I. Basic Physical Properties
Specific Gravity: The ratio of weight per unit volume to water, affecting material weight and product density.
Water Absorption: Influences dimensional stability and mechanical strength; Nylon/PET exhibit high water absorption.
Air Permeability: Related to gas transmission resistance, affecting packaging and gas barrier properties..
II. Mechanical Properties
Tensile Strength and Elongation: Measures material tensile strength and deformation capacity.
Flexural Strength and Modulus of Elasticity: Assesses material rigidity and bending resistance.
Impact Strength: Indicates energy absorption capacity during impact, commonly tested via Izod.
Hardness: Rockwell or Shore A/D tests indicate plastic softness/hardness levels.
III. Thermal Properties
Heat Deflection Temperature (HDT): Indicates whether material deforms at high temperatures; recommended operating temperature should be 10°C below HDT.
Long-Term Heat Resistance Temperature: As per UL746 standards, represents the temperature at which performance remains stable after tens of thousands of hours of use.
Melt Index (MI): Represents plastic flowability when heated; higher MI values indicate better processability.
Shrinkage Rate: The dimensional difference between the finished product and the mold. Crystalline plastics typically exhibit higher shrinkage rates.
IV. Chemical Properties
Chemical Resistance: Stability against solvents and chemicals affects durability.
Weather Resistance: Ability to withstand light, heat, and ozone exposure in outdoor environments.
Flame Retardancy: Complies with UL94 V0 to V2 standards, used in fire-resistant applications like electronic components and building materials.
V. Optical Properties
Transparency: PS, PMMA, and PC exhibit high transparency; PP transparency can be enhanced through cooling treatment.
Gloss: Reflects surface reflectivity, influenced by mold polishing and additives.
VI. Electrical Properties
Dielectric Breakdown Voltage: Critical voltage threshold causing insulation failure, dependent on material thickness.
Volume Resistivity: Indicates the material’s electrical insulation properties. Higher water absorption reduces electrical resistance (e.g., Nylon).
VII. Supplementary Notes
Adding glass fiber significantly improves heat resistance and reduces shrinkage.
Engineering plastics like PBT, Nylon, and PC exhibit varying properties due to differences in reinforcement and structure.