摘要:

AbstractTwo sets of dynamic mechanical property data and some stress relaxation data for semicrystalline, linear polyethylene are treated by data reduction methods previously described. These data can be represented by a master plot of reduced modulus versus reduced frequency and two sets of temperature‐dependent shift factors. The first of these factors reflects the change of viscoelastic relaxation times with temperature. The second represents a separable change of modulus with temperature which applies over the entire time or frequency range of the experiments. This change is larger and in the opposite direction to that found applicable in the behavior of noncrystalline plastics and rubbers. The two sets of dynamic data show the same frequency–temperature dependence which can be represented by an activation energy of 22 kcal./mole. Small differences in the modulus–temperature dependence are attributed to differences in molecular weight or annealing conditions. The stress relaxation data superposes to a curve in good agreement with the dynamic data but with a factor of 20 difference in time scale. This difference is attributed to the finite strains used in the stress relaxation measurements. Such strains might be expected to increase free volume in simple extension deformations and so accelerate the relax

ISSN:0449-2978    

DOI:10.1002/pol.1966.160040401

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractThe dynamic mechanical properties of poly‐4‐methylpentene‐1 have been measured in torsion in the temperature range from 25 to 160°C. at frequencies from 10−3to 10 cps. Two transitions are found. The first, with a peak at 40°C. at 1 cps, appears as a normal glass transition. A broad high temperature peak appears at 130°C. The dynamic compliance‐frequency data can be superposed by the conventional method of reduced variables for temperatures up to 100°C. The temperature dependence of the shift factors follows the WLF equation. Above this temperature, superposition can be achieved by applying horizontal and vertical shifts to both components of the dynamic compliance. When the vertical shift is permitted, the range of applicability of the WLF equation is exte

ISSN:0449-2978    

DOI:10.1002/pol.1966.160040402

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractThe changes in x‐ray orientation brought about by the treatment of cotton and ramie with caustic soda of different concentrations have been studied. With ramie the effect of the treatment is to decrease the x‐ray orientation, while with cotton the reverse is true. The cause of this difference is traced to a difference in the morphology of the two fibers rather than a difference in their fine struct

ISSN:0449-2978    

DOI:10.1002/pol.1966.160040403

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractNMR measurements on undrawn polyethylene (PE) samples in contact with a solvent such as C2Cl4indicate an increase in the mobility of the mobile chain segments as compared to dry samples. Highly drawn PE shows no such effect. This is becauseSa, the sorption per unit mass of noncrystalline material present, decreases from 20.9 wt.‐% (dry basis), found for undrawn quenched PE, to 0.63 wt.‐% after drawing (Sadetermined at 25°C. and 0.80 vapor activity). Drawing also reduces the segment mobility according to the NMR spectrum. It is shown that these effects are caused by considerable structural changes occurring in the noncrystalline regions of PE upon drawing. Annealing of drawn PE samples at successively higher temperatures leads to a gradual relaxation of the noncrystalline regions towards the state characteristic of undrawn PE. With increasing annealing temperatureSaas well as the mobility approach values found with undraw

ISSN:0449-2978    

DOI:10.1002/pol.1966.160040404

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractA method is described for the conversion of polystyrene to poly(styrenesulfonic acid) without change in the molecular weight distribution; the reaction is performed at room temperature in 100% H2SO4and uses Ag+catalyst. The resulting polyelectrolyte has solubility and other characteristics significantly different from those of previously investigated poly(vinylsulfonic acid). This permits a study of the influence of the aromatic group on the local and long range interactions in solution. The barium salt of poly(styrenesulfonic acid) is unusual in showing both upper and lower consolute temperatures in solution.

ISSN:0449-2978    

DOI:10.1002/pol.1966.160040405

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractEpitaxial deposition of homopolymers from solution [polyethylene, isotactic polystyrene, poly‐3,3‐bischloromethyloxacyclobutane (Penton) and polypropylene] was found on the (001) faces of cleaved alkali halide single crystals. Electron and optical microscopy studies have shown that the polymer usually grew from small, rodlike crystallites which were oriented in (110) directions of the halide crystal. Large oriented, four‐leaved, “rose” structures also were observed for polyethylene. Electron diffraction studies indicate that the polymer chain axes for polyethylene, isotactic polystyrene, and Penton generally lie parallel to the (001) faces of the halide crystal and are also oriented in the 〈110〉 directions of the crystal face. Investigations on the effect of various halide substrates upon the epitaxial crystallization habit of polyethylene inferes that lattice matching does not play the major role in orientation. Two possible explanations are offered for this epita

ISSN:0449-2978    

DOI:10.1002/pol.1966.160040406

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractThe effect of basic aluminium dibenzoate upon the supercooling of polypropylene fractions of molecular weight 9.2 × 103‐1.25 × 106was determined by differential thermal analysis. The response to heterogeneous nucleation within the precision of the method used appears to be only slightly dependent, if at all, upon the molecular weight of the poly

ISSN:0449-2978    

DOI:10.1002/pol.1966.160040407

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractWideline NMR techniques have been applied to both singly and doubly oriented specimens of nylon 66. Variations in the spectra obtained are observed for different orientations of the specimens relative to the applied field. These variations demonstrate that the zigzag chain axis is essentially parallel to the draw direction and that motion occurs in all of the sample. The motion is of two types: random in the mobile regions and rotation of segments about the chain axis in the rigid regions.

ISSN:0449-2978    

DOI:10.1002/pol.1966.160040408

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractThe crystallization kinetics of poly(n‐octadecyl methacrylate) has been studied at the air–water interface. The rate of the crystallization has been measured by the decrease in the area of monolayers with time at various temperatures and surface pressures. The crystallization isotherms have been analyzed by the general mathematical treatment of the kinetics of phase changes, and the results show linear growth to be dominant. The variation of the rate constant with temperature and pressure has been illustrated by the difference in the supersaturation defined by introducing the equilibrium pressure‐area isot

ISSN:0449-2978    

DOI:10.1002/pol.1966.160040409

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY

ISSN:0449-2978    

DOI:10.1002/pol.1966.160040410

出版商:John Wiley&Sons, Inc.    

年代:1966

数据来源: WILEY