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Shape memory polyurethane (SMPU) with its outstanding characteristics is categorized as smart materials and has been utilized in a wide range of applications. In this study, a series of palm kernel oil polyol (PKOp) - based SMPU with the combination of polycaprolactone (PCL) and polyethylene glycol (PEG) as soft segment was synthesized and characte...
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... The most commonly used signal-use plastics (water bottles, plastic bags) are made from polyethylene ( Fig. 13.1a) a linear ethylene polymer. Polyethylene is further modified to produce polyethylene terephthalate (PET) (Fig. 13.1b), which is having better properties such as flexibility, hydrophobicity, durability, strength, higher crystallinity, and thermoplasticity (Trinh et al. 2020). Polystyrene ( Fig. 13.1c) is an aromatic homopolymer discovered in 1839 by Eduard Simon in Germany. ...
Recent studies have shown the presence of microplastics in freshwater reservoirs, commercially available bottled drinking water and in most common drinking water sources, such as tap water from various locations. Microplastics have received more attention because of their potential in carrying pathogenic organisms, heavy metals, and new contaminants, such as phthalate esters, into organisms, possibly impacting the environment and finally human health. The unavailability of effective and targeted water treatment technology to remove microplastics leads to their unintentional consumption by humans, resulting in a variety of health issues. Limited information on microplastic pollution in drinking water is available, as different studies have used various analytical techniques for detecting and extracting microplastics from water samples collected without the standard operating procedure. Therefore, reported studies showed huge variations while determining the microplastic concentration, resulting in difficulty in concluding the exact microplastic content in both tap and bottled water. Microplastics are one of the classes of emerging new contaminants; and very few global-level regulatory attempts have been made for the reduction of microplastic production and usage in various commercial products. However, research on microplastics is in naive phase, and more research is needed for adverse effect on human health. The present chapter focuses on some aspects of microplastics in drinking water, including its genesis, fate of distribution in environment, human exposure, and effect on human health. The development of efficient microplastic removal technologies is a global concern for achieving the Sustainable Development Program goal 6 of clean drinking water to all human beings.
... LDPE can tolerate strong acids (acetic acid and hydrochloric acid), alcohols (methanol and ethanol), as well as alkali (ammonia and urea) due to its low density and branched structure [27,28]. Furthermore, tackling pollution from polyethylene terephthalate (PET), a modified form of polyethylene, is even more challenging due to its durability, strength, flexibility, hydrophobicity, and high crystallinity and thermoplasticity [29]. ...
Synthetic polymers have replaced natural polymers due to their low production cost, wide range of applications, and better resistant properties. Plastic polymers are the most preferred one among synthetic polymers as they have high tolerance against high temperature, photooxidation, and chemical degradation. While these properties make them desirable compound for manufacturing various products, it also imposes environmental hazards upon releasing microplastic particles which has negative impact on terrestrial as well as aquatic ecosystems. Although many plastic remediation technologies involving physicochemical methods have emerged in past decades, they have been inefficient when it comes to remediating microplastic pollutants. In the present scenario, mycoremediation approach has been suggested as an alternative green approach to remediate the microplastic pollution. Fungi possess diverse enzyme systems, metabolic processes, and bioactive compounds which are proven to be efficient in removing microplastic pollutants. The present review highlights the detailed mechanisms as well as evidences for microplastic remediation by fungal system. The types of microplastic pollutants, source, and their hazardous effects on various ecosystems have also been compiled.KeywordsMicroplasticsPolyethylenePolypropyleneMycoremediationDiketoneTerephthalateAntioxidants
... This is in accordance with the DSC analysis which will be discussed in the next section. The high DPS value obtained suggest the phase separation phenomenon while the low DPS values is corresponded to the phase mixing of both hard and soft segments in PU [13]. ...
Shape memory polyurethane (SMPU) is a very versatile material that has a broad array of applications. The selection of soft segments and hard segments play critical roles in determining the structure-property behaviors of SMPU. This research was conducted to evaluate the role of distinct types of diisocyanate on the final properties of polyurethane (PU). Palm kernel oil polyol (PKO) based PU were produced by using two-step bulk polymerization method with variations of diisocyanates. Isophorone diisocyanate (IPDI), 4,4-methylenebis (cyclohexyl isocyanate) (HMDI) and hexamethylene diisocyanate (HDI) were used in the preparation of PU and the soft segment crystallinity, thermal and shape memory properties of the PU were evaluated. Based on the analyses, it was found that different types of diisocyanate and combination of diisocyanates had huge impact on the properties of the synthesized PU. The Fourier transformation infrared (FTIR) analysis revealed that IPDI based PU achieved the highest hydrogen bonding index value which promoted the phase separation. This is in accordance with differential scanning calorimetric (DSC) and x-ray diffraction (XRD) analysis which showed that IPDI based PU exhibited crystalline soft phase, hence resulted in an excellent shape fixity behavior. On the other hand, HDI and HMDI based polyurethane prepared showed absence of crystalline soft phase based on the DSC thermogram and XRD diffractogram. These results suggest the phase mixing phenomenon between soft and hard segments which contributed to low shape memory behavior of the resulting polyurethane.
... Moreover, PU/PW (T80-t20) displayed constant and uniform phase change temperature and enthalpy after 100 cycles. Thus, PU/PW (T80-t20) with thermoplastic elastomer shell synthesized by miniemulsion polymerization has adequate long term energy store/ release performance and as a consequence, it has good thermal reliability [30](It should be mentioned that, primary peaks before 35 C are related to DSC equipment stability and not related to prepared sample). ...
The impact of this research is to present results obtained from synthesis of nanoencapsulated Paraffin wax core/Thermoplastic elastomer Polyurethane shell with various particle size distribution via mini-emulsion polymerization that could be utilized in thermal energy storage. To achieve this objective, five different types of Polyurethane shell/Paraffin wax core nanocapsules have been synthesized based on Polyethylene glycol and Isophorone diisocyanate with Polycaprolactone assistance to improve fusion enthalpy and thermal performance. Process conditions including ultrasonic time and reaction temperature have been assigned differently to study effect of reaction parameters on PU/PW particle size distribution and time-temperature performance. Findings have shown that, increasing sonication time from 15 to 20 min and reaction temperature from 60 to 80 °C, mini-emulsion core droplet size has been decreased and narrow size distribution has been attained. Furthermore, molecular and morphology analysis and phase change thermal investigations confirmed polyurethane shell formation around spherical paraffin wax core. Moreover, thermal cycling test has been indicated high thermal performance and improved resistance of prepared core/shell, even after 100 heating/cooling cycles and approved its great potential for thermal energy storage applications. To conclude, narrow size distributed paraffin wax nanocapsules demonstrated effective and superior time-temperature history in contrast with broad size distributed nanocapsule.
Developing a bio‐based polyol polyurethane foam with the desired properties for use as growing media for green vertical walls could be beneficial in the quest to create a more sustainable urban living. In this work, palm kernel oil‐based polyol (PKOP) was mixed with petroleum‐based polyol (PP) at different ratios in synthesizing polyurethane foam. The impacts of PKOP/PP formulation on the density, cell morphology, water absorption, water retention, swelling behavior, and their chemical functional groups were evaluated. It was determined that replacing PP with low levels of PKOP could reduce the water absorption ability due to the introduction of hydrophobic plant‐based fatty acids. On the contrary, polyurethane foam containing more than 30% PKOP has improved the water absorbing ability and retention properties. Fourier‐transform infrared (FTIR) spectrum indicates that the synthesized foams are isocyanate‐free and stable toward pH changes. The trial planting attempt was a success where the plants were grown from seeds using the synthesized foam media. It was proposed that 50% PKOP is most suitable for use as a growing media, based on its water absorbing and retention properties. The findings of this study highlight the potential for the use of bio‐based polyol polyurethane foam for more sustainable growing media in urban gardens.
Shape memory polyurethane (SMPU) has received tremendous interest because of its low cost, low density, as well as easy processing. However, its inferior mechanical properties compared to shape memory alloys have constrained its application in a broad range of engineering areas. Nanofillers are commonly added to polymers to overcome the problem associated with low mechanical characteristics. This study aims to examine the effect of various loadings of multiwalled carbon nanotubes (MWCNT) on the thermal stability, soft segment crystallinity, tensile and shape memory behaviour of palm oil polyol based SMPU nanocomposites. The SMPU nanocomposites were synthesised using a two-step polymerisation process. Microphase-separated SMPU nanocomposites obtained as the differential scanning calorimetric analysis showed two melting transitions, which belonged to the soft and hard phase domains. Furthermore, it was found that MWCNT had acted as a nucleating agent, which promoted the crystallisation process of SMPU nanocomposites. The thermal stability and tensile properties of SMPU/MWCNT nanocomposites were enhanced significantly as the MWCNT was added to the SMPU matrix. A considerable enhancement in the shape fixity (SF) value was revealed for PU-30 and PU-40 samples with the addition of MWCNT. The shape recovery (SR) time of SMPU was faster for samples reinforced with MWCNT, whereas SF increased while SR decreased upon increasing the shape memory cycle. The SMPU nanocomposites produced demonstrated enhanced thermal and tensile properties, which has the potential as smart material in many industrial applications.
Vegetable oil‐based shape memory polyurethane (SMPU) has been rapidly developed in the field of advanced polymeric materials due to its unique responsive characteristic. This research aimed to investigate the effect of prepolymer reaction time on the microphase separation, soft segment crystallinity, shape memory, and tensile properties of palm kernel oil polyol (PKO‐p)‐based SMPU. The SMPU samples were prepared via two‐step bulk polymerization process utilizing 4,4‐methylenebis (cyclohexyl isocyanate) (HMDI), polycaprolactone diol (PCL) and 1,4‐butanediol (BD). The reaction time after the addition of PKO‐p varied from 0.5 to 2.5 h in prepolymer synthesis. This reaction time resulted in excellent microphase separation and improve shape memory properties. The Fourier transform infra‐red analysis revealed that the degree of microphase separation of the polyurethane elastomer (PUE) increased with increasing prepolymer reaction time. In consequence, the shape fixity behavior of the PUE samples improved. The tensile strength and strain at break of PUE increased with increasing reaction time up to 2.0 h. However, when the reaction time was prolonged to 2.5 h, both values decreased. Thus, the results showed the advantages of using PKO‐p, which can minimize the usage of petroleum‐based polyol and improve the tensile and shape memory behavior of the PKO‐p‐based SMPU.
In polymer composites, the fiber–matrix interface is primarily influenced by the surface treatment of the fibers and polymer morphology. Previous studies have investigated the effect of surface treatment of carbon fiber on the mechanical properties of the resulting composites. However, very few studies have explored the chemical structural modification of polymer effect on the fiber–matrix adhesion. In this work, the interfaces of soft thermoplastic polyurethane (S-TPU) and hard-segmented TPU (H-TPU) were investigated through surface, thermal, and mechanical characterization. A textile-grade carbon fiber (TCF) with 1% concentration of epoxy sizing (an emerging material for nonaerospace applications with 450 K filament tows) was used as a reinforcement to investigate the structure–property relationship at the interface. Atomic force microscopy results showed 39% higher surface roughness for S-TPU than for H-TPU. X-ray photoelectron spectroscopy results revealed a 550% increase in C═O content, which can provide multiple hydrogen bonding networks in H-TPU, and these C═O bonds can produce a strong chemical bond at the fiber–matrix interface. Dynamic mechanical analysis and differential scanning calorimetry results confirmed the presence of hydrogen bonding that enhances the cross-linked density by 232% in H-TPU compared to S-TPU. The improved mechanical properties of H-TPU composites, such as flexural, impact and tensile by 30, 50, and 130% compared to S-TPU composites, prove that the crystallinity and hydrogen bonding significantly increase the load bearing capacity due to the strong interface. The mechanical properties of TCF–TPU composites validate the formation of chemical bonds through a nucleophilic addition reaction at the interface and improve the bond strength of the composites. Thus, tailoring the polyurethane structure broadens the performance of segmented TPU in conjunction with TCF reinforcement, which has implications for cost-effective, high-strength composites.
Self-healing synthetic polymers have attracted considerable scientific attention owing to their excellent durability and extended lifetimes. Among the categories of extrinsic and intrinsic self-healing, the intrinsic process is being focused on recently because it can realize rapid and reversible self-healing abilities and repeatability through dynamic chemical bonds. Intrinsic self-healing was categorized into two types: reversible covalent and non-covalent bonding, which include reversible cycloaddition reactions, exchange reactions, hydrogen interactions, and metal-ligand coordination interactions. This review focuses on recent studies about self-healing polyurethanes, which are known to exhibit remarkably high elasticity, high tensile strength, low-temperature resistance, and corrosion resistance. The various methods used for realizing efficient self-healing polyurethanes are also explored.
