Activist investor Nelson Peltz is stepping up his campaign to leave his mark on DuPont, announcing late last week that his Trian Fund Management will propose four candidates - including himself - for the US chemical giant's board of directors.

In addition to Peltz, Trian's nominees for the DuPont board include John H. Myers, former chief of General Electric's asset management group, Arthur B. Winkleblack, a former chief financial officer of Heinz, and Robert J. Zatta, acting chief executive of Rockwood Holdings.

Peltz has been pressuring DuPont since it announced plans to spin off its Performance Chemicals segment in November 2013. At the time, Trian called for the company to split into two separate entities, one containing faster-growing operations such as agricultural chemicals and another comprised of slower-growing, cash-generating businesses such as materials.

The investor, whose moves are similar to that of activist investor Daniel Loeb at Dow Chemical, owns not quite 3% of DuPont. Like Loeb, Peltz also has made no bones about the fact that his challenge is intended to be a referendum on the company's performance and its management strategy.

While analysts acknowledge that the Wilmington, Delaware-based chemical producer's shares are performing below their 1998 level, as Peltz notes, they point out that this is also true of most of its rivals - with the possible exception of Monsanto.

In its defense, DuPont has underscored that it improved its operating margin by 65% from 2008 to 2013 and also returned more than $12 billion to investors from 2009 to 2014 in the form of share buybacks and stock dividends. What's more, CEO Ellen Kullman said, over the last 12 months, the company's shares have risen by nearly 19%.

Kullman said also that DuPont is on track with its corporate redesign, which is expected to improve efficiency as well as cost structure. The company has also continued to trim its portfolio and peripheral assets - most recently saying it will sell a theater in Wilmington it has owned since its founding and traditionally uses for functions such as annual meetings.