Plastic pollution is a pervasive and growing problem. To estimate the effectiveness of interventions to reduce plastic pollution, we modeled stocks and flows of municipal solid waste and four sources of microplastics through the global plastic system for five scenarios between 2016 and 2040. Implementing all feasible interventions reduced plastic pollution by 40% from 2016 rates and 78% relative to "business as usual" in 2040. Even with immediate and concerted action, 710 million metric tons of plastic waste cumulatively entered aquatic and terrestrial ecosystems. To avoid a massive build-up of plastic in the environment, coordinated global action is urgently needed to reduce plastic consumption; increase rates of reuse, waste collection, and recycling; expand safe disposal systems; and accelerate innovation in the plastic value chain.

This chapter looks at the production of plastic and the recycling of plastic from an industrial point of view. Overviews are given of worldwide plastic production and the management of plastic waste. The recycling of plastic is looked at in-depth from the point of view of collection, recycling facilities, current advances, economic issues, and finally challenges and opportunities for improving plastic recycling.

Plastics and plastic packaging have become increasingly dominant in the consumer marketplace since their commercial development in the 1930 and 1940s and are now a ubiquitous part of 21st century life. According to Jambeck et al. (2015), at least eight million tons of plastics leak into the oceans every year. There is over 150 million tons of plastic waste in the oceans today, and without significant intervention, there could be more plastic than fish in the seas, by weight, by 2050 (Ocean Conservancy, 2015). The problems start on land. After being discarded, plastic is often inefficiently managed and therefore leaks into the oceans. Of the eight million tons of plastic that enters the world's ocean every year, less than 20% comes from ocean-based sources like fisheries and fishing vessels; the remaining 80% originates from land-based sources (GESAMP, 2015). This massive increase in plastic-waste leakage derives primarily from the increase in the use of plastics in fast-growing economies with underdeveloped waste management systems. The study by Jambeck et al. on 192 coastal countries estimates that they create 275 million tons of garbage annually, of which 4.8 to 12.7 million tons of plastics end up in the oceans. Currently. there are no effective tools available to collect and clean up the accumulation of plastics and microplastics once they have reached the oceans. Prevention at source is therefore the key action required to deal with plastics pollution and its associated impacts. A short list of six critical actions that need to be taken is included in the article. In response to growing concern over plastic waste in the oceans, individuals, community groups, businesses, and governments have initiated a wide range of programs to try and curtail the growth rate of plastics leakage from land sources. Some of these initiatives are detailed in the body of this article. In addition, a range of international, regional, and European agreements and conventions have been developed to protect the oceans from dumping and contamination. These important protocols typically require the adoption of measures aimed at controlling, reducing, and preventing pollution from land-based activities, from ships, from seabed and land-based activities, and from airborne pollution. These are useful frameworks that help governments of coastal countries to jointly work on these problems, but to date, they have not halted the continued increase in plastics pollution of the oceans.

Plastics are being manufactured globally at a rate exceeding 335 million tonnes annually and 8.3 billion tonnes have been made since the 1960's, with 4.9 billion tonnes accumulating in landfills or in the natural environment. The leakage of mismanaged plastics into rivers and oceans is now globally obvious and impacting the lives of birds and sea life. The recycling rate of manufactured plastics is only 9% and there is pressure to reduce the level of wastage and to dramatically increase the level of recycled plastics in short and long term products. This will involve stringent and tightly controlled recycling processes so that the recycled plastics can displace virgin plastics, especially in short lived applications such as food packaging. This article reviews the technologies and criteria that can be used to achieve food grade quality recycled plastics and novel ways of overcoming long standing gaps in recycling related to black plastics and identifying prior food grade usage. The boost in recycling efficiency through the use of these technologies will not only address the plastics wastage problem by creating a circular demand via higher recycled content, but also make plastics recycling technically more efficient and profitable thereby ensuring wide and long term adoption of recycling practices.

Kuraray, EVAL Europe N.V. (EE) produces Ethylene Vinyl Alcohol copolymers (EVALTM), which are used in multilayer structures in a combination with a wide range of materials such as High Density Polyethylene (HDPE) to produce multilayer bottles to provide superior barrier properties to gases, flavours or bring functional barriers against external contaminants such as mineral oils (MOSH,MOAH). Bottles are typically made by CoExtrusion blow moulding (Co-EBM) technology and are used for beverage packaging such as dairy products and specialty milk and other packaging applications for sauces or dressings or for the packaging of medical products for which the Water Barrier of HDPE is of added value. The objective of the study was to investigate if multilayer EVOH/HDPE rigid packaging material, which is a percentage of the post-consumer recycling stream, can be effectively sorted with the HDPE stream and decontaminated back to food grade approved for use as Post-Consumer Recycled (PCR)-HDPE into food packaging applications. Multilayer rigid food packaging found in the postconsumer recycling stream has been represented in the design of materials guides and recycling guides as ‘may be suitable’ for recycling. The present work investigates the recyclability of EVOH barrier packaging due to the growing trends of multilayer rigid food packaging and more importantly, as recovery systems strive towards a better circular economy. The steps taken to produce food grade rHDPE with analysis included; Audits of the HDPE fraction at Viridor MRF, testing on automated NIR sorting equipment at Tomra (Titech), compounding in a low pressure, elevated temperature, food-grade decontamination process and overall migration testing conducted by Smithers-Pira. The evaluation showed that post-consumer HDPE (rHDPE) material containing at least 0.25% EVOH (equivalent to 5% multilayer EVOH/HDPE packaging) can be “super cleaned” to food grade quality without any significant impact on the process performance or physical properties compared to rHDPE only. The results showed that at the levels of multilayer EVOH packaging typically found in the recycled HDPE stream, the rHDPE can be processed and utilized in a full range of applications, without impact on migration characteristics or physical properties compared to rHDPE alone. Introduction Food packaging has seen significant changes over recent decades with demand for pre-packaged food increasing, hence the requirement for research and development in barrier and shelf life extending materials. Demand for food packaging resin is also increasing with HDPE behind PET but above PP and PS. [1][2] Packaging must comply with food safety regulations to protect the consumer, therefore multilayer structures are essential in preserving and protecting the food. In certain cases, packaging provides a barrier to gas permeation because of the risk of microbial activity and food spoilage, in other cases, functional barrier helps keeping the food away from external contaminants. In Europe, the Plastics Regulation (EU) No 10/2011 defines layer B as a “functional barrier” if it reduces the level of migration of a substance from layer A to layer C to a level where it can meet regulatory limits. Section VII from the Food and Drug Administration (FDA) ‘Guidance for Industry: Use of Recycled Plastics in Food Packaging: Chemistry Considerations,’ defines the use of an effective barrier. Kuraray is a world leader in EVOH (ethylene vinyl-alcohol copolymers) production and technology. An EVALTM layer thickness of only a few microns helps avoid spoilage by keeping oxygen and odours out, while locking flavours, aromas and modified atmosphere inside the package. This prolongs shelf life reducing the need for artificial additives to be added into food. Fewer resources can often be used for the same packaging function. Optimized portion size, light weight and extended freshness help improve the efficiency of storage, transport and display, saving costs and preserving resources. Kuraray quote that “1 mm of EVALTM provides about the same gas barrier properties as a 10 metre thickness of LDPE.” [4] EVOH will continue to be used in packaging for these reasons and ideally would be recycled with minimal detrimental effects in the polyolefin industry. It is well known that EVOH offers great barrier protection against oxygen, odours and gases however EVOH has also been reported to absorb significant amounts of moisture in humid conditions which is why multilayer structures are needed. Kuraray, EVAL Europe N.V. produces Ethylene Vinyl Alcohol copolymer (EVOH) which is used in blow moulded HDPE multilayer bottles to provide gas barrier SPE ANTEC Anaheim 2017 / 493 properties for juice or specialised milk products. Food grade recycled HDPE (rHDPE) is produced in UK and other countries, primarily from clear (natural) coloured monolayer blow moulded white (fresh) milk bottles and is used back into the manufacture of new milk bottles at approximately 15%, providing closed loop recycling of this material in the UK. The food grade rHDPE is a commercial material currently only available from a few suppliers, but it will be available from an additional number of recyclers in the UK and other countries in the near future. For PP, the recyclability characterization in the WRAP guidance states that EVOH if less than 10% of total pack weight is ‘not ideal’ (Category B) and if above 10% pack weight then it is classed as ‘detrimental’ (Category C). For HDPE milk bottle recyclability, co-extruded EVOH barriers are within category C. Category B recommends coextruded tie-layer functional polyolefins if less than 3% total bottle weight. These constraints could have better definitions to enable manufacturers of EVOH to participate in the circular economy with growing pressures on recycling. Kuraray, EVAL Europe N.V. wanted to investigate in detail that multilayer natural coloured HDPE/EVOH material can be effectively recycled as a percentage of the post-consumer stream and used back into food packaging and applications. Nextek assisted with conducting this study and trials and evaluation of the recycling process with blow moulded multilayer HDPE barrier bottles. Food grade rHDPE recycling involves sorting that removes colored HDPE, although some white is often retained. The performance of EVOH was also assessed during the food grade decontamination or super cleaning stage to confirm that the presence of EVOH does not negatively impact on the process or the properties of the final food grade material. Market applications and percentage of EVOH in

The majority of disposable cups are made from paper plastic laminates (PPL) which consist of high quality cellulose fibre with a thin internal polyethylene coating. There are limited recycling options for PPLs and this has contributed to disposable cups becoming a high profile, problematic waste. In this work disposable cups have been shredded to form PPL flakes and these have been used to reinforce polypropylene to form novel paper plastic composites (PPCs). The PPL flakes and polypropylene were mixed, extruded, pelletised and injection moulded at low temperatures to prevent degradation of the cellulose fibres. The level of PPL flake addition and the use of a maleated polyolefin coupling agent to enhance interfacial adhesion have been investigated. Samples have been characterised using tensile testing, dynamic mechanical analysis (DMA) and thermogravimetric analysis. Use of a coupling agent allows composites containing 40 wt.% of PPL flakes to increase tensile strength of PP by 50% to 30 MPa. The Young modulus also increases from 1 to 2.5 GPa and the work to fracture increases by a factor of 5. The work demonstrates that PPL disposable cups have potential to be beneficially reused as reinforcement in novel polypropylene composites.

Post-consumer PET undergoes a reduction in intrinsic viscosity, [[eta]], when recycled in a normal extrusion system. The occurrence of thermal and hydrolytic degradation reactions during recycled PET melt processing is responsible for the reduction in [[eta]] or molar mass of the PET. The presence of water and polyvinyl chloride (PVC) in the recycled PET flakes produces PET chain scission during normal extrusion. At processing temperature (280[degrees]C), hydrolysis reactions occur between water and PET, resulting in shorter chains with carboxyl and hydroxyl end groups. The thermal cleavage of the PET ester bond results in PET chains with carboxyl and vinyl ester end groups. Recently, intensive drying to remove moisture, and vacuum degassing processing, were introduced by Erema in their plastic-recycling systems to minimize the effect of these reactions, resulting in higher PET [[eta]] in comparison with normal extruded PET (1). Solid state processing has also been reported to achieve higher PET [[eta]] (2, 3). However, this process is considered to be slow and expensive. In this study, chain extension by reactive extrusion was chosen to overcome the reduction of [[eta]] for several reasons. It is less expensive than solid state processing and easier to apply in an existing normal extrusion system, and because of the proven success of the chain extension process with virgin and recycled PET (3).

Plastics are inexpensive, lightweight and durable materials, which can readily be moulded into a variety of products that find use in a wide range of applications. As a consequence, the production of plastics has increased markedly over the last 60 years. However, current levels of their usage and disposal generate several environmental problems. Around 4 per cent of world oil and gas production, a non-renewable resource, is used as feedstock for plastics and a further 3-4% is expended to provide energy for their manufacture. A major portion of plastic produced each year is used to make disposable items of packaging or other short-lived products that are discarded within a year of manufacture. These two observations alone indicate that our current use of plastics is not sustainable. In addition, because of the durability of the polymers involved, substantial quantities of discarded end-of-life plastics are accumulating as debris in landfills and in natural habitats worldwide.Recycling is one of the most important actions currently available to reduce these impacts and represents one of the most dynamic areas in the plastics industry today. Recycling provides opportunities to reduce oil usage, carbon dioxide emissions and the quantities of waste requiring disposal. Here, we briefly set recycling into context against other waste-reduction strategies, namely reduction in material use through downgauging or product reuse, the use of alternative biodegradable materials and energy recovery as fuel.While plastics have been recycled since the 1970s, the quantities that are recycled vary geographically, according to plastic type and application. Recycling of packaging materials has seen rapid expansion over the last decades in a number of countries. Advances in technologies and systems for the collection, sorting and reprocessing of recyclable plastics are creating new opportunities for recycling, and with the combined actions of the public, industry and governments it may be possible to divert the majority of plastic waste from landfills to recycling over the next decades.

Recycled poly(ethylene terephthalate) (R-PET) has poor melt strength and viscosity. Hence, the use of R-PET in blow moulding applications, where high melt strength is required, is limited. In this study reactive extrusion of post-consumer R-PET with a low molecular weight modifier: pyromellitic dianhydradide (PMDA) has been used as a way of improving the rheological properties of R-PET. Rheological characterisation of the reactive extruded R-PET (RER-PET) was performed by means of a parallel plate rheometer. The unmodified R-PET and virgin PET were also tested for comparison purposes. The RER-PET samples exhibited higher complex viscosity and higher storage modulus compared to unmodified R-PET sample. Increase in complex viscosity and storage modulus became more pronounced as the percentage of PMDA in R-PET was increased. At high PMDA concentrations, the modified Cole–Cole plots demonstrated a shift towards higher storage modulus values at a given loss modulus value. Viscoelastic properties observed were related to the molecular structure of modified samples. Rheology studies confirmed the increase in molecular weight of post consumer R-PET with an increase of PMDA concentration, and the formation of branching at concentration above 0.25wt.% PMDA.

The polyethylene terephthalate (PET) bottles with petaloid shaped base are widely used for the carbonated soft drinks. There are currently various bottle designs with different petaloid shaped base in the market. While the PET bottles provide safe transportation and storage of soft drinks, occasional cracking of the petaloid base presents problems to the manufacturers of the PET bottles. In this study, dimensions of the petaloid shaped base are optimized against stress cracking by means of finite element analysis (FEA) and process simulation software. Based on the results, a new design for the petaloid shaped base is proposed. Introduction While there are many different kinds of bottles for carbonated soft-drink varying in size, material, shape, stability and cost , PET has been the most widely used material since it offers excellent clarity, good mechanical and barrier properties, and ease of processing. The bottles with petaloid shaped base are the ones most commonly used in industry. This petaloid shaped base not only gives a self standing feature to the bottles but its production cost is also less than that of the two-pieces bottle. One-piece bottles are advantageous over the two-pieces bottles in terms of lower production times, ease of processing and convenience of use. There is a number of parametric modeling in the literature for the ISBM process. Computer aided design and computer aided manufacturing software programs are needed to produce bottle-mould initial design with minimal modeling and production time as processing and mould design are time consuming and expensive. Compared to injection moulding, it is more convenient to use blow moulding systems in the manufacture of plastic items due to favorable cost factors, possibility of variable wall thicknesses, low stresses . Main problem with the one-piece bottle is the cracking of the petaloid shaped base during the storage of the soft-drinks, hence causing major inconvenience for carbonated soft-drinks distributors and producers. For this reason, bottle and petaloid shaped base need to be redesigned by using FEA computer programs to prevent cracking at the base of the bottles before being produced with the injection stretch blow molding (ISBM) process. So far, a few computer simulation programs have been used for this purpose. Both the bottle design and the ISBM processes parameters are optimized by means of these programs, reducing the time and cost of production of bottles with petaloid shaped base resistant to stress cracking. PET is subject to environmental stress cracking (ESC) and a brittle failure initiated by “surface imperfection”. ESC occurs when the glassy polymer is exposed to aggressive medium and loaded at low stress for long period of time. Since at least 15% of all plastic failures in service are caused by ESC , the investigation of ESC phenomena is very important for the applications of all engineering plastics. As the environmental stress cracking has been very big problem for manufacturers, some researchers focused on this issue and thought that this cracking problem was due to crsytallinity. The factors that affect the crystallinity have been identified as the processing temperature, pressure and environment. The temperature distribution on the preform during stretch blow molding and the packing pressure of the injection molded preform are fairly important and affect the total processing time and crystallinity. The greatest base clearance is obtained by processing a light weight preform at a low reheat temperature or a heavy weight preform at high temperature. Zagorala et. al have found that process conditions such as small cushion, low holding pressure and minimum holding times are needed for light weight preform and also reduce gate crystallinity and residual stresses. Many reasons were given for ESC phenomena and a number of studies are still continuing on it. Fellers ascertained that the craze initiation is independent of molecular weight. On the other hand, there are some researchers who regard that crystallinity is a very important parameter affecting the ESC behavior of PET material; and amorphous plastics are more susceptible to ESC than semi-crystalline plastics because of their poor permeation barrier. It is also found that ESC resistance decreases as crystallinity increases for polyethylene. Despite of all studies carried out, the results are controversial. The studies conducted with homopolymer and copolymer PET at 30 °C indicated that the number of cracks increased with increasing exposure time; higher the copolymer concentration, higher the number of cracks. However, when no stress acts on the samples, no cracks are developed. Hanley et. al have said that the cracking phenomenon is directly related to the polymer morphology at the petaloid base and therefore the cracking is due to the phases of production process. The hoop extension differences in the inner and outer surfaces of the bottle affect the morphological properties as well. As the movement of the stretch rod affects the hoop extension, the stretch rod speed should be adjusted carefully. In general, the central region of the petaloid base of bottle remains amorphous after the injection stretch blow molding. The bottom area is hardly stretched because of its relatively low temperature (around 80°C). After stretching stops, the other regions continue to be stretched by the preblowing pressure and the middle-upper area is forced to move up. Consequently, since the bottom area is compressed and not stretched sufficiently by stretch rod, crystallization and orientation is less . Lyu et al. have studied the stress cracking problem of the petaloid shaped base by considering the geometry of the shape, while the other researchers have studied this problem without considering the geometric shape of the petaloid base. Compared to the present research, Lyu et al. have studied the same volume of the bottle except for its shape. They have assumed an even wall thickness distribution of the bottle. They have conducted the stress analysis of the bottle by using commercial software, namely Abaqus, at two different pressures: 0.4 MPa. 0.6 MPa.; and at three different thicknesses: 0.35, 2.0, 3.36 mm. which are the average values of the sidewall, the base and the preform respectively. According to their measurement of tensile yield stress of stretched PET material, they have concluded that for a PET bottle to have a high mechanical properties, its stretch ratio should be higher than the strain hardening point which corresponds to a ratio of initial wall thickness to final wall thickness (t0/ t1) of 1.6. They observed that the structural weakness of the base was related to an abrupt change of the thickness between the center region and the region nearby. In spite of these studies, reasons behind the stress cracking at the base of the bottles remain unresolved. Current research addresses stress cracking phenomenon by considering not only the geometry of the petaloid shaped base but also the process conditions used in the manufacturing of the bottles. The geometrical parameters that affect the stress cracking at the base of the bottles are identified as the foot length, valley width and clearance. On the other hand, as for processing of the bottles, blow pressure, temperature distribution of preform at the blowing stage, velocity of the stretch rod, and total time of both the stretch and the blowing stages are identified as the processing parameters. In this study, firstly, the PET bottle to be studied was drawn by CATIA V5 R14 to comply with its actual dimensions. Three different wall thickness of the bottle was considered to be able to see the effects of the thickness on the petaloid shaped base of the bottle; and the thickness distribution throughout the bottle was also regarded as uniform. Two different internal pressure were applied to the inside surface of the bottle for each thickness. Von Mises stress values were recorded on each test conditions. Echip, which is a design of experiment and optimization software, was employed to determine the number of trials and consequently the optimum values of design parameters for the PET bottle. There are generally two different cracking directions observed at the base of the bottle. The first is in the radial direction (Fig.1a), which begins from the base center and goes towards the outside. The second is circumferential (Fig. 1b) where cracking appears at some distance from the base center and progresses circumferentially. However, circumferential cracking is phenomenon where the underlying causes are poorly understood. Lyu et al. have said that there are three parameters at the base, which affect the stress cracking and they have optimized the petaloid shaped base by modifying these three parameters, based on measurements of effective stresses at the base of the bottle. These parameters are foot length, valley width, clearance as seen in figure 2. They have found that the circumferential cracks are minimal at the valley in the case of large clearance, large foot length and narrow valley width. As injection stretch blow molding (ISBM) is the preferred process for the production of carbonated soft drink bottles made out of PET, the current research aims to prevent stress cracking which occurs at the base of the bottle by optimizing the petaloid shaped base via the above mentioned ISBM process parameters.

Two grades of metallocene-catalysed LLDPE and one grade of low-density polyethylene (LDPE) have been silane grafted and crosslinked by contact with water and their performance has been compared and evaluated. The effects of vinytrimethoxysilane (VTMOS) levels on the degree of crosslinking for each grade were also studied. It was found that increasing level of silane increases the degree of crosslinking. However, no significant increase of the gel content was observed beyond 1.5 phr of silane concentration. All grades studied are shown to crosslink adequately, albeit with differing sensitivities to the level of silane, curing time and temperature. However, metallocene-catalysed LLDPE grades performed better in terms of crosslinking than LDPE, and among the metallocene-catalysed grades; EG 8150 has achieved a higher degree of crosslinking under the same level of silane concentration, and same processing conditions. The influences of curing time and temperature on the degree and rate of crosslinking were investigated, and it was observed that increasing curing time and temperature had a significant effect of increasing both the degree and the rate of crosslinking for all grades. The mechanical properties of all crosslinked samples are reported and correlated with their silane content results, which shows the increase of tensile strength and decrease of elongation at break.

The thermal and melt rheological properties of highly filled polymer composites produced from waste papers, Recycled Paper Waste (RPW) and Liquid Paperboard (LPB), in a post-consumer Stretch-Wrap (SR) matrix have been evaluated. Thermal testing has indicated that large amounts of absorbed water are bound to the filler and, along with small levels of volatile emissions, would be released in compounding and moulding of the composite. The thermal limits of the waste paper fillers and matrix have been evaluated, indicating upper processing limits in the order of 240°C. Melt rheological testing has shown large increases in viscosity with filler volume fractions that have shown a good fit to an exponential equation. The frequency dependence of the viscosity of the composites has shown good agreement with the power-law relation and the composites have shown a decrease in relative change in viscosity with temperature compared to the unfilled matrix.

A nanostructured organometallic macromer trisilanolisobutyl-POSS (T-POSS) was used to prevent discoloration of poly(ethylene terephthalate) (PET) and to achieve molecular level stabilization during melt processing. The resultant material was investigated using thermal analysis and oscillatory rheology. The interaction between the PET and the nanostructured additive was investigated using X-ray photoelectron spectroscopy (XPS) and matrix-assisted laser desorption/mass spectrometry (MALDI-MS). Thermal studies show that the additive increases the thermooxidative stability and consequently prevents discoloration of the material. Rheological data demonstrate increased shear storage modulus with the addition of T-POSS to PET, indicating better melt elasticity and a broader window of processability of the material. The XPS and MALDI-MS results confirm that the stabilization is achieved by covalent interaction and branching of the nanostructured additive to PET.

Two grades of metallocene-catalysed LLDPE and one grade of low-density polyethylene (LDPE) have been silane grafted and crosslinked by contact with water and their performance has been compared and evaluated. The effects of vinytrimethoxysilane (VTMOS) levels on the degree of crosslinking for each grade were also studied. It was found that increasing level of silane increases the degree of crosslinking. However, no significant increase of the gel content was observed beyond 1.5 phr of silane concentration. All grades studied are shown to crosslink adequately, albeit with differing sensitivities to the level of silane, curing time and temperature. However, metallocene-catalysed LLDPE grades performed better in terms of crosslinking than LDPE, and among the metallocene-catalysed grades; EG 8150 has achieved a higher degree of crosslinking under the same level of silane concentration, and same processing conditions. The influences of curing time and temperature on the degree and rate of crosslinking were investigated, and it was observed that increasing curing time and temperature had a significant effect of increasing both the degree and the rate of crosslinking for all grades. The mechanical properties of all crosslinked samples are reported and correlated with their silane content results, which shows the increase of tensile strength and decrease of elongation at break.

In the first phase of our studies of the contaminants and their levels in curbside-collected poly(ethylene terephthalate) (PET) subjected to a recycling process, we analysed the washed and dried, shredded PET (flake). Of the semi-volatile contaminants found, 26 were below the US FDA threshold of 215 ppb and six were above. Additionally, it was found that surface levels of contaminants far exceeded average concentrations in the bulk of the flake, raising questions about the appropriateness of sampling procedures. In this second phase (again using dichloromethane Soxhlet extractions for the most part), we examined contaminant levels after the flake was subjected to vacuum extrusion, to complete the recycling process. Initially amorphous, extruded pellets were annealed to introduce crystallinity and allow grinding, in order to examine the effect of particle size. Much reduced concentrations of contaminants were found (all <215ppb). There were no significant differences in contaminant levels as a function of particle size, thus indicating a uniform distribution throughout the extruded material and no need for particle size reduction before sampling and analysis. However, whilst 3 h was sufficient to obtain quantitative extractions from the ground, annealed particles in each size range (0-300 μm, >300-425 μm and >425-700 μm), approximately 8 h were required for the unground annealed pellets.

Small-angle X-ray scattering (SAXS) studies were undertaken to explore possible morphological explanations for poor mechanical strength in the petaloid bases of poly(ethylene terephthalate) (PET) bottles. The bottles were manufactured using a two-stage injection stretch blow molding process. Splitting of PET bottle bases under load is both inconvenient and expensive. In this study, SAXS data were collected with a 100 mu m square X-ray beam to establish the molecular morphology as a function of position across the base topology. An amorphous region was identified in the base center (i.e., close to the injection gate of the preform) with biaxially orientated, semicrystalline regions in the feet and valleys of the bottle bases. For bottles that had split under load, the transition between these two regions displayed uniaxial orientation that would lead to reduced mechanical strength in the circumferential direction. Reasons for this effect are explored. (c) 2006 Wiley Periodicals, Inc.

The potential of catalytic processing as an effective method for polymer recycling was studied using various modfled zeolites catalysts in the degradation of low-density polyethylene (LDPE). Particular attention was paid to catalytic activity, and selectivity and yield of liquid products. Two types of catalysts were evaluated: acid catalysts (HX and HY), and, pure NaX and its base-modified derivatives (NaX impregnated with MgO, CaO, SrO and BaO). As a benchmark, thermal degradations were performed at 623 K, 673 K, 698 K, and 723 K, to identify optimum operating conditions for the catalytic reactions. Thermal degradation at 623 K showed no conversion during the first 7 hours run, while at other temperatures conversion was 100% and liquid yields at 673 K, 698 K, and 723 K were 21, 77 and 80wt% respectively. Catalytic cracking tests were performed at 673 K to improve liquid yield, and showed significant increases in the following catalyst order: HX (SOwtN) > HY (40wt%) > modified NaX (33wt%) NaX (30wt%) > thermal (21wt%).