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Introduction to Thermoplastic Composites
Published in R. Alagirusamy, Flexible Towpregs and Their Thermoplastic Composites, 2022
Among these three categories the isotactic PP has the highest melting point due to its high degree of crystallinity. This isotactic PP is mainly used as a matrix for composites and other industrial applications. The molecular weight and molecular weight distribution of any polymer affect its properties, especially the rheological and mechanical properties. PP has a very high molecular weight (Mw = 220,000 – 700,000) and high molecular weight distribution (Mw/Mn = 5.6 – 11.9). PP has a density of 0.906 g/cm3, which is lower than PE, but its glass transition temperature and melting temperature are higher than that of PE. Polypropylene has high toughness, good di-electrical properties and high chemical resistance, but it is susceptible to degradation by UV radiation. PP is available in different shapes such as chips, film, fibres, tapes etc. and it can be processed by compression moulding, injection moulding, blow moulding, extrusion and thermoforming techniques (Pleşa et al. 2019).
Introduction to Circular Economy and Recycling Plastics
Published in Rupinder Singh, Ranvijay Kumar, Additive Manufacturing for Plastic Recycling, 2022
Deepika Kathuria, Monika Bhattu
Closed-loop recycling, often known as “upcycling or horizontal recycling,” keeps the recovered plastic materials designed and manufactured qualities the same as their virgin counterparts. As a result, the recycled plastic can be utilized to make the same products as before. However, with the use of different ingredients, the product produced can be completely new. Recycling of PET bottles into new bottles is as an example of closed-loop recycling (Ahvenainen, 2003). Polymers such as polypropylene (PP) and high-density polyethylene (HDPE) can be recycled through this process as the properties remain intact in the manufacturer's products as of the original product (www.exeley.com). On the other hand, the designed and manufactured features of recycled plastic materials are degraded to use the material to generate other products which may be of lower-quality goods than the ones from which they were originally recovered. This process is known as open-loop recycling, also termed “downcycling” or “cascading” (Eriksen et al., 2019). Formation of PET fibers from PET bottles illustrates an example of the open-loop recycling process. Figure 1.3 depicts the closed- and open-loop recycling of PET bottles. Unfortunately, the currently known mechanical recycling processes are limited due to the following reasons: a) cost, b) inconsistency in the product quality, and c) mechanical properties degradation.
Plastics
Published in Arthur Lyons, Materials for Architects and Builders, 2019
Polypropylene (PP), with a softening point of 150°C, is slightly stiffer than polyethylene, to which it is closely related chemically. Like polyethylene, it is resistant to chemicals and susceptible to ultraviolet light, but unlike polyethylene it becomes brittle below 0°C. However, the block copolymer with ethylene does have improved low-temperature impact resistance. Polypropylene is used for pipes, drainage systems, water tanks, DPCs, connecting sleeves for clay pipes and WC cisterns. Polypropylene fibres are used in fibre-reinforced concrete to produce an increase in impact resistance over the equivalent unreinforced material. Polypropylene permanent shuttering for concrete is frequently a double-layer system, incorporating polystyrene insulation and radon protection where necessary. Certain breather membranes used for tile underlay and timber frame construction are manufactured from multilayer systems, incorporating polypropylene with polyethylene and glassfibre reinforcement. Such products are wind- and watertight but vapour-permeable. Many geotextiles for soil stabilisation are manufactured as a mat material from non-woven heat-bonded polypropylene continuous fibres. The material may be reinforced by woven polyester fibres. Polypropylene is highly fatigue-resistant, and therefore used for integral hinges in lightweight components.
The surface softness and mechanical properties of wood pulp–lyocell wet-laid nonwoven fabric
Published in The Journal of The Textile Institute, 2021
The demand of nonwoven materials for personal hygiene care, beauty care, medical care and household wipe cleaning products are growing massively in decade. Over 30% of nonwoven application is accounted for hygiene product, followed by 17.9% for construction and building materials, and 14.8% for household and industrial products (Sengupta & Debnath, 2019). Production of nonwoven is dominated by man-made fiber made from synthetic, natural, and inorganic materials with proportion polypropylene 63%, polyester 23%, viscose rayon 8%, acrylic 2%, polyamide 1.5%, and other specialty fiber 3% (Sengupta et al., 2019; Sengupta & Debnath, 2018). Polypropylene is the mostly used raw material since it provides good strength and abrasion resistance, good thermal and chemical stability, low density, and having hydrophobicity. These unique properties offer the nonwoven produced with excellent combination properties but mostly are non-biodegradable (Hubbe & Koukoulas, 2016). Thus, increasing the demand of nonwoven lead to increase environmental pollution (Hubbe & Koukoulas, 2016).
Estimation of biaxial tensile and compression behavior of polypropylene using molecular dynamics simulation
Published in Advanced Composite Materials, 2019
Ryuta Kitamura, Tomoya Kageyama, Jun Koyanagi, Shinji Ogihara
Polypropylene is one of the polymer materials that is inexpensive, lightweight, and has excellent formability, specific strength, and specific rigidity. Thus, it is expected to be used for automobile parts requiring light weight in the form of a neat material or matrix material of carbon fiber reinforced thermoplastic (CFRTP) [1–3]. Generally, polypropylene shows strong time–temperature dependency, and viscoelastic behavior [4–6]. The CFRTP also shows viscoelastic behavior due to its base resin material. Therefore, it is important to evaluate the viscoelastic behavior of the neat polypropylene resin matrix. Furthermore, the time–temperature superposition principle [7–13] and Arrhenius equation [14–18] are used to estimate long-term viscoelastic behaviors such as creep and stress relaxation. We have reported the verification of this concept for estimating the viscoelastic deformation in our previous paper [11]. Although it is important to consider the durability of materials in evaluating their reliability, there are a few reports on applying this concept to material destruction.
Electrochemical determination of urea using a gold nanoparticle-copolymer coated-enzyme modified gold electrode
Published in Instrumentation Science & Technology, 2019
Seyda Korkut, Sinan Uzuncar, Muhammet Samet Kilic, Baki Hazer
Polypropylene is a hydrophobic polymer which has a low cost, good mechanical property, and excellent recyclability.[1011121314] In our previous study, enzymatic fuel cell electrodes were coated with a nanocomposite, with excellent characteristics, was synthesized by combining gold nanoparticles with polypropylene chain.[15] The nanocomposite showed excellent adsorption capacity and provided fast electron transfer, yielding efficient energy production from municipal wastewater. In the present study, a gold nanoparticle embedded poly(propylene-co-imidazole)-coated gold electrode was used for the first time for the electrochemical detection of urea. The enzymatically produced ammonium was electrooxidized on the electrode with the aid of gold nanoparticles in the polymer chain. The biosensor offered relatively long storage stability and a good operational stability. The application of the designed biosensor to the sewage water real sample was conducted. The effect of possible interferants on the urea signals was also investigated.