Compression molding vacuum

PVC, PVA, PVAC, Copolymers) organosols forms available including hard and flexible types. Properties are highly dependent on plasticizer used. May be injection, extrusion, compression molded, vacuum formed. Low cost. antistatic sheet and hose, RF gaskets, heat-shrinkable tubing. 

Techniques commonly used to manufacture advanced composites from prepregs, which are available in unidirectional fiber or fabric form, include compression molding, vacuum-bag autoclave molding, stamp molding, thermoforming, and on-line (in situ) consolidation [3]. In compression and vacuum-bag autoclave molding techniques, the prepreg is cut to the dimensions of the structure, and the fiber directions are oriented to obtain the required... 

During the shaft seal molding process, the elastomeric compound has relatively large distances to travel/ flow in the mold, particularly when using shelf loaded compression molding (Fig. 17a) and injection molding (Fig. 17b). History has shown that without the use of a vacuum, either applied directly through the mold or... 

Figure 19 illustrates one type of compression mold suitable for molding lip type shaft seals with a metal outside diameter (O.D.). Figure 19a shows the compound preform resting on the shelf and the mold beginning to close. The mold continues to close until it gets to the position shown in Fig. 19b. Finally, the mold opens as shown in Fig. 19c. It can be seen that this molding technique produces a molded lip seal with the flash already removed. In general, when using a vacuum chamber on the press, to ensure that all the air and/or gases are evacuated from the mold after closure, one or...

Filament Winding, Hand Layup. Compression Molding. Iniectior. Molding. Vacuum Bag. Stamping. Coming. Pultrusion... 

Polymer Processing. Polymer films were cast in trimethylsilyl coated glass molds from membrane filtered 15% (w/v) methylene chloride or chloroform solutions. Transparent films were obtained which were dried to constant weight in high vacuum. Rectangular strips or round disks were cut from the films. For compression molding a Carver laboratory press equipped with thermostated, heated platens was used. Polymers were placed in a stainless steel mold and heated to 40 °C above their glass transition temperature. Then a load of 1-2 tons was applied for 5 min. 

Sample Preparation. Samples for mechanical studies were made by compression molding the polymers at 150°C between Teflon sheets for 15 minutes followed by rapid quenching to room temperature in air. These will be referred to as PQ (press-quenched or simply quenched) samples. The thickness of the PQ samples was around 10 mils (0.25 mm). The thermal history of all of the PQ samples (HBIB, HIBI, and LDPE) were essentially the same. They were used within one week after they were pressed. Samples for morphology, SALS and SEM studies were prepared from toluene solutions. These films were cast on a Teflon sheet at 80 C from a 1% (by weight) solution in toluene. These films were about 5 mils in thickness. When the polymer films had solidified (after 5 hrs), they were stored in a vacuum oven at 80°C for two days to remove residual solvent. These samples will be designated by TOL (solution cast from toluene). 

An important step in the manufacture of any plastic product is the fabrication or the shaping of the article. Most polymers used as plastics when manufactured are prepared in pellet form as they are expelled from the reactor. These are small pieces of material a couple of millimeters in size. This resin can then be heated and shaped by one of several methods. Thermoset materials are usually compression molded, cast, or laminated. Thermoplastic resins can be injection molded, extruded, or blow molded most commonly, with vacuum forming and calendering also used but to a lesser extent. 

The HDPE samples were compression-molded plaques (1.25 mm thick) prepared from Dow 04452N HDPE pellets. Styrene was vacuum distilled from calcium hydride, and ethylbenzene and tert-butyl perbenzoate (TBPB) were used as received (Aldrich). 

To imprint more complex structures, a Si master with positive relief structures was first created. Then the master was used to imprint the channel pattern on a PMMA plate (135°C for 5 min) (see Figure 2.22) [1011]. This method is called compression molding or embossing. In using this method, a vacuum chamber is needed to remove air bubbles trapped at small features and to remove water vapor from the polymer [7]. 

The samples were desiccated in a vacuum oven at 110°C for 24 hr. They were then compression molded on a Pasadena press at 280°C and 30,000 psi for 1 min. They were then immediately quenched in the ice-water mixture and melted again in the press without pressure for another minute. They were then immediately quenched in the ice-water mixture. A set of these amorphous samples was used in the determination of the Tg by DSC. Other samples were crystallized in a fluidized bed at 150°, 130°, 110°, and 90°C for 15, 30, 60, 120, 180, 240, 300, 600, 900, and 1,800 seconds, following which they were quenched again. 

Acrylics Good gloss, weaiher resistance, optical clarity, and color excellent electrical properties injection molding Vacuum forming Compression molding Continuous laminating... 

Compression Molding Flexible Plunger Flexible Bag Molding Laminate Hand Lay-Up Vacuum Bag Molding Vacuum Bag Molding and Pressure Pressure Bag Molding Autoclave Molding Autoclave Press Clave Wet Lay-Up... 

Crystallization at 52° and 60 °C was performed between polished steel plates in an air oven following compression molding in a laboratory press. The filament specimen used in the quenching experiments was fabricated by (1) inverting a capillary tube into the HMS powder, (2) evacuating the capillary and sample in a vacuum oven, and (3) admitting air pressure after the sample melted to force the sample into the evacuated capillary tube. Note in Figure 1 that this produces a uniform. — 1 mm diameter unoriented specimen that is easily quenched. 

Hydroxyl-functional dendritic (hyperbranched) polyestera of 2" and 4 generation, Boltom H40 were obtained from Perstorp Specialty Chemicals AB, Sweden, in the form of pellets. About 100 pm thick films were prepared via compression molding at 130°C in a Carver press followed by cooling under pressure by flowing water through the press platens. Prior to molding, as received pellets were dried in vacuum at 55°C for at least 24 hrs. 

Before use, all the polymer pellets were dried at Ta +20 K for at least 48 h. Then, sheets of controlled thickness B were firstly compression molded under vacuum at Ta + 50 K and then cooled down slowly through the glass transition region. Next, samples of dimensions suitable for the SENB tests were cut from the sheets with a diamond saw, machined to produce the notch, and annealed once more at Ta +20 K for 72 h. The purpose of this thermal treatment is double first, it allows the elimination of the residual stresses induced by sample pressing and machining and secondly, it permits removal of eventual moisture which is known to affect dramatically the SAPA mechanical properties [12]. The pre-crack was produced in the samples just before testing. 

Viscosity measurements at low shear rates were made with a Rheome-trics System 4 or Rheometrics RMS-800/RDS-II spectrometer in either cone and plate (cone angle =0.1, radius = 25 mm) or plate and plate (radius = 25 mm, distance = 1 mm). For higher shear rates viscosity measurements were made with an Instron capillary viscometer. A capillary with L/D = 51.4 and D = 0.889 mm was used. Sample discs were prepared by compression molding of the predried (at least 3 days at 125°C in vacuum) copolyesters at 250°C. Prepared discs were dried at 125°C in vacuum for 5 hr before use. The correction for non-Newtonian behavior was applied, but entrance pressure corrections were neglected. 

Samples were purified by swelling in a Soxhlet extractor followed by drying in vacuum. Disks were compression molded at 250°C for 5 minutes followed by air quenching of the mold. Two samples were subsequently annealed at 80° in vacuum for 36 hours followed by slow-cooling to the test temperature 24°. UET48-1... 

The infrared spectra of polystyrene, a 7.6 mole% SPS-acid derivative (H-SPS), and a 1.7 mole % Na-SPS are shown in figure 1. The SPS samples were compression molded at about 200°C and dried for 96 hours at 90°C under vacuum. The IR absorbances resulting from sulfonatlon and/or neutralization of the free acid and the band assignments are summarized in Table I. 

Three-arm star PIB ionomers were prepared by techniques described extensively before (16-17). Some relevant parameters for the sample are shown in Table I. The 3-arm PIB ionomers neutralized by NaOH were dried at room temperature under vacuum for 1 month, while another series of Na salts were dried at 140°C for a week. Samples were then compression molded at 150°C under an applied load of 4000 lbs/ in. Typical dimensions of the rectangular specimens for stress relaxation studies were 3.0 x 6.0 x 40 (mm). 

Equal amounts of LLDPE and PS by volume were dry-mixed with 5 wt% compatibilizer and 0.2 wt% antioxidant (Irganox 1076), and blended in a Banbury mixer for about 7 min at 175 °C. The blend was quenched in cold tap water ana dried overnight at 40 °C in vacuum. Plaques were compression-molded by preheating the blend in a press at 170 °C for about 15 min, then applying a pressure of 3.85 MPa for 8 min. The press was water-cooled to room temperature with the plaque under pressure. 

Preparation of iPS-b-iPP-iPS-iPP Polyblends. The blends of iPS-fo-iPP, iPS, and iPP were prepared by completely dissolving all polymers and an antioxidant into o-dichlorobenzene at 165 °C, and using a 1 1 mixture of acetone and methanol as a precipitant. After being thoroughly washed and dried under vacuum at 60 °C for 20 h, the precipitated powders were compression-molded at 300 °C into sheets or plates suitable for cutting specimens for mechanical testing and morphologic study. 

In those cases where plasticizers were added, this was generally effected by adding polymer and plasticizers to toluene/alcohol mixtures, evaporating the solvent, and finally drying the plasticized polymer at 80 °C under vacuum. Alternately, the polymer-plasticizer mixture could be prepared by direct addition of the plasticizer to the powdered base resin. Stress-strain measurements were made on microdumbbells obtained from compression-molded pads of. 020 mil thickness. Tensile measurements were conducted at strain rates of 1000% /min. 

The hydrogenated, sulfonated PP s were compression molded into films suitable for differential scanning calorimetry (DSC), dynamic mechanical, and dielectric measurements. Films were prepared by preheating at 140°-145°C for 5 min and then pressing at 140°—145°C and 20,000 lb for 5 min. Annealed samples were prepared by placing aircooled films between two metal platens and storing them in a vacuum oven at 80 °C for 3 days. The platens were necessary to prevent the films... 

The samples were synthesized by the same techniques as those used for the styrene ionomers (12). The protonated styrene-methacrylic acid copolymers were prepared by thermal initiation. The polymerization took place in sealed glass tubes in the bulk at 80 °C after several freeze-thaw cycles. A conversion of 10% was obtained after 19 hr. The polymer was precipitated in methanol and neutralized in a benzene-methanol solution. A similar procedure was used for the deuterated samples except that the unreacted deuterated styrene monomer was evaporated prior to the precipitation. The mixing of the deuterated and protonated styrene copolymers was performed in a benzene solution by stirring for 1 hr. The benzene used as the solvent contained a minimum amount of methanol necessary to dissolve the ionomer (approximately 5-10% for the samples of high ion content). The samples were freeze-dried, then dried further at 60°-80°C under vacuum, and finally compression-molded at Tg - - 30°C. 

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