Polyester Plastics Research Articles

Solubilization and Upgrading of High Polyethylene Terephthalate Loadings in a Low-Costing Bifunctional Ionic Liquid.

The solubilization and efficient upgrading of high loadings of polyethylene terephthalate (PET) are important challenges, and most solvents for PET are highly toxic. Herein, a low-cost (ca. $1.2 kg-1 ) and biocompatible ionic liquid (IL), cholinium phosphate ([Ch]3 [PO4 ]), is demonstrated for the first time to play bifunctional roles in the solubilization and glycolytic degradation of PET. A high loading of PET (10 wt %) was readily dissolved in [Ch]3 [PO4 ] at relatively low temperatures (120 °C, 3 h) and under water-rich conditions. In-depth analysis of the solution revealed that high PET solubilization in [Ch]3 [PO4 ] could be ascribed to significant PET depolymerization. Acid precipitation yielded terephthalic acid as the dominant depolymerized monomer with a theoretical yield of approximately 95 %. Further exploration showed that in the presence of ethylene glycol (EG), the [Ch]3 [PO4 ]-catalyzed glycolysis of PET could efficiently occur with approximately 100 % conversion of PET and approximately 60.6 % yield of bis(2-hydroxyethyl)terephthalate under metal-free conditions. The IL could be reused at least three times without an apparent decrease in activity. NMR spectroscopy analysis revealed that strong hydrogen-bonding interactions between EG and the IL played an important role in the activation of EG and promotion of the glycolysis reaction. This study opens up avenues for exploring environmentally benign and efficient IL technology for solubilizing and recycling postconsumer polyester plastics.

More reaction steps are better for making pentanediol

Creating high-value coproducts along with biofuels is an important part of helping biobased chemicals become economically viable so they can complement petroleum-derived chemicals. But this is a tricky proposition because hundreds of interrelated compounds exist in both the petrochemical and biomass chemical pathways. That means sorting through many possible reactions to find optimal routes to target products. In one of the latest examples, George A. Huber, James A. Dumesic, and coworkers at the University of Wisconsin, Madison, have found a new way to make 1,5-pentanediol, a building block for polyurethane and polyester plastics. An economic analysis of the possible routes surprised the team: A longer, multistep route turns out to cost about 40% less than a shorter, more direct route owing to better yield and lower catalyst and utility expenses (ChemSusChem 2017, DOI: 10.1002/cssc.201700178). The synthesis of biobased 1,5-pentanediol has focused on hydrogenating hemicellulose-derived furfural to tetrahyd...

Radiation damage and recovery properties of common plastics PEN (Polyethylene Naphthalate) and PET (Polyethylene Terephthalate) using a 137Cs gamma ray source up to 1.4 Mrad and 14 Mrad

Polyethylene naphthalate (PEN) and polyethylene teraphthalate (PET) are cheap and common polyester plastics used throughout the world in the manufacturing of bottled drinks, containers for foodstuffs, and fibers used in clothing. These plastics are also known organic scintillators with very good scintillation properties. As particle physics experiments increase in energy and particle flux density, so does radiation exposure to detector materials. It is therefore important that scintillators be tested for radiation tolerance at these generally unheard of doses. We tested samples of PEN and PET using laser stimulated emission on separate tiles exposed to 1 Mrad and 10 Mrad gamma rays with a 137Cs source. PEN exposed to 1.4 Mrad and 14 Mrad emit 71.4% and 46.7% of the light of an undamaged tile, respectively, and maximally recover to 85.9% and 79.5% after 5 and 9 days, respectively. PET exposed to 1.4 Mrad and 14 Mrad emit 35.0% and 12.2% light, respectively, and maximally recover to 93.5% and 80.0% after 22 and 60 days, respectively.

Mechanistic Insight into the Conversion of Tetrose Sugars to Novel α‐Hydroxy Acid Platform Molecules

Abstractα‐Hydroxy acids (AHAs) such as lactic acid are considered platform molecules in the biorefinery concept and have high‐end applications in solvents and biodegradable polyester plastics. The synthesis of AHAs with a four‐carbon backbone structure is a recently emerging field. New biomass‐related routes towards their production could stimulate their practical use in new polyester plastics. Herein, we report the unique catalytic activity of soluble tin metal salts for converting tetroses, namely erythrulose and erythrose, into new four‐carbon‐backbone AHAs such as methyl vinylglycolate and methyl‐4‐methoxy‐2‐hydroxybutanoate. An in situ NMR study together with deuterium labeling experiments and control experiments with intermediates allowed us to propose a detailed reaction pathway.

Evolutionary Engineering of Bacillus for Terephthalic Acid Degradation

Evolutionary engineering is a novel whole-genome wide engineering strategy inspired by natural evolution for strain improvement. Terephthalic acid (TA) is the most important starting material for making synthetic products, especially polyester fiber and plastics. Both TA and its manufacturing wastewater show acute, chronic and molecular toxicity to organisms. In textiles manufacturing, alkali de-weighting finishing of polyester fabrics was a main resource for producing waster water containing TA. Microorganisms can hardly adapt to the high pH caused by the alkali in wastewater of alkali de-weighting process. Although the strain for TA biodegradation already have been isolated, it is necessary to develop new innovative methods of treating TA in alkali de-weighting wastewater effectively. In this investigation, evolutionary engineering was applied to improve the characterization of Bacillus strain and the high pH resistance phenotypes were obtained. The approach of selection procedure presented in this investigation may provide an attractive promising alternative for improvement of pH resistance strain.

Research on Glass Fiber/Microcellular Unsaturated Polyester Composites

Glass fiber/microcellular unsaturated polyester composites (GF/MCUP) were prepared using the supersaturated gas technology. Technological process included three stages. The effect of processing parameters on average cell size, cell density, impact strength and tensile strength was investigaed by orthogonal experiment. The results indicated that the major factor affecting them was the temperature in stageⅡ(T2). Under the optimizing processing condition, the average cell size of GF/MCUP was about 8 μm and the cell density was 1.57×109 cells/cm3. It was found that impact strength of GF/MCUP increased 88.81 and 188.12 % than that of glass fiber/unsaturated polyester composites (GF/UP) and unsaturated polyester plastics (UP), respectively. The corresponding 16.56 and 69.25 % increase in tensile strength-to-weight ratio were gained over that of GF/UP and UP, respectively.

Failure of antimony trioxide to induce micronuclei or chromosomal aberrations in rat bone-marrow after sub-chronic oral dosing

Antimony trioxide (Sb 2O 3, CAS 1309-64-4) is widely used as a flame retardant synergist in a number of household products, as a fining agent in glass manufacture, and as a catalyst in the manufacture of various types of polyester plastics. It does not induce point mutations in bacteria or mammalian cells, but is able to induce chromosomal aberrations (CA) in cultured cells in vitro. Although no CA or micronuclei (MN) have been induced after acute oral dosing of mice, repeated oral dosing for 14 or 21 days resulted in increased CA in one report, but did not result in increased MN in another. In order to further investigate its in vivo genotoxicity, Sb 2O 3 was dosed orally to groups of rats for 21 days at 250, 500 and 1000 mg/kg day. There were no clinical signs of toxicity in the Sb 2O 3-exposed animals except for some reductions in body-weight gain in the top dose group. Toxicokinetic measurements in a separate study confirmed bone-marrow exposure, and at higher levels than would have been achieved by single oral dosing. Large numbers of cells were scored for CA (600 metaphases/sex group) and MN (12,000 PCE/sex group) but frequencies of CA or MN in Sb 2O 3-treated rats were very similar to controls, and not biologically or statistically different, at all doses. These results provide further indication that Sb 2O 3 is not genotoxic to the bone marrow of rodents after 21 days of oral administration at high doses close to the maximum tolerated dose.

Modification of Glass-Fibre Reinforced Polyester Plastics with 2,4-Toluene Diisocyanate During Moulding

The exotherms and mechanical strength changes due to different amount of 2,4-toluilenediisocyanate in glass-fibre reinforced polyesters are considered. It is found that the higher the concentration of 2,4-toluilenediisocyanate (i) the shorter the gelation time (ii) the faster the polymerization during gelation and (iii) the greater the exothermic effect of the process. As a whole, the reinforcement effect of the glass-fibre composites is bigger than that of non-reinforced polyester. Tensile, bending and impact strength improvements for reinforced polyesters are in the range of 15–25, 27–38 and 21–32%, respectively in comparison with 12% for the same tests of non-reinforced one. The data received reveal the opportunity for an effective modification of such plastic articles during the process of their formation. The reached impact resistance is comparable with those ones for some standard SMC (sheet moulding compound) materials. The tensile strength of 85 MPa (at 120 °C) is commensurable with and even higher than that one of many advanced polymeric materials tested at ambient temperature.

The thermal degradation of phosphorus-containing copolyesters

Two series of phosphorus-containing copolyesters were synthesized by poly-condensation of phosphorus-containing monomers: poly(ethylene terephthalate)-co-poly(ethylene phenylphosphonate)s [PET-co-PEPPs] and poly(ethylene terephathalate)-co-poly(ethylene DDP)s [PET-co-PEDDPs]. Both series are considered as flame retardants in polyester fibers and polyester plastics. The phosphorus-containing polymers were characterized by NMR, IR, TGA and acid titration. Experimental results indicated that for the PET-co-PEPP higher phosphorus content results in lower thermal stability. However, an insignificant effect on thermal stability was observed in the case of PET-co-PEDDPs. Thus, the incorporation of the phosphorus linkage into the main chain results in less thermal stability than that having the phosphorus linkage as a pendant group, i.e. PET-co-PEDDPs are more stable than PET-co-PEPPs.

The radiation resistance of thermoset plastics—VI. Unsaturated polyester plastics

Samples of two unsaturated polyester plastics, both with inorganic fillers, were irradiated under two very different conditions. One set of samples was irradiated with electrons, under exclusion of oxygen, using a high dose rate. The second set was irradiated with γ-rays, in air, using a very low dose rate of only 13.8 Gy/h. In the case of the short-term experiment the flexural strength, the impact strength and the deflection temperature passed through maxima as a function of dose. A significant deterioration of the strength did not occur up to a dose of 10 MGy. However, in contrast to this result, in the long-term experiment the strength was remarkably reduced at doses above 0.5 MGy. The electrical properties of four samples of different formulations were investigated. Irradiation with high dose rate had little influence on the electrical properties, but an abrupt drop of the surface resistance was found at 0.1 MGy in the long-term experiment. The tracking resistance showed a similar behaviour. Only the dielectric constants remained unchanged under all conditions of irradiation.

The radiation resistance of thermoset plastics—III. Oxygen permeation experiments

For the interpretation of the results of long term irradiation experiments in the presence of air it is necessary to know about the penetration of oxygen into the plastic material in the course of time. Therefore the oxygen permeability of two thermoset plastics (made from two unsaturated polyester resin thermosetting moulding compounds) was measured in the temperature range 20–60°C. For the Typ 802, the following data were generated at 23°C: permeability coefficient P=3.08 × 10 -15cm 3·cm⧸cm 2·s·Pa, diffusion coefficient D=1.03×10 -8cm 2⧸s, solubility coefficient S=3.00×10 -7cm 3⧸cm 3·Pa. The permeability of two thermoset phenol-formaldehyde plastics and one melamine-formaldehyde plastic was found to be immeasurably small, i.e. P<3×10 -17cm 3·cm⧸ cm 2· s·,Pa at 60°C. For discs of 4mm thickness made from the polyester plastics, oxygen concentration profiles were calculated which are built up in the course of time during storage in air at 23°C. For both other materials the profiles were estimated by assuming P=3×10 -17 at 60°C and the activation energy and the solubility being the same as in the case of polyester plastics.

Determination of airborne methyl ethyl ketone peroxide

A new method for the determination of airborne methyl ethyl ketone peroxide (MEKP) is based on the reaction of peroxides with 4-tert-butyl catechol, in which the peroxide radicals oxidize the catechol to the corresponding benzoquinone. The yellow colour generated is measured at 395 nm. Sampling from factory air can be performed by aluminium oxide sampling tubes. Glacial acetic acid is used as a solvent and for the desorption of the peroxide from the aluminium oxide. The detection limit (0.05 mg/m3 for 4 h samples) for the MEKP in air is well below the current hygienic reference value (1.5 mg/m3). The method was used for MEKP determinations during lamination applications in the production of reinforced unsaturated polyester plastics, where the airborne concentrations of the peroxide were well below the current hygienic reference values.

Cleaning gaseous discharges from foul-smelling material

Packed columns (Raschig or Pall rings or capillary tubes) are used abroad in equipment for liquid-phase oxidation of FSM. Titanium, special steels, polyester plastics, or fiber glass plastics are used as structural material. Carbon-graphite packed columns with high material content and of large dimensions are used in the indigenous engineering industry for these purposes. Structural characteristics of graphite have made possible such equipment.

Hazardous halogenated substances formed during combustion processes

Abstract The results of the emissions from combustion processes and/or from fire accidents show the risk to man and his environment and thus the need for strict legislation and critical analysis of unwanted compounds. These substances or their thermolysis products are often due to incomplete combustion or may result from the interaction of various substances. In the following we report the formation of octachlorostyrene (OCS) and of high‐toxic substances such as polybrominated dioxins (PBrDD's), dibenzofurans (PBrDF's) by the combustion. In order to determine a possible source of the non‐manufactured compound OCS, we conducted several model experiments in a combustion chamber at various temperatures from 400 °C to 800 °C. The thermolysis of chlorinated solvents like chloroform or of chlorinated aromatice like pentachlorobenzene produced—among other chlorinated substances—OCS as one of the major products. Analogous combustion experiments with polyester plastics containing decabromodiphenylether as flame re...

Airborne Fibrous Glass and Dust Originating From Worked Reinforced Plastics

The presence of respirable glass fibers in the dust from grinding, drilling and cutting of reinforced polyester plastics was investigated. The results show that 10% of the Swedish Threshold Limit Value (TLV®) for synthetic inorganic fibers (3 fibers/mL) seldom will be exceeded. On the other hand, the results indicate that the Swedish TLV for thermosetting plastic dust (3 mg/m3) will be exceeded quite often. The authors examined the possibility of longitudinal glass fiber division during the working of reinforced polyester plastic and whether respirable glass fibers were produced. The results show that such a division does not occur for glass fibers embedded in polyester plastic and that the respirable fibers are related to fiber-shaped plastic particles or organic fiber particles.

Greater Environmental Protection for Electrical Equipment Through New Technology

Corrosive environments have long presented problems in application, installation, and maintenance of electrical equipment. The causes of corrosion and the means taken to date to combat corrosive environments are briefly reviewed. The application of new technology in the glass-reinforced polyester plastics field is described as a solution to the problem of long-term protection of electrical equipment installed in aggressive environments. This new technology involves the use of chemical thickening of special polyester resins suitably formulated to provide high levels of structural strength and corrosion resistance both indoors and outdoors. Data are presented on the environmental resistance of the chemically thickened glass-reinforced polyester systems, and these are interpreted in terms of the diffusion of the environment into and out of the plastic. Examples are given of the application of chemically thickened glass-reinforced plastics in heavy duty industrial plugs and receptacles, industrial type light reflectors, and enclosures for electrical equipment. The degree of protection afforded by the chemically thickened glass-reinforced plastic is important in electrical installations in the petroleum, petrochemical, food, drug, fertilizer, and other process industries.

Determination of the magnitude and distribution of the initial stresses in glass-reinforced plastics

Photoelastic stress analysis is used to demonstrate the effect of coupling agents on the residual microstresses, i.e., the stresses that develop at near the glass-resin interface during the curing of polyester and epoxy glass-reinforced plastics and, as a rule, remain throughout the life of the product. Coupling agents of different chemical composition applied to the surface of the glass fibers have different effects on the components of the state of stress and thus can act as a powerful regulating factor.

Measurement of photochemical degradation in certain plastics by color reactions with phenylenediamines

AbstractSamples of polyester plastics, upon exposure to solar or carbon‐arc radiant energy, were found to form oxidation products which, when reacted with N,N‐dimethyl‐p‐phenylenediamine (DMPDA), produced yellow to brown reaction products. The extent of the reaction was determined directly by the amount of diamine reacted or indirectly by differential colorimetry. Research with this color reaction was extended into the development of tests for measuring the photooxidative degradation of polyesters, rigid poly(vinyl chloride), acrylics, and cellulose acetate–butyrate plastics. The basic colorimetric method was modified as needed for each of these plastics types, by directly measuring the absorbance of the DMPDA solution instead of measuring the amount of DMPDA reacted, by the use of o‐, m‐, and p‐phenylenediamines as replacements for DMPDA in the color reaction, or by a change in the solvent. The reliability of “yellowness” as an indicator of the photochemical stability of plastics was examined.

化学工業における強化ポリエステルプラスチックの性質と実績

化学工業における強化ポリエステルプラスチックの性質と実績

Properties and Performance of Reinforced Polyester Plastics in the Chemical Industry

Abstract The use of reinforced polyester resins as a material of construction in the chemical industry is relatively new and is one which warrants periodic review. This paper discusses some of the basic properties of polyesters which must be considered by designers and fabricators, and gives some examples of actual field installations. The use of reinforced polyester resins for alum evaporators, stacks, dryer trays, filter troughs, and filter press plates and frames are discussed in detail. This detailed information is given so that other end users may evaluate this material for their specific requirements. 6.6.8