tailieunhanh - Materials Selection Deskbook 2011 Part 12

Tham khảo tài liệu 'materials selection deskbook 2011 part 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Appendix A Glossary of Plastics and Engineering Terms 153 Glass transition Transition region or state in which an amorphous polymer changed from or to a viscous or rubbery condition to or from a hard and relatively brittle one. Transition occurs over a narrow temperature region similar to solidification of a liquid to a glassy state. This transformation causes hardness brittleness thermal expansibility specific heat and other properties to change dramatically. Gum Class of colloidal substances prepared from plants. Composed of complex carbohydrates and organic acids that swell in water. A number of natural resins are gums. Halocarbon plastics Group of plastics composed of resins generated from the polymerization of monomers consisting of a carbon and a halogen or halogens. Hardener Compound or mixture that when added to an adhesive promotes curing. Heat treat Refers to annealing hardening tempering of metals. Hot soils Soils having a resistivity of less than 1000 Q cm generally very corrosive to base steel. Hydrocarbon plastics Plastics composed of resins consisting of carbon and hydrogen only. Inhibitor Material that retards chemical reaction or curing. Isocyanate plastics Group of plastics produced by the condensation of organic isocyanates with other plastics. Examples are the urethane plastics. Isotactic Type of polymeric molecular structure that contains sequences of regularly spaced asymmetric atoms that are arranged in similar configuration in the primary polymer chain. Materials having isotactic molecules are generally in a highly crystalline form. Isotropic Refers to materials whose properties are the same in all directions. Examples are metals and glass mats. Laminate Article fabricated by bonding together several layers of material or materials. Laminated cross Laminate in which some of the layers of materials are oriented at right angles to the remaining layers. Orientation may be based on grain or strength direction considerations. 154 Materials .