摘要:

AbstractAcetalized poly(vinyl alcohol)s which were synthesized from poly(vinyl alcohol) (PVA) and aldehyde or ketone were evaluated as electron beam (EB) resists, in order to investigate the relationship between EB sensitivity and chemical structures of the polymers. It was found that the acetalized PVAs were easily crosslinked by EB exposure. The main mechanism of crosslinking may be radical reaction at acetal group. The sensitivity of the acetalized PVA depended on the structure of the acetal group. Acetalized PVAs synthesized from benzaldehyde, in which the electron attracting group was substituted on the benzene ring and from linear aliphatic aldehyde having a long alkyl chain, had high sensitivity. A high sensitivity of 7.2 × 10−7C/cm2was attained when the acetalized PVA synthesized from p‐chloro‐benzaldehyde was used. Acetalized PVAs synthesized from PVA and aldehyde having a cyclic structure had an excellent dry etching durability and were suitable as negative EB r

ISSN:0032-3888    

DOI:10.1002/pen.760290602

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractPoly(ethylene terephthalate) (PET) and bisphenol‐a‐polycarbonate (PC) are known to form a miscible blend whereas ternary blends of PET, PC, and polypropylene (PP) form two phases. This is based on the considerations of various chemical events which may occur in these systems. The role of ester‐carbonate interchange reactions during melt mixing and fabricating is found to be unimportant. Differential scanning calorimetric analysis of the ternary blends shows that there appears to occur an exothermic transition in the heating mode of the instrument. This exothermic event was found to be suppressed considerably by incorporating suitable additives into the system. Degradation reactions studied by thermogravimetric analysis and a dilute solution viscometric technique reveal that there exists some kind of interaction among the components even with the immiscible PP comp

ISSN:0032-3888    

DOI:10.1002/pen.760290603

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractThe glass transition temperature has been measured carefully for the fluoroelastomer, Tecnoflon, a copolymer of vinylidene fluoride and hexafluoropropene, diluted with variable amounts of 2‐butanone. Of the several different theoretical treatments found in literature, that presented by Gordon and coworkers appears to give the equation that describes well the experimental results, without making use of adjustable parameters. Some features found at very high diluent content can be interpreted with a treatment based on free volum

ISSN:0032-3888    

DOI:10.1002/pen.760290604

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractThis work proposes a cascade model reference adaptive algorithm to control a continuous polymerization reactor, which is operated under forced oscillations of its feeds. The objective is to produce a polymer with desired average values of the average chain length, of the average polydispersity and of the average polymer production; in spite of the fact that some of the model parameters may be unknown and/or may vary slowly with time. This objective is achieved by imposing the first two moments of the number chain length distribution (NCLD) to follow predetermined periodic trajectories. The proposed control scheme is an extension of that by Eliçabe,et al., when the number of independent controls is less than the number of system states. Computer simulations have shown the feasibility of the proposed technique, provided continuous state measurements are available

ISSN:0032-3888    

DOI:10.1002/pen.760290605

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractUltrahigh molecular weight polyethylene (UHMWPE) gel films were prepared by gelation crystallization from decalin solutions. According to wide‐ and small‐angle X‐ray scattering (WAXD and SAXS) studies, single crystal mat texture with crystal c‐axis oriented normal to film surface generally develops. However, randomly oriented structure can also develop if an external force is applied to gel films during gelation crystallization. Both textures invariably yield high drawability in uniaxial mode with outstanding modulus and strength. Biaxial films, typically 5 × 5, 6 × 6, 8 × 8, and 10 × 10 times the original dimensions, were prepared at 130°C–135°C in a biaxial stretcher. Optical microscopic Investigations reveal the development of interwoven fibrillar structure in all specimens. WAXD and SAXS studies show that lamellar structure transforms to fibrillar texture during biaxial stretching. Crystal orientation is characterized by WAXD pole figure and infrared dichroic methods. Mechanical studies suggest that tensile modulus and strength appear uniform. In comparison with uniaxial deformation, significant improvement in the lateral strength is seen in the biaxially

ISSN:0032-3888    

DOI:10.1002/pen.760290606

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractThe effect of molecular weight distribution on the Theological and mechanical properties of a series of polypropylenes is evaluated. The polypropylenes tested were produced by controlled chemical degradation in a single‐screw plasticating extruder. Measured properties include shear, extensional and intrinsic viscosity, melt flow index, extrudate swell, melting and crystallization temperatures, impact strength, flexural modulus, and tensile stres

ISSN:0032-3888    

DOI:10.1002/pen.760290607

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractInterpenetrating polymer networks of polyurethane and unsaturated polyester were prepared by reaction injection molding (RIM) and transfer molding. The structures of the molded samples were analyzed by electron microscopy and dynamic mechanical analysis. It was found that polymer morphology and dynamic mechanical properties depend strongly on the molding temperature, reaction rate and reaction sequence. Simplified structure models based on Takayanagi's model and sample morphology can predict the storage modulus reasonably well but not the tanδ

ISSN:0032-3888    

DOI:10.1002/pen.760290608

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractPoly(ether‐ether‐ketone) (PEEK) is a newly developed engineering thermoplastic with potentially vast application in advanced composites due to its exceptional performance. It is thus desired to understand the relationship between physical processing, microstructure and fracture in this semicrystalline polymer. Both oriented and unoriented PEEK were mechanically characterized using static test of three‐point bend specimens. The molecular chain orientation was imposed using a rolltrusion technique. The effects of thickness, strain rate, Initial crack length ratio, and orientation on fracture toughness (Kc) are investigated. The crystallinity is also examined by density measurement. The degree of orientation is determined qualitatively by wide‐angle X‐ray scattering diffraction patterns and quantitatively by further measurement using an image analysis system. Fractographic analysis, using scanning electron microscopy, provides precise information about the mode of fracture, Results indicate that both the modulus and the fracture toughness are remarkedly increased in the direction of drawing (T‐type) as opposed to the transverse directi

ISSN:0032-3888    

DOI:10.1002/pen.760290609

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractMelt temperature in an extrusion process can significantly influence production rate, product quality, and yield. However, prediction of melt temperature is extremely difficult because errors in the predictions of output rate, screw power, and heat transfer, which are used to calculate melt temperature, cumulatively cause a very large error in the prediction of melt temperature. This paper analyzed the overall energy balance of an extruder and developed a simple equation to predict the melt temperature of a projected extruder in scale‐up as a function of screw diameter, depth, and speed based on the experimental results of an experimental extruder and the polymeroperties. The predicted melt temperatures agreed reasonably with the measured values reported in a previous scale‐up st

ISSN:0032-3888    

DOI:10.1002/pen.760290610

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractHerein is more detail to microscopic aspects of electron transport through a conductor‐filled polymer than has yet been considered in the literature (irrespective of quantum mechanical tunneling and thermal expansion). Some of these details only clarify earlier theories, but others lead to new discoveries such as the cubic conduction path coordination number z = 18 (contrasted with the classical geometric coordination number of z = 6). New also are simplified derivations of the high and low fill asymptotes of the master equation for conductance as a function of fill fraction in the effective medium theory of conductor‐filled polym

ISSN:0032-3888    

DOI:10.1002/pen.760290611

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY