Molding index

BS 2782. Part 7, Method 720B, Cup flow of phenolic and alkyd molding materials 1979. ASTM D731-95. Molding Index of thermosetting molding powder. 

Molding index n. A practical measure of the difficulty of molding of thermosetting compound. A calculated weight of the candidate molding powder, is placed into a flash-type cup mold that has been preheated to the temperature prescribed for the material. The mold is closed and the total minimum force required to close it is reported as the molding index of the compound. 

Processability pra- se-s9- bi-l9-te (1954) n. The ease with which a polymer, elastomer, or plastic compound can be converted to high-quality, useful products with standard melt-processing techniques and equipment. Some quantitative tests of process-abihty have been devised for example, see molding index and thermoformability. 

Special Injection Molding Machines Insert Molding, Index and Rotary Machines, and Multicolor Molding... 

Besides appHcation as heat-resistant molding powders for electronic and other appHcations, DAIP copolymers have been proposed for optical apphcations. Lenses of high impact resistance contain 50% DAIP, 20% benzyl methacrylate, and larger amounts of CR-39 (59). A lens of refractive index 71- = 1.569 andlow dispersion can be cast from phenyl methacrylate, DAIP, and isopropyl peroxide (60). Lenses of better impact properties can be obtained by modifying DAIP with aHyl benzoate (61). 

The color of TSR L is measured with a Lovibond Comparator using methods outlined in the relevant International Standard (16). Raw mbber is molded into a disk 1.6 mm thick, and the color is compared and matched with that of standard glass disks. These glass disks provide a color index scale in which the higher index values correspond to darker colors. Generally the specification for TSR L is a maximum Lovibond individual value of 6 and range... 

Physical Properties. Physical properties include specific gravity, water absorption, mold shrinkage, transmittance, ha2e, and refractive index. Specific gravity affects performance and has commercial implications. The price of the material divided by the specific gravity gives the yield in cost per unit volume. Comparison of yields gives an evaluation of raw material costs. 

Thermal Properties. Thermal properties include heat-deflection temperature (HDT), specific heat, continuous use temperature, thermal conductivity, coefficient of thermal expansion, and flammability ratings. Heat-deflection temperature is a measure of the minimum temperature that results in a specified deformation of a plastic beam under loads of 1.82 or 0.46 N/mm (264 or 67 psi, respectively). Eor an unreinforced plastic, this is typically ca 20°C below the glass-transition temperature, T, at which the molecular mobility is altered. Sometimes confused with HDT is the UL Thermal Index, which Underwriters Laboratories estabflshed as a safe continuous operation temperature for apparatus made of plastics (37). Typically, UL temperature indexes are significantly lower than HDTs. Specific heat and thermal conductivity relate to insulating properties. The coefficient of thermal expansion is an important component of mold shrinkage and must be considered when designing composite stmctures. 

Most PET botties are produced by injection blow mol ding (71) the resin over a steel-core rod. The neck of the bottie is formed with the proper shape to receive closures and resin is provided around the temperature-conditioned rod for the blowing step. The rod with the resin is indexed to the mold, and the resin is blown away from the rod against the mold walls, where it cools to form the transparent bottie. The finished bottie is ejected and the rod is moved again to the injection-molding station. This process is favored for single cylindrical botties, but cannot be used for more complex shapes such as botties with handles. 

Teflon AF can be extruded and injection or compression molded It can be formed by spm casting or applied from solution by spray coatmg or direct apphea-tion [5] Its extremely low refractive index and its solubihty make it highly useful as a coating for the core of optical fibers... 

To be successful, molded optical elements of plastics must be produced with careful control of the fabricating process. In the case of these optical products it is particularly important that the molding conditions be carefully controlled to minimize molded-in stress. In addition to these stresses reducing the dimensional stability of the products leading to distorted images, the stresses themselves affect the quality of the image. This is a result of the fact that the stresses/strained areas have a different refractive index from that of the... 

RCM. See Ring-closing metathesis (RCM) Reaction by-products, removing, 83 Reaction extrusion, 204 Reaction index, 237 Reaction injection molding (RIM), 205 Reaction-in-mold (RIM) nylon, 149 Reaction kinetics, 76, 77 Reaction mechanisms, polyesterification, 66-69... 

SF Spiral Flow index, the length of specimen molded into spiral mold Injection molding machine. Allrounder 221-75-350 Arburg... 

Recent advances in the application of ultrafine talc for enhanced mechanical and thermal properties have been studied [12]. A particularly important use is of finely divided filler in TPO as a flame-retardant additive. In a representative formulation, 37 parts of E-plastomer, Ml 2.0, density 0.92, 60 parts of amorphous EPR, and 4 parts of fine carbon black were dry blended, kneaded at 180°C, pelletized, and press molded into test pieces, which showed oxygen index 32 versus 31 in the absence of a filler. The oxygen index is a measure of flame retardancy. 

Polyethylene is used in extrusion and injection molding processes. When used to manufacture blown films a standard polyethylene will have a melt index of approximately 1 g/10 min, while that used for injection molding typically has a melt index of 5 to 20 g/10 min. Why are the polymers used for these two processes so different ... 

The brominated phosphate is an efficient flame retardant for polycarbonate resin. UL-94 ratings of V-0 with oxygen index values of greater than 40 are obtained. Polycarbonate resin containing brominated phosphate processes with greater ease than resin containing brominated polycarbonate as measured by injection molding spiral flow measurements. The heat distortion temperature is reduced... 

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