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Wood-Filled Feedstocks
Published in Antonio Paesano, Handbook of Sustainable Polymers for Additive Manufacturing, 2022
Coupling agents (more) and plasticizers (less) have been studied as additives to improve compatibility between WF and PLA (Xie et al. 2017). For example, Dow DuPont Fusabond® M603 a coupling agent made of ethylene copolymer for wood/polymer composites that not only strengthens the composite but also improves wood fiber dispersion, wood/polymer bonding, and reduces water absorption. Common coupling agents are silanes and titanates. Lee et al. (2008)extruded polymer blends not specific for AM by combining 1 and 3 wt% silane with WF, PLA and talc, and measured that, vs. plain PLA, silanes enhanced tensile properties: strength raised from 60 MPa to 85 MPa, and modulus from 1,300 MPa to 2,043 MPa. Plasticizer are monomeric liquids and low-MW materials that improve melt flow properties, reduce brittleness, and enhance flexibility. Basically, they are small molecules that push the molecules of the polymer to which they are added further apart, and thus weaken the forces between the polymer's molecules, and render the polymer softer and more flexible, acting almost as “lubricant” between segments of the polymer chains. Examples of plasticizers are phthalate esters. Plasticizers are present in PVC cables and (mostly) films, rubbers adhesives, and coatings.
Processing and Thermomechanical Properties of PHA
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Vito Gigante, Patrizia Cinelli, Maurizia Seggiani, Vera A. Alavarez, Andrea Lazzeri
The council of the IUPAC (International Union of Pure and Applied Chemistry) defined a plasticizer as “a substance or material incorporated in a material (usually a plastic or elastomer) to increase its flexibility, workability, or distensibility”. These substances reduce the tension of deformation, hardness, density, viscosity, and electrostatic charge of a polymer, and at the same time increase the polymer chain flexibility, resistance to fracture, and dielectric constant. The low molecular size of a plasticizer allows it to occupy intermolecular spaces between polymer chains, reducing the secondary forces among them. In the same way, these molecules change the three-dimensional molecular organization of polymers, reducing the energy required for molecular motion and the formation of hydrogen bonding between the chains. As a consequence, an increase in the free volume and, hence, in the molecular mobility is observed. Plasticizers are widely used additives for polymeric materials to enhance their flexibility, processability, and ductility. Generally, an efficient plasticizer reduces the glass transition temperature (Tg) and melting temperature of the plasticized materials [95].
Polymer Technologies
Published in Ghenadii Korotcenkov, Handbook of Humidity Measurement, 2020
A plasticizer is a material incorporated into a plastic to increase its workability and flexibility. The addition of a plasticizer may lower the melt viscosity, elastic modulus, and glass transition temperature (Tg). Plasticization can occur through the addition of an external chemical agent or may be incorporated within the polymer itself (Carraher 2008). Internal plasticization can be produced through copolymerization, giving a more flexible polymer backbone, or by grafting another polymer onto a given polymer backbone. Thus, poly(vinylchloride-co-vinyl acetate) is internally plasticized because of the increased flexibility brought about by the change in the structure of the polymer chain. The presence of bulky groups in the polymer chain increases segmental motion and the placement of such groups through grafting acts as an internal plasticizer. Internal plasticization achieves its end goal at least in part by discouraging association between polymer chains. External plasticization is achieved by incorporating a plasticizing agent into a polymer through mixing and/or heating.
Plasticizers in the neonatal intensive care unit: A review on exposure sources and health hazards
Published in Critical Reviews in Environmental Science and Technology, 2022
Lucas Panneel, Govindan Malarvannan, Philippe G. Jorens, Adrian Covaci, Antonius Mulder
Plasticizers are chemical compounds added to rigid plastics, such as polyvinyl chloride (PVC), to make them more flexible, softer and extend their lifetime. Phthalates are the best-known and most widespread group of plasticizers. Human exposure to these phthalates is ubiquitous and occurs from various environmental sources, including food, dust, pharmaceuticals and household products (Wallner et al., 2016). Another route of exposure is through plastic medical devices, which for a long time have been mainly plasticized with di-(2-ethylhexyl) phthalate (DEHP). Due to low cost, enhanced flexibility, elasticity and physical stability, DEHP is incorporated in many (invasive) medical devices, such as intravenous (IV) infusion sets, IV storage bags, endotracheal tubes, nasogastric tubes and blood bags (Lai & Bearer, 2008; Malarvannan et al., 2019). However, phthalates, such as DEHP, have been reported to leach from plastic products into the environment and the human body due to their lipophilic nature and noncovalent binding to PVC. Once the parent compound enters the body (see Figure 1), hydrolysis will occur, producing mono-ester metabolites (e.g., mono-(2-ethylhexyl) phthalate (MEHP) from the initial di-ester DEHP). This process is catalyzed by lipases and esterases (Bui et al., 2016; Wang et al., 2019). MEHP undergoes further phase I metabolism into secondary oxidative or hydroxylated metabolites. Phase II metabolism involves the conjugation of all metabolites through glucuronidation (via UDP-glucuronyl-transferase) and enhances urinary excretion (Wang et al., 2019).
Plastic microbeads: small yet mighty concerning
Published in International Journal of Environmental Health Research, 2021
Shaima S. Miraj, Naima Parveen, Haya S. Zedan
In order to improve certain desirable properties of the plastic, several organic substances have been added during the production of plastic material. These substances are called as additives. Molecular size is the major property of the additive when evaluating how fast it migrates through and out of the plastic (Hahladakis et al. 2017). Smaller additive will migrate faster. Additives are the hazardous substances added to the plastic as reported by Norwegian Environment Agency in 2013. They revealed that 43 substances added in plastic products are listed in the Norwegian list of hazardous substances (Thomas and Naes 2014). Plasticizers, fillers, stabilizers, colorant, curing agents, coupling agents, antistats are the types of additives used in plastic materials. Plasticizers are added to inflexible plastics to make it more flexible. Two types of plasticizers are used internal plasticizers and external plasticizers. Internal plasticizers are added into the plastic while processing the polymer whereas external plasticizers are added after polymerization. The plasticizers are mostly used as softener for hard plastic material and more than 90% of all additives are used in conjunction with PVC (Cadogan and Howick 2000; Heudorf et al. 2007; Salvo et al. 2019).
Emerging contaminants in the atmosphere: Analysis, occurrence and future challenges
Published in Critical Reviews in Environmental Science and Technology, 2019
Pedro José Barroso, Juan Luis Santos, Julia Martín, Irene Aparicio, Esteban Alonso
Plasticizers are substances added to the material in order to achieve optimum flexibility characteristics and to be able to process these materials more easily. Plasticizers include compounds like BPA, phthalates and non-chlorinated OPE. They help to reduce the yield strength, the viscosity of the material and allow working at lower temperatures during the manufacturing process. Thereby, these compounds are added to a wide spectrum of products such as polyvinylchlorine products, building materials and even toys, but also clothing, perfumes and food packaging (Annamalai & Namasivayam, 2015). BPA is one of the most studied endocrine disruptors in the world (Beronius, Rudén, Hakansson, & Hanberg, 2010). Its fundamental use is to produce epoxy resins and polycarbonate plastics fulfilling the role of monomer. The air emissions of BPA have been estimated at 16,584 kg year−1 (EC European Union Risk Assessment Report, 2010; Salapasidou et al., 2011). Fu and Kawamura (2010) investigated the abundance and the spatial and temporal distributions of BPA in the atmospheric aerosols collected at urban, rural and marine sites, as well as the polar regions. The concentrations of BPA (1–17,400 pg m−3) range between more than 4 orders of magnitude in the world, with a declining trend from the continent (except for Antarctica) to remote sites. These data indicate that the continuous presence of BPA in the atmosphere may generate problems in human and animal health, being necessary an evaluation of effects on them, in order to control its emission sources (for example, from plastic burning).