Open windrow composting of polymers: An investigation into the rate of degradation of polyethylene

The compostability of degradable polymers under open windrow composting conditions is explored within this paper. Areas for consideration were the use of, and impacts of, degradable polyethylene (PE) sacks on the composting process and the quality of the finished compost product. These factors were investigated through polymer weight loss over the composting process, the amount of polymer residue and chemical contaminants in the finished compost product, the windrow temperature profiles and a bioassay to establish plant growth and germination levels using the final compost product. This trial also included a comparative study of the weight loss under composting conditions of two different types of ‘degradable’ polymer sacks currently on the European market: PE and a starch based product. Statistical analysis of the windrow temperature profiles has led to the development of a model, which can help to predict the expected trends in the temperature profiles of open compost windrows where the organic waste is kerbside collected using a degradable PE sack

Bioplastics made from upcycled food waste. Prospects for their use in the field of design

In recent years, the negative effects on the environment of the intensive use of synthetic, oil-derived plastics to make products, even those with a limited required duration, have given renewed impetus to the search for biodegradable and/or compostable materials obtained from renewable sources, particularly biopolymers derived from vegetable, animal or microbial matter that could prove a valid alternative in a number of applications: not only in the packaging industry, but also for making objects with a longer required duration. Indeed, as well as offering the possibility of being used as they are, immediately after having undergone traditional-type mechanical processing, it is also possible to mix, supplement and modify them both on a macro- and nanometric scale, allowing us to significantly increase their properties and performance and adapt them to a wide variety of needs. However, the real challenge is to create new materials from food waste and not from specially grown crops, whose production has, in any case, an environmental cost. This allows us to reduce the waste produced when processing foods, which is usually a practical problem and involves a considerable investment in economic terms. It also helps us address one of the worst problems of our time: that of the waste that sees a third of the food produced worldwide lost along the various steps of the food production chain. There is an enormous variety of vegetable, animal and microbial waste that can be used to create biopolymers: from the orange peels left over from fruit juice production to the grapes used to produce wine; from chocolate production waste to egg shells and prawns. We can extract the starches, cellulose, pectin, chitin, lactic acid, collagen, blood proteins and gelatin that form the basis of bioplastics from these materials, either extracting them directly or using mechanical or chemical processes. These are true ‘treasure troves’ of substances that can become useful materials thanks to processes of varying complexity. In recent years, the testing of substances made from food waste has increased significantly; the sheer abundance of raw materials that can be used to make them has encouraged institutional research, as well as an approach to project development that has been widely embraced by many young designers who craft these materials. Nevertheless, there is still no systematic record of the results achieved. This has slowed down their adoption, which in contrast offers enormous potential that is still almost entirely unexplored. This paper considers all aspects of these materials, starting with the most interesting experiments underway, and envisages possible future scenarios

Equilibrium and dynamic moisture adsorption behaviour of bloodmeal based bioplastic

Bioplastics can be manufactured from protein or carbohydrate sources such as wheat gluten, corn, sun flower, keratin, casein, soy, gelatine and whey. A recently developed bioplastic is Novatein thermoplastic (NTP), which is produced from bloodmeal by adding water, urea, sodium sulphite, sodium dodecyl sulphate and tri-ethylene glycol (TEG), allowing it to be extruded and injection moulded. Bioplastics, compared to their petroleum counterparts, can readily adsorb or lose water, which then changes their physical properties such as tensile strength and glass transition temperature. NTP at different TEG and water contents was exposed to 20-85% relative humidity (RH) environments and change in mass recorded over 35 days to determine equilibrium and dynamic moisture adsorption behavior. Equilibrium behavior was modelled using modified Freundlich and Langmuir- Freundlich isotherms, and dynamic behavior modelled using Pilosof, Singh- ulshrestha, exponential, Langmuir-Freundlich and simple rate equations. Excellent fits were obtained for both isotherms and the last three rate equations gave best overall fits for dynamics. NTP adsorbed up to 28% by weight in water at 85% RH, reaching equilibrium within 20 days. Plastics with high TEG had a greater affinity for water but lower water adsorption rates, while dry plastic samples had a lower adsorption rate than wet samples. The two parameter Freundlich model and the exponential or simple rate model is recommended for modelling NTP equilibrium and dynamic water adsorption

Assessment of polymer-based nanocomposites biodegradability

The management of solid waste is a growing concern in many countries. Municipal solid waste is a major component of the total solid waste generated by society, and the composting of municipal solid waste has gained some attention even though a composting treatment for it is not yet widespread. It may not be realistic to replace large portions of these plastics with biodegradable materials, and it may be more important to separate plastics unsuitable for the composting process at the generating spots. However, for food packaging, there is still a great deal of interest in using biodegradable plastics that are difficult to sort at the generation spots. Under these circumstances, nanocomposites of biodegradable polymers as matrix and nanoparticles, that can be degraded along with organic wastes during composting could be a solution. Therefore, this chapter aims to give an overview on the biodegradability studies of bio-nanocomposites. It will focus on different polymers, nanocomposites containing different clay types and inorganic particles exposed under different environments.(undefined

PLA/WOOD BIOCOMPOSITES: IMPROVING COMPOSITE STRENGTH BY CHEMICAL TREATMENT OF THE FIBERS

A resol type phenolic resin was prepared for the impregnation of wood particles used for the reinforcement of PLA. A preliminary study showed that the resin penetrates wood with rates depending on the concentration of the solution and on temperature. Treatment with a solution of 1 wt% resin resulted in a considerable increase of composite strength and decrease of water absorption. Composite strength improved as a result of increased inherent strength of the wood, but interfacial adhesion might be modified as well. When wood was treated with resin solutions of larger concentrations, the strength of the composites decreased, first slightly, then drastically to a very small value. A larger amount of resin results in a thick coating on wood with inferior mechanical properties. At large resin contents the mechanism of deformation changes; the thick coating breaks very easily leading to the catastrophic failure of the composites at very small loads