1,721,327 research outputs found
The aliphatic counterpart of PET, PPT and PBT aromatic polyesters: effect of the molecular structure on thermo-mechanical properties
No full textThe aliphatic counterparts of the most used aromatic polyesters (PET, PPT, and PBT) have been synthesized by a two-stage polycondensation process, starting from dimethyl 1,4-cyclohexane dicarboxylate and different diols. The fully aliphatic polyesters are characterized by two cis/trans isomeric ratios (50 and 90 mol%) of the 1,4-cycloaliphatic rings. According to the cis/trans content, the properties of the materials notably change. Indeed, polymers rich in trans isomer are semicrystalline, whereas polymers with low trans content are fully amorphous, due to the presence of kinks along the chain. Trans isomer is characterized by higher rigidity than the cis one and the corresponding polymers have high glass transition temperatures. Moreover, the length of the methylene sequences in the diol has a notable influence on the final thermal and mechanical properties. Therefore, tunable properties can be easily obtained. This characteristic, in association with good mechanical performances, potential sustainability of the monomers and biodegradability, makes these aliphatic polyesters an interesting class of polyesters for some specific applications
Hydroxydes doubles lamellaires organo-modifies et materiaux polymeres composites les comprenant
No full textHydroxide doubles lamellaire organo-modifiespar l'acide 3-(4-hydroxyphenyl)propionique (HPPA) par l'acide 2-(4-hydroxyphenyl)ethylsulfonique ou par un acide hydroxphenylypropenoique, et materiaux polymeres composites les comprenant. les materiux composites sont avantageusement a base de polymeres biosources comme le poly(butylene succinate). Ces materiaux composites presentent des proprietes ameliorees par rapport aux polymeres entrant dans leur composition, et par rapport aux composites de l'art anterieur
Biocomposites based on poly(butylene succinate) and curaua: Mechanical and morphological properties
No full textBiocomposites based on poly(butylene succinate) (PBS) and curaua fibers have been produced by compression molding, and investigated as a function of fiber length and amount. Mechanical tests, water uptake and morphology studies were carried out in order to assess the composite features according to the characteristics of the reinforcing agents. It turns out that the impact and flexural strengths increase with fiber content. Moreover, the fiber length, varying from 1 to 4 cm for the composite reinforced with 20 wt% of fiber, influences impact strength, which is higher for shorter than for longer fibers. However, flexural strength is not greatly influenced by the length of the fibers. Water uptake studies reveal a higher sensitivity of the material to fiber content rather than fiber size. Biocomposites, which are characterized by enhanced mechanical properties as compared to PBS, can have different applications, for example in rigid packaging or interior car parts
Fully biobased poly(propylene 2,5-furandicarboxylate) for packaging applications: excellent barrier properties as a function of crystallinity
No full textHigh molecular weight, amorphous poly(propylene 2,5-furandicarboxylate) has been aged at 135 °C for different times. The crystal phase contributes to achieve exceptionally low oxygen transmission rates and also good impermeability to water vapors, making PPF one of the most interesting fully biobased polyesters for packaging applications
Chemical recycling of post-consumer compact discs towards novel polymers for powder coating applications
No full textNew processes for the chemical recycling of bisphenol A polycarbonate (PC), directly from post-consumer compact discs, have been developed. The first recycling method is based on the use of molecules that can be derived from renewable resources (isosorbide, ethylene carbonate and succinic acid). A second procedure involves a one-pot reaction of post consumer PC with ethylene carbonate, without complete degradation to low molecular weight products. The final polymers feature properties that make them suitable for powder coating applications
Sustainable food packaging from agro waste: from Nature for Nature
No full textWorld plastic production reached 368 million tons in 2019 and about 40% of them is used for the packaging sector. Recently, the problems related to the depletion of oil, from which the 98% of plastics derives, and to the plastic pollution, mainly due to not biodegradable materials, have driven research, industrial and end-user interests towards sustainable plastic products, derived from biomass and responding to the principles of recovery, reuse and recycling. In particular, the creation of a new packaging for the food sector, especially if intended for the packaging of organic food products, cannot ignore the logic of a sustainable development, as also requested by consumers who are increasingly attentive to concepts such as waste reduction, circularity of materials, food safety.
In this perspective, the research activity of the AgriCo.Pack project, funded by the Emilia Romagna Region, concerns the development of a packaging material for fresh fruit and vegetables, that is biobased and biodegradable / compostable and characterized by good performances. In particular, the new packaging is obtained by using a bio-based biodegradable polymer as the matrix and a high amount of fillers derived by agricultural production waste. The fillers are chosen according to their seasonality and availability and properly pre-treated, in order to improve their affinity with the polymeric matrix. The objective of the work is to produce polymeric bio-composites that can replace, in terms of performances and costs, materials derived from non-renewable and non-biodegradable sources. The project covers the full value chain, starting from agricultural companies, for the supply of vegetable waste, to research centers and companies interested in the development of the new packaging, designed also according to LCA analysis, to final end-users that will use a traceability system of the product
Poly(1,4-dimethylcyclohexane adipate) nanocomposites with organoclays modified with ionic liquid based on phosphonium salt
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