional foaming methods (i.e., batch foaming, foam extrusion, foam injection molding, and bead foaming).

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Section: Processesmentioning

confidence: 99%

Chemical Modification and Foam Processing of Polylactide (PLA)

et al. 2019

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“…To demonstrate this, they compared the tensile strength and bulk densities of composite foams made from amorphous PLA mixed with plain cellulose fibers and acetylated cellulose fillers at varying concentrations. The foams were made using CO 2 gas as blowing agent for 6 h at a temperature and pressure range of 60 °C and (12)(13)(14)(15)(16)(17)(18)(19)(20) MPa respectively in the batch process. Results showed that while the foams made with acetylated cellulose gave higher bulk density with improved interfacial properties and tensile strength for up to 9 wt.% filler loading, the foams made with plain unfunctionalized cellulose fibers had a morphology with smaller average cell sizes and exhibited higher flexibility and toughness.…”

Section: List Of Symbolsmentioning

confidence: 99%

“…Using the extrusion foaming process with CO 2 and N 2 gas as a blowing agent, the mechanical properties of plain PLA foams were compared with those reinforced with joncryl chain extender. From the results, it was observed that the foams with chain extender inclusion showed increased elongation and overall improved tensile mechanical properties compared to foams without the chain extender 14 . Although PLA is a bio-based polymer with good processability it is slightly weak in toughness and thermal stability.…”

Section: Introductionmentioning

confidence: 99%

“…Major applications of biobased foams are in biomedical and food packaging applications 6 – 8 , 11 , 12 . The processing parameters used in the production of porous composites from polymer via the supercritical CO 2 (sc-CO 2 ) foaming process have been reported to play significant roles in defining their morphology and mechanical properties 13 , 14 . Using the extrusion foaming process with CO 2 and N 2 gas as a blowing agent, the mechanical properties of plain PLA foams were compared with those reinforced with joncryl chain extender.…”

Section: Introductionmentioning

confidence: 99%

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Compostable, fully biobased foams using PLA and micro cellulose for zero energy buildings

Oluwabunmi

D’Souza

et al. 2020

Sci Rep

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Ecological, health and environmental concerns are driving the need for bio-resourced foams for the building industry. In this paper, we examine foams made from polylactic acid (PLA) and micro cellulose fibrils (MCF). To ensure no volatile organic compounds in the foam, supercritical CO2 (sc-CO2) physical foaming of melt mixed systems was conducted. Mechanical and thermal conductivity properties were determined and applied to a net zero energy model house. The results showed that MCF had a concentration dependent impact on the foams. First structurally, the presence of MCF led to an initial increase followed by a decrease of open porosity, higher bulk density, lower expansion ratios and cell size. Differential Scanning Calorimetry and Scanning Electron Microscopy revealed that MCF decreased the glass transition of PLA allowing for a decrease in cell wall thickness when MCF was added. The mechanical performance initially increased with MCF and then decreased. This trend was mimicked by thermal insulation which initially improved. Biodegradation tests showed that the presence of cellulose in PLA improved the compostability of the foams. A maximum comparative mineralization of 95% was obtained for the PLA foam with 3 wt.% MCF when expressed as a fractional percentage of the pure cellulose reference. Energy simulations run on a model house showed that relative to an insulation of polyurethane, the bio-resourced foams led to no more than a 12% increase in heating and cooling. The energy efficiency of the foams was best at low MCF fractions.

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“…Continuous manufacturing of low-density foamed thermoplastic sheets has unremittingly remained to be a big challenge for many manufacturers despite the initial breakthroughs that have been accomplished in the last two decades [1][2][3][4][5][6][7]. Numerous researchers and diverse inter-disciplinary industries have been very active in the field of extrusion foaming in the last few years, primarily because it allows them to manufacture thermoplastic foams continuously [8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Die opening-induced microstructure growth in extrusion foaming of thermoplastic sheets

Gandhi

Bhatnagar

2015

Journal of Polymer Engineering

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Abstract In this study, the influence of die opening gap on foam attributes during a microcellular extrusion foaming process was investigated. Lower die openings developed higher pressure drops on the foams, as a result of which greater thermodynamic instability was stimulated and, consequently, higher cell density foams along with enhanced expansion ratios were achieved. Further investigations were performed to study the synergistic influence of altering die opening with critical process parameters, namely, screw rotational speed and die temperature, on the foam expansion ratio and morphological transformations. Higher screw rotational speed induced shear nucleation phenomenon, which further enhanced the foaming process significantly. Also, an optimum die temperature was observed, which developed maximum expansion ratio at the lowest die opening gap. This study intends to enhance the understanding of extrusion foam processing among academia as well as among industries.

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Tailor-Made High Density PLA Foam Sheets - Strategies to Improve the Mechanical Properties

Cited by 5 publications

References 11 publications

Chemical Modification and Foam Processing of Polylactide (PLA)

Chemical Modification and Foam Processing of Polylactide (PLA)

Compostable, fully biobased foams using PLA and micro cellulose for zero energy buildings

Die opening-induced microstructure growth in extrusion foaming of thermoplastic sheets

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