NIRI: Prototype-scale labs for cost-effective...

Prototype-scale labs for cost-effective biopolymers

(Source: NIRI)
(Source: NIRI)

Environmental imperatives such as the EU’s ambition to become the first carbon neutral continent by 2050 are transformational for the nonwovens industry, and the introduction of novel materials demands the input and collaboration of materials, textile, chemical and mechanical engineers.  This is an area of applied research for the expert multidisciplinary team at the Nonwovens Innovation and Research Institute Ltd. (NIRI), Leeds/UK,
The demand to reduce CO2 emissions, globally, includes those generated from polymer production, nonwovens production, converting and product assembly processes, and end of product life concerns. Alongside production, manufacturers are increasingly obliged to consider the longer-term product lifecycle, including reuse; recycling and returning materials back into the production cycle, or returning materials to the natural ecosystem.
In this context, the shift away from fossil fuel-derived materials to alternative materials is leading a transformation in nonwovens. But looking at alternative biopolymers, for fiber/filament formation, there are currently a range of options available, including:
-    Reconstituted/regenerated polymers from agricultural resources (starch: starch binders; cellulose: viscose rayon, lyocell, modal)
-    Polymers from microbial production: PHA, PHBV
-    Polymers synthesized from agricultural resources into biopolymers: PLA, PCL, PBAT, PBS, PGA
-    Polymers synthesized from bio-resources into conventional polymers: bioPET, bioPP, bioPE, bioPA

To achieve trouble-free processing and conversion of novel materials using conventional equipment is one challenge. The current alternative approach is to adapt conventional equipment to achieve trouble-free processing. Whichever route is pursued, for novel materials to be commercially viable they must meet the specifications and performance demands of the materials and products they are to replace.
Combining materials with the required properties into a blend that combines the best of both materials is one option to overcome such challenges and obtain the desired performance. Alternatively, process or performance additives can be added either during raw material preparation or during processing. Blending can be done in the polymer preparation stage (compounding), by mixing different fiber types prior to carding, airlaying or wetlaying. In wetlaying, process additives can be added to the fiber slurry, while performance enhancers in non-fibrous forms such as powders can be added during the fiber laydown process or into the formed webs.
NIRI’s laboratories are equipped with prototyping-scale equipment to assess processability, explore polymer combinations with processing and performance additives, and to optimize process conditions for biopolymer extrusion into filaments, spunbound, and meltblown nonwovens. Equally, the demand to match the specification and performance properties of novel materials to conventional fabrics and products can be met. Laboratory-scale prototyping machines allow for cost-effective and time-effective changes to be made to the prototypes. This means a rapid succession of adaptations can be made, less intensive in material use, leading to effective optimization to provide confidence before more costly pilot and production trials take place.
Once nonwoven webs are successfully formed, they require bonding.  Carded, airlaid and wetlaid webs from novel biopolymers can be assessed for bonding using NIRI’s extensive range of bonding techniques, including mechanical (which requires no additional materials to consolidate webs into fabrics), thermal, and chemical. The main requirements for binders are their compatibility with diverse application methods - including spraying, coating, printing, and saturation - affinity to fibers, and bonding strength.
As in the case of fiber and web formation, NIRI’s prototyping-scale bonding equipment is ideal for assessing the binder’s processability, exploring polymer combinations, and optimizing process conditions for bicomponent biopolymer extrusion into filaments, as well as the implementation of bonding techniques.  The specifications and performance properties of the biopolymer prototypes can be tested according to industry standards using the analytical facility.
Clients can utilize NIRI’s facilities and expertise to implement low energy and less water-intensive processes, assessing their impact on the parameters and performance of the alternative fabrics and conducting rapid optimization. Again, at the manufacturing stage, managing waste reintroduction into production - pre-consumer waste - can be explored, and impact assessment made.
Nonwovens are rarely designed to be reused, mainly being classified as durable (e.g. floor coverings); semi-durable (e.g. air filters and upholstery fabrics), or disposable (including hygiene and medical products). End of life strategies differ depending on the application, and material composition is as great a factor as production methods. As the use of biopolymers grows across multiple sectors, the waste collection and recycling infrastructure will need to expand - thus extending products’ service life into recycled, reused materials before end-of-life degradation.

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