摘要:

The past 20-year period has seen the initiation and growth of research in new polymer type, one which contains the hexafluoroisopropylidene (HFIP) group. The availability of monomers has made this possible, compounds derived from the condensation of hexafluoroacetone with aromatic nuclei, either with HF under high pressure and temperature to give 2,2-bisarylhexafluoroiso-propylidenes (I) or, under milder conditions (e.g., aryl Grignards with hexafluoroacetone), to yield 2-arylhexafluoroisopropanols (11).

ISSN:1532-1797    

DOI:10.1080/15321799408009631

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The large-scale commercial use of synthetic polymers and their disposal in the environment is a phenomenon less than half a century old, a duration which is minuscule in the evolutionary time scale required for microbial evolution on earth. Consequently, unlike their naturally-occurring counterparts, the biopolymers, which enjoyed long-term interactions with the microbial biosphere, synthetic polymers never had the opportunity to serve as a source of a microbial nutrient of any significance. Hence, few, if any, of the microorganisms are biochemically equipped to catabolize synthetic macromolecules. This lack of development of metabolic pathways capable of utilizing synthetic polymers is often cited as the main reason for recalcitrance of synthetic polymers in the environment [1]. The term “recalcitrant” is used here to describe organic compounds that persist for extended periods of time in the environment, but not necessarily as a result of microbial fallibility.

ISSN:1532-1797    

DOI:10.1080/15321799408009632

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Commercial poly(viny1 chloride) (PVC) contains approximately 10% crystallinity. This relatively low level of order has a surprisingly significant effect on both its processing and properties. In this review, the nature of PVC crystallinity, which is very different from that found in more conventional crystalline polymers, will be discussed. Methods of measuring crystallinity will be considered, and aspects of PVC behavior which are affected by its crystalline nature will be highlighted. The majority of work reported in this area is concerned with bulk and suspension polymerized polymers, so this review will focus on these polymer types.

ISSN:1532-1797    

DOI:10.1080/15321799408009633

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor