Heterogeneous Double Metal Cyanide Catalyzed Synthesis of Poly(ε-caprolactone) Polyols for the Preparation of Thermoplastic Elastomers

A series of polycaprolactones (PCLs) with molecular weights of 950–10,100 g mol−1 and Ð of 1.10–1.87 have been synthesized via one-pot, solvent-free ring-opening polymerization (ROP) of ε-caprolactone (CL) using a heterogeneous double metal cyanide (DMC) catalyst. Various initiators, such as polypropylene glycol, ethylene glycol, propylene glycol, glycerol, and sorbitol, are employed to tune the number of hydroxyl end groups and properties of the resultant PCLs. Kinetic studies indicate that the DMC-catalyzed ROP of CL proceeds via a similar mechanism with the coordination polymerization. Branched PCLs copolymers are also synthesized via the DMC-catalyzed copolymerization of CL with glycidol. The α,ω-hydroxyl functionalized PCLs were successfully used as telechelic polymers to produce thermoplastic poly(ester-ester) and poly(ester-urethane) elastomers with well-balanced stress and strain properties.

Heterogeneous Double Metal Cyanide Catalyzed Synthesis of Poly(ε-caprolactone) Polyols for the Preparation of Thermoplastic Elastomers

A series of polycaprolactones (PCLs) with molecular weights of 950–10,100 g mol−1 and Ð of 1.10–1.87 have been synthesized via one-pot, solvent-free ring-opening polymerization (ROP) of ε-caprolactone (CL) using a heterogeneous double metal cyanide (DMC) catalyst. Various initiators such as polypropylene glycol, ethylene glycol, propylene glycol, glycerol, and sorbitol are employed to tune the number of hydroxyl end groups and properties of the resultant PCLs. Kinetic studies indicate that the DMC-catalyzed ROP of CL proceeds via a coordination mechanism. Branched PCLs copolymers are also synthesized via the DMC-catalyzed copolymerization of CL with glycidol. The α,ω-hydroxyl functionalized PCLs were successfully used as telechelic polymers to produce thermoplastic poly(ester-ester) and poly(ester-urethane) elastomers with well-balanced stress and strain properties.

CHARACTERISTICS OF LEACHATE AT IHIAGWA DUMPSITE, IMO STATE NIGERIA AND THEIR IMPLICATIONS FOR SURFACE WATER POLLUTION

Open dumpsite is the most common way to eliminate solid urban wastes in this part of the world. An important problem associated to landfills and open dumpsite is the production of leachates. The leachates from these dumpsites have many toxic substances, which may adversely affect the environmental health. Thus in order to have a better management of characteristics of Ihiagwa-Nekede waste dump leachates, representative leachate samples were collected and analyzed for Physico-chemical properties and levels of heavy metals in them. Results indicate pH7.38, temperature 28.30 ℃ - 28.40℃, total dissolved solid 124.01mg/l-125.45mg/l, magnesium hardness 4.40mg/l-7.32mg/l, sulphate 3.60mg/l-3.70mg/l, and nitrate 27.00mg/l-27.60mg/l. Other parameters indicated as follows Conductivity1910𝜇𝑠/𝑐𝑚-1930.00 𝜇𝑠/𝑐𝑚, total chloride 891.72mg/l-891.74mg/l, carbonate 1708.00mg/l-1904.00mg/l, Ammonia 9.39mg/l-9.40mg/l, calcium hardness 373.17mg/l-375.61mg/l, total solid 2423.00mg/l-2454.00mg/l, phosphate 13.52mg/l-13.54mg/l. The heavy metal: cyanide 2.25mg/l-2.33mg/l, zinc 18.08mg/l-18.38mg/l, copper 19.90mg/l20.48mg/l, iron10.67mg/l-10.82mg/l, lead 1.27mg/l-1.41mg/l, and manganese 3.00mg/l-3.61mg/l, all these exceeded the WHO standards. The obtained results showed that the landfill leachates are characterized by high concentrations of heavy metals and other disease causing elements and therefore require urgent treatment to forestall the contamination of groundwater system and the nearby Otamiri River.