摘要:

AbstractPolypropylene/Polyamide‐6 (PP.PA) blends containing maleic anhydride grafted elastomers were prepared by reactive blending. Three different types of core shell morphologies were obtained and characterized by transmission electron microscopy (TEM). The midulus of these elastomer midified PP/PA (70/30) blends with core shell type morphology is compared to predictions derived from the Kerner model. The multiphase morphology of these blends could be modeled by sequential application of the Kerner equation to two‐phase subinclusions. Using morphological data ontained by TEM, good agreement between experimental and calculated values was ontained. The results are used to tailor PP/Pa‐6 blends combining stiffness and toug

ISSN:0032-3888    

DOI:10.1002/pen.760352402

出版商:Society of Plastics Engineers    

年代:1995

数据来源: WILEY

摘要:

AbstractPoly(ether ether ketone) (PEEK) is high performance semicrystalline thermoplastic with a glass transition temperature of 143°C. The melting point (Tm) is quoted as 334°C. Because of its high thermal transitions, PEEK, requires high temperatures for processing, at least 370–400°C. It has been determined that under the recommended processing conditions PEEK can undergo branching and eventually crosslinks. An alternative to melt processing PEEK is to apply the powder metallurgy technique of sintering. This involves cold (room temperature) compaction of the polymeric powder, followed by pressure free sintering of the resultant green body. We have reported a process for preparing submicron PEEK particles, and the focus here is on the free sintering of these particles with emphsis on the effects of particle size, sintering temperature, and compaction pressure. The data is evaluated using the two particle model developed by Frenkel as well as the crack healing theory developed by

ISSN:0032-3888    

DOI:10.1002/pen.760352403

出版商:Society of Plastics Engineers    

年代:1995

数据来源: WILEY

摘要:

AbstractOne of the major factors limiting the use of thermoplastics in engineeing applications is the inadequacy of existing design data. Much of the data do not span appropriate ranges of stress, strain, time, or temperature. This study addresses the need to develop an accelerated method for generating long‐time design data to support the innovative use of engineering thermoplastics. In particular, stress relaxation tests (SRT) were performed on polycarbonate (PC) and midified poly(phenylene oxide)(PPO), and used to generate time‐dependent design data through the short‐time measurement of the material's current state without dependence on elastic modulus. The test results and analyses reported here indicate the SRT method to be an efficeint means of generating accurate and repeatable creep and secant modulus data which may be directly used in design. Therefore, SRT shows great potential both as a design parameter development tool, and as a quality control instrumetn for assessing batch‐to‐batch va

ISSN:0032-3888    

DOI:10.1002/pen.760352404

出版商:Society of Plastics Engineers    

年代:1995

数据来源: WILEY

摘要:

AbstractThe difference between reactive and nonreactive polymer blends in terms of processing and morphology has been investigated. The glassy phases for the blends are an oxazoline functional polystyrene (PS‐Ox) and a similar non‐functional polystyrene (PS). The rubbery phases are an ethylene‐propylene rubber (EP) and a similar ethylene‐propylene rubber (EP‐MA) with 07% grafted maleic anhydride. In the case of PS‐Ox/EP‐MA blends, the oxazoline group may react with the grafted rubber functionality at the interface between the two immiscible components during blending to form a compatibilizing agentin‐situ. The nonreactive blends systems of PS‐Ox/EP and PS/EP‐MA were used for comparison to the reactive system. The blend components are rheologically matched to simplify the interpretation of the process and morphological data. The blends were prepared in a batch mixer with roller blades. The torque required for mixing was measured during the blending process. The torque traces for the reactive blends exhibited a peak in torque, attributed to the chemical reaction at the interface. The weight fraction of gel in the blends was used to measure the extent of reaction. It correlates well with the mixing torques and rheological properties. The nonreactive PS‐Ox/EP and PS/EP‐MA blends show poor interfacial adhesion between the two phases. In contrast, the reactive PS‐Ox/EP‐MA blends show excellent during annealing is also much greater for the reactive blends. Varying the functionality concentration in the PS phase shows that the dispersed phase rubber particle size is reduced by increasing the concentration of oxazoline in the matrix. Blends with no or small amounts of functionality in the PS phase exhibit yield behavior in tension. However, a level of concentration of reactive functionality may be reached where t

ISSN:0032-3888    

DOI:10.1002/pen.760352405

出版商:Society of Plastics Engineers    

年代:1995

数据来源: WILEY

摘要:

AbstractExperiments on coated films of water borne, coatings (WBC) under controlled conditions (i.e., 25°C, 65% RH) were carried out to study the mechanism of leveling. Data in a companion paper imply that the development of the surface tension gradients plays an important role in promoting leveling. The stress due to surface tension gradients is found to be much greater than the stress introduced by hydrostatic pressure gradients in the film caused by surface tension and the free boundary curvature of the film. This reconfirms that the use of a co‐solvent, which evaporates faster than water, greatly accelerates the leveling of a W

ISSN:0032-3888    

DOI:10.1002/pen.760352406

出版商:Society of Plastics Engineers    

年代:1995

数据来源: WILEY

摘要:

AbstractThe influence of film thickness on the leveling of a thermosetting waterborne coating (WBC) was examined. The theory of Patton has been revised to give the proper force balance and modified to include the changes in surface tension and viscosity during leveling by the evaporation of volatile components. However, the predicted leveling process by a numerical method did not coincide with the observed results. Thus, the driving force in the theory, the hydrostatic pressure gradient in the film, was considered to be insufficient to describe the leveling process of the WBC. The hydrostatic pressure gradient can be a component of the driving force to promote leveling, but the existence of an additional component is suggested.

ISSN:0032-3888    

DOI:10.1002/pen.760352407

出版商:Society of Plastics Engineers    

年代:1995

数据来源: WILEY

摘要:

AbstractPolypropylene (PP) composites containing 0.30 vol% of talc filler, in addtion to blends modified with an ethylene‐propylene copolymer (EPR) elastomer were prepared and their fracture resistance was determined by the standard Ixod impact test and by a fracture mechanics technique. Effects of composition, type of modification, specimen size, and temperature were studied. The validity of linear elastic freacture mechanics (LEFM) conditions were checked: It was shown that under the conditions applied they can be satisfied even twith specimens of reasonable size (4 × 10 × 80 mm) prepared by conventional processing techniques. Calculations of minimum specimen thickness must be carried out, with material properties obtained under the conditions of impact. For heterogeneous blends and composites yield stress should be corrected for the effect of decreasing load‐bearing cross section. Linearity of the fracture energy (U) vs.BDϕ orU vs. B(D‐a) plots is not a proof for either elastic of plastic fracture. The composition dependence of fracture properties proved to be practicaly independent of specimen size, temperature, or measurement t

ISSN:0032-3888    

DOI:10.1002/pen.760352408

出版商:Society of Plastics Engineers    

年代:1995

数据来源: WILEY

摘要:

AbstractThe processing of high temperture thermoplastic polymers as a hot melt adhesive is one means of joining thermoplastics to metals. The presetn study establishes the role of processing in thermoplastic joining of a titanium alloy (Ti‐6A1‐4V) using thin flim poly(etherketoneetherketoneketone) (PEKEKK). A design of expriments (DOE) was performed to determine the effects of the soak above melt temperature (Tm= 380°C), hold at the isothermal recrystallizztion temeprature (Tiso= ∼ 340°C) and cooling rates on the joint strength, Extended soak times are required to remove the residual spherulitic crystallinity in the polymeric adhesive. Whit the elimination of the residual crystallinity, high‐strength transcrystalline regions are enhanced at the polymer‐metal interface during the hold time atTisoand during cooling to ambient temperature. Average tensile strengths of 137 MPa were achieved, exceeding the bulk polymer tensile strength of 118 MPa by 16%, X‐ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) show that extended soak times aboveTmled to excessive polymer squeeze‐out, resulting int he creation of strength‐reducing shrink voids or unwetted regions. As a result, the failue mode of the joint, which was normally cohesive for high‐strength joints, became a mix of cohesive and adhesive in parts with excessive

ISSN:0032-3888    

DOI:10.1002/pen.760352409

出版商:Society of Plastics Engineers    

年代:1995

数据来源: WILEY

摘要:

AbstractThe rheological behavior of multilayer polyjeric structures has been investigated Measurements of the bulk viscoelastic properties via small‐amplitude oscilatory rheometry indicated that the shear viscosity is independent of both the numbe of layers (83 vs. 165) and the composition (30/70, 50/50, and 70/30 PC/PMMA by weight) within the limits of the data obtained. It is also apparent tha tthe shear viscosity is influenced strongly by the skin layer material. In additon, a model has been developed tha tcan be used to proedict the shear viscosity and shear stress ofa multilayer structure experiencing shear flow. The model predicts tha thte shear viscosity of a multilayer structure should be independent of the number of layers and strongly dependent on the material in the skin layer. These predictions are in agreement with experimental dat

ISSN:0032-3888    

DOI:10.1002/pen.760352410

出版商:Society of Plastics Engineers    

年代:1995

数据来源: WILEY

ISSN:0032-3888    

DOI:10.1002/pen.760352401

出版商:Society of Plastics Engineers    

年代:1995

数据来源: WILEY