Table of Contents
What are tie molecules?
A tie-molecule occurs when intercrystallite spacing d does not include a kink in the chain with respect to the field direction. We develop an analytical theory to calculate the average distance a chain extends before a kink occurs.
What is it called when you have many polymers chained together?
Chain-growth polymerization (AE) or chain-growth polymerisation (BE) is a polymerization technique where unsaturated monomer molecules add onto the active site on a growing polymer chain one at a time.
How does cross-linking make polymers more elastic?
To make a material elastic, the polymer chains are crosslinked by covalent bonds. The more crosslinks, the shorter the polymer chains and the stiffer the material.
What are crystalline polymers?
Crystalline polymer structure is described by a three-phase model, that is, a crystalline phase, an amorphous phase, and mesosphere (crystalline and amorphous interface). The fact is that radiation cross-linking of the crystalline polymer mainly occurs in the amorphous region.
Why are most polymers amorphous?
Polymers with an amorphous morphology have their atoms held together in a loose structure, but this structure is never orderly or predictable, which is why chemists will say that amorphous solids have no long-range order. To understand this better, think of a polymer chain as a piece of spaghetti.
What is a chain polymer?
Polymer chains are fractal objects whose dimensionality is determined by interactions between the monomeric units and solvent molecules.
What is the process by which monomers are linked together to form polymers?
polymerization, any process in which relatively small molecules, called monomers, combine chemically to produce a very large chainlike or network molecule, called a polymer.
Which monomer will give a cross-linked polymer?
So, melamine-formaldehyde is a cross-linked polymer. Therefore, option (C) Melamine-formaldehyde, is correct. Note: The unit which repeats again and again is known as monomer or repeating unit. Based on the type of polymer units the polymer is divided into two types.
What is difference between crystalline polymer and amorphous polymer?
Amorphous polymers are polymers that have no ordered pattern in its molecular structure. Crystalline polymers are polymers that have a well-organized structure. Amorphous polymers are made out of atactic polymer chains. Crystalline polymers are made out of syndiotactic and isotactic polymer chains.
What is difference between amorphous and crystalline polymers?
Definition. Amorphous polymers are the polymers that contain amorphous regions where molecules are arranged randomly. Crystalline polymers are the polymers with crystalline regions where molecules are arranged in a partial pattern.
What is the difference between semi-crystalline and amorphous polymer?
The most considerable difference between amorphous and semi-crystalline polymers is in the molecular structure. As mentioned, amorphous polymers are random, entangled chains, while semi-crystalline polymers are structured. The difference in molecular structure provides unique advantages for both.
How is polymer chain formed?
Monomers join together to make polymer chains by forming covalent bonds—that is, by sharing electrons. Other bonds then hold the groups of chains together to form a polymer material.
What is polymer and monomer?
monomers. Polymers are a class of synthetic substances composed of multiples of simpler units called monomers. Polymers are chains with an unspecified number of monomeric units. a polymer. Homopolymers are polymers made by joining together monomers of the same chemical composition or structure.
What is the name of the process in which monomers get together to build polymers while absorbing energy quizlet?
What is the Process by which monomers are linked together to form Polymers? Dehydration or condensation reactions. (When monomers are linked together to form a more complex polymer, a water molecule is removed by dehydration(condensation) reactions.
Why is crosslinking important in polymers?
Introduction. Chemical cross-linking has been widely used to alter the physical properties of polymeric materials, the vulcanization of rubber being a prototypic example. Linking of polymer chains through chemical linkages gives a material a more rigid structure and potentially a better-defined shape.