Controlled degradable polymers

Note 2 A controlled-degradable polymer is a polymer designed to degrade into products at a predictable rate. Such products are usually of lower molecular weight than the original polymer. 

Controlled degradable polymer is A polymer that by design degrades at a... 

Controlled degradable polymer is a polymer designed to degrade at a defined rate. 

Controlled degradable polymers 838 Cook-Gordon model 63 Cooling phase 341 Copolymerization... 

A controlled degradable polymer is a polymer which degrades at a predictable time. 

Gilead D and Scott G (1984) Controllably Degradable Polymer Compositions , US Patent 4,461,853. 

B. Gilg, H. MuUer, and K. Schwarzenbach. Paper presented Advances in Stabili tion and Controlled Degradation of Polymers, New Paltz, N.Y., June... 

The consequence of this inappropriate materials selection is the squandering of natural resources that characterises the industrialised nations of the world, coupled with a growing problem of waste disposal. Control is certainly necessary to prevent the uncontrolled dumping of these non-degradable polymers in the environment. Arguably control is also needed to prevent these kinds of material being fabricated into barely serviceable items in the first place. 

After the completion of the fracturing treatment, the fluid viscosity should decrease to allow the placement of the proppant and a rapid fluid return through the fracture. It is important to control the time at which the viscosity break occurs. In addition, the degraded polymer should produce little residue to restrict the flow of fluids through the fracture. 

J. C. Dawson and H. V. Le. Controlled degradation of polymer based aqueous gels. Patent US 5447199,1995. 

Disadvantages Difficult to control kinetics owing to multiple processes of release Potential toxicity of degraded polymer must be considered... 

Decker, C. Second International Conference on Advances in the Stabilization and Controlled Degradation of Polymers, Preprints, Luzern, Switzerland, June 1980. 

Edlund, U. and Albertsson, A.-C. Degradable Polymer Microspheres for Controlled Drug Delivery. Vol. 157, pp. 53-98. 

Short shot can be avoided by proper mold design and control of polymer melt conditions—namely, temperature and injection pressure. This relationship is shown in Figure 7.76. Within the area bounded by the four curves, the specific polymer is moldable in the specific cavity. If the pressure and/or temperature are too low, short shot will result. If the temperature is too high, thermal degradation of the polymer can occur. If the temperature is too low, the polymer will not be molten. If the pressure is too high or the polymer is too fluid, the melt can flow into the gaps of the mold, creating thin webs of polymer attached to the molded article in an undesirable part... 

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