Preparation and properties of biodegradable poly(propylene carbonate)/starch composites

Transparent Bioplastic Derived from CO2-Based Polymer Functionalized with Oregano Waste Extract toward Active Food Packaging

Active packaging materials, biodegradable and from renewable resources, are the most promising substitutes of nonbiodegradable, petroleum-based plastics, toward green and sustainable packaging solutions. In this study, an innovative bioplastic system, composed of carbon dioxide-derived poly(propylene carbonate) (PPC) and nature-originated cellulose acetate (CA), was developed. The extract from oregano waste was incorporated into the bioplastics as a low-cost and effective antioxidant resource. Thin, freestanding, and flexible PPC.CA bioplastic films were obtained by a simple, easily scalable solvent casting technique. The pristine films, without the oregano extract, featured good transparency and high water vapor barrier ability, along with suitable mechanical and thermal properties that are comparable to commercial plastics used for packaging. Interestingly, the incorporation of oregano waste extract added to the bioplastics high UV protection and high antioxidant activity, suitable features for active food packaging applications, without compromising the intriguing properties of the pristine films. The biocomposite films were not only biocompatible but also started biodegrading after just 1 week in seawater. The reported biocomposites are foreseen as promising candidates for several packaging applications, but in particular for sustainable active food packaging.

A literature review on life cycle tools fostering holistic sustainability assessment: An application in biocomposite materials

Sustainability of products and services has become a compulsory requirement and an essential requirement for organizations, governments, markets and society in general. Among the various ways of measuring sustainability that have been developed, those based on life cycle thinking provide one of the frameworks for assessing the potential impacts of products and services. However, despite sustainability of triple bottom line parameters (ecological, financial and social), the life cycle assessment is the most mature and prominent available tool. In addition, integration methodologies have come up, like life cycle sustainability assessment (integrating the three sustainability dimensions) and life cycle engineering (including the technical or functional aspect). The application of these methodologies to emergent materials and technologies represents a huge challenge, because there is lack of proper indicators, lack of information and contradictory information is common. This is the case of biocomposites, built with nature-based materials harvested in a myriad of ways in several regions of the globe. So, this paper presents a systematic literature review about the research done on the realm of sustainability assessment methods application to biocomposites. It reveals knowledge and information gaps to apply these methodologies. The integration of the existing methodologies is proposed as a way to allow a holistic sustainability assessment of biocomposite materials.

Biodegradable and Toughened Composite of Poly(Propylene Carbonate)/Thermoplastic Polyurethane (PPC/TPU): Effect of Hydrogen Bonding

The blends of Poly(propylene carbonate) (PPC) and polyester-based thermoplastic polyurethane (TPU) were melt compounded in an internal mixer. The compatibility, thermal behaviors, mechanical properties and toughening mechanism of the blends were investigated using Fourier transform infrared spectra (FTIR), tensile tests, impact tests, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and dynamic mechanical analysis technologies. FTIR and SEM examination reveal strong interfacial adhesion between PPC matrix and suspended TPU particles. Dynamic mechanical analyzer (DMA) characterize the glass transition temperature, secondary motion and low temperature properties. By the incorporation of TPU, the thermal stabilities are greatly enhanced and the mechanical properties are obviously improved for the PPC/TPU blends. Moreover, PPC/TPU blends exhibit a brittle-ductile transition with the addition of 20 wt % TPU. It is considered that the enhanced toughness results in the shear yielding occurred in both PPC matrix and TPU particles of the blends.

One-pot, mouldable, thermoplastic resins from poly(propylene carbonate) and poly(caprolactone triol)

Co-polymers of poly(propylene carbonate) (PPC) and poly(caprolactone triol) (PCLT) were synthesised via a simple yet effective one-pot, two-step method, without the need for a catalyst or solvent.

Ring-opening graft polymerization of propylene carbonate onto xylan in an ionic liquid

The amidine organocatalyst 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) is an effective nucleophilic catalyst. Biocomposites with tuneable properties were successfully synthesized by ring-opening graft polymerization (ROGP) of propylene carbonate (PC) onto xylan using DBU as a catalyst in the ionic liquid (IL) 1-allyl-3-methylimidazolium chloride ([Amim]Cl). The effects of reaction temperature, reaction time and the molar ratio of PC to anhydroxylose units (AXU) in xylan were investigated. The physico-chemical properties of xylan-graft-poly(propylene carbonate) (xylan-g-PPC) copolymers were characterised by FT-IR, NMR, TGA/DTG, AFM and tensile analysis. The FT-IR and NMR results indicated the successful attachment of PPC onto xylan. TGA/DTG suggested the increased thermal stability of xylan after the attachment of PPC side chains. AFM analysis revealed details about the molecular aggregation of xylan-g-PPC films. The results also showed that with the increased DS of xylan-g-PPC copolymers, the tensile strength and Young's modulus of the films decreased, while the elongation at break increased.

Bio-based thermoset composites from epoxidised linseed oil and expanded starch

Bio-based thermoset composites comprising epoxidised linseed oil (ELO), a bio-derived diacid crosslinker (Pripol 1009) and starch are reported.

Preparation and properties of biodegradable polymeric blends from poly(propylene carbonate) and poly(ethylene-co-vinyl alcohol)

Biodegradable blends of poly(propylene carbonate)/ethylene-vinyl alcohol copolymers (PPC/EVOH) were melt prepared. The mechanical strength, crystallization and melting behavior, morphologies, and thermal properties of these blends were fully investigated using tensile tester, modulated differential scanning calorimetry, scanning electron microscopy, and thermogravimetric analysis, respectively. The results indicated that the thermal stability of blends could be enhanced by increasing EVOH content. No change was observed for the tensile strength when EVOH content was lower than 30 wt %. The tensile strength, however, increased obviously with increasing EVOH content when EVOH content was higher than 30 wt %. The crystallization behavior of the PPC/EVOH blends was studied accordingly. The degradability test showed that the weight loss of PPC/EVOH blends increased with increasing EVOH content because of the strong moisture sorption of EVOH. Morphology observation indicated that the PPC/EVOH blends exhibited a two-phase microstructure. The blends with EVOH contents ranging from 40 to 60 wt % showed the best comprehensive properties as biodegradable thermoplastic for many applications.

Biodegradability and thermal stabilityof poly(propylene carbonate)/starch composites

Poly(propylene carbonate)/starch (PPC/starch) composites with different starch contents were prepared by melt compounding. The biodegradability of the composites was studied by soil burial for a period of 6 months. FTIR study, thermal analysis and morphology observation indicated clearly the changes of the buried specimens. The weight loss curves and the molecular weight changes of the specimens revealed a three-stage biodegradation, corresponding to the propagation of microorganisms, the degradation of starch and the degradation of PPC. The experimental results showed that the addition of starch accelerated the degradation of PPC. Specimens with higher starch content exhibited greater weight loss in the second stage and smaller weight loss in the third stage.