i) Fillers

ii) Plasticizers

iii) Lubricants

FE > Semester 1 > Applied Chemistry 1

Marks : 05

Years : DEC 2015

i) Fillers- fillers impart better tensile strength, hardness, finish, workability, opacity etc. to the plastic material. The percentage of filler varies with types of plastic. The highest percentage can be up to 50% of the total moulding mixture. The fillers which are added only to improve the mechanical strength of the plastic are known as reinforcing fillers. They reduce shrinkage and brittleness. They also cost of the plastic per unit weight. The fillers May be of organic or inorganic origin.

ii) Plasticizers- these help to increase the plasticity of the plastics. Plasticizers are essentially used in thermosoftening plastics. They are added to the extent of 8-10% of the total bulk of plastic. Plasticizers are not used in thermosets; they are added in thermosoftening resins only. It increases flexibility. The plasticizers used are normally liquids and hence only disadvantage is, if they are not consistent, they ooze out in finished product.

iii) Lubricants and stabilizers - lubricants help during moulding operations, especially during low or room temperature moulding. The use of lubricants imparts flawlessness, and glossy finish to the plastic products. Commonly used lubricants are soaps, or esters of fatty acids such as oleic and stearic acids or waxes. Stabilizers help improve stability of the plastic besides impart rigidity.