In recent year, there has been increasing concern about the growing amount of plastic waste coming from daily life. Different kinds of synthetic plastics are currently used for an extensive range of needs, but in order to reduce the impact of petroleum-based plastics and material waste, considerable attention has been focused on “green” plastics. In this paper, we present a broad review on the advances in the research and development of bio-based polymers analogous to petroleum-derived ones. The main interest for the development of bio-based materials is the strong public concern about waste, pollution and carbon footprint. The sustainability of those polymers, for general and specific applications, is driven by the great progress in the processing technologies that refine biomass feedstocks in order to obtain bio-based monomers that are used as building blocks. At the same time, thanks to the industrial progress, it is possible to obtain more versatile and specific chemical structures in order to synthetize polymers with ad-hoc tailored properties and functionalities, with engineering applications that include packaging but also durable and electronic goods. In particular, three types of polymers were described in this review: Bio-polyethylene (Bio-PE), bio-polypropylene (Bio-PP) and Bio-poly(ethylene terephthalate) (Bio-PET). The recent advances in their development in terms of processing technologies, product development and applications, as well as their advantages and disadvantages, are reported.
Nicola Schiavone, Vincent Verney, Haroutioun Askanian
An eco-friendly solution to produce new material for the material extrusion process is to use quarry waste as filler for biopolymer composites. A quarry waste that is still studied little as a filler for polymer composites is pozzolan. In this study, the optimization of the formulations and processing parameters of composites produced with pozzolan and bio-based polyethylene for 3D printing technology was performed. Furthermore, a precision irrigation system in the form of a drip watering cup was designed, printed, and characterized. The results showed that the presence of the pozzolan acted as a reinforcement for the composite material and improved the cohesion between the layers of the 3D printed objects. Furthermore, the optimization of the process conditions made it possible to print pieces of complex geometry and permeable parts for the control of the water flow rates with an order of magnitude in the range from mL/h to mL/day.
A. Martínez-Romo, R. González-Mota, J. J. Soto-Bernal
et al.
The changes in structural properties of high density polyethylene films (HDPE), low density polyethylene films (LDPE), biodegradable polyethylene (PE-BIO), and oxodegradable polyethylene (PE-OXO) films exposed to UV-B radiation were studied. The carbonyl(ICO)and vinyl(IV)index, the crystalline phase fraction, and the dichroic ratio were used to evaluate the photooxidation of these polymers. The results obtained show that LDPE and HDPE undergo a major degree of oxidation and an increase in the crystalline phase fraction comparing to PE-BIO and PE-OXO. If the LDPE and HDPE are pretreated by an accurate radiation UV-B dosage before its different commercial uses or in its final disposition, they can become an option for biodegradable material without the necessity of adding organic agents or photosensitizers.
This study introduces biodegradable thin-film encapsulation of bio-based phase change materials (Bio-PCMs) using PLA and Bio-PE polymers as a novel materials-engineering solution for geotechnical freeze–thaw applications. Expansive subgrade soils in cold climates suffer severe deterioration due to freeze–thaw cycling, leading to premature pavement distress. By embedding PLA/Bio-PE encapsulated Bio-PCMs (coconut oil, soy wax, lauric acid) into black cotton soil, the approach combines thermal buffering with environmental sustainability. This study evaluates the feasibility of using biodegradable thin-film encapsulated phase change material (Bio-PCM) capsules to enhance thermal stability and mechanical durability of black cotton soil subgrades. Bio-PCMs (coconut oil, soy wax, lauric acid) were encapsulated in PLA/Bio-PE films using a heat-seal process and incorporated into soil at dosages of 0–6% (by dry weight). Laboratory tests included compaction, unconfined compressive strength (UCS), California bearing ratio (CBR), and freeze–thaw durability over 20 cycles, complemented by thermal profiling. Results showed that PCM-treated soils reduced freeze–thaw temperature amplitude by ≈4.5 °C, delaying freezing onset and mitigating frost penetration. The 4% PCM dosage achieved the best balance of properties: after freeze–thaw cycling, the UCS was 230 kPa compared to 145 kPa for the control, representing 74.2% retention of its own initial strength versus only 58.0% for the control. Similarly, the post-cycle CBR was 5.1% for PCM-4 compared to 3.0% for the control, corresponding to 78.5% retention of its initial value versus 57.7% in the untreated soil. While 6% PCM produced a slightly higher CBR (5.2%), it also lowered maximum dry density, indicating diminishing compaction efficiency. These findings demonstrate that biodegradable thin-film PCM capsules can significantly improve freeze–thaw resilience in expansive soils while offering an environmentally sustainable alternative to conventional stabilizers.
Laurentia Alexandrescu, Mihai Georgescu, Maria Sonmez
et al.
Environmental concerns related to the implementation of circular economy has led to the development of new generations of materials. Interest in polymer composites reinforced with natural-organic/inorganic fillers is growing. Producers of polymer composites convert their production to optimize and replace traditional products with new ones with a high content of bio, recyclable materials, for sustainability and responsible actions. Research and industrial awareness are focused on ecological composites based on natural fillers from food production and aquaculture waste due to their low cost and high availability. This work aims to test �green� dynamically vulcanized thermoplastic polymer composites based on PE/PE-g-MA/EPDM reinforced with functionalized seashell waste, resistant to high temperatures for specific products used in the food, pharmaceutical and electronics industries. Seashell waste contains a high percentage (95-97%) of CaCO3 and will be ground to sizes of 100-500nm and functionalized in controlled conditions by silanization for compatibility with the polymer matrix. These composites will have characteristics such as resistance to microorganisms, at high temperatures for long working time and eco-friendliness derived from the use of seashell waste and the recycling of products injected from these materials. There will be a major impact on society due to the solutions that will be offered for reintegration into the natural circuit by increasing the degree of biodegradability after the end of the products� life cycle.
This study indicates that the application of kinetin to a recently formed fruit enhances its ability to import photosynthetic assimilates. Cytokinins are known to influence .the transport of plant metabolites (Letham 1967), and in the case of vine shoots Shindy and Weaver (1967) have recently demonstrated an effect of the kinin 6-(benzylamino)-9-(2-tetrahydropyranyl)-9H-purine on the translocation of 14C_ labelled assimilates. The present paper reports an effect of kinetin (6-furfurylaminopurine) on the accumulation of14C-labelled substrates by citrus fruits (cv. Washington Navel). In such crops the newly formed fruitlet is often unable to compete successfully with adjacent expanding leaves for substrates and this is thought to result in early fruit drop (Haas 1949; Sauer 1954).
A process, called Bio-Denipho, for combined biological phosphorus and nitrogen removal in a combination of an anaerobic tank and two oxidation ditches is described. In this process the anaerobic tank consisting of three sections working in series is followed by two oxidation ditches. These too are working in series, but with both inlet to and outlet from the tanks changing in a cycle. The Bio-Denipho process is described specifically for the process itself and as a case study for the implementation of the process on a 265,000 pe wastewater treatment plant for the city of Aalborg in Denmark. The plant was designed and erected in two stages and the last stage was inaugurated October 31,1989. Lay-out and functions for the plant is described and design loads, plan lay-out and tank volumes are given in this paper together with performance data for the first year in operation.