BIOPLASTICS | FORMULATION AND COMPOUNDING
Condensia has recently developed a new grade
of its Glyplast OLA range of lactic acid oligomers, Glyplast OLA 550, which Fiori says can be a useful crystallinity promoter. “In particular, the combina- tion of Glyplast OLA8 (mainly used as a plasticiser for PLA and PHA) and Glyplast OLA 550 can act as nucleating agents,” he says. “The effect is promot- ed by the formation of stereocomplex crystals.”
Above: SEM image of Evonik’s Accurel XP 951B carrier particles, which is based on PLA
absorbing 50% of their volume. Once they have released the additives into the polymer melt, they become part of the matrix. The Accurel XP particles have dimensions similar to those of standard pellets. “We expose the polymer pellets to a unique process, which creates the porosity in the polymer pellet without changing the configuration and the dimension,” says Dang.
Additive success US-based distributor CAI Performance Additives has launched an additive solution to help proces- sors to work with biopolymers. ST-PA210 is claimed to be well suited for increasing melt flow index, compatibility, elongation, and improving disper- sion of compounded bioplastics. “Customers are seeing high success rates with doses at 2-3%, without the waxy residues found in other flow enhancement additives,” says CEO Richard Marshall. ST-PA210 is said to be well suited for use in PLA, PBAT and PHA as well as traditional resins such as PC, PC/ABS and PET. CAI Performance Additives is currently serving customers across North America and elsewhere. “ST-PA210 is unique and much needed,” says Marshall. “Performance additives like ours can have an enormous impact on the final product even in small doses.” One of major limitations of PLA is the polymer’s low crystallisation rate. “Enhancing the PLA crystallinity and crystallisation rate could boost the possibilities of use significantly and concomitantly would do good to the material properties such as stiffness, strength, heat deflection temperature and chemical resistance,” says Stefano Fiori, Technical Manager at Condensia in Barcelona, Spain. “Efficient routes to enhance the crystallisation kinetics of PLA include the increase of nucleation density by adding a heterogeneous/homogeneous nucleating agent and the increase of chain mobility by addition of plasticisers. When using a biode- gradable nucleating agent in combination with a biodegradable biopolymer, the resulting product could be completely biodegradable,” he says.
28 COMPOUNDING WORLD | September 2021
Degradable glass Finnish company Arctic Biomaterials produces high-performance bio-based and biodegradable compounds and composites. An unusual feature of its ABMcomposite technology is the use of propri- etary high-strength degradable glass fibres. R&D Director Ari Rosling says: “These glass fibres
start to slowly dissolve and degrade under moist conditions. The technology is well-known in the medical implant sector. The main ingredients are the same as in conventional window glass – only the proportions are different, which enables fibre production and the unique dissolution chemistry.” Arctic Biomaterials brought a new commercial- scale glass production facility online in 2019 to meet needs in technical materials. The company is currently validating its degradable glass fibre-rein- forced grades, which Rosling says have shown excellent cycle times combined with high strength, heat resistance and compostability.
Feedstock options The number of different possible feedstocks for biocompounds continues to grow. Spanish research organisation Aimplas, for example, has recently developed diverse formulations based on biopolymers. It says starch from sources such as
Chart showing the effect of the addition of ST-PA210 on MFI of PLA Source: CAI Performance Additives
www.compoundingworld.com
IMAGE: EVONIK
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