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Compounding and Compatibilization of High-Performance Polymer Alloys and Blends
Published in Gabriel O. Shonaike, George P. Simon, Polymer Blends and Alloys, 2019
Wen-Yen Chiang, Chi-Yuan Huang
Magnetic properties of plastic magnets (94–96) composed of polymer matrices and magnetic powder are inferior to general casting or sintered magnets; nevertheless, they have some advantages, e.g., high producibility, possible production of complicated small and thin shapes with precision, etc. Therefore they have been widely used in various fields and have played important roles in the rapid development of electronic and communications instruments, household utensils, audio equipment, and so on (97). Low-density polyethylene (LDPE) is a widely used, general purpose plastic for commodity products. Its properties such as extreme toughness, chemical inertness, low-temperature brittleness, low-temperature flexibility, high environmental stress crack resistance, etc. show excellent processibility and highlight their usefulness as the matrix of plastic magnets. However, a variety of inorganic particles dispersed in LDPE yields substantial incompatibility in many processes and leads to performance problems exemplified by poor dispersion, agglomeration, elevated viscosity, cosmetic defects, and adhesion failure. On the other hand, titanate coupling agents (CA) are molecular bridges at the interface between two substrates. They will generally improve the dispersion of the fillers and the interface of the blend. Therefore CA-treated magnet powders for plastic magnets have many physical properties better than those of the untreated blends that are traditionally used.
ε-Caprolactone)s: Synthesis and Applications
Published in Sophie M. Guillaume, Handbook of Telechelic Polyesters, Polycarbonates, and Polyethers, 2017
Timm Heek, Marc Behl, Andreas Lendlein
A key challenge of polymer chemistry is the synthesis and development of polymeric materials whose chemical and physical characteristics fit their intended field of application. In general, three distinct features of a polymer determine these properties: the chemical composition (i.e., the used (co-)monomers)), the topology (e.g., linear, branched, network), and the nature and distribution of chemical functional groups, as these determine potential chemical reactivity or physical interactions with the environment. The combination of these design motifs is referred to as the polymer architecture [1]. A modification in one of these parameters can cause significant changes in the resulting properties of a certain polymer. For example, high-density polyethylene (HDPE) has a lower degree of branching compared to low-density polyethylene (LDPE) and therefore provides high robustness, which is for instance used in fuel tanks, whilst the counterpart LDPE is flexible and can be used in plastic wraps [2]. Of course, the architecture of a polymer can be controlled by many different synthetic strategies, depending on the type of the targeted structure. A very versatile synthetic approach toward various different polymer architectures is based on the utilization of well-defined, end-group-functionalized prepolymers so-called telechelics [3].
Characteristics of Polymers and Polymerization Processes
Published in Manas Chanda, Plastics Technology Handbook, 2017
Low-density polyethylene (LDPE) is extensively used for the manufacture of films. During processing, which is carried out at temperatures of approximately 200°C, cross-linking, and thus formation of gel, can occur through oxidation if the polymer is not stabilized. Such gel particles are visible in the film as agglomerates, known as fish eyes or arrow heads. The processing stabilizers used in LDPE consist of systems commonly used for polypropylene, namely, combinations of a phosphite or phosphonite and a long-term heat stabilizer (hindered phenol) in overall concentrations up to 0.1%. Concentrations seldom exceed 0.1%, since the compatibility of any additive in LDPE is considerably lower than in any other polyolefins.
Mechanical, thermal, and morphological properties of low-density polyethylene nanocomposites reinforced with montmorillonite: Fabrication and characterizations
Published in Cogent Engineering, 2023
Safaa Kh. Al-Jumaili, Wasan A. Alkaron, Maithem Y. Atshan
During the last decades, polymers have gained a great deal of global interest in industries and for academic use due to the wide applications and properties of polymers, in addition to the lightweight and ease of manufacturing of polymers (Al Rashid et al., 2021; Alkaron et al., 2023; Kudva et al., 2022). Low-density polyethylene (LDPE) is among the most promising plastics due to its beneficial properties, such as lightweight, flexibility, processability, and low cost (El-Bagory et al., 2021; Goswami & Mangaraj, 2011). However, polymers like LDPE have common mechanical and thermal properties compared to other materials, such as metals (Chi et al., 2017; Jordan et al., 2005; Rezgar et al., 2019). Improvement of thermal and mechanical properties is required to increase the demand for LDPE in different applications (Chaurasia et al., 2019; Verma, Kumar, et al., 2019; Verma, Parashar, et al., 2019).
An approach toward augmenting materials, additives, processability and parameterization in rotational molding: a review
Published in Materials and Manufacturing Processes, 2020
Nikita Gupta, PL. Ramkumar, Vrushang Sangani
Ease in processibility and better chemical resistance are provided in low-density polyethylene (LDPE) which is flexible and tough also. LLDPE or linear medium density polyethylene (LMDPE) has proved in providing better mechanical properties than LDPE. Even higher stiffness and exceptional low temperature impact strength with excellent environmental stress crack resistance properties are found better in LLDPE and LMDPE as compared to that of LDPE in rotational molding process. The stiffest resin in the family of polyethylene is high-density polyethylene (HDPE). HDPE has excellent chemical resistance and good processibility. HDPE while being stronger than LDPE is more susceptible to distortion and warpage due to its greater crystallinity when used for roto-molded product.[54] Cross linkable polyethylene (XLPE) forms a cross-linked molecule which is similar to thermoset plastic which can improve the stress crack resistance of the roto-molded product.[48]
Potential adverse health effects of ingested micro- and nanoplastics on humans. Lessons learned from in vivo and in vitro mammalian models
Published in Journal of Toxicology and Environmental Health, Part B, 2020
Laura Rubio, Ricard Marcos, Alba Hernández
Different synthetic polymers are used in the constitution of plastics, depending upon their intended use. Among these, low-density polyethylene (LDPE) is employed in packaging materials, and by far is the major component of terrestrial plastic litter in form of plastic bags and sheets (Barnes et al. 2009). High-density polyethylene (HDPE) is utilized among other applications for corrosion-resistant piping, geomembranes, and plastic lumber, while polyethylene terephthalate (PET) is used overall in plastic bottles (Bouwmeester, Hollman, and Peters 2015). Altogether, polyethylene is the most produced polymer comprising more than 40% of the total plastics produced (U.S. Environmental Protection Agency, 2012). Other polymers commonly employed include polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC) and polyactide (PLA) (Andrady and Neal 2009).