Title of Invention

A PROCESS FOR THE PREPARATION OF FLYASH FILLED THERMOPLASTIC BLEND

Abstract

The present invention provides a process for the preparation of flyash filled thermoplastic blends which comprises heating a thermoplastic polymer to its melting temperature, adding flyash powder to the said melted thermoplastic polymer under constant stirring followed by adding a second thermoplastic polymer to the mix under constant stirring to obtain a flyash filled thermoplastic blend. The thermoplastic blend is used for the preparation of tubes , pipes, tiles , doors ,window shutter , boxes and building materials.

Full Text

This invention relates to a process for the preparation of flyash filled thermoplastic blend. This invention particularly relates to making of thermoplastic/ thermoplastic blend compositions with Fly ash by melt blending of incompatible, non-interacting polymers into homogenous mixture. Homogeneously Fly ash mixed polymer blends can be used for moulding to make utility items Such as tubes, profiles, pipes, tiles, doors, window shutters, roofing elements, containers, boxes, building materials and insulation items. These Fly ash particles are fine and have better thermal conductivity as compared to polymers. Addition of these Fly ash particles, increases the thermal conductivity of the system and reduces the rate of crystallization. Since polymers possess very low thermal conductivity, temperature of mixture remains non-uniform, Which leads to the change in viscosity and stresses due to uneven temperature. Fillers on thermoplastics are added to reduce the cost and to improve the dimensional stability, thermal stability and dielectrical strengths. Several mineral particles such as red mud, calcium carbonate, talc, silica, and metal powders have been added to polymers in the past. Blending of polymer with fillers or blending of two polymers is also done to improve the properties of individual polymer in order to achieve desirable properties such as strength, toughness, barrier properties, electric properties, easy processing etc. in the resulting polymer mixture. Mixing of fillers and melt blending of polymers is carried out either by using extruder, kneader, banbury mixer or by two roll mixing mill at elevated temperature. For making utility items mentioned above filled polymers/ filled blends are moulded in a mould at high temperature and then cooled. Most of the polymers such as polyethylene, polypropylene, Nylon-6 etc. are incompatible with the other polymers i.e. polystyrene, polycarbonate, polymethylmethacrylate etc., which leads to the phase separation of the polymers during cooling. Phase separation produces a non-homogeneous material and thus a material of inferior quality is obtained which can not be used for utilising it for preparing items. Main reasons of phase separation as follows : a) On increasing temperature of molten polymer, viscosity reduces but at the cost of degradation of polymer molecules, which is not recommended. b) Repeat units of polymer are connected with each other by covalent bonds. Repeat units containing saturated hydrocarbons make the polymer a material. In absence of any interacting force, Such as coupling agent different polymers do not combine to form bonds etc. Reference may be made to A. Tager, Physical Chemistry of Polymers, Mir Publishers, Moscow 1978. c) Crystallization of one of the polymer occurs prior to the other polymer which has low melting temperature as compared to first one Higher melting point polymer crystallizes at a temperature above the melting temperature of second polymer and in this process segregation of one polymer gains momentum. This phenomenon leads to exclude the second polymer and then creates non-homogeneity among the polymer blends. Reference may be made to N. Chand, S.A.R. Hashmi and S. Vashishtha, Research and Industry, 40, 193, 1995. Phenomenon is most important and occurs in most of the cases. The main object of the present invention is to provide a process for the preparation of flyash filled thermoplastic/thermoplastic blends. Accordingly, the present invention provides a process for the preparation of flyash filled thermoplastic blends which comprises heating a thermoplastic polymer to its melting temperature, adding flyash powder of the particle size 5-400 microns to the said melted thermoplastic polymer in a ratio ranging from 5.3:1 to 8:1 under constant stirring followed by adding a second thermoplastic polymer to the mixture of said thermoplastic polymer and flyash under constant stirring to obtain a homogeneous flyash filled thermoplastic blend composition of the tensile strength ranging from 15.469-21.75 mpa . In an embodiment of the present invention the thermoplastic polymer used is such as polypropylene, polyethylene, polyvinyl chloride, polymethyl methacrylate, poly-carbonate, polyamides and crystalline polymers or mixtures thereof. In another embodiment of the present invention the ratio of two thermoplastic polymers used for blending ranges from 1-95% by weight. In yet another embodiment of the present invention the amount of flyash powder added ranges from 1-95% of the total polymer The particle size of the flyash powder used may be in the range of 5 to 400 micron meter. The present invention provides new homogeneous thermoplastic/ thermoplastic filled fly ash based compositions prepared by melt blending of polymers into homogenous mixture which comprises heating of the polymer to its softening (melting) temperature, adding flyash filler particles to improve the uniformity in the mixture. Additions of the second polymer, is then done until a uniform composition is obtained. In case of-blend compositions Isotactic polypropylene (polymer 1) is melted and Fly ash (Fly ash) particles/ powder is added to it. Mixing is started at softening temperature of polymer 1. After homogeneous mixing of particles, Polyethylene (polymer 2) is added and mixing of all component is carried out until a homogenous mix is obtained. Crystallization of one polymer excludes the other polymer if crystallization temperatures are different. Addition of Fly ash particles will reduce the rate of crystallization by creating several number of nucleating points. This will stop formation of big crystals. Thermal conductivity is improved and temperature remains uniform in the mixture. Thus the possibility of phase separation or formation of big domain reduces. The invention is described with the help of the following examples which should not therefore be construed as limiting the scope of the invention. Example 1 160 gms. of polypropylene granules were heated at 165°C on a two roll mill for 10 minutes, when temperature of granules reach to the melting point of polypropylene, the rotation of roll mill is started. Gap between two rolls and differential speed of rolls is adjusted so that maximum shear force is applied to polypropylene granules. When whole mass is in semi molten form, 20 gms. fly ash particles of diameter less than 45 micrometer were added. Mixing was continued for 5 minutes to get a homogeneous material. At this stage LDPE was added into PP/Fly ash mixture. The mixing on two roll mill was continued for ten minutes. Resultant mass i.e. PP/LDPE/Fly ash was removed from mixing mill. This was a homogeneous material which can be moulded easily. Tensile strength of this composition was 21.75 MPa. Example 2 160 gms. of polypropylene granules were heated at 165°C on a two roll mill for 10 minutes, when temperature of granules reach to the melting point of polypropylene, the rotation of roll mill is started. Gap between two rolls and differential speed of rolls is adjusted so that maximum shear force is applied to polypropylene granules. When whole mass is in semi molten form, 30 gms. fly ash particles of diameter less than 45 micrometer were added. Mixing was continued for 5 minutes to get a homogeneous material. At this stage polycarbonate was added into PP/Fly ash mixture. The mixing on two roll mill was continued for ten minutes. Resultant mass i.e. PP/LDPE/Fly ash was removed from mixing mill. This was a homogeneous material which can be moulded easily. Tensile strength of this composition was 15.469 MPA. ADVANTAGES OF THE PRESENT INVENTION 1) This process provides cheaper thermoplastic/ thermoplastic blend compositions. 2) This process provides homogeneous mixed materials having improved thermal stability. 3) Homogeneously mixed polymer blend can be used for molding purposes. 4) This process used flyash which is a waste product of thermal power plant. We Claim: 1. A process for the preparation of flyash filled thermoplastic blends which comprises heating a thermoplastic polymer to its melting temperature, adding flyash powder of the particle size 5-400 microns to the said melted thermoplastic polymer in a ratio ranging from 5.3:1 to 8:1 under constant stirring followed by adding a second thermoplastic polymer to the mixture of said thermoplastic polymer and flyash under constant stirring to obtain a homogeneous flyash filled thermoplastic blend composition of the tensile strength ranging from 15.469-21.75 MPa . 2. A process as claimed in claim 1, wherein the thermoplastic polymer used is such as polypropylene, polyethylene, polyvinyl chloride, polymethyl methacrylate, poly-carbonate, polyamides and crystalline polymers or mixtures thereof. 3. A process as claimed in claims 1-2, wherein the ratio of two thermoplastic polymers used for blending ranges from 1-95% by weight. 4. A process as claimed in on claims 1-3, wherein the amount of flyash powder added ranges from 1-95% of the total polymer. 5. A process for the preparation of flyash filled thermoplastic blends substantially as herein described with reference to the examples.

Documents:

1120-del-1998-abstract.pdf

1120-del-1998-claims.pdf

1120-del-1998-correspondence-others.pdf

1120-del-1998-correspondence-po.pdf

1120-del-1998-description (complete).pdf

1120-del-1998-form-1.pdf

1120-del-1998-form-19.pdf

1120-del-1998-form-2.pdf