Grades of plastic

Plaspec Material Selection Database Data Resources, Inc. Dialog, STN detailed engineering and design data, chemical descriptions, and trade names for over 11,500 grades of plastics materials... 

The technology of manufacturing the same basic type or grade of plastics (as with steel and other materials) by different suppliers may not provide the same results. In fact a supplier furnishing their material under an initial batch number could differ when the next batch is delivered and in turn could effect the performance of your product. Taking into account manufacturing tolerances of the plastic, plus variables of equipment and procedure, it becomes apparent that checking several types of materials from the same or from different sources is an important part of material selection and in turn their use. 

Based on past performances it has been proven that the so-called interchangeable grades of plastics have to be evaluated carefully by the designer as to their affect on the performance of a product. An important consideration to include as far as equivalent... 

After special pretreatments, specific grades of plastics can be put through electroplating processes similar to those used in the plating of metals. Electroplated plastic products are very durable and provide... 

Table 10.1 Grades of plastic igniter cord that are commercially available.

Various grades of plastic, for example, differ widely in their permeability to perfume. Low-density polyethylene is far more permeable... 

Although the above items have been listed separately, in actual practice several have to be considered in combination. For example, the practicability of any design has to be related to the process of manufacture, the grade of plastic employed and the constituents found in the plastic. 

Although certain of the above factors have been listed separately, in practice quite a few have to be considered in combination. For example, the practicability of any design has to be related to the process of manufacture and this may equally apply to the grade of plastic employed and the constituents found in the plastic. It is therefore intended to discuss some of the above factors on a broad basis and then consider the safety and functional clearance of a particular plastic pack in greater depth. Design can be considered as a relationship between size, shape, texture, colour, including opacity or transparency, the type of closure and the functional and aesthetic requirements of the pack. 

Sterilisation may give rise to adverse actions depending on the process and the particular grade of plastic, pack, etc. This means that if a pack is to be sterilised, either as a terminal operation or as part of an aseptic process, careful checking for possible changes is essential. Textbooks which make general statements should be treated with caution, as individual grades of plastic may react differently. 

Establish suitable grade of plastic. Determine that the plastic and constituents meet food grade standards. Discuss residues, additives and processing aids, etc. which may be present with relevant parties. Check available safety data. Note— additive content should be low and certain heavy metals absent (Cd, Pb, etc.). 

The above in total represents over 100 variables which may exist within a conventional container/screw closure system. If one adds to this the variables associated with different grades of plastic and the constituents which may be contained therein, the torque range applied, the method of application, the temperature/RH of the environment at the time of application, etc., then the total variables can exceed 150 factors. Some examples of how these variables may interact are given below. 

The disintegrating behavior of substances with any such characteristics can be substantially improved by addition of carbon dioxide ice or by embrittlement with liquid nitrogen. The use of direct or indirect cooling, in combination with mechanical comminution techniques, facilitates adequate processing of many types and grades of plastic, rubber, organic tissue, pharmaceutical products, spice, herbs, and food samples. 

Haze n. Haze and luminous transmittance are tests to measure the fight transmittancy of different types and grades of plastic materials Haze is defined in ASTM D 1003 as the percentage of transmitted fight passing through the specimen which deviates more than 2.5° from the incident beam by... 

Up to 125°C, well above the thermal stability of many commercial plastics. The next higher grade of plastics, so-called high-performance plastics, is usually suitable for product designs requiring stabihty above 175°C. 

The melt index of extrusion or thermoforming grade of plastics is typically less than 1 gram per 10 minutes. The melt index for injection grade plastics is typically greater than 1 gram per 10 minutes. 

Several common types and grades of plastic have good to very good resistance to PEGs, for example, polyethylene, which is frequently used as packaging material and is also suitable for PEG storage containers. 

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