REINFORCEMENT | NATURAL FIBRES AND FILLERS
Figure 1: Comparison of key mechanical properties of a 20% sisal fibre reinforced PP compound compared with a 20% glass fibre reinforced alternative
Source: Green Dot Bioplastics
results. The goal of this test series was to demon- strate that we could increase the sustainability content (i.e., increase the natural fibre content and decrease the glass fibre content) within a PP com- pound and maintain a high level of performance,” says Fisher. The company is building a commercial plant for NFC production that is expected to start production towards the end of 2022. US-based Green Dot Bioplastics manufactures biobased and compostable polymers and commer- cialised its Terratek Natural Fiber Reinforced Plastic (NFRP) product line in 2020. These biocomposite materials use fibres such as sisal, American Bam- boo, and reclaimed jute fibres to replace glass fibre in PP, PE, or PA. While natural fibres are not a 1:1 replacement for glass fibres, they provide a sustainable option in many applications where reinforcement and stiffness are required beyond unfilled materials, says the company, which supplies both compounds and natural fibre masterbatches. “Performance and supply are the two key drivers
in natural fibre selection. We have to be able to ensure a repeatable product and performance for our customers,” says Mark Remmert, CEO at Green Dot Bioplastics. “American Bamboo is a native grass with excellent physical properties and sustainable growing practices.” Last year, Green Dot Bioplastics partnered with
Tier 1 automotive supplier Mayco International to take trim waste and scrap jute fibers from Mayco’s process to create a new NFRP material. “Rather than the scrap and trim being landfilled, we take it and incorporate that into a biocomposite pellet for use in other applications,” says Sarah Harbaugh, Sales and Marketing Director at the company. Spanish research organisation Aimplas has
investigated many natural fibres for use as reinforc- ing additives in biobased plastics composites over
18 COMPOUNDING WORLD | May 2022
the years, including hemp, kenaf, sisal, flax, jute, cotton, and others, according to Luis Roca Blay, Leader of Compounding. When developing a compound from bio-based plastic, he suggests it is more desirable to use natural fibres so that as many components as possible are renewable, and in some cases also compostable.
Composting concern Compostability is an attribute that is attracting growing attention in Europe, particularly for packaging. However, packaging items made using a compostable plastic reinforced with plant-based fibres might have difficulty achieving the EN 13432 standard for industrial compostability, depending on the percentage of fibre used and the thickness of the part, says Roca. Grinding the package before composting may provide a solution to this prob- lem, he says. Composite strength and weight are key factors in many end-uses. Roca also says natural fibres are not a direct replacement for glass fibre in their reinforcing properties, but adds that they can replace mineral reinforcing fillers and reduce weight. Other additives (such as impact modifiers) might also be used to create the necessary property balance. Aimplas recently studied the flame retardancy of
formulations containing natural fibres. Roca reports that in a flame-retarded formulation, natural fibres were not found to have a negative effect on flame retardancy; replacing plastic with a percentage of natural fibre caused a decrease in heat release. The study also examined formulations containing natural fibres and phosphorous-based flame retardants and confirmed that they did not interact in a detrimental manner. Norwegian research association RISE PFI says it
www.compoundingworld.com
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