AKRON, OHIO (Sept. 13, 3:55 p.m. ET) — North American prices for solid polystyrene and PET bottle resin each headed up in August.

Solid PS prices surged an average of 5 cents per pound, while PET jumped an average of 4 cents per pound, according to buyers and market watchers contacted recently by Plastics News. These changes are shown on this week’s PN resin pricing chart. The chart also shows a 10-cent downward correction on North American ABS prices to reflect further price erosion that occurred earlier this summer.

The PS move was tied into a 7 percent jump in the price of benzene, a chemical feedstock used to make styrene monomer. Benzene prices closed at $4.60 per gallon for August. The PS price hike came after regional prices fell 3 cents for crystal PS and 5 cents for high-impact PS June and July combined. Those drops were surprising because benzene prices rose somewhat during that time period.

Some facilities making styrene monomer in the Louisiana area were shut down in advance of Hurricane Isaac, which hit the region on Aug. 28. Most of those plants now have been re-started or are in the process of doing so, sources said.

Crystal (general-purpose) PS supplies in the region could be affected by force majeure conditions that are in place at plants operated by Americas Styrenics in Ohio and Connecticut. Low water levels on the Mississippi River have prevented those plants from receiving the styrene monomer they need for full operation, according to an official with the firm in The Woodlands, Texas.

North American PS sales posted negative results in the first half of 2012, falling almost five percent vs. the first half of 2011, according to the American Chemistry Council in Washington. Among major end markets, food packaging/food service held up the best in the first half, falling less than 2 percent.

In 2012, North American PS has been affected by price volatility and by competition from other resins, according to Stacy Shelly, a PS and ABS market analyst with Resin Technology Inc. in Fort Worth, Texas.

Regional PS prices now are up a net of 17 cents since Jan. 1, an increase of about 16 percent, based on prices for injection molding grades of HIPS. But some market watchers are saying the August increase might be short-lived since benzene process for September already have settled down 9 percent to $4.20 per gallon.

For PET, the 4-cent price hike came at an unusual time — late in the summer, when demand for carbonated soft drinks and bottled water tends to ebb. Feedstocks played a role in the increase, market watchers said. Some levels of monoethylene glycol feedstock also were taken offline during Hurricane Isaac, but have since been restarted.

PET prices have bounced around for much of the year, but the August increase ends a streak of four consecutive months where prices either fell or remained flat. Prices now are almost equal with where they were at the start of the year.

The 10-cent downward correction on ABS covers additional price erosion that’s hit that market since June. Imported ABS has been “more prevalent” in North America this year, as a result of lower tariffs and excess supply around the world, according to Shelly at RTI. Coming into the year, market watchers were hopeful that ABS demand in the region could grow 3-5 percent in 2012, but Shelly said the market now “could end up fairly flat” for the year.

Regional ABS prices now are down about 15 percent from their mid-2011 peak, based on grades of the material used to make extruded sheet.