摘要:

Cold-drawn uniplanar-axially oriented sheets of nylon 6 have been annealed at 195°C, hot-rolled at 130°C, and then chemically treated with phenol to form the α crystalline phase. The morphology is parallel-lamellar, with the molecular chains at right angles to the lamellar plane. The long period is 96.7 ± 0.7 Å. The extensional compliances S33(parallel to the draw direction) and S11(the transverse direction in the sheet) and the shear compliances S44, S55, and S66have been measured at 20.0 ± 0.3°C by dead-loading creep and torsional methods, in two relative humidity ranges, 0–10% and 61–69% RH. Dependence upon time (creep), strain, and humidity have also been determined. The extensional compliances show the cross-over of S33above S11when the αatransition or Tgis reduced to below room temperature by increasing the relative humidity from zero to 65%. The results are explained by using Takayanagi models for the extensional compliances and interlamellar shear or crystallite shear for the shear compliances.

ISSN:0022-2348    

DOI:10.1080/00222348008241371

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Infrared and Raman spectra of a highly crystalline sample of trans-1, 4-poly-2, 3-dichlorobutadiene are presented. The line group of an isolated chain of this polymer in the preferred conformation is isomorphous to the point group Ci. This predicts mutual exclusion between the infrared and Raman active modes and an outstanding example of this phenomenon is observed in the experimental vibrational spectra. Normal coordinate calculations have been preformed on both trans-1, 4-poly-2, 3-dichlorobutadiene and trans-1, 4-polychloroprene by using a common valence force field. A good fit between the observed and calculated frequencies throughout the whole spectral region has been obtained for both polymers. The assignment of the normal modes of both polymers is discussed.

ISSN:0022-2348    

DOI:10.1080/00222348008241372

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The morphology of poly-p-phenylene(PPh) formed during the polymerization of benzene by molybdenum pentaehloride(MoCl5) or ferric chloride(FeCl3) has been studied. It has been found that well-developed fibrillar structures are formed during the polymerization by MoCl5. Electron diffraction confirms that the molecular axes of PPh are oriented parallel to the fibril axis. These fibrillar structures suggest that the nascent PPh possesses a predominantly para structure. It is thought that the fibrillar structures result from simultaneous polymerization and crystallization. The reflections in electron diffraction patterns can be indexed by assuming a monoclinic unit cell with dimensions a = 7.78 Å, b = 5.62 Å, c = 4.26 Å, (fiber axis), and β = 79%. It can be assumed that the most likely space group is P21a. Aggregates of many crystalline fragments with an indefinite shape were formed during the polymerization by FeCl3. They give electron or x-ray diffraction pattern having broad Debye rings. It is thought that subsequent reaction of the polymer with benzene to form polyphenyl side chains or polynuclear structures occurs much more frequently during the polymerization by FeCl3. These side reactions may prevent the formation of the fibrillar structures with higher crystallinity.

ISSN:0022-2348    

DOI:10.1080/00222348008241373

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Bromine atoms have been attached to the surface of polyethylene single crystals and the effect of these surface masses on the longitudinal acoustic mode has been determined. As the amount of bromine is increased, the LA mode peak frequency decreases and the bandwidth increases. The observed peak frequency decrease is in good agreement with values calculated from the composite rod model.

ISSN:0022-2348    

DOI:10.1080/00222348008241374

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The tensile, dynamic mechanical and morphological properties of PC/HDPE, PC/LDPE and PC/PS blends have been investigated with the intent of clarifying the major factors governing the modulus of these essentially incompatible blends. Scanning electron microscopy shows that all of the PC/HDPE, PC/LDPE and PC/PS blends have a domain structure whose morphology is strongly dependent on the concentration of the dispersed phase; when the dispersed phase concentration is less than 15%, the domains are mostly of spherical shape, while above 20% agglomeration takes place to form rodlike structures. Dynamic mechanical data shows there is essentially no adhesion at the PC-HDPE and PC-LDPE boundaries, while there is appreciable adhesion at the PC-PS interface. The existence of an intermixed zone was postulated to explain this interfacial adhesion. Morphological and thermal analysis results also indicate that both the HDPE and LDPE inclusions are loosely sitting in the holes in the PC matrix while the PS inclusions are compactly embedded in the PC matrix. These differences in boundary nature give marked effects on the tensile properties including the modulus. For the modulus, PC/HDPE and PC/LDPE blend systems can be regarded to be mechanically equivalent to a PC matrix alone with holes in it when the dispersed phase concentration is lower than 15%, while in the case of PC/PS blends the PS inclusions contribute substantially to the sample's overall modulus.

ISSN:0022-2348    

DOI:10.1080/00222348008241375

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The tensile and Izod impact strength of polycarbonate (PC) based polyethylene (PE) and polystyrene (PS) blends has been examined. The tensile strength can best be described as being proportional to an exponential function of the volume fraction of PE and the first power of volume fraction of PS. The variation of Izod impact strength with composition also differs considerably for the two blends, a small amount of PS causing a marked drop in impact strength. The impact strength of the PE/PC blend is related to the area under the tensile stress-strain curve, whereas for PS/PC blends no correspondence is found. The variation in properties is related to the composition, morphology, interfacial adhesion at the phase boundary and failure surfaces of the various blends.

ISSN:0022-2348    

DOI:10.1080/00222348008241376

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor