Plastics Week

And for both of these tests contact times , temperature and the size of contact area are all very important, where the first of these contact times are considerably small in the case of rubbers specifically (in the order of minutes or even shorter), which is very different if compared to plastics (weeks or more). 

To prepare the standard pH buffer solutions recommended by the National Bureau of Standards (U.S.), the indicated weights of the pure materials in Table 8.15 should be dissolved in water of specific conductivity not greater than 5 micromhos. The tartrate, phthalate, and phosphates can be dried for 2 h at 100°C before use. Potassium tetroxalate and calcium hydroxide need not be dried. Fresh-looking crystals of borax should be used. Before use, excess solid potassium hydrogen tartrate and calcium hydroxide must be removed. Buffer solutions pH 6 or above should be stored in plastic containers and should be protected from carbon doxide with soda-lime traps. The solutions should be replaced within 2 to 3 weeks, or sooner if formation of mold is noticed. A crystal of thymol may be added as a preservative. 

Once dried, the treated paper or cloth is fairly stable and, stored in a cool place, it may be kept for several weeks or months before pressing into laminated plastic sheets. 

Plastics Nem, Crain Communications, Akron, Ohio, pubHshed weekly. 

In the absence of impurities there is frequently no termination step in anionic polymerisations. Hence the monomer will continue to grow until all the monomer is consumed. Under certain conditions addition of further monomer, even after an interval of several weeks, will eause the dormant polymerisation process to proceed. The process is known as living polymerisation and the products as living polymers. Of particular interest is the fact that the follow-up monomer may be of a different species and this enables block copolymers to be produced. This technique is important with certain types of thermoplastic elastomer and some rather specialised styrene-based plastics. 

Once again I should acknowledge that I have drawn heavily from the journals European Plastics News, Kunstojfe, Modern Plastics International and Plastics and Rubber Weekly for data on production and consumption statistics. 

It is speculated that the water does not diffuse as easily into the polycarbonate as into the PTMEG urethane, making the polycarbonate more resistant to plasticization by water and subsequent hydrolysis. The tensile properties of the PTMEG polyurethane eventually returned to nearly the original tensile properties, if the material was allowed to dry at room temperature for 2 weeks. This observation lends credence to the idea that the PTMEG urethane was plasticized by water. 

Example 2.5 In a small polypropylene pump the flange on the cover plate is 2 mm thick. When the rigid clamping screws are tightened, the flange is reduced in thickness by 0.03 mm. Estimate the initial stress in the plastic and the stress after 1 week... 

Plastics and Rubber Weekly No. 1776, 5th March 1999, p.lO INSULATION PANELS TO ABSORB BOTTLE WASTE... 

Plastics and Rubber Weekly No. 1746, 24th July 1998, p.6 CRACKING AHEAD WITH POLSCO... 

Plastics and Rubber Weekly No.1645, 19th July 1996, p.7 PACKAGING THE WASTE CHALLENGE... 

Materials Recycling Week 164, No.9, 28th Oct. 1994, p.4 PLASTICS INCINERATION CHEAPEST RECYCLING, SAY DUTCH... 

Plastics and Rubber Weekly No. 1545, 22nd July 1994, p.7 CRACKING SOLUTION IS NEAR... 

Materials Reclamation Weekly 163, No.10, 7th May 1994, p.l4 PLASTIC FIRMS PUSH FOR ENERGY RECOVERY... 

Materials Reclamation Weekly 161,No.l7, 12th June 1993,p.l3/15 CHEMICAL TECHNOLOGY TO RECOVER QUALITY FEEDSTOCKS FROM USED PLASTICS... 

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