Melt fabricated plastic articles with improved solvent and vapor barrier properties are of great need in the packaging industry. Various techniques, such as coextrusion, surface treatments, and coatings, are being employed currently towards this objective. Present work has identified a unique polymer blend approach to impart solvent and gas barrier properties to a polyolefin material. This involves incorporation of small amounts of a modified nylon barrier material, and processing under controlled conditions, in single step blowmolding or other extrusion processes. The unusual barrier effects obtained at small concentrations of the barrier material are obtained by the controlled morphology of the dispersed phase and optimum formulation of the ingredients.

Polymer‐polymer blends offer a route for enhancement of various properties. When immiscible polymers are blended together (in the presence of a compatibilizer), the blend properties are dependent on the morphology of the phases. Uniform, fine dispersions generally result in “average” properties. Discussed here are blends of polyamides or polyesters with polyolefins, particularly polyethylene, where small amounts (3–20 percent) of the former polymers dispersed as essentially parallel, thin, large laminae produce substantial reduction (3–100 times) of permeability properties in blow‐molded/extruded articles. Physical properties of such blends, their permeability properties, and morphologies are discussed.

Poly(ethylene terephthalate) (PET) offers good properties as a material of choice for various packaging, electronic, and other applications. In these applications in general, the PET articles achieve improved toughness and other physical properties through molecular orientation resulting from stretching at temperatures slightly above its Tg. Without such orientation, these articles suffer from poor impact toughness. We have been investigating modifications of PET for improving toughness and retaining the permeability properties. PET having intrinsic viscosities of 0.5 to 0.7 have been modified with low modulus polymers, particularly ethylene copolymers such as ethylene‐methacrylic acid (EMAA) copolymers. The effect of crystallinity on toughness was determined. The crystallinity was established by Differential Scanning Calorimetry (DSC) techniques. Many of these modified PET compositions have good toughness and permeability barrier properties for various packaging and other controlled permeability applications such as containers and films.

Articles such as containers, films, etc., prepared from polyolefins suffer from significant permeation of organic solvents and flavors, making polyolefins less desirable for a variety of packaging and industrial applications (e.g., automotive fuel tanks). Enhancement of the permeability barrier properties of polyolefins by blending with a polymer having high barrier properties has limited applica bility in most cases, because such barrier polymers are relatively expensive and the conventional blend technology offers only limited barrier enhancements at low concentration of these additives because of the homogeneous nature of their dispersion. Described here are polymer blends having "laminar" morphologies of the dispersed barrier polymer phase in the matrix of the polyolefin resulting in significant enhancement of the hydrocarbon barrier properties of the polyolefin composition. Thus, using 3-10% of a polyamide as the barrier polymer, permeability loss can be reduced by a factor greater than 200 times over that from unmodified polyethylene. This significant enhancement of hydrocarbon barrier properties approximates that obtained by a complex multilayer coextruded system, but achieved here by using a simple process with only a single extruder system. The "laminar" or platelet mor phologies in these structures can be established by microscopic examination of the cross section of the fabricated article. These can also be indirectly established by nondestructive ultrasonic exam ination of the molded article. Using this technology, small and large containers with good physical properties and permeability bar rier to hydrocarbon fuels as well as fuels containing alcohols have been prepared and characterized.Polyolefins such as polyethylene (PE) and polypropylene (PP) are ideal candi dates for the fabrication of a wide variety of films, containers, trays, etc., for various packaging and industrial applications. While these hydrocarbon polymers

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PrefaceCONCERNS FOR THE ENVIRONMENT and the limited resources of the Earth have finally awakened many of its citizens. They now recognize the need for more efficient and conservative use of resources. Recycling can be an effective way to conserve global material resources and minimize disposals in landfills. We currently recycle less than 500 million kg of the worldwide production of about 60 billion kg of plastics. Significant amounts of industrial plastic waste are recycled, but this recycling is not very visible, and meanwhile, consumer waste from packaging, automobiles, and durable goods is filling up landfills.In 1989, approximately 150 million kg of postconsumer plastics was recycled in the United States versus 140 million kg in 1988. The vast majority of this was poly(ethylene terephthalate) from soda bottles and X-ray film, and polyethylene detergent and milk bottles. The quality of these recycled plastics varies greatly as a result of impurities such as paper, adhesives, residues, other polymers, and metals. The polymers themselves differ significantly in molecular weight, branching, and additives. Recycling of plastics from discarded automobiles and other durable goods is in its infancy. Major manufacturers of plastics for durable goods are beginning to address recycling issues.The accelerating pace of polymer recycling technology development shows the need for a book of this type. We hope that this book stimulates scientific research in polymer recycling by summarizing the scope of the problem, highlighting current areas of activity, and demonstrating that science and technology have critical roles in helping decide what problems are worth solving and then providing the technical parts of the solutions. Development of the science and technology represented here is necessary to support the increasing public demands for recycling waste plastics in all forms.No symposium or book of this sort could start to cover the field of polymer recycling in a comprehensive way. We therefore tried to select a range of topics that represent activities in the field. The first section is a selection of general chapters covering the background of recycling and outlining the major areas of current activities. The remaining sections cover topics from basic science development to technology application in specific polymer systems.Polymer recycling is an emerging technology that will continue to grow. Research on molecular design of more recyclable polymers and xi Downloaded via 44.224.250.200 on July 5, 2020 at 09:01:04 (UTC).See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.

Polymer-Polymer blends containing ethylene-methacrylic copolymers (EMAA) and polyethylene terephthalate (PET) (where PET is the minor component) have been investigated. The permeability properties and the morphology of these blends, when the polyolefin phase is mildly crosslinked with small amounts of an agent that preferentially crosslinks the ethylene copolymer was also studied. The permeability barrier properties of such polymer blends increase as the concentration of the crosslinking agents increase until excessive crosslinking takes place. The morphology of the blends – the size of the dispersed particles – change significantly as more coupling agents are used. These techniques afford us a novel technique to improve the permeability barrier properties by control of the particle size of the barrier polymer.

Background-Giant cell tumour (GCT) is a benign bone tumour with aggressive characteristics. They are more prevalent in the third decade of life and demonstrate a preference for locating in the epiphyseal region of long bones. They have a high local recurrence rate, which depends on the type of treatment and initial tumour presentation. Objective- To evaluate the results of the treatment with regard to relapse. Methods- It was a hospital based follow up study done for periods of 7 months. Fifty patients of GCT were recruited in the study through purposive sampling technique.Study being conducted on patients with followup for 12 months. Demographic profile and all the necessary investigation were done. SPSS ( Version 22.0) was used for analysis. Chi-Square test was used as test of significance. Results-There was a predominance of males (80%). The most common location was the distal femur. All patients presented with pathologic fracture at diagnosis, recurrence seen after 9months of followup.the most common location for GCT was distal femur seen in 84% of patients, while curettage with cement was the most common treatment done in 89% which was statistically significant (p<0.05). Endoprosthesis was done in 11% patient.