摘要:

AbstractAn experimental study of the spinnability and the variation in crystallinity and orientation in high‐density and low‐density polyethylene fibers with melt spinning and drawing conditions has been carried out. Three polymers (two high‐density and one low‐density) and eicosane (C20H42) were studied. The maximum spinnability was in the lower molecular weight high‐density polyethylene. Hermans‐Steina,b, andccrystallographic axis orientation factors were computed from wide‐angle x‐ray scattering patterns. In the spun fiber, small take‐up velocities cause thebaxis to become perpendicular to the fiber axis in each fiber. Thecaxis increasingly orients itself parallel to the fiber axis as take‐up velocity increases. Theaaxis orientation is different for each polymer. The results are interpreted in terms of modern theories of crystalline morphology, specifically the development of row structures. In the drawing experiments, the two high‐density polyethylenes necked. A phenomenological theory of necking is discussed. Thea,b, andcaxis orientation factors were determined for different stages of drawing. In the necked regions and in completely drawn fibers, thecaxis was parallel to the fiber axis and theaandbaxes are perpendicular to the fiber axis. The tangent Young's modulus and tensile strength of the spun fibers increased with take‐up velocity and in the drawn fibers were an order of magnitude higher than in the spun fiber. The mechanical properties of spun fiber may be correlated with thecaxis (Hermans) orientation factor. The drawn fiber shows significant variations in Young's modulus and tensile strength at constan

ISSN:0021-8995    

DOI:10.1002/app.1974.070180901

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

年代:1974

数据来源: WILEY

摘要:

AbstractA study of a melt‐spun threadline has been carried out to determine the effect of molecular weight on the elongational viscosity of the polymer being spun. Polymer chosen for this study was poly(ethylene terephthalate) having different molecular weights. Conventional nonisothermal spinning of the polymers was carried out with cooling by free convection. Threadline surface temperatures were measured by a null‐balance technique. Threadline tension at the take‐up device was measured, and samples of the threadline were taken to obtain linear density profiles. Nonlinear least‐squares fits were applied to the linear density data to obtain equations for velocity and elongation rate. These measurements were then used to determine the threadline elongational viscosity. Least‐squares fits were made to a polynomial relating absolute temperature and elongation rate to the elengational viscosity. These results were then used to determine an activation energy of elongational flow which was found to decrease with elongation rate. Elongational viscosity was found to increase with molecul

ISSN:0021-8995    

DOI:10.1002/app.1974.070180902

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

年代:1974

数据来源: WILEY

摘要:

AbstractIsothermal melt spinning experiments were carried out to investigate the elongational flow behavior and spinnability of polymer blends and a calcium carbonate‐filled polypropylene. Blends chosen for study were mixtures of polystyrene (Dow Chemical, Styron 678) with high‐density polyethylene (Union Carbide, DMDJ 4309), and mixtures of polystyrene (Dow Chemical, Styron 686) with high‐density polyethylene (Union Carbide, DMDJ 4309). For the study, measurements were taken of the thread diameter by photographic techniques and of the thread tension by means of a Saxl tensiometer. These measurements were later used to determine the elongational viscosity of the material investigated. It was found that, in all the blends and filled systems investigated, the elongational viscosity decreases with elongation rate and that the relationship between the elongational viscosity and blending ratio is very complex. An attempt is made to offer explanations of the observed complicated relationship with the aid of microphotographs of fiber samples, which display the complexity of fiber morphology in two‐phase systems. It was also found that there exists some correlation between the elongational viscosity and the maximum stretch ratio which may be considered as representing fiber spinn

ISSN:0021-8995    

DOI:10.1002/app.1974.070180903

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe prepolymer of diallyl isophthalate is employed as a material for a moistureprotective coating which is applied in the solution form, free of radical initiator. The effect of the absence of radical initiator, temperature and time of cure, and thickness of coat is evaluated in terms of the permeability of water through the protective films of the polyphthalate. Temperature of the noncatalytic cure can be as low as 170°C, and the presence of an initiator in the coating formulation does not bring about any improvement in the moisture resistance of the films

ISSN:0021-8995    

DOI:10.1002/app.1974.070180904

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

年代:1974

数据来源: WILEY

摘要:

AbstractVarious methods are used by the paint and coating technologists to evaluate the resistance of protective coatings to penetration of water through them. This article intends to introduce a new, simple method for the moisture resistance evaluation. The method uses thin metal films as the sensor and is not absolute. However, it may be very useful for comparative experiments when the paint formulator seeks an optimum performance of coating developed for moisture protection.

ISSN:0021-8995    

DOI:10.1002/app.1974.070180905

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

年代:1974

数据来源: WILEY

摘要:

AbstractThis paper deals with the results of the experimental investigations of mechanical breakdown of individual polymers in mixtures with other polymers depending on different factors of mechanical treatment, polymer and mixture properties.

ISSN:0021-8995    

DOI:10.1002/app.1974.070180906

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

年代:1974

数据来源: WILEY

摘要:

AbstractChemisorption and crosslinking of cotton cellulose has been carried out with DMEU, DMPU, DHEU, and DMDHEU. Various physicochemical properties of resin‐treated samples have been studied and the data subjected to a linear regression analysis. Using the techniques of liquid retention and optical microscopy it has been found that the chemisorbed cotton is characterized by a lower level of bound resin, greater amount of methylol HCHO, and higher swellability of structure in comparison to the crosslinked cotton. This difference of behavior between the two cottons is attributed to greater rigidification and a collapse of porous structure in crosslinked cotton as a result of catalytic activity at the curing temperature. For various resin‐treated samples there exists a linear relationship between the strength and recovery characteristics of single fibers and those of fiber bundles. The losses in fiber strength and extensibility are found to be proportional to the level of bound resin in various samples. Crosslinked fibers show appreciably higher magnitudes of elastic recovery and bundle crease recovery than chemisorbed fibers. The significance of these results is discus

ISSN:0021-8995    

DOI:10.1002/app.1974.070180907

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

年代:1974

数据来源: WILEY

摘要:

AbstractA theoretical expression has been derived to describe the strain behavior of rigid plastic composites containing spherical filler particles. By combining the predicted ultimate strength values with the appropriate modulus relationship, the complete stress–strain history and corresponding fracture energy may be estimated. The theoretical predictions were compared with experimental values obtained for a general‐purpose polyester resin containing spherical glass beads. The influence of silane coupling agents and filler adhesion was also evaluated. Although the experimental values showed considerable scatter, the general trend agreed fairly well with the theoretical predicti

ISSN:0021-8995    

DOI:10.1002/app.1974.070180908

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe influence of forced diffusion by a d. c. electric field on the graft polymerization of ionic 4‐vinylpyridine onto a host membrane was determined. The host was a commercial cation exchange membrane. Initiation was by a redox couple of titanious ions at the exchange sites of the membrane andt‐butylhydroperoxide in the bulk solution along with the monomer. Undesirable effects of electrode reactions were avoided by isolation of the electrode compartments with permselective membranes. Measurements were at monomer concentrations of 0.05, 0.1, and 0.2Mand d.c. current densities of 0.08 and 0.16 mA/cm2. Applying the field accelerated the graft rate and provided greater control of the amount and distribution of the polymer than when free diffusion alone directed the reaction. This suggests possible value of forced diffusion by an electric field to tailormake membranes to special properties such as in the case of ampholytic mosaic membra

ISSN:0021-8995    

DOI:10.1002/app.1974.070180909

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe thermal decomposition of poly(oxypropylene) glycols was studied under nitrogen and dynamic operating conditions over the temperature range of 320° to 700°K by means of a differential scanning calorimeter. The differential energy losses due to changes in emissivity of the reference and sample pans were computed by modifying the baseline of the thermograms. Kinetic parameters obtained with the help of the Borchardt and Daniels theory indicate that the reaction is zero order and that the activation energy increases with molecular weight of the polymer. The rate of heating of the sample, the rate of flow of nitrogen, and the initial mass of the sample do not have significant effects on the kinetics of the decompositio

ISSN:0021-8995    

DOI:10.1002/app.1974.070180910

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

年代:1974

数据来源: WILEY