Propylene oxide melting temperature

On the other hand, the temperature of melting and crystallinity measurement can describe only those stereosequences that crystallize. In propylene oxide polymers which we have studied, for example, isotactic sequences are the only ones that crystallize. Therefore, in these polymers we can determine only the stereosequence length of isotactic units and the average length of the uncrystallizable units. The syndiotactic and atactic sequences in the uncrystallizable blocks are not distinguishable from the crystallinity and melting temperature measurements. 

Table I. Temperature of Melting and Percent Crystallinity of Crystalline Fractions of Propylene Oxide Polymers from Different Catalysts...

Poloxamer Poloxamers are copolymers of ethylene oxide and propylene oxide. Different molecular weight grades that are different in physical form, solubility, and melting point are available. Poloxamer 124 is a colorless liquid, whereas poloxamers 188, 237, 338, and 407 are solids at room temperature. All poloxamer grades are freely soluble in water and form gels at higher concentrations. The pH of aqueous liquids ranges between 5 and 7.5 [33],... 

Aminic polyols are low molecular weight adducts of propylene oxide (PO) [and/or ethylene oxide (EO)] made from aliphatic or aromatic polyamines such as ethylenediamine (EDA), diethylene triamine (DETA) [1, 2], ortho-toluene diamine (o-TDA) [3, 4] or diphenylmethanediamine (MDA) [2, 5, 6]. Because these starters are liquid at room temperature (EDA, DETA) or low melting point solids (o-TDA, MDA), they are alkoxylated in the absence of solvents. 

To a 2-liter, three-necked, glass, round-bottom flask equipped with a mechanical stirrer, thermometer, addition funnel, and dry-ice-acetone condenser is added 600 gm (4.0 mole) of p-tert-butylphenol. The flask is heated in order to melt the latter phenol and then 8.0 gm (0.2 mole) of sodium hydroxide is added. The temperature is raised to 150°C and then 929 gm (16 moles) of propylene oxide is added in 50-ml increments over a 7.5-hr period while slowly raising the temperature to 225°C during this period. Heating is continued. After cooling to room temperature the product is neutralized with a solution of 20.8 gm cone HCl in 150 ml water. The organic layer is separated and washed with 500 ml saturated salt solution. This product is filtered, dried and distilled under reduced pressure to give 4 products ... 

The melting temperatures of multiblock copolymers of ethylene oxide with propylene oxide, P(EP)m, can be compared with the triblock polymer PEP.(198,200) The ethylene oxide and propylene oxide sequences have discrete lengths that range... 

Fig. 6.12 Plot of melting temperature against characteristic ratio for indicated polymers. (1) Polyethylene (2) i-poly(propylene) (3) i-poly(isopropyl acrylate) (4) s-poly(isopropyl acrylate) (5) i-poly(methyl methacrylate) (6) s-poly(methyl methacrylate) (7) poly(dimethyl siloxane) (8) poly(diethyl siloxane) (9) poly(dipropyl siloxane) (10) poly(cis-l,4-isoprene) (11) poly(trans-l,4-isoprene) (12) poly(cis-1,4-butadiene) (13) poly(trans-1,4-butadiene) (14) poly(caprolactone) (15) poly(propiolactone) (16) poly(pivalolactone) (17) poly(oxymethylene) (18) poly(ethylene oxide) (19) poly(trimethylene oxide) (20) poly(tetramethylene oxide) (21) poly(hexamethylene oxide) (22) poly(decamethylene oxide) (23) poly(hexamethylene adipamide) (24) poly(caprolaetam) (25) poly(ethylene terephthalate) (26) poly(ethylene sulfide) (27) poly(tetrafluoroethylene) (28) i-poly(styrene) (29) poly(acrylonitrile) (30) poly(l,3-dioxolane) (31) poly(l,3-dioxopane) (32) poly(l,3-dioxocane) (33) bisphenol A-poly(carbonate).

The melting temperature of multiblock copolymers of ethylene oxide with propylene oxide, P(EP), can be compared with that of the triblock polymer PEP [59, 61]. The ethylene oxide and propylene oxide sequences have discrete lengths that range from 45 to 136 units for E and from four to 12 units for P. The value of m varies from 1 to 7. The level of crystallinity in these multiblock copolymers is only about 60% of that observed for comparable PEP copolymers. The melting temperatures of the P(EP) , and PEP copolymers with the same sequence length for E are, however, comparable to one another, the differences in melting temperature being only about 1-3 °C. Similar results are found when multiblock copolymers of poly(styrene) and poly(ethylene oxide) are compared with diblock and triblock ones. 

There are a few polymers, such as polyfbutylene terephthalate) [178], poly-(trimethylene terephthelate) [179], poly(pivalolactone) [180,181], poly(methylene oxide) [182], linear polyethylene over an extended temperature range [183-185], and isotactic poly(propylene) [186-190], that crystallize in a temperature interval well removed from T, for which III-II regime transitions have been reported but without a maximum in the rate. There are many problems associated with the proper assignment of this transition. A major problem is the correct selection of the equilibrium melting temperature. This turns out to be a cmcial matter. 

Fig. 4.29 Plot of melting temperature, T, , against crystallization temperature, T for polyidl-propylene oxide) (after Magill).

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