Reactive Extrusion of TPE-E Nanocomposites - Case Study Example

? Reactive Extrusion of TPE-E Nanocomposites Introduction TPEE is resistant to oil and chemical as well as having low temperature properties. These properties make it to be a good compound for use in automobile, electric and electronic applications. Chloroprene was earlier used for automobiles but it was replaced with TPEE because it has low durability. In addition, TPEE is widely used in Europe and North America because of its lightweight and its resistant properties to fatigue and chemicals. TPEE is produced through extrusion blowing at its melt state thus the resin must have good melt viscosity and tension in order to produce thickness distribution during extraction. It is very difficult to do extrusion blending with TPEE because it has a low melt viscosity and tension. Its melt viscosity and tension can be increased by adding branching agent during polymerization. Even with this increase, it is not sufficient to perform extrusion blowing. There are several attempts, which have been made to increase melt viscosity and tension during extrusion by use of a chain extender during melt polymerization. Reduction of crystallization time through reactive extrusion of PBT with the use of diepoxy group as a chain extender provides a simpler method of getting high molecular weight of PBT than the conventional method of poly-condensation. Researchers acknowledge that multifunctional polymers such as TMP, TME and trimesic acid can be used to produce high molecular weight of PET. There is an effect of the modified m-MDI in the blending process of PET since the increase of m-MDI increases the molecular weight of PET. However the reaction should not be abled to continue for a long time and m-MDI should not be added because there will be crosslinking of the product because of the excessive reaction of isocyanate. This will later affect the ductility of the blend. In a situation where the correct amount of m-MDI is used then the molecular weight of PET is reduced with increasing time of blending. This is because of degradation hydrolytic and isocyanate group. It is very important to complete the process within a short time to avoid degradation. If the time is not enough to complete the process of forming urethane then there will be production of carbon dioxide by unreacted isocyanate groups at the stage of post extrusion. fluoromica pristine clay modified with alkyl-ammoniums (ODTMA) Moreover, the unreacted group of isocyanate might result into undesirable side reaction at the post processing stage (Brown & Alder, Pp 35). Hence, it is very important to ensure that the process is completed and the physical properties are maintained. The best processing parameters for blending m-MDI and TPEE must be found. The current thermoplastic polyester elastomer (TPE) is characterized by qualities such as excellent heat resistance, resistant to light, heat-aging resistance, and good in block order retaining ability and low temperature traits. The TPE is made up of hard section, which consists of polyester, which comprises of aromatic dicarboxylic acid and aliphatic or alicyclic diol, and a soft section, which consists of aliphatic polycarbonate as the main ingredient. Through which where the hard and soft section becomes connected, and the melting points of the TPE are arrived at by taking their measurements using a differential scanning calorimeter in three stages. First temperature is raised from room temperature to 3000 C, at a 200 C/min heating rate, then for three minutes maintain temperatures at 3000 C after which lower it to room temperature at a cooling rate of 1000 C/min. (Tm1 – Tm3) obtains the melting point difference (Brown, Alder, 65). Materials pTMEG, 1,4-BD, Irganox 1010 and modifies m-MDI, MM103C. In addition, poly (butylene terephthalate) was also used. In addition phenol, together with 1, 1, 2, 2-tetrachloroethane, CF3COOD and TBT were used without any purification. The inner viscosity of the polymer was determined by use ubbelohde viscometer at 35 degrees (Chang, Pp 54). Usually IV is used for indicating the molecular weight of polymers. The MIR is the throughput ration under the load of 2.16kg to the load of of 21.6 kg, which was measured through a melt indexer at 230 degree Celsius at a time range of 10 minutes. Reactive modifier Preparation of chain extended TPEE TPEE branched was synthesized from a soft PTMG segment, DMT as hard segment and a branching agent known as glycerol. Unfortunately, the melt viscosity of the synthesized TPEE was rather low for the moulding process. Hydroxyl groups are introduced in the TPEE chain to provide an extension together with diisocyanate. During the melt, reaction of a branch of TPEE together with MDI is an attractive process of preparing high molecular weight of polycondensation polymers. Hydroxyl and isocyanate groups are able to react to conditions that are mild and form urethane bonds that are thermally and hydrolytically stable. The melt viscosity of TPEE is increased by reacting it with MDI in a twin-screw extruder (Cho, Pp 25). A TPEE that is branched has two kinds of chain ends, which are hydroxyl, and carboxyl group ends. Carboxyl group ends and the isocyanate start reacting forming amide bonds. The reaction between hydroxyl and isocyanate is higher compared to that of carboxyl and isocyanate. Characteristics In the last twenty years polymer blending has become a very crucial part in coming up with new commercial plastics materials that are lower in cost and enhanced on performance. Most of the polymers pairs are considered and known to be immiscible, although a few of them are considered thermodynamically miscible (Al Ghatta, Cobror & Severini, Pp 50). Overall, immiscible pairs are more preferred due to their high performance, and because those pairs that are miscible tend to retain their own characteristics. In the case of Polyethylene terephthalate (PET) and polystyrene (PS), they are both immiscible. Two reactive dual compatbilizers are used in the blending PET and PS. The compatibilizers include styrene maleic anhydride random sopolymer (SMA-8 wt % MA) and tetra-glycidyl ether of diphenyl diamino methane (TGDDM). TGDDM’s function groups can react with terminal groups of PET thatis –OH and –COOH and groups of anhydride SMA at the interface to create PET-co-TGDDM-co-SMA copolymers. PS is miscible with SMA that has a low MA content, whereas PET’s segments and phase are structurally identical. The in-situ created copolymers act as effective compatibilizers of the blends when they anchor at the interface (Ashcroft, Pp 20). Depending on the quantities of the TGDDM and SMA addition, the compatibilized blends lead to a higher viscosity, enhanced mechanical properties and in a smaller phase domain (Davis, 40). Lately it has been discovered that composites obtained from the dispersed fillers in polymers on the nanometer, have improved properties as compared to conventional polymer composites (Awaja & Dava, Pp 15). The presence of the nanofillers has improved the thermal, physical, barrier and mechanical aspect of the composites. This new and improved class composite is referred to as polymer matrix nanocomposites. Investigations to prove that there is improved toughness in nanocomposites with impact modified polyamide matrices. However, investigations or studies on nanocomposites created from organically modified clay as the reinforcing agent and modified PET as the matrix have not been done. PET is thermoplastic polyester that has high notch sensitivity and poor impact resistance. In PET or the clay nanocomposites, drawbacks may be imparted on the outcome of the product due to addition of clay. Therefore, for the above reason PET impact modification can be arrived at by dispersing elastomeric polymers in thepolymer matrix. Works Cited Awaja, Firas & Dava Fugen. Recycled Poly(ethylene terephthalate). 2004 Ashcroft, Wan. Chemistry and Technology of Epoxy Resins; Ellis, B., Ed.; Blackie Academic & Professional: Glasgow, UK, 1993; Chapter 2. Al Ghatta, Han. Cobror, Sam., and Severini,Tim . Polymers for Ad-vanced Technology, 8, 161 (1996). Brown, Can & Alder, peter. in: “Polymer Blends and Alloys”,Chapt. 8, M. J. Folkes, P. S. Hope, Eds., Chapman & Hall, Glasgow pg 65 (1993). Chain Extension by a Reactive Extrusion Process. 2004 Cho Sunghwan etal. High Molecular Weight Thermoplastic Polyether Ester Elastomer by Reactive Extrusion. 2009 Cai, Yibing. Synthesis and characterization of thermoplastic polyurethane/ montmorillonite nanocomposites produced by reactive extrusion. 2007 Chang, Cho ., in: “Handbook of Thermoplastics”, Chapt. 21, O. Olabisi, Ed., Marcel Dekker Inc., New York 1997. Davis, Chan, Herald,Mathias, L.James ,Gilman, J.W., Schiraldi, J.R. Shields, A. Trulove, P., Sutto, T.E., and Delong,H.C., Polym.Sci. Part B: Polym. Phys., 40, 2661. (2002). Imai, Y.; Nishimura, S. , Abe, E.; Tateyama, H. A. Abiko, A., Yamaguchi, A. Aoyama, T. and Taguchi, H. Chem. Mater.,14,477 (2002). Kalfoglou, N. K.; Skafidas, D. S.; Kallitsis, J. K.Polymer 1996, 37, 3387. Lee, Tae-young. Enhancement of physical properties of thermoplastic polyether-ester elastomer by reactive extrusion with chain extender. 2011. Le Bras M, Caniino G, Bourbigot S, Delobel R (eds), Fire retardancy of polymers. The Royal Society of Chemistry, Cambridge Wiley, John. Reactive Extrusion of Polymers: A Review. 1989. Read More