摘要:

AbstractIon beam mixing was used to improve the adhesion between deposited Cu film (400 Å) and polyimide (PI) substrate. Ar+ion with the energy levels between 180 and 200 keV, and the dose between 1014to 4 × 1016ions/cm2were used. The surface analyses were carried out by Rutherford Backscattering Spectroscopy (SEM). RBS analysis, using 2 MeV He+ions, showed mixing of Cu and FI and the mixing depended on the Ar+energy and dose. The X‐ray study showed a very broad halo for deposited Cu film but the (111) peak appeared after the Ar+implantation and the peak increased with Ar+ion dose. Optical micrographs showed that Cu film formed circular bubbles after many thermal cycles when adhesion was poor and fracture cracks when adhesion was g

ISSN:0032-3888    

DOI:10.1002/pen.760300302

出版商:Society of Plastics Engineers    

年代:1990

数据来源: WILEY

摘要:

AbstractSome design strategies for structural reaction injection molding (S‐RIM) and resin transfer molding (RTM) are presented. Our approach makes use of moldability diagrams to define the parameters necessary to meet the process requirements. Moldability diagrams are presented for the filling and curing steps. The criterion for selecting the amount of fiber reinforcement, injection time, catalyst level, and process temperatures in order to optimize properties and demold time is describe

ISSN:0032-3888    

DOI:10.1002/pen.760300303

出版商:Society of Plastics Engineers    

年代:1990

数据来源: WILEY

摘要:

AbstractUltrasonically induced bubble formation for the production of thermoplastic foam was investigated experimentally and theoretically as a basic study. A general purpose polystyrene and blends of low density polyethylene and polyethylene wax were saturated with nitrogen gas under various pressures and the ultrasonic excitation was applied to the polymer system upon release of gas pressure. The ultrasonic nucleation of bubbles in the polymer matrix was modeled by utilizing the classical nucleation theory. The negative pressure generated by the ultrasonic excitation was considered as the environmental pressure at the moment of nucleation. The experimental results showed that the heterogeneous nucleation must be used for ultrasonic foaming of the viscous fluid and the homogeneous nucleation for the low viscosity fluid. The theoretical analysis also indicated that the ultrasonic nucleation can be applied to the production of thermoplastic foam if the ultrasonic excitation generates large enough negative pressure.

ISSN:0032-3888    

DOI:10.1002/pen.760300304

出版商:Society of Plastics Engineers    

年代:1990

数据来源: WILEY

摘要:

AbstractThe general domain in which this work resides is that of mixing in creeping flows. Mixing, in this context, refers to the stretch of an interfacial line, or area in a strain field. The advancement of mixing technology is applied to the design of continuous mixers used in polymer processing. The geometric designs included single screw extruders, static motionless mixers, and co‐ and counter‐rotating twin screw extruders. The co‐rotating twin screw extruder was chosen to be studied in detail since it enjoys wide applications and, for which, little understanding of the contribution to mixing in the different screw geometries is known. In order to evaluate the rate of mixing for the non‐uniform strain history flows, the method for measuring mixing had to be reexamined and broadened. An automated method has been developed which incorporates a digital camera and a computer to analyze the cross‐sections of interest. Two measures of mixing—the correlation function and the distribution function—are developed to describe mixing in these regimes. These measures are applied successfully to the mixer geometries revealing subtle differences as to the nature of m

ISSN:0032-3888    

DOI:10.1002/pen.760300305

出版商:Society of Plastics Engineers    

年代:1990

数据来源: WILEY

摘要:

AbstractThis paper describes the basic design features of a new reaction injection molding (RIM) processing device, Rotary Injection RIM (RI‐RIM). The new design includes a novel mixing concept which furnishes high intermaterial contact area upon shear imposed rotary injection of the RIM components for effective in situ polymerization. This system operates in low pressure and laminar flow conditions, as opposed to the high pressure and turbulent flow, found in conventional RIM systems. The mixing process is described and quantified in terms of the various forces which govern the injection process. A progressive diminution in the average size of the dispersions generated is found with increasing rate of shear, continuous‐phase viscosity, and injection rate. These results are compared with those expected from traditional shear mixing (bulk convective shearing) under comparable conditions and the current system found to be more efficacious. Reaction molding experiments with RI‐RIM using a model polyurethane system are described and the influence of operating conditions on the mechanical properties of the finished moldings are elucidated. A detectable change in the morphology of the system is observed following increase in the total shear strain imparted to the initial mix of the multiphase reactants. It is suggested that the observed change is affected by a segregation between the components of the segmented po

ISSN:0032-3888    

DOI:10.1002/pen.760300306

出版商:Society of Plastics Engineers    

年代:1990

数据来源: WILEY

摘要:

AbstractThis paper describes the shear imposed interfacial segregation of release systems for the facilitated attenuation of polyurethane (PU) adhesion to metal coun‐terfaces using a RI‐RIM system. It is shown that the migration rate of the dispersed release additives due to a shear imposed stress in the resin fluid is much greater than that arising from Fickian diffusion, thereby removing a vital constraint from conventional practice. The novel rotary injection RIM system is presented to simulate the on‐line injection and shear induced interfacial segregation in model PU/abherent systems. A wide range of recipes comprising single (liquids or solids) and multicomponent (liquid‐liquid and solid‐liquid) release materials were injected into the polymerizing resin mixture to provide cohesively weak and friable “particle” boundary layer assemblies at the PU/metal interface. An instrumented Blister Test was employed to evaluate the quality of the molded interfaces in terms of adhesion and the concentration distribution of the injected species in the final cured moldings was determined through high pressure liquid chromatography (HPLC). A comparison of the results on the shear modified and the compounded interfaces confirm an accentuated lateral migration of the additives to the interface resulting in an appreciable diminution in the adhesion of the system. Finally, transport models are suggested to account for the observed augmen

ISSN:0032-3888    

DOI:10.1002/pen.760300307

出版商:Society of Plastics Engineers    

年代:1990

数据来源: WILEY

摘要:

AbstractA continuous loop tubular reactor (CLTR) with a Bodenstein number of 100 and a recycle ratio of 0.992 (obtained under the conditions of a mean residence time of 25.0 to 59.95 min and a stirring rate of 418 rpm) was used for studying the emulsion polymerization of styrene (St). The recipe used in the study is 76.8 g St/l‐water, 3.73 g sodium lauryl sulfate (SLS)/l‐water, and 2.30 g potassium persulfate (KPS)/l‐water. The effects of the mean residence time on the performance of emulsion polymerization were studied. The overshoots in the monomer conversion and the particle number concentration were found to be higher as the mean residence time increased. The overshoots diminished at about 3 times the mean residence time. The steady state particle number concentration was independent of the mean residence time, while the steady state monomer conversion increased with increasing mean residence

ISSN:0032-3888    

DOI:10.1002/pen.760300308

出版商:Society of Plastics Engineers    

年代:1990

数据来源: WILEY

摘要:

AbstractThe effect of solvent evaporation on spun‐on polymer thickness is investigated. Film thickness is shown to be proportional to spin speed raised to the negative of a constant,b.This constant is specifically considered. Of particular interest is the short initial period during spin coating signified by a rapid increase in solution viscosity, but where solvent diffusion in solution is not yet significant. Many previous theories have suggested the existence of a single value forbdependent only upon environment and spin coating system. Here, a single polymer dissolved in five pure solvents is examined. The polymer is Thermid IP‐600 (National Starch and Chemical Co.), an isoimide precursor. The solvents considered are n‐methyl‐2‐pyrrolidinone, dimethyl sulfoxide, dimethyl formamide, ethylene glycol dimethyl ether, and 2‐methoxyethyl ether. Spin Speed ranges from 0.6 to 7.0 kRPM and spin time is held at 15 s. It is shown that b varies from 0.97 for n‐methyl‐2‐pyrrolidinone to 0.57 for 2‐tncthoxycthyl ether. An empirical relation describing the behavior of b for this particular polymer and spin conditions used isb= [(MW)s(Pvap)s]/[(MW)n(Pvap)n]−0.1, where (MW)sand (MW)nare the molecular weights of the solvent and of n‐butyl acetate, respectively and where (PVaP)sand (Pvap)nare the vapor pressure of the pure solvent and the vapor pressure of n‐bu

ISSN:0032-3888    

DOI:10.1002/pen.760300309

出版商:Society of Plastics Engineers    

年代:1990

数据来源: WILEY

ISSN:0032-3888    

DOI:10.1002/pen.760300301

出版商:Society of Plastics Engineers    

年代:1990

数据来源: WILEY