摘要:

AbstractPolymer materials are making an impact on optical storage technology to develop high information density and fast access type memories with a high read‐out efficiency. The principle and advantages of three‐dimensional (3‐D) data storage in the form of interference patterns (holograms) have been outlined. Three different information storage materials have been developed by doping metal ions such as Cr(VI) and Fe(III) in water‐soluble polymers, namely poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA), which need no further thermal or chemical treatment. Volume transmission holograms have been recorded in dichromated poly(vinyl alcohol) (DCPVA), ferric chloride doped poly(vinyl alcohol) (FePVA) and dichromated poly(acrylic acid) (DCPAA), with and without an electron donor (dimethyl formamide), and xanthene dyes (fluorescein, eosin Y and Rose Bengal). Different parameters influencing the holographic performance have been optimized to achieve a high real‐time diffraction efficiency (∼70%). An electron transfer process from the polymer matrix to Cr(VI)/Fe(III), leading to the photocrosslinking of the polymer in the form of an interference pattern, has been suggested as the mechanism of information storage (hologram recording) in thes

ISSN:1042-7147    

DOI:10.1002/pat.1993.220041001

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe effect of introducing a bridge group into the diamine moiety on the thermal stability of aromatic polyamides substituted with nitro group in the diamine ring at the ortho position to the amide group was studied. Our present work showed that the bridge group, whether it was electron withdrawing or releasing, did not have a significant effect on the activity of the nitro group for the intramolecular cyclization reaction to poly(benzoxazole)s.

ISSN:1042-7147    

DOI:10.1002/pat.1993.220041002

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractSterilization by irradiation techniques is considered to be an improved method to treat polluted products of human consumption. Secondary effects, that may be generated in the components of packaging materials, could induce organoleptic damage and some physico‐chemical modifications, observed especially in plastic materials. In order to demonstrate any such secondary changes, we have investigated the effects of beta‐irradiation (a treatment which could induce either a reticulation or a cleavage in a polymeric sequence) on three polymers; namely, low density polyethylene, polystyrene and polyvinyl chloride. The techniques used to identify irradiation‐induced modifications of these polymers were size exclusion chromatography and thermal analysis. Thermal analysis showed a decrease in the percentage of crystallinity of polyethylene after its radiosterilization. Exclusion chromatography highlighted a reticulation for irradiated polyvinyl chloride and polyst

ISSN:1042-7147    

DOI:10.1002/pat.1993.220041003

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe dynamic behavior of latex polystyrene/crosslinked polystyrene (PS/XPS) systems has been studied. PS and XPS lattices were either physically blended, or used as seeds in semi‐continuous sequential two‐stage polymerizations. The Cox–Merz equation is not met by any PS/XPS system. Power‐law relaxation has been observed for the physically blended PS–b–XPS system in the terminal region. A two‐parameter equation suggested for polymers at the critical gel point fits the experimental data for XPS contents beyond 60%. This has been attributed to the formation of a “continuous” XPS network. This network is able to disrupt upon flow, due to the unique morphology of the XPS phase. It is possible that, for the sequential system with XPS seed particles, such a network may appear at a lower XPS content, due to a PS occlusion effect. A qualitative model is presented for the

ISSN:1042-7147    

DOI:10.1002/pat.1993.220041004

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY