Thermoplastic-based disposal

Advantages The major advantages of the thermoplastic-based disposal systems are by dispiosin of the waste in a dry condition, the overall volume of the waste is greatly reduced most thermoplastic matrix materials are resistant to attack by aqueous solutions microbial degradation is minimal most matrices adhere well to incorporated materials, therefore, the final product has good strength and materials embedded in a thermoplastic matrix can be reclaimed if needed. 

Disadvantages The principal disadvantages of the thermoplastic-based disposal systems are the following (1) expensive, complicated equipment requiring highly specialized labor is necessary for processing (2) the plasticity of the matrix-waste mixtures may require that containers be provided for... 

South Korean company SK Chemicals produces SKYGREEN polybutylene succinate (PBS) thermoplastics based on aliphatic polyester and aliphatic/aromatic co-polyesters that were developed from SK Chemicals polyethylene terephthalate (PET) technology. SKYGREEN BDP products offer LDPE-like properties. They are used in films, disposable cutlery, food trays, hairbrush handles and paper coatings. Aliphatic versions biodegrade more rapidly and offer better processing and tensile properties than the aromatic-aliphatic grades, which cost less. 

Vesicular films have a honeycomb-like cross-section and are constructed of a polyester base coated with a thermoplastic resin and a light-sensitive diazonium salt. Photopolymer films contain carbon black as a substitute for silver. These films are processed in a weak alkaline solution that is neutralized prior to disposal. As such, they produce a nonhazardous waste. 

Polymer encapsulation is an ex situ S/S technique involving the application of thermoplastic resins such as bitumen, polyethylene and other polyelfins, paraffins, waxes, and sulfur-based cements, as opposed to cements and pozzolans. Polymer encapsulation has been used primarily to immobilize low-level radioactive wastes and those waste types that are difficult to immobilize in cement, such as Cl- and SO4-based salts. Bitumen (asphalt) is the least expensive and (hence) used most often. Thermoplastic encapsulation heats and mixes the contaminated soil with the resin at 130 to 230°C in an extrusion machine. Organic pollutants and water boil off during the extrusion and are collected for treatment or disposal. The final product, a stiff yet plastic resin, is then discharged into a drum or other container and land-filled (U.S. EPA, 1997). 

Natural polymers such as starch and protein are potential alternatives to petroleum-based polymers for a number of applications. Unfortunately, their high solubility in water limit their use for water sensitive applications. To solve this problem thermoplastic starches have been laminated using water-resistant, biodegradable polymers. For example, polylactic acid and P(3HB-co-3HV) were utilised as the outer layers of the stratified polyester/PWS (plasticized wheat starch)/polyester film strucmre in order to improve the mechanical properties and water resistance of PWS which made it useful for food packaging and disposable articles [65]. Moreover, improved physic-chemical interactions between P(3HB-CO-3HV) and wheat straw fibres were achieved with high temperature treatment. It resulted in increased P(3HB-co-3HV) crystallization, increased Young s moduli and lowered values of stress and strain to break than the neat matrix of P(3HB-co-3HV). There was no difference in the biodegradation rate of the polymer [66]. 

The fascinating properties exhibited by nanoparticles, such as blue shift of the absorption spectrum, size-dependent luminescence, etc., are various manifestations of the so-called quantum confinement effect. These unique properties make ZnO a promising candidate for applications in optical and optoelectronic devices [35-38]. Polymer-based nanocomposites are the subject of considerable research due to the possibility of combining the advantages of both polymers and nanoparticles. There are several applications of polymeric nanocomposites based on their optical, electrical and mechanical properties. Further, nanocrystals dispersed in suitable solid hosts can be stabilized for long periods of time. Polystyrene (PS)— an amorphous, optically clear thermoplastic material, which is flexible in thin-film form—is often chosen as a host matrix because of its ideal properties for investigating optical properties. It is one of the most extensively used plastic materials, e.g., in disposable cutlery, plastic models, CD and DVD cases, and smoke-detector housings. 

Despite significant improvement in properties, disposal and recycling problems, combined environmental and societal concerns make continued use of petroleum-based nanocomposites unattractive. As a consequence, natural fibre-reinforced thermoset and thermoplastic composites have been intensively studied in the last... 

A number of reviews have been studied on the potential of natural fibers such as sisal, kenaf, hemp, flax, bamboo, and jute for the preparation of thermoplastic composites. In this work, however sisal fiber (SF) has been used as reinforcement due to easily availability and comparatively low cost. The xmtreated and treated SF-reinforced RPP composites have been prepared and investigated their thermal, mechanical, morphological, weathering and impact properties. An improved mechanical, thermal, and morphological property has been observed for chemical treated SF as well as clay loaded RPP. The analysis revealed that SF-reinforced RPP composites with enhanced properties can be successfully achieved which warrants to replace the synthetic fillers-based conventional thermoplastic composites. These SF-based RPP composites can be the material of choice in the field of aeronautic, automobiles, civil engineering, etc., due to its low cost, low density, non-toxicity, recyclability, acceptable strength, high specific properties, and minimum waste disposal problems. 

The environmental impact of disposable products is becoming a major concern throughout the world in recent years [6-7], These disposable products are usually produced from traditional thermoplastic resins, such as polypropylene (PP), polyethylene (PE), polyester (PET), polyamide (PA), polycarbonate (PC), which are not biodegradable. However, due to increasing environmental consciousness and demands of legislative authorities, the manufacture, use and removal of products made of such traditional polymers are considered more critically. The remedy to this problem could be found in the development of substitute products based on biodegradable, and ideally from natural and renewable materials. 

Pressure sensitive adhesives based on a variety of elastomers and applied from either latex, solvent, or hot melt systems have shown rapid growth in recent years. In addition, the development of hot melt assembly adhesives based on the styrenic thermoplastic elastomers is a key factor in the production of disposable diapers and other sanitary products. Even though the current emphasis of elastomer-based adhesive development is on pressure sensitive adhesives, large volumes of solvent cements, latex cements, and mastics are still produced. 

The business system for thermoplastics is illustrated in Figure 11.9, where both a renewable-based system and a petrochemical-based system are shown. The major difference in these two systems is that in the renewable-based system the raw material is com, while in the petroleum-based system it is petroleum. Both systems use fossil resources for process energy. Both systems make a plastic product that needs to be disposed at the end of its useful life. Another difference between a PLA and a petrochemical-based system is that PLA can be conventionally recycled, re-monomerizedback to lactic acid, or composted. 

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