ISSN:0032-3888    

DOI:10.1002/pen.760030202

出版商:Society of Plastics Engineers, Inc.    

年代:1963

数据来源: WILEY

ISSN:0032-3888    

DOI:10.1002/pen.760030203

出版商:Society of Plastics Engineers, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractThe relationships between crystallinity and physical and technological properties of high polymers are examined. In addition, the relationships between structure and crystallinity are discussed and polymers consisting of asymmetric monomeric units are examined in particular. In correspondence with the different possible configurational successions, different conformational characteristics (chain structures) and different physical properties are observed. Polytactic polymers are taken into consideration for the most part. With regard to copolymers, various types of crystalline polymers, in particular those which due to isomorphism of monomeric units are crystalline for any composition, and new classes of alternating copolymers are described.

ISSN:0032-3888    

DOI:10.1002/pen.760030204

出版商:Society of Plastics Engineers, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractAn attempt has been made to categorize the various materials which have been utilized in polyester compositions to impart or enhance the fire‐retardancy of these compositions. Examples of halogen‐containing and phosphorus‐containing compounds are classified according to where they may be thought to occur in the complex chemical structures which are polyesters. The classifications are basically designed to take advantage of the known chemical reactions which lead to polyesters; the fire‐retardant component may be incorporated into the final composition in the diacid, diol, crosslinking agent or may be merely mechanically added as a

ISSN:0032-3888    

DOI:10.1002/pen.760030205

出版商:Society of Plastics Engineers, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractVariations were made in the concentration of tin and amine catalysts used in a typical one‐short polyether flexible foam system. Differences in foaming characteristics and foam stability were correlated with the relative rates of the chemical reactions which are believed to occur during the foaming process. Physical properties measured on the samples showed in many cases a dependence on the balance between the tin and amine catalyst

ISSN:0032-3888    

DOI:10.1002/pen.760030206

出版商:Society of Plastics Engineers, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractTo date, quantitative stereochemical data are available for a few polymers only. A convenient and graphic representation of this data has been developed. Analysis of this data yields two parameters characterizing a polymer, one representing the tacticity and the other representing the nature of the tactic sequence distribution. The statistical parameters obtained may be related to the polymerization conditions and, hence, to the mechanism of stereoregulation. Furthermore they may be related to a number of physical properties, such as melting point, equilibrium crystallinity, and melting curve. Thus, the proper analysis of the NMR data supplies a link between polymerization conditions and the properties of the resulting polymer.

ISSN:0032-3888    

DOI:10.1002/pen.760030207

出版商:Society of Plastics Engineers, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractThe diameter increase of a molten thermoplastic extrudate is discussed in terms of the viscoelasticity of the resin. A swelling index, the ratio of the extrudate diameter to the orifice diameter, is defined. It was observed that swelling data taken at different temperatures can be correlated with stress in the die. An unexpected influence on the swelling for polyethylenes is the length of the die where short dies show larger swelling than long dies. Some suggestions for reducing swelling tendencies are made based on a simple model for flow in a capillary.

ISSN:0032-3888    

DOI:10.1002/pen.760030208

出版商:Society of Plastics Engineers, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractBased on the simplified, flat‐plate, isothermal, Newtonian flow model of the screw pump, an expression for pressure as a function of time at a fixed point on the extruder barrel has been derived. This expression predicts a periodic saw tooth pressure cycle under most flow conditions. It also establishes the flow conditions under which an inversion of the saw tooth cycle will occur. Pressure transducer data, in conjunction with extrusion rate data, can be used to calculate the average fluid viscosity in a region near the transduce

ISSN:0032-3888    

DOI:10.1002/pen.760030209

出版商:Society of Plastics Engineers, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractThe melt extrusion of a commercial polypropylene resin was studied with a screw extruder and a series of capillary dies of length:radius ratios varying from 0 to 65. Three temperatures and the range of shear rates encountered in industrial processing were covered. The temperature dependence of the apparent melt viscosity of polypropylene was intermediate between linear and branched polyethylene. Extrapolated zero shear activation energy for viscous flow was 9 ± 1 Kcal/mole. Shear dependence of the apparent viscosity of polypropylene melt was greater than for branched polyethylene in turn, greater for linear

ISSN:0032-3888    

DOI:10.1002/pen.760030210

出版商:Society of Plastics Engineers, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractBasic considerations are presented for the formation of three‐dimensional or “polymer” units from the conglomeration of freely moving reactive molecules. The resulting “heterophase” conditions are shown between these swelling units and the not‐polymerized fluid matter. Systematic variations of the ratio of the phases and changes in material ar

ISSN:0032-3888    

DOI:10.1002/pen.760030211

出版商:Society of Plastics Engineers, Inc.    

年代:1963

数据来源: WILEY