摘要:

AbstractX‐Ray diffraction pole figure measurements have been made on six films blown from high‐density polyethylene. Five were prepared on an experimental unit; the sixth, blown on commercial equipment, had a higher degree of overall orientation thus enabling more extensive results for thea‐, b‐, andc‐axis distributions to be obtained. The results provide information on the orientation present, how it may be related to the stress crystallization process of Keller and Machin, and the dependence of the tear strengths in the machine and transverse directions on the orientation. The typical behavior, with theaandcaxes at 90° and both at an angle to the plane of the film, is shown to be the result of a composite process involving several types of stress during the blowing operation and a partial relaxation arising at one or possibly two stages of the process. The predicted relative tear strengths, obtained from the concentration ofcaxes inclined towards the machine direction, are in line with the experimental values. There is some evidence that transcrystallization in the surface layers of the films may lead to a better balance of the tear strengths in the machine and transverse

ISSN:0021-8995    

DOI:10.1002/app.1978.070221001

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractX‐Ray diffraction pole figure measurements have been made on a series of films, blown under various conditions from three high‐density polyethylenes. The results are interpreted in terms of two distinct types of orientation. The first, and probably the more normal, is the result of the type of stress crystallization process described by Keller and Machin and has theaandcaxes inclined at an angle to the plane of the film. The second type of orientation is crystallographically analogous to that found in cold drawn polyethylene in having thec‐axis distribution substantially along the machine direction. This is termed high‐stress orientation. The type of orientation obtained is dependent both on the blowing conditions and the particular polyethylene. With an experimental Rigidex grade and with Shell LPPE 040 there are always substantially amounts of the conventional low‐stress orientation although certain combinations of machine conditions predispose towards the high‐stress form. This latter type forms readily in the case of Hostalen GM 9955F over a rather wide range of machine conditions and appears to be favored by slower cooling

ISSN:0021-8995    

DOI:10.1002/app.1978.070221002

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractX‐Ray diffraction orientation measurements have been made on a wide range of films blown from three high‐density polyethylenes, to determine more precisely the conditions which lead to the high‐stress crystallization type of orientation. The most extensive measurements relate to films from Hostalen GM 9955F; the results show that there is a very wide range of orientational behavior. Under very low‐stress conditions there is almost purea‐axis orientation; with very high stress there is substantialc‐axis orientation, both with reference to the machine direction. Commercial blowing conditions give rather high stress and theaaxis is inclined at 60° to 70° to the machine direction in the sheet‐normal—machine‐direction plane. Calcium stearate, used to improve the surface finish, increases the stress for a given set of machine conditions and, of these, a high draw ratio and a low extrusion temperature are most effective in promoting high‐stress crystallization. The less extensive results for an experimental Rigidex grade and Shell LPPE 040 fit into this overall pattern; for a given set of blowing conditions they have lower stress than the Hostalen polymer. Commercial blowing conditions give ana‐axis i

ISSN:0021-8995    

DOI:10.1002/app.1978.070221003

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractInfrared dichroic measurements have been made on a number of blown polyethylene films for which x‐ray diffraction pole figure studies are reported in the three preceding papers; they complement them in some respects, and lead to several conclusions. Gauche chain conformations in loose chain folds in amorphous regions, characterized by bands at 1303, 1352, and 1368 cm‐1, show appreciable orientation in films with high‐stress orientation but very little with low‐stress orientation. Conversely, extended tie chains in amorphous regions, assessed by the band at 1080 cm‐1, are appreciably orientated with the more normal type of low‐stress film but not with high‐stress films. It is therefore possible, rapidly and inexpensively, to distinguish between the two types of orientation. The method for studying the orientation of extended tie chains is capable of further development. There is probably an empirical correlation between the dichroic ratios at 720 and 730 cm‐1and the tear strengths and balances of the films with low‐s

ISSN:0021-8995    

DOI:10.1002/app.1978.070221004

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractThe rheology of sagging and slumping of high solid coatings on vertical surfaces is analyzed in terms of a non‐Newtonian power‐law model. The results indicate that, in order to have good sag control and good sprayability at the same time, high solid coatings should be pseudoplastics with a power constant of about 0.6 and a viscosity at 1 sec‐1of about 25 poise at the temperature of interest. This theoretical prediction is confirmed experimen

ISSN:0021-8995    

DOI:10.1002/app.1978.070221005

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractThe rheology of combined sagging and leveling of high solid coatings is analyzed in terms of non‐Newtonian power‐law model. The results indicate that, in order to have good leveling, good sag control, and good sprayability at the same time, high solid coatings should have pseudoplastic rheology with power constant of about 0.5 and viscosity at sec‐1of about 50 poises. This theoretical prediction is confirmed experimen

ISSN:0021-8995    

DOI:10.1002/app.1978.070221006

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractA low‐angle x‐ray scattering technique has been applied to determine the submicrostructure of plasma‐formed polyethylene and polystyrene. The plasma‐formed polymers appear to closely approximate a “filler—binder” structure where polymer spheres constitute the filler material and a lower‐density polymer, the binder. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs confirm the spherical diameters predicted by the low‐angle x‐

ISSN:0021-8995    

DOI:10.1002/app.1978.070221007

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractA transmission electron microscopy (TEM) and scanning electron microscopy (SEM) study of plasma‐formed polyethylene and polystyrene is reported. A two‐phase structure of spheres embedded in a polymer binder is evident, supporting the predictions of earlier low‐angle x‐ray scattering data taken of these two plasma‐deposited

ISSN:0021-8995    

DOI:10.1002/app.1978.070221008

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractThe results of a study of irradiated and unirradiated samples of polymers prepared by plasma polymerization in an inductively coupled radiofrequency (rf) reactor using infrared, elemental, thermogravimetric, and ESR analyses and density and refractive index measurements are presented. The plasma‐formed polymers studied include polypropylene, poly(ethylbenzene), poly(methyl methacrylate), poly(tetrafluoroethylene), poly(chlorotrifluoroethylene), and poly(trimethylchlorosilane

ISSN:0021-8995    

DOI:10.1002/app.1978.070221009

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractDomains of cholesteric liquid crystal structures exist in films of heterogeneous network polymers from poly(L‐glutamic acid) (PGA) and poly(oxyethylene glycol) (PEGM̄n= 302, 1003). The sizes and the amounts of the domains are dependent on the PGA content, the evaporation rate of the solvent, and the molecular weight of PEG. At the PGA content of 40% by weight, the sizes of the domains increase, the glass transition temperatures shift to higher temperatures, and the densities increase with increase in the rate of solvent evaporation. These observations suggest that the phase separation of PEG takes place at a PGA content of 40% when the evaporation rate is small. On the other hand, at a PGA content of 70% by weight, the sizes of the domains increase, the glass transition temperatures shift to higher temperatures, and the densities vary little with decrease in the rate of solvent evaporation. These observations suggest that PEG molecules are accommodated among α‐helices of PGA and that the cholesteric liquid crystal phase grows at a PGA content of 70% when the evaporation rate is

ISSN:0021-8995    

DOI:10.1002/app.1978.070221010

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY