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Issue 01/2021

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  • Products
  • Automotive
  • Packaging
  • Sustainable
  • Carbon
  • Plastics
  • Materials
  • Biobased
  • Foam
  • Bioplastics
Highlights: Automotive Foam Basics: Enzymes

Brand Owner A

Brand Owner A Brand-Owner’s perspective on bioplastics and how to unleash its full potential Yum China Holdings, Inc. the Shanghai based licensee of Yum! Brands in mainland China announced that it has launched a series of plastic reduction and environmentally friendly packaging initiatives across its brands in line with the latest regulations in China. As a result of these initiatives, Yum China expects a reduction of approximately 8,000 tonnes of non-degradable plastics annually starting from 2021. Brands include (among others) KFC, Pizza Hut, and Taco Bell. From January 2021, over 50 % of KFC restaurants in mainland China will replace non-degradable plastic bags used for delivery and takeaway with either paper bags or biodegradable plastic bags. By the end of 2025, all KFC restaurants will phase out non-degradable plastic bags and cutlery in mainland China. Pizza Hut is already a step further, as 70 % of all Pizza Hut restaurants in mainland China have already replaced existing plastic bags with paper bags or biodegradable plastic bags at the end of 2020. Building on these achievements, Pizza Hut will eliminate the use of non-degradable plastic bags by the end of 2022. Joey Wat, CEO of Yum China Photo Provided by Yum China, CC BY 4.0 “The new plastic reduction initiatives reinforce our sustainability strategy to drive meaningful change through packaging innovation and reduction,” said Joey Wat, CEO of Yum China. “In line with our longterm commitment to supporting economic, social and environmental development, we are committed to working with customers, partners, and all other stakeholders to promote a more sustainable future.” In addition to complying with regulatory requirements, these latest actions reflect Yum China’s company-wide packaging strategy that aims to reduce disposable packaging with new packaging solutions, new materials, as well as innovative technologies. The strategy includes ensuring that all customer-facing, plastic-based packaging is recyclable, refusing to purchase paper products from suppliers that knowingly cause deforestation, and working towards a 30 % reduction on non-degradable plastic packaging weight by 2025. AT http://ir.yumchina.com Magnetic for Plastics www.plasticker.com • International Trade in Raw Materials, Machinery & Products Free of Charge. • Daily News from the Industrial Sector and the Plastics Markets. • Current Market Prices for Plastics. • Buyer’s Guide for Plastics & Additives, Machinery & Equipment, Subcontractors and Services. • Job Market for Specialists and Executive Staff in the Plastics Industry. Up-to-date • Fast • Professional 44 bioplastics MAGAZINE [01/21] Vol. 16

Automotive www.engr.wisc.edu bioplastics MAGAZINE [01/11] Vol. 6 37 10 Years ago Foam tinyurl.com/pbatfoam2011 Published in bioplastics MAGAZINE In January 2021, Srikanth Pilla, now Clemson University, Greenville, South Carolina, USA said: “The study, conceived about 10 years ago, was timely back then when the need for biobased and biodegradable/compostable packaging materials including foams was in high demand. Today they almost became certain. With the emergence of circularity, plastics being biobased and/or biodegradable has become a necessity that their presence is more authenticated now. While a commercial potential is yet to be realized, my own lab has started to constitute more advancements in this field that is much closer to commercialization.” www.clemson.edu Volume Expansion Ratio Open Cell content (%) Article contributed by Srikanth Pilla, George K. Auer, Shaoqin Gong University of Wisconsin, USA Seong G. Kim, Chul B. Park, University of Toronto, CA Figure 2: Volume Expansion Ratio vs Temperature 1.8 1.6 1.4 1.2 1 60 50 40 30 20 10 0 PLA Ecovio PLA+55%PBAT Figure 3: Open Cell Content vs Temperature PLA Ecovio PLA+55%PBAT 125 130 135 140 145 150 155 36 bioplastics MAGAZINE [01/11] Vol. 6 PLA+0.5%Talc Ecovio+0.5%&Talc PLA+55%PBAT+0.5%Talc 130 140 150 Die Temperature (°C) PLA+0.5%Talc Ecovio+0.5%&Talc PLA+55%PBAT+0.5%Talc Die Temperature (°C) Biodegradable PLA/PBAT Foams I Foam investigated the foaming ability of PLA blended with starch using microcellular extrusion. Reignier et al. [32] have studied extrusion foaming of amorphous PLA using CO 2 ; however, due to very narrow processing window of the unmodified PLA, a reasonable expansion ratio could not be achieved. In this study, PLA/PBAT blends have been foamed by the microcellular extrusion process using CO 2 as a blowing agent. Two types of blend systems were investigated: (1) Ecovio ® , which is a commercially available compatibilized PLA/PBAT blend (BASF); (2) A non-compatibilized PLA/PBAT blend at the same PLA/PBAT ratio (i.e., 45:55 by weight percent) as Ecovio. The effects of talc,compatibilization and die temperature on the cell size, cell density, volume expansion and open cell content were evaluated. n this study, a unique processing technology viz. microcellular extrusion foaming, was used to produce biodegradable foams that could potentially replace existing synthetic foams thereby reducing carbon footprint and contributing towards a sustainable society. Introduction Effects on Cell Size and Cell Density Representative SEM images of the cell morphology of different formulations are shown in Figure 1. From the figure, it can be noted that the addition of talc has decreased the cell size. This shows that talc has acted as a nucleating agent thereby reducing the cell size. Thus, as more cells started to nucleate, due to excess nucleation sites provided by talc, there was less amount of gas available for their growth that lead to reduction in cell size. Also, the addition of talc significantly increased the melt viscosity, which made it difficult for the cells to grow, leading to smaller cell sizes [33]. Also, from Figure 1 it can be observed that the cell size of the compatibilized blends (both Ecovio and Ecovio-talc) is much less than that of the non-compatibilized ones (PLA/PBAT and PLA/PBATtalc). Thus it can be concluded that compatibilization has reduced the cell size. This might be due to increase in the melt strength of the blend as a result of the compatibilization [34]. In general, as shown in Figure 1, the addition of talc has increased the cell density because of the heterogeneous nucleation. In a heterogeneous nucleation scheme, the activation energy barrier to nucleation is sharply reduced in the presence of a filler (talc in this case) thus increasing the nucleation rate and thereby the number of cells [35]. While comparing the compatibilized and non-compatibilized samples, it can be observed that the cell density As a biodegradable and biobased polymer, polylactide (PLA) has attracted much interest among researchers world-wide in recent times; however, its commercial application is still limited due to certain inferior properties such as brittleness, relatively high cost, and narrow processing window. Certain drawbacks can be overcome by copolymerizing lactide with different monomers such as ε-caprolactone [1-4], trimethylene carbonate [5] and DL-β-methyl-δ-valerolactone [6] and by blending PLA with poly(butylene adipate-co-terephthalate) (PBAT) [7], poly(εcaprolactone) (PCL) [8-12] and many other non-biodegradable polymers [13-19]. Though the blended polymers exhibited certain improved mechanical properties compared to non-blended parts, immiscible polymer blends may lead to less desirable properties that were anticipated from blending. Thus, compatibilizers are often used to improve the miscibility between the immiscible polymer blend. is the much higher for Ecovio samples (i.e. both Ecovio and Ecovio-talc). Thus as seen in cell size, compatibilization had positive effect on the cell morphology of the foamed materials, i.e., increasing the cell density. This is in agreement with the published literature [36]. Effects on Volume Expansion Ratio (VER) Volume expansion ratio denotes the amount of volume that has proportionately expanded as a result of foaming. Figure 2 presents the volume expansion ratio with respect to temperature. The addition of talc has decreased the VERs of PLA and non-compatibilized PLA/PBAT blend. This is due to increase in stiffness and strength of the polymer melt. For Ecovio, the addition of talc had no significant effect on VER. While comparing the non-filled and talc filled compatibilized and non-compatibilized PLA/PBAT blends, it can be inferred that non-compatibilized PLA/PBAT blends possesses higher VER in comparison to compatibilized blends. Thus, compatibilization had a negative effect on the VER which could be due to increase in the melt strength of the compatibilized blends [37]. PLA Effects on Open Cell Content (OCC) The open cell content illustrates the interconnectivity between various cells. A highly open cell structured foam can be used in numerous industrial applications such as filters, separation membranes, diapers, tissue engineering etc. Figure 3 shows the variation of open cell content (OCC) with temperature. In general, the open cell content is governed by cell wall thickness [37]. As per the cell opening strategies discussed in [37], higher cell density, higher expansion ratios, creating structural inhomogeneity by using polymer blends or adding cross-linker and using a secondary blowing agent, all decrease the cell wall thickness thereby increasing the OCC. Some of them work in conjunction with the other. With the addition of talc, the OCC decreased for PLA and noncompatibilized PLA/PBAT blend which might be attributed to an increase in stiffness and strength of the talc filled samples. For Ecovio, the OCC increased with the addition of talc. Thus, talc had a varying effect on the OCC of PLA and its blends (compatibilized and non-compatibilized). In the analysis of OCC for compatibilized and non-compatibilized blends, it can be inferred that compatibilization has reduced the OCC significantly among non-filled blends but increased the OCC slightly among talc filled blends. Further investigation is required to study the varied effects of compatibilization on the OCC of blends. In summary, biodegradable PLA/PBAT foams have been successfully produced using CO 2 as a blowing agent. Two types of blends systems have been investigated, compatibilized and non-compatibilized. The effects of talc and compatibilization have been studied on different foam properties such as cell morphology, volume expansion, and open cell content. The financial support from National Science Foundation (CMMI-0734881) is gratefully acknowledged. PLA + 0.5% Talc Ecovio Ecovio + 0.5%Talc PLA + 55% PBAT PLA + 55% PBAT + 0.5%Talc 500 μm Foamed plastics are used in a variety of applications such as insulation, packaging, furniture, automobile and structural components [20-21]; especially, microcellular foaming is capable of producing foamed plastics with less used material and energy, and potentially improved material properties such as impact strength and fatigue life [22]. Also compared to conventional foaming, microcellular foaming process uses environmentally benign blowing agents such as carbon dioxide (CO 2 ) and nitrogen (N 2 ) in their supercritical state [23]. Microcellular process also improves the cell morphology with typical cell sizes of tens of microns and cell density in the order of 109 cells/cm 3 [23]. Additionally, compared to conventional extrusion, the microcellular extrusion process allows the material to be processed at lower temperatures, due to the use of supercritical fluids (SCF), making it suitable for temperature- and moisture-sensitive biobased plastics such as PLA. Solid PLA components processed by various conventional techniques such as compression molding, extrusion and injection molding have been investigated by many researchers [24-25]; however, foamed PLA produced via microcellular technology has been a recent development. Pilla et al. [26-29] and Kramschuster et al. 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