Project Progress: BIOGEARS rope development and testing
Over the first year of the project a lot of progress has been made in designing and developing suitable biogears (biobased ropes) prototypes at lab scale. Several compounds have been defined to date, and a compounding strategy is planned to obtain the balance between the functional and biodegrading properties of biogears.
Different strategies of compounding have been assessed, including mineral and organic additives, and blends with other biopolymers with higher biodegradability behaviour in mesophilic conditions (home composting).
Traditional aquaculture ropes are manufactured from polypropylene multifilament, tape yarns and polyethylene monofilament yarns with UV stabilisation for long term sun exposure. Polypropylene rope is cost-effective and suitable for a wide range of fishing applications. To develop fit-for-purpose biogears for aquaculture, the materials’ suitability needed to be determined, and initial designs for long-line aquaculture created. Different rope types were selected, their properties analysed, and target properties for the biogears were identified for maximum mussel culture efficiency
Image of Picture of selected aquaculture ropes
A lot of work has taken place on identifying suitable biobased/biodegradable polymers from what is available on the market including PLA (Polylactic acid) and PLA-based blends. Other biopolyesters have been tested for monofilament production at an XPLORE lab-scale extrusion line. A combination of flat monofilaments are used to manufacture ropes. The range of linear density, tenacity and elongation for the biogears prototype intermediate filaments have already been defined. The lab-scale fibre extrusion line used by partner GAIKER is composed of 3 main elements:
- DSM Microcompounder unit equipped with a mixing chamber that include conical double screw to produce the compounds at scale of 15 cc (approximately 12 g)
- DSM Xplore Spinning unit connected to microcompounder to obtain monofilament by melt spinning in bobbins of up to 200-250m per batch of 15cc of material. The amount in grams depends on the density of the material
- DSM XPLORE conditioning unit which the spinned monofilaments is stretched to maximize the mechanical properties.
Image of sample filament
So far, at least six formulations have already been tested at pilot scale at the monofilament extrusion line at CENTEXBEL. In parallel, CENTEXBEL have been working in the optimisation of processing parameters. Mono and multifilaments have also been produced to perform twisting trials at ITSASKORDAThis trial has primarily been to assess the technical feasibility of this first batch, in terms of type of yarn and fulfilment of the mechanical specifications required at the grouping/twisting step of the production of ropes. During the trial, bobbins contained the biodegradable multifilament where combined with black bobbins containing conventional fossil-based filaments, using current production parameters.
As well as rope development, an objective of BIOGEARS is to conduct field trials to validate the prototypes at sea, which has already seen significant progress. Test facilities have been identified in different sea environments: offshore high energy conditions in a longline system, low energy conditions in a raft system, and lastly an IMTA proof of concept at lab scale in a research centre. The field demonstrations are set up and will perform and monitor at least two production cycles with biobased ropes under best practices for eco-friendly aquaculture.
Last edited 15/01/2021