摘要:

AbstractBlends of poly(2,6‐dimethyl‐1,4‐phenylene ether) (PPO) and atactic polystyrene (PS) have been prepared by mechanically mixing powders of the two polymers and subjecting the mixtures to three different thermal treatments. Three different compositions were studied by the dynamic mechanical and DSC techniques. The weight fractions of PPO in the mixtures were 0.25, 0.50 and 0.75. The dynamic mechanical measurements indicate that partial mixing took place but that two distinct phases, one rich in PS and the other in PPO, exist in all the mixtures studied. Each phase exhibits a characteristic relaxation peak associated with the glass transition of that phase. DSC measurements, on the other hand, reveal only a single glass transition apparently characteristic of the PS rich phase in each case. The results indicate that a given type of experiment will indicate compatibility or incompatibility depending upon the size of the molecular process it repre

ISSN:0032-3888    

DOI:10.1002/pen.760100302

出版商:Society of Plastics Engineers, Inc.    

年代:1970

数据来源: WILEY

摘要:

AbstractThis paper discusses the influence of fiber‐glass reinforcement content on the physical properties of four theroplastic injection molded materials. In addition, the effects of binder difference (i.e., thermoplastic vs. thermosetting), associated with the reinforcement, are described.Several properties that were expected to show response to glass content and binder differences have been examined. Among these are short‐ and long‐term tensile strength, flexural properties, compressive resistance, impact strength, deflection temperature under load (DTL), and environmental stress cracking.This work has demonstrated that fiber‐glass reinforcement of the particular thermoplastics described in this paper has led to substantial improvements in both the stiffness and strength characteristics of the base resins. The responses to binder chemistry difference was found to be slight in many instances for the resins, as reflected by the tests described herein. However, the long‐term tensile, impact, DTL, and stress‐cracking tests have shown considerable sensitivity to binder change in some cases, especially with respect to the polypropylene, SAN and polyamide plastics. The particular response to a given binder system, however, appears to vary both with the material under test and the property used to detect su

ISSN:0032-3888    

DOI:10.1002/pen.760100303

出版商:Society of Plastics Engineers, Inc.    

年代:1970

数据来源: WILEY

摘要:

AbstractA method for determining the melt elasticity is developed. The method requires the measurement of axial pressure distribution in a capillary and makes use of the extrapolated value of the pressure at the exit of a capillary, the so‐called “residual pressure.” The same measurement also provides data for determining the flow curve. Measurements were taken with polyethylene and polypropylene. The results are presented and discussed with particular emphasis on the application of the method to various ways of processing pol

ISSN:0032-3888    

DOI:10.1002/pen.760100304

出版商:Society of Plastics Engineers, Inc.    

年代:1970

数据来源: WILEY

摘要:

AbstractIn injection molding certain polymers, fracture of the polymer stream sometimes occurs at the mold surface. This phenomenon has been found to be a tearing apart of the polymer surface layer accompanied by downstream slip of the flowing melt at the polymer/mold interface. Fracture occurs early in mold filling and is initiated usually at the gate to the mold cavity. Analysis of the fracture mechanism indicates that fracture is caused by: (1) high shearing stress in the melt as it fills the mold; (2) poor polymer/mold adhesion; and (3) low polymer surface cohesive strength.

ISSN:0032-3888    

DOI:10.1002/pen.760100305

出版商:Society of Plastics Engineers, Inc.    

年代:1970

数据来源: WILEY

摘要:

AbstractThe thermal instability of polybutadiene‐based rubber used to improve the impact strength of vinyl‐type polymers often presents processing problems. Rubber manufacturers have attempted to alleviate this situation by incorporating various types of stabilizers. However, this is not always successful. One of the consequences of using a rubber that is not sufficiently stable in the production of modified vinyl‐type polymers is the formation of insoluble gel particles during processing. In an attempt to prevent this from occurring, a test was developed that can differentiate between rubbers of acceptable and non‐acceptable thermal stability. In principle, the test consists of exposing the rubber in question to a controlled thermal abuse of such intensity and duration as to approximate the thermal abuse to which the rubber will be subjected in a normal processing sequence. (The extent of abuse will vary for different processes and must be empirically established for each system.) Following this controlled exposure, the rubber is tested for gel‐particle content by filtration of a specific solution, much the same way that the rubber manufacturer tests for initial gel‐particle content. Sufficient data have been compiled to statistically describe the validity

ISSN:0032-3888    

DOI:10.1002/pen.760100306

出版商:Society of Plastics Engineers, Inc.    

年代:1970

数据来源: WILEY

摘要:

AbstractThe unusual physical properties of polybutylene are ascribed to details of morphology and a unique crystalline transformation. Inherent properties important for industrial film uses include toughness, low creep, relatively high temperature resistance, stress crack resistance and flexibilty. Four types of packaging applications are described for a new polybutylene resin based on butene‐1 monomer. These include industrial film, easy opening tear packages, shrink film, and rotationally molded tanks.A polybutylene shrink film is described having a combination of optical and shrink properties similar to vinyl shrink film, but with mechanical properties typical of polyolefin shrink films.Rotationally molded parts exhibit an unusual degree of toughness, stress crack resistance, and low crystallization stresses in thick part

ISSN:0032-3888    

DOI:10.1002/pen.760100307

出版商:Society of Plastics Engineers, Inc.    

年代:1970

数据来源: WILEY

摘要:

AbstractVersamid cured‐epoxy specimens were loaded in tension, compression, and flexure at different strain rates and temperatures to determine the yield stress and strain, and tangent, secant, and relaxation moduli. A torsion pendulum was used to measure the dynamic properties as a function of temperature and frequency. The time‐temperature superposition principle was used to reduce this data to master curves. It was concluded that the time‐temperature shift factors for secant moduli up to the yield point, for stress relaxation and for dynamic moduli were identical and were independent of the mode of loading. It was also shown that the presence of fillers or reinforcing agents likewise had no effect on the shift fa

ISSN:0032-3888    

DOI:10.1002/pen.760100308

出版商:Society of Plastics Engineers, Inc.    

年代:1970

数据来源: WILEY

摘要:

AbstractIncreases in modulus, tensile strength, and swelling caused by reinforcing silicone rubber with silica filler were correlated with the thermoelastic parameter, fe/f. A new semiempirical equation of state, containing a generalized front factor, was derived to explain the experimental results. While the retractive force in pure gum elastomers is largely entropic in origin, reinforcement in silicone rubber‐silica systems appears to arise by greatly augmenting the deformational free energy change stored in energetic mode

ISSN:0032-3888    

DOI:10.1002/pen.760100309

出版商:Society of Plastics Engineers, Inc.    

年代:1970

数据来源: WILEY

摘要:

AbstractThe recent history of planar reinforced plastic resins, including glass flake, high modulus ceramic flake, and continuous vapor coated film composites, is reviewed. The theoretical mechanics of both continuous (film) and discontinuous (flake and ribbon) reinforcements are summarized in simple form. A novel set of design curves is presented from which the lower bound requirements for the flake composite constitutents may be read directly. At the same time, the dependence of the composite ultimate strength on the shear strength of the plastic resin matrix is demonstrated.The mechanical properties of experimental film and flake composites representative of recent work are reported and compared with the theoretical predictions. In conclusion, the potential of planar reinforced plastic resin composites is discussed and found to be significant for applications where low weight and high isotropic stiffness are required, for example in aero‐structural, airfoil, or blade component

ISSN:0032-3888    

DOI:10.1002/pen.760100310

出版商:Society of Plastics Engineers, Inc.    

年代:1970

数据来源: WILEY

ISSN:0032-3888    

DOI:10.1002/pen.760100301

出版商:Society of Plastics Engineers, Inc.    

年代:1970

数据来源: WILEY