At Ideal Group, under more than 20 years exercise ,here are top 3 common plastic resins for injection molding in our factory :
ABS 
ABS materials can be processed using any of the standard thermoplastic processing methods. It easily adheres to itself, similar plastics, and metal coatings, making it well-suited for a range of different products.
For instance, it’s frequently used in appliances, telephone handsets, computer and other office equipment housings. ABS can also be used in musical instruments, golf club heads, medical devices, lawn mower covers, motorcycle helmets, canoes, toys, enclosures for electronics and electronic assemblies, luggage, interior and exterior automobile trim, showerheads, and handles. When extruded into a filament, ABS is  ideal for use in 3D printers.
ABS does not have good chemical resistance, however, and should not be used in applications requiring electrical insulation or UV resistance.
It should not be used for applications in high-heat environments, however, and is subject to UV degradation.
 
 
Polypropylene carbonate(PC)
Polypropylene carbonate is soluble in polar solvents like lower ketones, ethyl acetate, dichloromethane and chlorinated hydrocarbons and insoluble in solvents like alcohols, water, and aliphatic hydrocarbons. It also forms stable emulsions in water. PPC allows the diffusion of gases like oxygen through it. Having a glass temperature (T_g) between 25 to 45 °C, PPC binders are amorphous. The glass temperature of PPC is slightly greater than polyethylene carbonate (PEC), Polypropylene carbonate is used to increase the toughness of some epoxy resins. It is used as a sacrificial binder in the ceramic industry, which decomposes and evaporates during sintering. It has a low sodium content which makes it suitable for the preparation of electroceramics like dielectric materials and piezoelectric ceramics.
Nylon is a generic designation for a family of synthetic polymers, based on aliphatic or semi-aromatic polyamides. Nylon is a thermoplastic silky material^[1] that can be melt-processed into fibers, films or shapes.^[2]:2
Nylon (PA)
 
Nylon was the first commercially successful synthetic thermoplastic polymer.^[3] DuPont began its research project in 1930. The first example of nylon (nylon 6,6) was produced using diamines on February 28, 1935, by Wallace Hume Carothers at DuPont's research facility at the DuPont Experimental Station.^[4][5] In response to Carothers' work, Paul Schlack at IG Farben developed nylon 6, a different molecule based on caprolactam, on January 29, 1938.^[6]:10[7]
Nylon was first used commercially in a nylon-bristled toothbrush in 1938,^[8][9] followed more famously in women's stockings or "nylons" which were shown at the 1939 New York World's Fair and first sold commercially in 1940.^[10] During World War II, almost all nylon production was diverted to the military for use in parachutes and parachute cord. Wartime uses of nylon and other plastics greatly increased the market for the new materials.^[11]
Nylon is made of repeating units linked by amide links^[12] similar to the peptide bonds in proteins. Commercially, nylon polymer is made by reacting monomers which are either lactams, acid/amines or stoichiometric mixtures of diamines (-NH₂) and diacids (-COOH). Mixtures of these can be polymerized together to make copolymers. Nylon polymers can be mixed with a wide variety of additives to achieve many different property variations. Nylon polymers have found significant commercial applications in fabric and fibers (apparel, flooring and rubber reinforcement), in shapes (molded parts for cars, electrical equipment, etc.), and in films (mostly for food packaging).