Polymer Processing Parameters

Other important parameters are the following the voltage supplied, the feed rate, the solution s temperature, collector s type, the needle s diameter, and the distance between the needle tip and the collector. These parameters can control the fiber morphology but they are less significant compared to the solution parameters. 

---

Research on polymer fabrication is used to develop parameters that allow obtaining polymer processing parameters from a determined set of macroscopic properties, which yields parameters that are suitable for the thermodynamic properties and phase behavior of polymeric materials during its melt condition. It is necessary to have an extensive experimental detail to minimize the troubles during polymer processing. Therefore,... 

Since most recent polymers are complex mixtures, in which the composition and molar mass depend in multiple ways on the polymerization kinetics, the polymerization technique, and the process conditions, the polymer processing parameters must be carefully controlled and monitored to obtain polymeric materials with the desired properties. It is essential to understand the influence of molecular parameters on polymer properties and end-use performance. Molar mass distribution and average chemical composition may no longer provide sufficient information for process and quality control nor define stmcture-property relationships. Modern characterization methods now require multidimensional analytical approaches rather than average properties of the whole sample [5]. 

Families of finite elements and their corresponding shape functions, schemes for derivation of the elemental stiffness equations (i.e. the working equations) and updating of non-linear physical parameters in polymer processing flow simulations have been discussed in previous chapters. However, except for a brief explanation in the worked examples in Chapter 2, any detailed discussion of the numerical solution of the global set of algebraic equations has, so far, been avoided. We now turn our attention to this important topic. 

The effect of mechanical treatment on floe behavior is illustrated in Figure 5. In one work (40), identical slurries were treated with varying doses of the same polymer. At each dosage, it can be assumed that the same type of floe formed at the same rate. However, the dosage response was completely different depending on which parameter of the flocculated slurry was measured. Thus the term optimal flocculation caimot be appHed to any flocculant—substrate combination if the soHd—Hquid separation process or process parameter is not specified. 

Although Eq. (13) has been reported to fit the data well for Cl = 3.5, and C2 = - 2.0, it provides no information on the phase separation process. In fact, there is little understanding about how the physical morphology and mechanical properties evolve with polymerization and time. The effect of various process parameters on the phase separation and morphology is obtained implicitly via final properties of the polymers. This is illustrated... 

Literature Survey on Thermal Degradation, Thermal Oxidation, and Thermal Analysis of High Polymers. Ill , PLASTEC Note 20 (1969) 29) N T. Baldanza, Literature Search Injection Molding Processing Parameters , PLASTEC Note 21 (1969) 30) A.H. Landrock, Polyurethane... 

The type of initiator used affects the molecular weight and conversion limits in a reactor of fixed size and the molecular weight distribution of the material produced at a given conversion level. The initiator type also dictates the amount of initiator which is necessary to yield a given conversion to polymer, the operating temperature range of the reactor and the sensitivity of the reactor to an unstable condition. Clearly, the initiator is the most important reaction parameter in the polymer process. 

Minimizing the cycle time in filament wound composites can be critical to the economic success of the process. The process parameters that influence the cycle time are winding speed, molding temperature and polymer formulation. To optimize the process, a finite element analysis (FEA) was used to characterize the effect of each process parameter on the cycle time. The FEA simultaneously solved equations of mass and energy which were coupled through the temperature and conversion dependent reaction rate. The rate expression accounting for polymer cure rate was derived from a mechanistic kinetic model. 

The goal of all fabricators is to minimize the cycle time and maintain part quality. The process parameters involved are winding speed, mold and press temperatures and polymer formulation. 

Detection of Crystallization and Melting. A problem frequently tackled by monitoring WAXS peaks is the detection of crystallization and melting as a function of temperature, time, pressure, or other processing parameters —> As long as some of the characteristic peaks of a polymer material are observable, a fraction of the material is in crystalline state. 

Sensitivity impacts upon the limit of detection and resolution of the device, making it a key performance parameter. Recently, several strategies have been developed in order to provide sensitivity enhancements for optical sensor platforms based on both optical absorption and fluorescence phenomena. These strategies are the result of rigorous theoretical analyses of the relevant systems and, combined with polymer processing technology and planar fabrication protocols, provide a viable route for the development of low-cost, efficient optical sensor platforms. 

The foregoing review of the alkylation mechanism and the influence of the catalyst type and reaction conditions show that, in essence, the chemistry is identical with all the examined acid catalysts, liquid and solid. Differences in the importance of individual reaction steps originate from the variety of possible structures and distributions of acid sites of solid catalysts. Changing process parameters induces similar effects with each of the catalysts however, the sensitivity to a particular parameter depends strongly on the catalyst. All the acids deactivate by the formation of unsaturated polymers, which are strongly bound to the acid. 

Etch selectivity is crucial to the gas-phase functionalized resist schemes. Since the thickness of the etch resistant Ti02 layer that forms on the polymer film should depend on the amount of water sorbed on the polymer surface, we studied the influence of various processing parameters on the surface water content as measured by the amounts of Ti deposited. 

Huang and Tang49 trained a neural network with data relating to several qualities of polymer yarn and ten process parameters. They then combined this ANN with a genetic algorithm to find parameter values that optimize quality. Because the relationships between processing conditions and polymer properties are poorly understood, this combination of AI techniques is a potentially productive way to proceed. 

We are now in a position to discuss the effects of low frequency (< 400 kHz) high intensity (> 3 W cm ) ultrasonic waves on macromolecules (polymers) and examine how the parameters such as frequency, intensity, hydrostatic pressure etc affect both the polymerisation and also the depolymerisation processes. We will also consider in this chapter the use of ultrasound in polymer processing. 

---