Barker said that the board and senior management would be running "a tighter organisation from now on".
He joins newly-appointed non-executive director Robert Kaye and Andrew Price, who was brought onto the Paperlinx board on September 1, despite Boon voicing concerns in a letter to shareholders about Price becoming a non-executive director, in the run up to an extraordinary AGM in April.
Michael McConnell will remain with the board as a non-executive director until the day before the postponed AGM, scheduled for 15 November. Barker said that his input was providing "continuity" to the board’s decisions.
Barker said that the directors had elected him as chairman as his experience in financial and risk management was most relevant to the current economic situation within Europe, Paperlinx’s most troubled market.
He said he was confident that interim chief executive Dave Allen was "completely fulfilling" the role and said that the board had no imminent plans to replace him. He claimed that Allen would be more demanding of his staff and could implement more internal management changes.
Barker added: "Dave is really on top of the strategy. Part of the problem in the past was that the implementation was a bit slow, now we are fully into implementation mode.
"Our main thrust is to diversify with packaging and a broader range of products. When you’ve got a shrinking market and several players the best way out is to grow your range of products rather than just taking share from other people."
He added that he would be reviewing the situation in Europe closely with chief financial officer Richard Barfield.
He said: "The risk is not so much internal to Paperlinx but it is what the financial environment can do. We have big operations in several countries and buying paper in one place and warehousing it another creates cross-border risks.
"It is that sort of risk where I can add value."
Despite never having met departed chief executive Toby Marchant, Barker said he was under the impression that his management style was "laissez faire".
Dissatisfied shareholder Graham Critchley said he now expected a "leaner and keener approach to running Paperlinx and a new sense of urgency" following the fast turnaround of directors.
He added: "It looks like [the company] is going for a team of highly skilled experts – Andrew Price will implement the lean and mean where needed. PaperlinX is at rock bottom which is a solid foundation."
Boon left his post a day early along with non-executive directors Lyndsay Cattermole and Anthony Clarke after announcing their resignation on 19 September.
Boon replaced by actuary Michael Barker as Paperlinx chairman
Michael Barker, who was appointed to the board only last Thursday (27 September), has replaced Harry Boon as chairman with immediate effect from 1 October.