Study On Preparation And Properties Of Functional Poly(Ethylene Terephthalate) (FPET)

Poly(ethylene terephthaltae) (PET) is one kind of saturated polyester contained aromatic ring, which is condensed from terephthalic acid and glycol. PET is mainly being made to fibred products widely, used for cloth and garment since it was invented. But for the excellent PET can resist the etching against to most of organic solvent and inorganic acid, and it has not only high impact strength, outstanding insulation, little moisture absorption, but also avirulence, flavourless, wearable and rigid properties, it can be easily process to products with good stabilization in a broad temperature range, PET has been used in more field as non-fiber application. Especially, the application of PET in packaging bottle, film and engineering plastic which has been developed quickly recent ten years.However, there some inherent disadvantage of PET hold it back been used more widely and progress properly. For example, PET can not be used as especial packaging materials to contain the merchandise which have sensitivity for oxygen (such as beer and biochemical medicine) for it has no high gas barrier and heat-resistant properties. Secondly, PET has a great resistivity, triboelectricity voltage and long time of electrostatic half life; it can bring electrostatic charge easily to the membrane and fibre, influence badly to application and manufacture progress. Thirdly, PET is the finest aromatic polyester with lowest price, top-quality and widest application, but there have three mainly limitations restricted it's utility in engineering plastic which was PET crystallize slowly, the size of PET products can not stabilize for enough time, and there no enough tension strength of PET melting to process expediently. For this reason, the mould of PET produce in process must attains to 130℃, it can not to be manufacture by injection quickly in PET industry. This research work focused on the imperative problem of PET, designed a special molecular structure of modified PET, synthesized and modified a several functional PET materials by means of PET industrial manufacture ways (PTA technique), to improve PET' properties of heat-resistant, gas barrier and antistatic.To finish this objective, above all, a set of mini reactor was designed and manufactured by ourselves, in which PET can be synthesized as industrial manufacture ways (PTA technique) in the laboratory. Four different steps of reaction technics in synthesizing PET progress such as making PTA and EG to be pasty, esterification reaction in high press, condensation reaction in lower vacuum and condensation reaction in the lowest vacuum would be actualized in this one equipment, PET and co-PET also be synthesized in one unit as this facility in the laboratory.A branch tube shape like "Y" was designed and fixed on the mini reactor, it connects two passageways together. Condensation reaction in lower vacuum was realized in one pipeline in which product and material can be separated completely, and condensation reaction in the lowest vacuum was realized in another pipeline. A "T" needle was designed and fixed on the exit down below the mini reactor, it can seal reactor easily in the state of lowest vacuum and take the PET product with high viscosity out off the reactor after the synthesis reaction. Not only the liquefacient reaction but also liquid- solid- gaseous reaction can be actualized in this mini reactor. It is a sharp "weapon" to research PET and functional PET in laboratory at present and future.For there few ways to test the quality of gas barrier on barrier polymer materials, especially to the particular type of polymer which has lowest gas permeability (the rate of gas transmission is lower than 3.8 cm³. mm/m².24h.MPa≈19 x10^-5 cm³. 20μm / m². d. Pa ). One set of gas permeation meter named KWY-02 was invented in this work, it can test the rate of gas transmission accurately to most of polymer films which gas permeability is froml.0 x10²cm³. 20μm/ m.2. d. Pa to 10^-8cm³. 20μm/m². d. Pa.A screw cap switch was devised and installed on the KWY-02 gas permeation meter; make it can be operated simply, quickly and automatically. Most of gas' permeability in polymer film can be measured on this set (except corrosive gas). There no pollution for the pressure gauge without mercury. Inductive time of esterified reaction between the terephthalic acid and ethylene glycol under high pressure and temperature was shortened by additional isophthalic acid(IPA). By contrary, inductive time of condensation reaction of isophthalate-bis-β-hydroxide ethyl ester (BHIT) was retarded by the amount of IPA. Inductive time of condensation reaction of pure BHIT reached to 200mins, but the temperature of condensation reaction was lower than terephthalate-bis-β-hydroxide ethyl ester (BHET). The cooling crystal peak of co-polyester of PTA, IPA and ethylene glycol (PELT) contains 20%wt IPA was disappeared, it means that PEIT with 20%wt IPA is random copolymer. The mechanical properties of PEIT improve with the content of IPA, it becomes badly when the content of IPA over 10%.PTA and glycerol will become to glyceride under high pressure and temperature by esterification reaction, but it is impossible that esterification reaction while there some glycol and glycerol exist in same system. BHET and glycerol can become to glyceride by ester interchange reaction. There is a little dissociative first hydroxyl group in the co-polyester of terephthalic acid, glycol and glycerol (PEGC), which improve the mechanical properties and gas barrier. When the amount of glycerol exceed over 2%, it becomes very difficult that polymerization reaction of terephthaltae acid, glycol and glycerol.A several heat stability organic hydroxyl alkyl ammonium with morpholine ring were synthesized in this work, such as hydrochloric morpholine salt, 4-morpholineethanol hydrochloric salt,α-methyl-4-morpholineethanol hydrochloric salt, N-(1,1-dimethyl- hydroxyl ethylene) morpholine hydrochloric salt, N-(6- hydroxyl hexane) morpholine ammonium bromide and N-(10- hydroxyl decane) morpholine ammonium bromide. The heat decompose temperature of N-(6- hydroxyl hexane) morpholine ammonium bromide and N-(10- hydroxyl decane) morpholine ammonium bromide go beyond 360℃. They can come into the interior of montmorillonite (MMT) layer by cation exchange reaction, expands the distance of MMT layer. The distance of MMT layer can be distended to more than 20A by N-(6- hydroxyl hexane) morpholine ammonium bromide and N-(10- hydroxyl decane) morpholine ammonium bromide.15.8% weight of antimony glycol could be dissolved in glycol at 180℃, and adsorbed on MMT for 6%. PET-MMT nanocomposite was condensation polymerized from BHET and MMT loaded antimony glycol, the cooling crystal temperature of PET-MMT nanocomposite with 2% of MMT falls to 130.2℃from136.5℃of virgin PET; the melt point climbs to 264.5℃from 246℃of pure PET, the onset temperature of degradation is about 114℃higher for nanocomposite; oxygen barrier ability is three times than origin PET, but mechanical properties goes to the bad.Oxidation reaction is took place on the parietal wall or the tail of carbon nanotubes (CNTs) in the solution of forceful oxidizer (such as the mixture of thick nitric acid, oil of vitriol and H202), a few active group of hydroxide or carbonyl are generated in this reaction, it can improve the solubility of multi wall carbon nanotubes (MWNT) in polar solvents. The stability of the mixture of functional MWNT and glycol or water prolongs to two weeks. PET-CNTs nanocomposite was in situ polymerized from PTA, glycol and functional MWNT which has been treated with ultrasonic and dispersed equably to glycol.MWNT can be dispersed equably to PET while the content below 0.2%, it acts as nucleus of crystal to PET. The strength at break of PET-CNTs nanocomposite with 0.05% MWNT increases to 61.1MPa from48.2MPa of virgin PET; modulus improves to 2.52GPa from2.21MPa of origin PET and the elongation at break attains to 318%.Electric conductivity of PET-CNTs nanocomposite film is improved with the content of MWNT. 100 times of electric resistance for PET is higher than PET-CNTs nanoeomposite with 0.05% MWNT which acts as anlistatig to PET. There is a critical point of MWNT content in PET that is about to 0.2%. Molecular chain of PET can crystallize on MWNT which can dispersed equably in PET while the content of MWNT below 0.2%, there is little improvement of electric conductivity for PET-CNTs nanocomposite film. On the other hand, MWNT will tangle to each other and couldn't to be dispersed equably in PET while the content of MWNT beyond to 0.2%, affects availably electric conductivity of PET-CNTs nanocomposite film.