Temperature compression moulding

P963 is a liquid phenolic resole designed to be used with catalyst P964 (para tolune sulphonic acid phosphoric acid) for the production of hand-lay or low pressure/low temperature compression moulding. The resin contains 10% acetone to provide a useable mix viscosity, fast binder breakdown and reinforcement wet-out. Principal use is for thin-walled aircraft components. 

The polymer is not easy to process and in injection moulding melt temperatures of 300°C are employed. In order to prevent excess embrittlement by shock cooling of the melt, mould temperatures as high as 150°C may be used. The polymer may also be compression moulded at temperatures of 250-260°C. 

The thermosetting materials are said to be initially linear but are cross-linked by heating in air to a temperature of at least 345°C. It is claimed that they have a useful working range up to 315°C. The materials may be used in compression mouldings powders, as the binder resin in glass cloth laminates and as the polymer base in heat-resistant metal coatings. 

It is likely that the quinone methide and related structures formed at these temperatures account for the dark colour of phenolic compression mouldings. It is to be noted that cast phenol-formaldehyde resins, which are hardened at much... 

During compression moulding, the charge of material may be put into the mould either as a powder or a preformed cake . In both cases the material is preheated to reduce the temperature difference between it and the mould. If the material is at a uniform temperature in the mould then the process may be analysed as follows. 

Fig. 15. Percent content of the a form in the crystalline phase (PJ for compression moulded samples from y form powders of s-PS, versus the maximum temperature of heating of the melt (TmsJ [9]. The percent content of the P form is (100 — PJ...

Stamping or compression moulding at temperatures close to the melting point of the matrix can be used to produce parts made with GMTs ... 

Up to 15 3-10 500-20000 Low-temperature pressure compression moulding Car body elements... 

The efficiency of azodicarbonamide and sodium bicarbonate blowing agents for PE foams was considered (253). These systems, which generate GO2 gas, are more suitable for compression moulding of foams. Blends of the blowing agents have a reduced exotherm, so are more suitable for polymer systems that are temperature sensitive, such as ethylene copolymers. 

Low density PE foam sheets having a thickness of 10 mm were cut from a block produced by compression moulding and their thermal conductivities over the temperature range from 24 to 50C determined. The evolution of the properties along the block was analysed and the cell structure, apparent mean cell diameter, anisotropy, mean cell wall thickness and relative fraction of polymer determined using quantitative image analysis and a previously reported model utilised to predict the thermal conductivity of the foams. 30 refs. 

Transfer moulding involves the distribution of the uncured stock from one part of the mould called as pot into the actual mould cavity. This process permits the moulding of intricate shapes or the introduction of inserts like metals in many composite products. These procedures are difficult in compression moulds. Although these moulds are relatively more expensive than compression moulds, the actual process permits shorter cure times through the use of higher temperatures and better heat transfer which is obtained due to higher pressure applied to force the compound into the mould. 

Composites containing 0-50 vol% glass were prepared by milling at 170°C for 15 min on an open two-roll mill and compression moulding at 190°C into 3 mm thick plates. The cooling rate was approximately 40°C/min. The samples were stored at room temperature for several years before the measurements. 

Pieces of the compression-moulded sheets were pressed into dogbone-shaped specimens of thickness 1.7 mm and a gauge width of 15 mm for the tensile tests. Stress-strain curves were obtained at room temperature with a Zwick tensile tester at a strain rate of 0.0001 s. The samples were strained up to 3.6% strain and the strain was measured with an extensometer with a gauge length of 50 mm. The tensile tests were done only on the composites with 50 vol% glass beads, with different amounts of the silane. 

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