Splay problem

Ogando, ]., Screw Design Cures Splay Problems, Plast. TechnoL, November (1995)... 

These are usually self-adhesive, precut, printed patterns on a substrate that are simply adhered to the surface of a product. Decals generally use a transparent plastic film while labels are usually on an opaque plastic, metallic and multilayer sandwich base. Labels of sufficient thickness are useful for hiding unavoidable appearance problems such as gate and sprue removal areas, sink marks, blushes, splays, and weld lines. 

Melt in a plasticator must be freed of gaseous components that include moisture and air from the atmosphere and from plastics, plasticizers, and/or other additives as well as entrapped air and other gases released by certain plastics. Gas components such as moisture retention in and on plastics have always been a potential problem for all processors. All kinds of problems develop on products (splay, poor mechanical properties, dimensions, etc.). This situation is particularly important when processing hygroscopic plastics (Chapter 1). One major approach to this plastic degrading situation is by using plasticators that have vents in their barrels to release these contaminants. 

Problem 10.8 You are measuring the elasticities and viscosities of a room-temperature nematic at reduced temperatures and you find that below about 10°C the twist and bend constants K2 and become very large, while the splay constant Ki retains a modest value. Also, the Miesowicz viscosity t], becomes enormous while r) goes up only modestly. What could explain this behavior ... 

The elastic problem for a membrane with a cylindrical insertion, accounting for both compression and splay contributions, was first studied by Huang [87]. In this study, Eq. 

The automotive indushy is an extremely competitive market for the injection molding industry. Automotive manufacturers are reducing the number of supphers which produce components for their vehicles. To stay competitive, injection molders need to be proactive in both technology and pricing. Interior trim is a very competitive market for the injection molding industry. Much of the interior of an automobile is comprised of plastic parts molded from many different materials. The variety of plastics used in interior trim makes it very difficult for the assembler to obtain color match between all components. Each type of base resin requires a different formulation of colorant to achieve the same finished color. This problem is further complicated by the addition of additives such as UV stabilizers, lubricants, fillers, etc. Other problems include molding faults such as flow lines, weld lines, sink, splay, and blush... 

We have already mentioned in the Introduction that microemulsions containing long-chain amphiphiles can be described by interfacial models. These models are based on the curvature elasticity of the amphiphilic monolayer and thus contain as material parameters the bending rigidity and the saddle-splay modulus. These parameters have to be calculated from a more microscopic model. A somewhat similar problem occurs in the... 

Moisture retention in and on plastics has always been a problem for all processors. Surface moisture or moisture absorbed within the plastic can cause splay, an unsightly surface defect of the molded part, and reduce mechanical properties. The increased use of hygroscopic plastics (see Chapter 9) also requires care and the assurance of proper drying of material via the usual technique, using dryers and/or vented barrels (Fig. 2-11). There are advantages of using vented barrels as opposed to the more familiar dryers (100) ... 

Molded-in stresses are minimal. The thick but hollow sections provide rigidity and do not create sink or warpage problems. The cycle time is reduced because the thick sections are hollow. As the gas is not mixed with the melt, there is no surface splay, which is typical of low-pressure structural foam molding (1). Gas injection is being used with commodity and engineering resins. 

Need for Drying TPEs. Many TPEs can absorb sufficient moisture in a short time to cause difficulties such as poor surface appearance (or splay) on injection molded parts and rough surfaces and porosity in extrusions. A moisture pickup of 0.10 percent or greater can give highly significant problems, even in the case of nonpolar hydrocarbon TPEs. An exposure of less than one day can be unacceptable. 

When individual lamellae are naturally elongated, the problem of constructing a spherulite from them devolves into mechanisms of branching and splaying of lamellae. Details of both these processes have been identified from the first use of permanganic etching to... 

This problem can be considered in the framework of the Helfrich approach to the nematic, though we have to take into account the specific viscoelastic properties of smectics and a proper sign of the conductivity anisotropy. First of all, it makes sense to consider only the onset of a splay deformation in a homeotropic structure for smectic A, since => 00. This approach is developed in [121], where the following expression for the threshold field of an instability is derived ... 

PAEK typically absorb around 0.5% moisture. This has a negligible effect on properties and will not cause chemical changes during processing. However, it will cause splay marks and other processing problems. Accordingly PAEK are typically dried for 3 hours at 150 °C or 2 hours at 160 °C before processing. 

Problems and Troubleshooting - Injection Molding Flow chart 5.2.15 - Splay marks/Delamination... 

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