Subject:
All Disciplines Arts & Humanities Biology & Life Sciences Business & Economics Chemistry & Materials Science Computer Science & Mathematics Engineering Environmental & Earth Sciences Medicine & Pharmacology Physical Sciences Public Health & Healthcare Social Sciences
Sort:
Most Viewed Latest Alphabetical (A-Z) Alphabetical (Z-A)
Filter:
All Topic Review Biography Peer Reviewed Entry Video Entry
Topic Review
Pyrolysis
Pyrolysis: Thermochemical decomposition of organic materials in the absence of oxygen. Polymer-derived carbon: Carbon obtained by heat-treatment (pyrolysis followed by carbon-carbon bond formation and rearrangement) of natural or synthetic polymers. In addition to the supplied heat, surrounding gaseous environment, presence of magnetic field and applied pressure influence pyrolysis.
  • 3.7K
  • 01 Nov 2020
Topic Review
Covalent Adaptable Networks
Thermosets are known to be very reliable polymeric materials for high-performance and light-weight applications, due to their retained dimensional stability, chemical inertia and rigidity over a broad range of temperatures. However, once fully cured, they cannot be easily reshaped or reprocessed, thus leaving still unsolved the issues of recycling and the lack of technological flexibility. Vitrimers, introduced by Leibler et al. in 2011, are a valiant step in the direction of bridging the chasm between thermoplastics and thermosets. Owing to their dynamic covalent networks, they can retain mechanical stability and solvent resistance, but can also flow on demand upon heating. More generally, the family of Covalent Adaptable Networks (CANs) is gleaming with astounding potential, thanks to the huge variety of chemistries that may enable bond exchange. Arising from this signature feature, intriguing properties such as self-healing, recyclability and weldability may expand the horizons for thermosets in terms of improved life-span, sustainability and overall enhanced functionality and versatility. In this review, we present a comprehensive overview of the most promising studies featuring CANs and vitrimers specifically, with particular regard for their industrial applications. Investigations into composites and sustainable vitrimers from epoxy-based and elastomeric networks are covered in detail.
  • 3.6K
  • 26 Oct 2020
Topic Review
Poly(lactic Acid)
Poly(lactic Acid) is one of the most promising polymers used in these applicationsand is properly called “polymer of the 21st century “. It is the only one, synthesized on a greater scale that is concurrently: biocompatible, biodegradable and biobased. PLA is an aliphatic biobased polyester derived from lactic acid (2-hydroxypropionic acid), which is mostly derived from animal or plant sources such as cellulose, starch, corn, fish waste and kitchen waste.
  • 3.5K
  • 15 Jun 2021
Topic Review
Electroactive Polymers
Electroactive polymers (EAPs) are a versatile class of electrically deformable polymers. These polymers have the ability to deform when excited by electrical potentials due to their inherent electro-mechanical properties. The piezoelectric couplings in EAPs provide them with unique capabilities that are of significant interest in actuators and soft robotics.
  • 3.3K
  • 12 Oct 2021
Topic Review
Water-Soluble Photoinitiators in Biomedical Applications
Light-initiated polymerization processes are currently an important tool in various industrial fields. The advancement of technology has resulted in the use of photopolymerization in various biomedical applications, such as the production of 3D hydrogel structures, the encapsulation of cells, and in drug delivery systems. The use of photopolymerization processes requires an appropriate initiating system which, in biomedical applications, must meet additional criteria: high water solubility, non-toxicity to cells, and compatibility with visible low-power light sources. This article is a literature review on those compounds that act as photoinitiators of photopolymerization processes in biomedical applications. The division of initiators according to the method of photoinitiation was described and the related mechanisms were discussed. Examples from each group of photoinitiators are presented, and their benefits, limitations and applications are outlined.
  • 3.1K
  • 10 Jun 2020
Topic Review
Citric Acid for Wood Modification
Citric acid (CA) can be found naturally in fruits and vegetables, particularly citrus fruit. CA is widely used in many fields but its usage as a green modifying agent and binder for wood is barely addressed. Esterification is one of the most common chemical reactions applied in wood modification. CA contains three carboxyl groups, making it possible to attain at least two esterification reactions that are required for crosslinking when reacting with the hydroxyl groups of the cell wall polymers. In addition, the reaction could form ester linkages to bring adhesivity and good bonding characteristics, and therefore CA could be used as wood binder too. The environmental impacts and future outlook of CA-treated wood and bonded composite are considered.
  • 3.0K
  • 31 Jul 2020
Topic Review
Poly (Butylene Succinate) and PBS Copolyesters Degradation
The impact of plastics on the environment can be mitigated by employing biobased and/or biodegradable materials (i.e., bioplastics) instead of the traditional “commodities”. Poly (butylene succinate) (PBS) emerges as one of the most promising alternatives due to its good mechanical, thermal, and barrier properties, making it suitable for use in a wide range of applications. Nevertheless, less information regarding PBS biodegradation is available, as research is still ongoing. PBS degradation methods include hydrolytic degradation, enzymatic degradation, and biodegradation in environmental conditions, such as burial, activated sludge, and compost.
  • 3.0K
  • 22 Mar 2022
Topic Review
Aggregation-Induced Emission and Fluorescent Mechanochromism
Mechanochromic fluorescent polymers are defined as materials that are able to detect a mechanical stress through a fluorescence output. This feature has evoked a growing interest in the last decades, thanks to the progress of fluorogenic molecules whose optical characteristics and chemical functionalities allow their effective insertion in many thermoplastic and thermoset matrices. Among the different types of fluorogenic probes able to detect mechanical solicitations, those with aggregation-induced emission (i.e., AIEgens) have attracted tremendous interest since their discovery in 2001. In this contribution, the main principles behind the AIEgens working behavior are introduced along with the current state of knowledge concerning the design and preparation of the derived mechanochromic fluorescent polymers. Examples are provided concerning the most ingenious solution for the preparation of chromogenic materials, starting from dierent types of commodity plastics or synthetic polymers and combined with the latest AIE technology to provide the most sensitive response to mechanical stress.
  • 2.9K
  • 30 Oct 2020
Topic Review
Elongational Flow
Elongational flow is a particular kind of flow involved in many industrially relevant processing operations of thermoplastics (such as fiber spinning, film blowing, foaming and thermoforming) in which the velocity gradient develops in the same direction as the flow itself.
  • 2.9K
  • 26 Oct 2021
Topic Review
Polystyrene vs. Polylactide
Polystyrene (PS) is a thermoplastic polymer made of aromatic hydrocarbon monomer styrene that is derived from fossil-fuels. The synthesis of PS is based on the free radical polymerization of styrene using free-radical initiators. It is mostly used in solid (high impact and general purpose PS), foam and expanded PS forms. The main advantages of PS are low-cost, easy processing ability, and resistance to ethylene oxide, as well as radiation sterilization. Polylactide (PLA)—biodegradable and compostable aliphatic polyester—is one of the key biopolymers with the largest market significance. 
  • 2.9K
  • 28 Dec 2022
Topic Review
Ultra-Heat Treatment on Milk Proteins
Milk contains approximately 3.5% by weight protein, which is a highly complex system. This milk protein is usually divided into two main fractions based on their solubility nature. Casein proteins are about 75% to 80% of the total protein in the milk and precipitate at pH 4.6 at 20 °C, while 20% of the protein remains in the serum.
  • 2.8K
  • 07 Oct 2021
Topic Review
Semiconductor Gas Sensors
Semiconductor materials include metal oxides, conducting polymers, carbon nanotubes, and 2D materials. Metal oxides are most often the first choice due to their ease of fabrication, low cost, high sensitivity, and stability. Some of their disadvantages are low selectivity and high operating temperature. Conducting polymers have the advantage of a low operating temperature and can detect many organic vapors. They are flexible but affected by humidity. Carbon nanotubes are chemically and mechanically stable and are sensitive towards NO and NH3, but need dopants or modifications to sense other gases. Graphene, transition metal chalcogenides, boron nitride, transition metal carbides/nitrides, metal organic frameworks, and metal oxide nanosheets as 2D materials represent gas-sensing materials of the future, especially in medical devices, such as breath sensing.
  • 2.8K
  • 10 Dec 2020
Topic Review
Polyethylene Terephthalate
Terephthalate (PET) is one of the most significant modern plastics to be invented. PET is a semi-crystalline polymer, with mechanical properties that depend on crystallinity level. This material is considered to be a thermoplastic polyester material, which is now used globally. 
  • 2.8K
  • 08 Feb 2021
Topic Review
Modified Starch-Based Adhesives
Consumer trends towards environmentally friendly products are driving plastics industries to investigate more benign alternatives to petroleum-based polymers. In the case of adhesives, one possibility to achieve sustainable production is to use non-toxic, low-cost starches as biodegradable raw materials for adhesive production. While native starch contains only hydroxyl groups and has limited scope, chemically modified starch shows superior water resistance properties for adhesive applications. Esterified starches, starches with ester substituents, can be feasibly produced and utilized to prepare bio-based adhesives with improved water resistance. Syntheses of esterified starch materials can involve esterification, transesterification, alkylation, acetylation, succinylation, or enzymatic reactions.
  • 2.8K
  • 31 May 2022
Topic Review
Biological Degradation of Polymers
Biodegradable plastics can make an important contribution to the struggle against increasing environmental pollution through plastics. This entry provides an overview of the main environmental conditions in which biodegradation takes place and then presents the degradability of numerous polymers. 
  • 2.7K
  • 23 Nov 2020
Topic Review
Basalt Fiber-reinforced Polymer Properties
Reducing the fingerprint of infrastructure has become and is likely to continue to be at the forefront of stakeholders’ interests, including engineers and researchers. It necessary that future buildings produce minimal environmental impact during construction and remain durable for as long as practicably possible
  • 2.7K
  • 08 May 2021
Topic Review
Low Molecular Weight Chitosan
Chitosan is a biopolymer with high added value, and its properties are related to its molecular weight. Thus, high molecular weight values provide low solubility of chitosan, presenting limitations in its use. Based on this, several studies have developed different hydrolysis methods to reduce the molecular weight of chitosan.
  • 2.6K
  • 13 Aug 2021
Topic Review
Lignin
Lignin is an extremely abundant substance that has a chemical functionality that endows it with the necessary properties to be an attractive platform material for the new millennium. We must continue to explore and exploit its potentiality as a stand-alone material, raw feedstock for refining to chemicals, polymeric filler, and co-composite material. This review highlights hardwood-derived lignin, a little explored form of lignin, as a promising platform material.
  • 2.4K
  • 13 Aug 2020
Topic Review
Polyethylene Composites
Polyethylene (PE) is one the most used plastics worldwide for a wide range of applications due to its good mechanical and chemical resistance, low density, cost efficiency, ease of processability, non-reactivity, low toxicity, good electric insulation, and good functionality.
  • 2.4K
  • 10 Feb 2021
Topic Review
Polymer-Derived Ceramics
Ceramics derived from organic polymer precursors, which have exceptional mechanical and chemical properties that are stable up to temperatures slightly below 2000 °C, are referred to as polymer-derived ceramics (PDCs).
  • 2.4K
  • 09 Feb 2021
  • Page
  • of
  • 23
Featured Entry Collections
>>

Featured Books

>>
Encyclopedia of Social Sciences
Encyclopedia of COVID-19
Encyclopedia of Fungi
Encyclopedia of Digital Society, Industry 5.0 and Smart City
ScholarVision Creations
Feedback