The topology of the polymer i.e., linear, stars, and branched, affects the macroscopic flow characteristics of melts, where introducing one branch is sufficient to increase the viscosity significantly.
Table of Contents
What is topology in chemistry polymers?
Topological polymers may refer to a polymeric molecule that possesses unique spatial features, such as linear, branched, or cyclic architectures. It could also refer to polymer networks that exhibit distinct topologies owing to special crosslinkers.
How does cross linking affect the properties of a hydrogel?
Cross linking either physically or chemically gives hydrogel a 3D network structure, making it insoluble. This insoluble cross-linked structure allows effective immobilization and release of active agents and biomolecules. Hydrogels appear similar to natural soft tissues because of their high water content.
What does topology mean in chemistry?
In chemistry, topology provides a way of describing and predicting the molecular structure within the constraints of three-dimensional (3-D) space.
Why is topology important in polymers?
The topology of polymer molecules is often a basis to control their properties and functions at static and dynamic states both in bulk and in solution.
What is the most common topologies for polymers?
The chain is the most basic of polymer structures. This topology is often referred to simply as a chain or, to underscore the structure, a linear polymer.
What is known as linear topology?
Definition. A linear topology is a network topology consisting of a main run of cable with a terminator at each end. All nodes (file server, workstations, and peripherals) are connected to the linear cable. Ethernet and LocalTalk networks use a linear bus topology.
What topology did LDPE and HDPE exhibit?
HDPE has linear structure with very few or no branching and possesses high degree of crystallinity. On the other hand, LDPE has chaotic structure with short and long chain branches and lower degree of crystallinity in comparison to HDPE.
Why do branched polymers have a low density?
Branched polymers display lower density as consequence of reduced packing efficiency of the branched chains. The length of the side chains or branches differentiates between long- or short-branched polymers. Long branches could have comb-like, random, or star-shaped structures.
Does cross linking increase density?
The bulk density increases with the increase of crosslink density for crosslinked polymers. The higher the temperature is, the more discrete the bulk density distribution is. The distribution of the bulk density with various temperatures for different crosslink densities.
What is cross linking in chemistry?
Background: Chemical crosslinking refers to intermolecular or intramolecular joining of two or more molecules by a covalent bond. The reagents that are used for the purpose are referred to as ‘crosslinking reagents’ or ‘crosslinkers’.
Why is cross linking important?
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.
What is chain topology?
Chain Topology—Each unit is connected to the neighboring unit, but there is no cable connection between the first and last unit. • Ring Topology—Each unit is connected to the neighboring unit. The last unit is connected to the first unit.
What do you mean by bus topology?
Bus topology, also known as line topology, is a type of network topology in which all devices in the network are connected by one central RJ-45 network cable or coaxial cable. The single cable, where all data is transmitted between devices, is referred to as the bus, backbone, or trunk.
What are the network topologies?
A network topology is the physical and logical arrangement of nodes and connections in a network. Nodes usually include devices such as switches, routers and software with switch and router features. Network topologies are often represented as a graph.
What is form network polymers?
28 The polymer networks are prepared by a crosslinking reaction of poly(vinyl butyral) and hexamethylene diisocyanate.
What is the difference between linear and cross linked polymer?
Linear Polymer: A linear polymer is a macromolecule made out of many monomer units arranged in a straight line. Crosslinked Polymer: A crosslinked polymer is a macromolecule that has covalent bonds between the polymer molecules.
How does the structure of a polymer affects its properties?
Polymers consist of very long molecules that contain chains of carbon. They too are held together by very strong covalent bonds. There are greater intermolecular forces between the long chains compared with smaller simple molecules. This means that polymers have a higher melting point than many other organic molecules.
Which polymer structure is the strongest?
The increase strength of the interactions between polymer chains makes polyamides among some of the strongest polymer materials known. Possible hydrogen-bonded structure for crystallites of nylon 66, an amide-type polymer of hexanedioic acid and 1,6-hexanediamine.
What are the factors that must be considered before making a choice for the topology?
- Available hardware resources.
- Application invocation patterns.
- Types of business processes that you plan to implement (interruptible versus non-interruptible)
- Individual scalability requirements.
- Administrative effort involved.
What is the most common topology?
Star topology is by far the most common. Within this framework, each node is independently connected to a central hub via a physical cable—thus creating a star-like shape. All data must travel through the central node before it reaches its destination.
Which topology combines two or more structure?
Hybrid topology combines two or more topologies.
What is the difference in structure between low-density polyethylene LDPE and high-density polyethylene HDPE )?
As its name suggests, low-density polyethylene (LDPE) has a lower density, strength, and temperature resistance. Meanwhile, high-density polyethylene (HDPE) is characterized by higher specific strength and heat resistance.
Why does HDPE and LDPE have different densities?
In a nutshell: the chemistry of LDPE and HDPE From that chain another chain branches off. These side branches stop the polymer molecules from lining up in an orderly fashion. LDPE’s structure is not crystalline. This irregularity is what gives LDPE its lower density.
Why HDPE is more rigid and stronger than LDPE?
However, HDPE has quite a high grade of strength over LDPE. This is due to its structural composition. HDPE has a rigid structure with very less branching. This gives it more tensile strength and has stronger intermolecular forces.