Dynamic mechanical study has been made of ethylene-methacrylic acid copolymer containing 4.1 mol% of methacrylic acid units and its sodium, lithium, and calcium salts;it is proposed that structures of ionized copolyme...
详细信息
Dynamic mechanical study has been made of ethylene-methacrylic acid copolymer containing 4.1 mol% of methacrylic acid units and its sodium, lithium, and calcium salts;it is proposed that structures of ionized copolymers consist of three distinct phases -- crystalline polyethylene phase, amorphous polyethylene phase, and ionic phase consisting of ionic domains;it is further proposed that unionized acid copolymer consists of two phases -- crystalline polyethylene phase and amorphous phase consisting of polyethylene crosslinked with hydrogen bonded, carboxylic acid dimers.
Ethyl α-chloroacrylate was polymerized by anionic and free radical initiation under a variety of conditions to yield polymers of differing tacticities ranging from predominantly syndiotactic to slightly isotactic on ...
Poly(ethyl α-chloroacrylates) of different tacticities have been investigated by nmr spectroscopy at 220 MHz. Tetrad assignments and relative intensities of the tetrads are reported. The results obtained indicate a s...
A study has been made of the mechanical‐relaxation behavior of an ethylene‐methacrylic acidcopolymer containing 4.1 mole % acid units and its partially ionized sodium salts. Degrees of ionization, estimated from inf...
详细信息
A study has been made of the mechanical‐relaxation behavior of an ethylene‐methacrylic acidcopolymer containing 4.1 mole % acid units and its partially ionized sodium salts. Degrees of ionization, estimated from infrared analysis, ranged from 0% to 78%. The weight‐percent crystallinity of the samples, determined by differential‐scanning calorimetry, varied from about 15 for the acidcopolymer to about 7 for the 78% ionized copolymer. Four relaxation regions have been observed. They are labelled α, β′, β and γ, and each has been assigned to motions within the amorphous phase of the polymer. In plots of the logarithmic decrement against temperature (at 1 cps), the α peak for the annealedacidcopolymer occurs at 50°C and shifts to higher temperatures with increasing degree of ionization. This trend is consistent with the increase in melt flow viscosity with increasing ionization and, on this basis, the α process is attributed to the long‐range diffusional motions of chain segments. The β′ peak occurs at 23°C for the annealedacidcopolymer and decreases in magnitude with increasing ionization. Hence the β′ mechanism is attributed to the micro‐Brownian motions of chain segments involving the breaking and reforming of intermolecular hydrogen bonds between dimerized carboxylic‐acid groups. The latter assignment is supported by infrared studies of hydrogen bonding as a function of temperature. The β peak is absent for the acidcopolymer but appears at ?10°C for the ionized polymers and increases in height with increasing ionization. Thus, the β process is attributed to motions of branched chain segments including the ionic (carboxylate) side groups. The onset of the γ peak is observed at ?120°C and is associated with the local motions of linear methylene sequences. The observation that the β peak is located at a temperature very close to the β peak (?20°C) for ordinary branched polyethylene, must cast considerable doubt on the widely held view that the ionic side groups are ass
The study of the relationship between the structure, morphology and properties of polymer films has significantly progressed in recent years through the use of a number of phyiscal techniques - some new and some old. ...
详细信息
ISBN:
(数字)9781461589518
ISBN:
(纸本)9781461589532
The study of the relationship between the structure, morphology and properties of polymer films has significantly progressed in recent years through the use of a number of phyiscal techniques - some new and some old. These methods include small and large angle x-ray diffraction, bire fringence, light scattering, infrared dichroism, fluorescence polarization, light and electron microscopy and interferrometry. This collection of papers, most of which were presented at a symposium at the Boston American Chemical Society Meeting in April, 1972, represent a collection of recent studies using many of these methods by some of the leading scientists in their fields. It is evident that these various techniques permit the study of various aspects of film structure such as crystal structure and orientation, amorphous orientation, the interrelation of crystalline and amorphous regions in lamellar, fibrillar, and spherulitic superstructure and the relationshi. p of these structural variables to the mechanical and optical properties of the films. Film structure is sufficiently complex that a complete understanding of the relationship between structure and properties will come from the employment of a combination of several of these methods. vii CONTENTS Optical Studies of the Morphology of polymer Films ••• • • 1 Richard S. Stein Light Scattering by Oriented Native Cellulose Systems 25 R. H. Marchessault Superstructure in Films of Bio and Biorelated Small Angle polymers as Noted by 39 Light Scattering • • Garth L.
暂无评论