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CHDMConceptual Health Data Model (Canadian Institute for Health Information)
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By Robert Leaversuch, Executive Editor COMPOSITION OF TPA-BASED POLYESTERS Type & Class Composition Attributes Homopolymers PET TPA + EG Superior stiffness, HDT PBT TPA + 1,4- Easier to process, better butanediol warp-resistance than PET PTT TPA + 1,3- Good dimensional stability, propanediol excellent surface properties PCT TPA + CHDM Better heat resistance than other polyesters Copolyesters PETG TPA + EG Glass-like clarity, high (greater than stiffness 50%) + CHDM PCTG TPA + CHDM Excellent clarity, better (greater than impact and elongation than 50%) + EG polycarbonate PCTA TPA + CHDM + IPA Higher HDT and elongation than PETG; easier processing and drying; high clarity, neutral color Key: TPA = Terephthalic Acid EG = Ethylene Glycol CHDM = Cyclohexanedimethanol IPA = Isophtalic Acid
Some examples of this include: ethylene glycol gives excellent oil and fuel resistance, but a poor hydrolysis resistance; butanediol or even better methylpropanediol give outstanding low temperature properties; hexanediol leads to a good hydrolysis and heat resistance; cyclohexanedimethanol brings outstanding gas impermeability (ref.
However, aliphatic diacrylates with improved hardness, scratch resistance, chemical resistance, and weatherability are still desired for the next generation of UV-cured coatings, and cyclohexanedimethanol diacrylates are a class of monomers that can potentially offer these benefits.
Commercially available cyclohexanedimethanol diacrylates arc prepared from 1, 4-cyclohcxanedimethanol, which is a solid diol at room temperature.
To alleviate this problem, the solid diol (1,4-cyclo-hexanedimethanol) can be alkoxylated with either ethylene oxide or propylene oxide and then reacted with acrylic acid to form alkoxylated cyclohexanedimethanol diacrylate derivatives, with structures such as those shown in Fig.
(5) In contrast to 1,4-cyclohexanedimethanol, this new diol (henceforth referred to as 1,3/1,4-CHDM) is a liquid, and can be used to synthesize liquid cyclohexanedimethanol diacrylate monomers that are free of alkoxylation.
Table 2: GC method for analyzing diacrylate samples Instrument HP 6890 Column ZB-1 60 m x 0.32 mm x 1.0 [micro]m Injection temperature 300[degrees]C Detector temperature 300[degrees]C Oven program 50[degrees]C for 2 min, 300[degrees]C @ 10[degrees]C/min, hold 6 min Carrier gas and flow He carrier @ 1.5 mL/min constant flow Injector flows Split ratio 100:1 FID detector flows [H.sub.2] @ 45 mL/min, Air @ 450 mL/min He makeup @ 30 mL/min Chromatogram time 33 min Data system Beckman-Coulter PeakPro Sample injection size 0.2 [micro]L injection Preparation of cyclohexanedimethanol diacrylates from standard 1,3/1,4-CHDM (Sample #1)
The synthesized liquid 1,3/1,4-cyclohexanedimethanol diacrylate (1,3/1,4-CHDMDA) in Sample #3 was then compared to commonly used diacrylate monomers, as well as alkoxylated cyclohexanedimethanol diacrylates.
The comonomers of this bottle-grade PET were found to be diethylene glycol (5.9 mol%) and cyclohexanedimethanol (1.1 mol%), while the average molecular weights were [M.sub.n] = 25.3 kg/mol and [M.sub.w] = 65 kg/mol (19).
PETG is an amorphous, glycol-modified poly(ethylene terephthalate) made from terephthalic acid, ethylene glycol, and cyclohexanedimethanol by a polycondensation process.