Difference between Polymer and Plastic
Abstract: The melt or LX process, involving the solventless transesterification of diphenyl carbonate (DPC) with bisphenol A (BPA), is the preeminent commercial non-phosgene route to bisphenol A polycarbonate. Polycarbonate purity and manufacturing cost are highly ...
Revolutionary patented new design ensures a top-quality polymer
There is a fundamental difference between the manufacture of most polyurethanes and the manufacture of many other plastics. Polymers such as poly(ethene) and poly(propene) are produced in chemical plants and sold as granules, powders or films. Products are subsequently made from them by heating the polymer, shaping it under pressure and cooling it. The properties of such end-products are almost completely dependent on those of the original polymer.
Plastics in Daily Life - plastics recycling and commodity plastics – identification of uses and recycling processes. Emphasis on social and environmental issues, such as the questions on the toxicity (or not) of plastics; the leaching of plasticizers from PVC and bispenol-A from polycarbonate (PC); and the reasons certain plastics are used in certain applications. Goal is an educated public.
Making Polycarbonates - Polymer Science Learning …
For this reason, polystyrene (Styrofoam, Tg = 100oC) and polyethylene terephthalate (Dacron, Tg = 70oC) are rather stiff, glassy polymers.
One of the most important factors controlling polymer properties are the forces between polymer chains.
We're going to make polycarbonates on this page
Silicones have long been known to be biostable and biocompatible in most implants, and also frequently have the low hardness and low modulus useful for many device applications. Conventional silicone elastomers can have very high ultimate elongations, but only low to moderate tensile strengths. Consequently, the toughness of most biomedical silicone elastomers is not particularly high. Another disadvantage of conventional silicone elastomers in device manufacturing is the need for cross-linking to develop useful properties. Once cross-linked the resulting thermoset silicone cannot be redissolved or remelted. In contrast, conventional polyurethane elastomers are generally thermoplastic with excellent physical properties. TPUs combine high elongation and high tensile strength to form tough, albeit fairly high-modulus elastomers. Aromatic polyether TPUs can have excellent flex life, tensile strength exceeding 5000 psi, and ultimate elongations greater than 600 %. They are often used for continuously-flexing chronic implants, such as ventricular assist devices, intraaortic balloons, and artificial heart components*. TPUs can easily be processed by melting or dissolving the polymer to fabricate it into useful shapes. The prospect of combining the biocompatibility and biostability of conventional silicone elastomers with the processability and toughness of TPUs is an attractive approach to what would appear to be a nearly ideal biomaterial. Silicone acts synergistically with polycarbonate-based polyurethanes to improve in vivo and in vitro stability. This class of polyurethanes also has low-energy silicone surface and outstanding oxidative stability.
Before we do that, let's take a look at our cast of characters
Control of polymerization by means of catalysts and additives has led to a large variety of materials based on polyethylene that exhibit differences in densities, degrees of chain branching and crystallinity, and cross-linking. Some major types are low-density (LDPE), linear low density (LLDPE), high-density (HDPE).
PMMA Synthesis | Polymerization | Poly(Methyl …
Chlorine is one of the top ten industrial chemicals in the US more than 20billion pounds are produced annually. About 20% of this chlorineis used to make vinyl chloride (CH2=CHCl) for theproduction of poly(vinyl chloride), or PVC. The chlorinesubstituents on the polymer chain make PVC more fire-resistantthan polyethylene or polypropylene. They also increase the forceof attraction between polymer chains, which increases thehardness of the plastic. The properties of PVC can be varied overa wide range by adding plasticizers, stabilizers, fillers, anddyes, making PVC one of the most versatile plastics.