functionalities (Figure 8).
In order to improve some intrinsic properties of PHB and PLA, such as VI-CAT
softening temperature, thermal stability, hydrophobicity, toughness
and elongation, alkoxysilanes have been incorporated into its structure
by reactive extrusion (Figure 9). In addition, this covalent incorporation
has been carried out in other polymeric matrices of different composi-tion,
formed by PHB / PLA in different proportions. In addition, in order
to improve the properties of said compounds, as well as their miscibility
and homogeneity, a disilane has been incorporated as a compatibilizing
agent between both polymers.
For its part, with the aim of obtaining multifunctional polymers, titanium
nanoparticles have been incorporated, providing the polymeric matrices
with UV and antibacterial protection properties, from metal alkoxides as
a source of titanium.
The characterization results of the different materials obtained, such as
rheological studies, thermogravimetric analysis (TGA-DTA), nuclear mag-netic
resonance of solids (NMR) and differential scanning calorimetry
(DSC) confirm the incorporation of metal alkoxides in the matrix polymer
of the polymers.
It is worth highlighting the wide application of this research in the fas-hion,
home, agriculture and fishing sectors, by means of PLA, PHB and
PLA / PHB flat-belt tape products, and PLA, PHB and PLA / PHB multifi-lament
This project has the support of the Conselleria d’Economia Sosteni-ble,
Sectors Productius, Comerç i Treball of the Generalitat Valenciana,
raw materials, which implies an increase in pollution and a depletion
of limited resources, such as fossil fuels. On the other hand, polymeric
materials of fossil origin have been known for almost a century and offer
a very broad field of application, ranging from the packaging sector to
medicine, so they play a very important role in the quality of life of our
society. The main problem of synthetic polymers is their non-biodegra-dable
and non-renewable character, which results in the generation and
accumulation of waste that is difficult to manage. In addition, during its
production, gases and polluting particles are emitted into the atmosphe-re.
Therefore, in a society with a growing concern for the environment,
the possibility of obtaining products from sustainable and completely
biodegradable sources at the end of their useful life is an exciting and
The main objective of the project is to obtain 100% biodegradable
threads with improved properties by reactive extrusion. For this, the fo-llowing
specific objectives are set:
1. Monofilament extrusion of biodegradable / compostable polymers
(PLA and PHB).
• Flat-belt extrusion for composability studies, a comparative
study of PHB versus PLA (already commercialized).
• Multifilament extrusion (with the monofilament extruder) of
PHB and PLA polymers (on a pilot scale)
• Multifilament extrusion (with multifilament extruder) of PHB
and PLA polymers (on a semi-industrial scale)
2. PHB and PLA reactive extrusion to improve their thermal properties.
• PHB reactive extrusion to increase its VICAT softening tem-perature,
thermal stability, hydrophobicity, toughness and
elongation, thus facilitating the spinning process.
• PLA reactive extrusion to increase its VICAT softening tempe-rature
from 60 ° C to 90 ° C.
• Reactive extrusion between PHB and PLA in the presence of
compatibilizers, which allows miscible and irreversible mixtu-res
of both polymers to be obtained.
• Monofilament and multifilament extrusion of the new poly-mers
Throughout the GREENFILS project, PLA and PHB flat-belt tapes have
been developed with two main objectives. First, in order to study how
some process variables, affect their mechanical properties, specifica-lly,
the temperature of the cooling bath, the speed of the godets, the
stretching ratio, the subsequent annealing treatments, the presence of
a nucleating agent in the polymer matrix and the passage of time after
A composability study of these two biomaterials has been carried out
under the current ISO 20200: 2015 standard. Specifically, polymeric ma-trices
of different composition and crystallinity have been studied.
Secondly, after performing the composability tests, the biodegradability
of both polymers was confirmed, because all flat-belt tapes, regardless
of their composition and crystallinity (0-50%), degraded in less than 8
Another of the results with the objective of obtaining 100% biodegra-dable
fabrics, multifilament extrusion has been carried out in a monofi-lament
pilot plant for a variety of polymeric matrices based on PHB and
PLA / PHB. To achieve this, the use of nucleating agents and metal alkoxi-des
has been necessary, which allows the minimization of the aging of
the PHB, improving the mechanical properties and incorporating specific
Figura 9. (a) Extrusora reactiva, (b) bomba de cromatografía HPLC (Gilson
305) y módulos manométricos, (c) sonda alimentadora de líquidos y (d) cris-talizador.
Figure 9. (a) Reactive extruder, (b) HPLC chromatography pump (Gilson
305) and manometric modules, (c) liquid feeding probe and (d) crystallizer.