Synthesis of Acrylonitrile Butadiene Styrene (ABS) Polymers
ABS is made by emulsion or continuous mass technique. Globally, the most important is the emulsion process. ABS can be processed by injection moldings or extrusion technique.
Synthesis of ABS Polymer
ABS is a terpolymer made by polymerizing styrene and acrylonitrile in the presence of polybutadiene. The proportions can vary from 15 to 35% acrylonitrile, 5 to 30% butadiene and 40 to 60% styrene. The result is a long chain of polybutadiene crisscrossed with shorter chains of poly (styrene-co-acrylonitrile). The nitrile groups from neighboring chains, being polar, attract each other and bind the chains together, making ABS stronger than pure polystyrene. The styrene gives the plastic a shiny, impervious surface. The polybutadiene, a rubbery substance, provides resilience even at low temperatures. For the majority of applications, ABS can be used between −20 and 80 °C (−4 and 176 °F) as its mechanical properties vary with temperature. The properties are created by rubber toughening, where fine particles of elastomer are distributed throughout the rigid matrix.
ABS resins consist essentially of two phases: a rubbery phase dispersed in a continuous glassy matrix of styrene–acrylonitrile copolymer (SAN) through a boundary layer of SAN graft. The dispersed rubbery phase is rubber polymerized from butadiene. Styrene and acrylonitrile are graft-polymerized to the rubber thus forming the boundary layer between the dispersed rubber phase and the continuous glassy matrix.
Properties of ABS Polymers
The acrylonitrile, butadiene and styrene ratios along with two other factors are important in determining the properties of ABS polymers. First, it is not a homogeneous mixture and consists of a dispersed phase. Second, the dispersed phase always consists of both rubber and occlusions of the SAN matrix within the rubber. Its outstanding material qualities made ABS become one of the most popular plastics materials and an essential element in everyday life. Here are some general properties listed below of the ABS polymers.
- Flexible design
- Excellent surface quality
- Brilliant and deep colors
- Attractive feel and touch
- Dimensional stability
- Chemical resistance
- Impact resistance
Thus, changing the proportions of its components ABS can be prepared in different grades. Two major categories could be ABS for extrusion and ABS for injection moldings, then high and medium impact resistance. Generally, ABS would have useful characteristics within a temperature range from −20 to 80 °C (−4 to 176 °F).
Acrylonitrile Butadiene Styrene (ABS) Polymers History
Acrylonitrile-Butadiene-Styrene has been available since the 1940's. In attempts to produce bulletproof plastic sheets during the last years of World War II, polymer systems were developed from special butadiene acrylonitrile copolymers and styrene acrylonitrile copolymers with high molecular masses.
Aramid Fibers/Polymers: History, Synthesis, Properties, Applications/Uses
The Federal Trade Commission definition for aramid fiber is: "A manufactured fiber in which the fiber-forming substance is a long-chain synthetic polyamide in which at least 85% of the amide linkages, (-CO-NH-) are attached directly to two aromatic rings."
Why do fabrics shrink? Shrinkage in Fabrics!
During the manufacturing process of fabric or we call it fabric processing, fabric comes in lot of tension and stretches when it moves from one machine to another which causes stretching in fabric structure and when this tension is removed, and fabric is relaxed it tends to get back in its original structure causing shrinkage.
Worsted Yarn Manufacturing Process
A fine smooth yarn spun from combed long staple wool. Worsted yarns are more tightly twisted than the bulkier woolen yarns. The soft, heavy yarn is strong and durable and is often used for sweaters. Worsted yarns are also used for fine dress fabrics and suit materials.