Natural Compounds as Sustainable Additives for Biopolymers

Abstract

In the last few decades, the interest towards natural compounds, coming from a natural source and biodegradable, for biopolymers is always increasing because of a public request for the formulation of safe, eco-friendly, and sustainable materials. The main classes of natural compounds for biopolymers are: (i) naturally occurring fillers (nFil), such as nano-/micro- sized layered alumino-silicate: halloysite, bentonite, montmorillonite, hydroxyapatite, calcium carbonate, etc.; (ii) naturally occurring fibers (nFib), such as wood and vegetable fibers; (iii) naturally occurring antioxidant molecules (nAO), such as phenols, polyphenols, vitamins, and carotenoids. However, in this short review, the advantages and drawbacks, considering naturally occurring compounds as safe, eco-friendly, and sustainable additives for biopolymers, have been focused and discussed briefly, even taking into account the requests and needs of different application fields.

Bionanocomposite Films Containing Halloysite Nanotubes and Natural Antioxidants with Enhanced Performance and Durability as Promising Materials for Cultural Heritage Protection

“…Similarly, both TS and EB values decrease by HNT adding, see Figure 4 b,c, respectively, while due to the presence of HNT:VA and HNT:Q, the properties at break increase in comparison to that of HNT. The latter suggests that the samples become more ductile due to the VA and Q presence, and this could be understood considering that the low molecular weight molecules, such as naturally occurring antioxidants VA and Q, exert a well-pronounced plasticizing effect, which is in accordance with the literature [ 27 , 65 , 66 ].…”

“…Therefore, due to the presence of HNT, and even more the presence of HNT:Q and HNT:VA, the hydroxyl absorption band appears much lower and both peaks at 1630 cm −1 and 1530 cm −1 shift towards a lower wavelength. These effects can be understood considering that the presence of alumino-silicates nanoparticles modifies the biopolymers constituents’ interactions, i.e., it influences the interactions between carboxylic anions and N–H groups, and according to literature, these nanoparticles can act as physical compatibilizers for biopolymer blends [ 27 ].…”

“…The film morphology was observed under an optical microscope to evidence the surface characteristic. The structure observation of biopolymers through high energy analysis, such as SEM and TEM, is a hard matter because, as known, these materials are susceptibility to fast degradation under a high energy beam [ 27 ]. Therefore, the Ch:P blend at the neutralization mass ratio (Ch:P = 0.13) clearly evidenced the presence of some fiber-like structures, while casting the more stable dispersion at Ch:P = 1 generates a very homogeneous film, see Supplementary Figure S2a,b .…”

“…The introduction of natural additives, such as reinforcement agents, cross-linking agents, and antioxidants, to single biopolymers or biopolymer blends favors the formulation of sustainable, eco-friendly, and non-toxic materials, having a beneficial effect on human health and the environment [ 27 ]. Among natural fillers, halloysite represents an emerging nanomaterial for the fabrication of bionanocomposites useful in numerous applications, such as food packaging [ 28 , 29 , 30 ], tissue engineering [ 31 , 32 , 33 , 34 ], delivery systems [ 35 , 36 , 37 , 38 ], photo-protection [ 39 , 40 ], and restoration [ 41 , 42 ].…”

Influence of the Ultrasonic Treatment on the Properties of Polybutylene Adipate Terephthalate, Modified by Antimicrobial Additive

“…In this regard, it became necessary to create packaging materials with antimicrobial properties, which remains relevant today. Today there are many developed antimicrobial polymeric materials [ 14 ], where substances of natural origin [ 15 , 16 , 17 ] and synthetic origin [ 18 ], including nanoparticles [ 19 , 20 ], act as antimicrobial components. Modification of PBAT will make it possible to obtain biodegradable packaging materials with antimicrobial properties [ 21 ].…”