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Alkali treatment has long been used to improve natural-fiber composites, but whether it actually strengthens the fibers themselves has remained unclear.

A new study by Thanistha Akarapoowadol, Kheng Lim Goh and Taweechai Amornsakchai, published in ACS Omega, builds on this longer history of use by examining how a simple and widely used alkali treatment can more consistently improve the fiber's structural and mechanical properties for epoxy composite reinforcement.

Alkali treatment, usually carried out using sodium hydroxide, is already one of the most common methods for improving natural fiber composites. It is typically understood as a way to clean the fiber surface by removing noncellulosic materials such as lignin and hemicellulose, thereby improving bonding between the fiber and polymer matrix.

However, this explanation is incomplete. Many previous studies have attributed better composite performance mainly to improved fiber–matrix adhesion, even though composite testing alone cannot easily separate interfacial effects from changes occurring within the fiber itself.

Moreover, improvements in the intrinsic mechanical properties of natural fibers after alkali treatment are not universal. While some fiber species show enhanced performance, others exhibit little improvement or even reduced stiffness following treatment. These differences suggest that the response to alkali treatment depends strongly on the internal structure of each fiber.

The new study shows that alkali treatment can strengthen the fiber itself, rather than merely improving its bonding with the surrounding polymer. Using X-ray diffraction, the researchers found that the cellulose I crystalline phase was retained, while the crystalline order of the fiber increased. This structural refinement was linked to the removal of amorphous components such as hemicellulose and lignin.

To measure the fiber's intrinsic mechanical properties, the team used the Impregnated Fiber Bundle Test, which reduces the influence of fiber–matrix interfacial adhesion. The results showed that alkali treatment increased the fiber modulus from 18 to 29 GPa and the fiber strength from 390 to 530 MPa. These findings provide direct evidence that alkali treatment strengthens the fiber itself, rather than improving composite performance solely through better fiber–matrix bonding.

These fiber-level improvements translated into stronger composites. When 20 wt% treated pineapple leaf fiber was incorporated into epoxy, the resulting unidirectional composites showed increases of 200% in flexural modulus, 180% in flexural strength and 400% in notched impact resistance compared with neat epoxy.

The findings help clarify why alkali treatment can work effectively for pineapple leaf fiber composites. Rather than improving performance only through better adhesion, the treatment can also reinforce the fiber's internal structure. This provides a clearer basis for designing stronger, more reliable biobased composites from agricultural residues.

Because pineapple leaves are an abundant agricultural byproduct in many tropical countries, including Thailand, improving their reinforcing performance could increase the value of agricultural waste, reduce reliance on synthetic reinforcements and support the development of sustainable materials within the circular bioeconomy. More broadly, the work illustrates how agricultural residues can be converted into value-added materials for advanced engineering applications.

Publication details

Thanistha Akarapoowadol et al, Effect of Alkali Treatment on the Mechanical and Structural Properties of Pineapple Leaf Fiber for Epoxy Composite Reinforcement, ACS Omega (2026). DOI: 10.1021/acsomega.5c07292

Who's behind this story?

Lisa Lock

BA art history, MA material culture. Former museum editor, paramedic, and transplant coordinator. Editing for Science X since 2021. Full profile →

Andrew Zinin

Master's in physics with research experience. Long-time science news enthusiast. Plays key role in Science X's editorial success. Full profile →

Citation: Simple treatment strengthens pineapple leaf fibers for sustainable composites (2026, July 8) retrieved 13 July 2026 from https://phys.org/news/2026-07-simple-treatment-pineapple-leaf-fibers.html

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The midfielder recovered in time to win the World Cup with Spain in 2023 and was part of the squad that finished runners-up to England at Euro 2025.

In short, she had won it all and sources say she felt it was time for a change.

With her contract expiring at Barcelona, Putellas made the decision to leave and it is believed she always liked the idea of a move to the WSL.

That put London City Lionesses in the driving seat and they pursued her for some time despite competition from the majority of the world's top clubs.

She had offers from England, Mexico and the United States, with sources close to the player stating Boston Legacy provided the stiffest competition.

However, it's believed she admired US billionaire Kang's ambitions for the women's game, having been a long-standing rival to the owner's successful French club Lyon.

There was a connection between Putellas and Kang, with sources close to the owner suggesting a business partnership beyond the midfielder's playing career is likely to establish and flourish.

The Spaniard revealed on Wednesday the pair first met in Miami four years ago when they had dinner, and they discussed their vision for the game.

Putellas' hopes were to join a club she could impact off the pitch, as well as on it, and to leave a legacy which will help grow the future of the game.

She has given up the chance of playing Champions League football this season - a huge decision for someone who captained Barcelona to victory in 2026.

But it is in London City's five-year plan to be competing for trophies and they hope to challenge for a European qualification spot in the WSL this season.

With a World Cup looming next year, Putellas would have wanted to have been settled in 2027, with a three-year deal in Bromley securing her future.

Kang's influence was massive on Putellas with the US owner engaging in regular conversation at events and award ceremonies.

As a result, London City Lionesses were always confident they could persuade Putellas to join, despite only agreeing terms in recent weeks.

The club did not put in a request to Barcelona to approach Putellas in January, which they would have been eligible to, because she had stated she wanted to see out the season with no distractions.

Her contract was signed this month and it is understood Putellas did not discuss her decision with any team-mates.

Naturally, Kang's money was helpful. She could provide the funds needed to pay Putellas what she is worth and make her the club's highest paid player.

Sources at London City say she is earning less than £1m as a base salary, though potential add-ons and bonuses will increase it. There are no image rights deals.

WSL players cannot earn higher than 80% of the club's total revenue, plus any additional investment up to £4m.

For example, the WSL's highest earners Arsenal and Chelsea had revenue of £21.5m and £21.3m in 2025, meaning they had a potential wage structure of around £21m if they had the £4m extra investment.

For London City, that investment is from Kynisca (Kang's business) and Putellas' wages must sit within their soft salary cap. Their total revenue has not been released yet having only earned promotion to the WSL last year.

But it was the project Kang has funded - an ambitious independent club, with hopes of competing for a European spot, and with intentions to grow the women's game - which largely attracted Putellas.

There is also Spanish influence at London City Lionesses with General Manager Gonzalo Rodriguez Garcia and former Barcelona executive Markel Zubizarreta in key organisation roles, as well as manager Eder Maestre.

Putellas' close friend Jana Fernandez has flourished since her move from Barcelona to London City last year, and the arrival of Spain defender Mapi Leon is imminent.

Putellas is expected to join London City's leadership group and there are hopes she will set the standards in training and with her professionalism.

It's understood she is arriving in London earlier than planned for pre-season, turning down commercial opportunities at the men's World Cup.

Her profile will help grow London City's brand and marketing opportunities - crucial components for a club building a fanbase from scratch.

Her arrival could also be the catalyst for other top players to join the club. Sources at London City say they have already had enquiries based on their links to Putellas.

But for London City Lionesses' rivals, Putellas' arrival is a terrifying sight.

Kang and Putellas symbolise a powerful partnership which can help propel WSL football, as well as launch the club into one of Europe's powerhouses.

It is likely to cause a stir among the WSL's elite as they will know they need to continue to invest to stay ahead. That is a good thing for the competition.

While the United States has historically dominated the international scene and the National Women's Soccer League (NWSL) remains an attractive league, they are falling behind the WSL's ability to bring in the world's best players.

Spain, the reigning world champions, are losing more players to the WSL, with London City Lionesses set to have at least seven Spaniards in their squad this season.

There is also a question of financial disparity. While Putellas joined on a free, the ability of top clubs to pay substantial wages is worrying for teams in the bottom half of the WSL.

It could spark new debate on the WSL's salary cap and whether it helps boost investment, or hinders the development of other clubs who simply don't have the capacity to grow at the same rapid rate.

There will also be one eye on Uefa's ruling which prevents multi-club owners from having more than one club in the Champions League.

Will Kang stand down at Lyon or London City Lionesses should the latter achieve their ambitions? %!s()

Beaumont, now 35 and having just announced her retirement from international cricket after this week's Test against India, refers to her debut as a whirlwind.

It is also a fitting word to describe a career that has seen her bat in every position from one to 11, become a World Cup winner, an Ashes double-centurion and now bowing out in the historic occasion of a first women's Test at Lord's from Friday.

"It's been an emotional week since I made the final decision," Beaumont told BBC Sport.

"At the end of the 50-over World Cup last year, there were a few doubts. I didn't necessarily have the lightbulb moment when I knew.

"But I had a few conversations with Lottie [head coach Charlotte Edwards] over the past few months about where the team was going and I didn't really see myself in that, so I made the decision about a week ago, to definitely go for it."

It has also been a career of resilience, though Beaumont jokingly refers to her dad's speech at her wedding in which he used that word in inverted commas to mean "stubborn" instead.

After a fluctuating start in the international game, it was in 2016 when then-coach Mark Robinson promoted her to open and she never looked back.

A year later, she was player of the tournament and leading run-scorer during England's 50-over World Cup win at home soil.

From there, she was one of the first names on the teamsheet with her consistency at the top of the order but another turning point came in 2022 when she was left out of the T20 side and missed a home Commonwealth Games as a result.

Earlier this summer, though, when Edwards left Beaumont out of the one-day international squad against New Zealand, there was a difference.

The stubbornness was not kicking in.

And last week, when men's Test captain Ben Stokes announced his retirement, Beaumont found herself drawing comparisons.

"I think that was the first time that I had been left out of a squad and not had that fire to go again, to prove people wrong one more time, and force my way back in," Beaumont said.

"When I heard Ben Stokes talking about 'going back to the well', I don't think I've ever connected with someone else more.

"I've said many times that you get knocked down seven times and get up eight. But that moment was a bit of a wake-up call - the moment where I thought I couldn't keep doing it and didn't want to."

Beaumont has always been outspoken and honest as a cricketer, whether that is about her own highs and lows or the issues facing the women's game, and even when discussing her retirement has continued to rally for more Test matches going forward.

Lord's is fresh from hosting more than 28,000 people for the Women's T20 World Cup final on Sunday, when Nat Sciver-Brunt's England lost to Australia and another healthy crowd is expected this week, but the timing of the match is peculiar and tricky to attach relevance to.

"People always ask me what's my favourite format and I could never say Test cricket, even though it hands down would be if we had the opportunity to play it enough," Beaumont added.

"This will be my 12th Test in 17 years so you're always feeling like you're playing catch-up.

"In the men's game, you still have players being defined as great by their Test records and I think for me, the women's game has lagged behind in that.

"Most of us want to play Test cricket but not in a tokenistic kind of way, in a way that we can really sink our teeth into it and try to master it. We're all professional sportspeople at the end of the day, we want to be great at what we do, and playing one Test every two years kind of puts a halt to that."

But it is when discussing her team-mates when Beaumont becomes the most emotional, fighting to hold back tears.

Alongside the likes of Sciver-Brunt, Danni Wyatt-Hodge, Amy Jones and Heather Knight, it feels like a core group who have grown up together.

The first central contracts, a World Cup win and a couple of defeats, weddings, babies - now on to retirements.

As Beaumont says, it is simply the next chapter, although she has not quite mapped out how that will look yet, other than knowing she will continue playing domestically.

Once the media duties are done, it is straight back to the nets and Beaumont asks where she is supposed to be.

"Short-leg practice," is the answer.

Stood at close range to the batter, right in the firing line, one of the most challenging jobs in Test cricket - and yet she seems genuinely excited by it.

It sums up Tammy Beaumont perfectly. %!s()

Kentucky Gov. Andy Beshear on Wednesday asked the office of Sen. Mitch McConnell's, R-Ky., to provide an update on the senator's health, escalating public pressure for more information as the 84-year-old remains hospitalized more than three weeks after being admitted.

"Over the last several weeks, Kentuckians have grown increasingly concerned about the health and well-being of Sen. McConnell," Beshear, a Democrat, said in a statement. "As Governor — and a fellow public official who understands the commitment we've made to the people we serve — I am requesting the Senator provide an update on his current health status."

The governor made his request two years after the Kentucky legislature overrode Beshear's veto to pass a law that bars Kentucky governors from appointing a temporary senator and instead requires a special election. The process has never been tested.

If McConnell, considered a master of legislative rules, were to resign, die or be expelled before then, Kentucky's vacancy process would begin.

Republicans hold a narrow, 53 to 47, Senate majority and the absence of a voting member, or even the remote chance of a Democrat filling the post temporarily, could change the power dynamics in Washington. The Senate is due to consider a boost in defense spending that President Donald Trump has requested, and McConnell is the chair of the subcommittee on defense appropriations.

"The Senate is so evenly divided right now that every Senate seat counts," Stephen Voss, a University of Kentucky political science professor, told CNBC. "Losing a Republican vote, even for a few weeks" he added, would be "an inconvenience with likely policy consequences."

McConnell's office did not immediately respond to a request for comment about his health on Wednesday. His office has said the senator is recovering in a hospital.

Kentucky Gov. Andy Beshear in an interview with the Lexington Herald-Leader in June 2024.

Ryan C. Hermens | Tribune News Service | Getty Images

How Kentucky's vacancy law works

Kentucky Republicans rewrote the state's U.S. Senate vacancy law in 2024, stripping the governor of the power to appoint a temporary senator and requiring a special election instead.

Under the law, the governor would issue a proclamation calling for a special election. The winner would serve the remainder of McConnell's unexpired term until January. Until a winner is certified, the seat would remain empty.

The timing is not automatic. Kentucky law does not appear to set a firm deadline for the governor to issue the proclamation, legal experts said.

Once the proclamation is issued, the election clock starts: It must be sent to county sheriffs at least 63 days before the election, and candidates must file at least 56 days before Election Day.

If a vacancy occurred July 8 and Beshear immediately sent the proclamation to county sheriffs, the earliest special election outside the regular November election — assuming it were held on a Tuesday, as Kentucky law generally requires for special elections — would appear to be Sept. 15. Candidate filings for such a race would be due July 21.

Because of the compressed timeline, Kentucky's political parties would choose their nominees for the special election.

For the general election, Republican Rep. Andy Barr is facing off against Democrat Charles Booker, but it is not guaranteed that party officials would select the same candidates for a special election. The Cook Political Report with Amy Walter rates the race as "solid" for Republicans.

Rep. Andy Barr, R-Ky., speaks during a signing ceremony for a resolution that disapproves of a rule related to the "Prudence and Loyalty in Selecting Plan Investments and Exercising Shareholder Rights, in the U.S. Capitol on Thursday, March 9, 2023.

Tom Williams | CQ-Roll Call, Inc. | Getty Images

The timing problem

The calendar gets more complicated closer to November.

Sept. 1 is the practical deadline for holding a special election on Nov. 3, the same day Kentucky voters are already scheduled to choose McConnell's successor for the next full six-year term.

To hold both elections that day, Beshear's proclamation would have to reach county sheriffs by Sept. 1, and special election candidates would have to file by Sept. 8.

Voss said a special election could be risky even for the Republicans who created the process.

"Special elections are highly unpredictable, with low turnout that can produce outcomes at odds with the overall orientation of the state's electorate," Voss said. "Candidates with a small but highly committed base tend to do well."

That makes the process awkward for Kentucky Republicans, who designed the law to keep a Democratic governor from filling a Senate seat by appointment.

"There's just no upside in it for the state GOP to want to hold a special election, although they may be legally compelled to do so," Voss said.

U.S. Sen. Mitch McConnell (R-KY) rides an escalator at the U.S. Capitol on March 25, 2025 in Washington, DC. 

Kevin Dietsch | Getty Images News | Getty Images

A possible court fight

The vacancy law could also face a court challenge.

Legal experts say the central question is whether Kentucky lawmakers can fully remove the governor's appointment role, given language in Kentucky's Constitution dealing with vacancies in statewide offices and the U.S. Constitution's 17th Amendment's rules for filling U.S. Senate seats.

"It's actually pretty complicated, and I think there's a decent chance the issue could end up in the courts," Josh Douglas, an election law expert and associate dean at the University of Kentucky Rosenberg College of Law, told CNBC.

The 17th Amendment says state legislatures may allow governors to make temporary Senate appointments until voters fill a vacancy by election, the opposite of the new law from Kentucky's Republican-led legislature.

The Kentucky Constitution says vacancies in offices for the state at large, or districts larger than a county, "shall be filled by appointment of the Governor." Legal experts say that could give Beshear, or another party, an argument that the 2024 law conflicts with the state constitution.

"The Governor may simply deem the statute a violation of his powers and then disregard it," Josh Blackman, a professor at the South Texas College of Law in Houston who has written about Kentucky's vacancy laws, told CNBC. "Ultimately, the courts will be dragged into the process and I don't know that they'll intervene."

A court could uphold the special election law. It could allow Beshear to appoint a temporary senator. Or litigation could stretch on while Kentucky's second Senate seat remains vacant.

"There are lots of players who have incentives to drag it out," Voss said.

U.S. Senator Rand Paul (R-KY) speaks to the media as he walks on the day that members of Congress work to resolve a dispute over immigration enforcement and avert a looming partial government shutdown, on Capitol Hill in Washington, D.C., U.S., January 29, 2026.

Kent Nishimura | Reuters

The Senate stakes

McConnell, a former longtime Senate majority leader, declined to seek an eighth term following a series of health scares. McConnell was admitted to a hospital on June 14, according to his office, which has released few details about his condition or the circumstances surrounding his hospitalization.

If McConnell's seat were to remain vacant, Kentucky would be represented by only one senator, Rand Paul.

Asked by CNBC on Tuesday for the latest update, McConnell's office pointed to a brief statement it issued last week saying the senator "appreciates the outpouring of support he's receiving while he continues his recovery in the hospital."

"The Senator continues to improve, and is working closely with his staff on Kentucky and Senate matters while the Senate is out of session," the statement said. %!s()

The surprise announcement came on Tuesday as Farage faced the possibility of a parliamentary investigation into at least two funding scandals. A finding against him could have seen Farage suspended from parliament, possibly triggering a recall petition and a by-election in his constituency, Clacton, in eastern England.

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By stepping down preemptively, the Reform leader, whose popularity has soared over the past two years and who is now viewed as a favourite to be the next prime minister, has triggered a by-election on his own terms – in which he himself can stand.

“The people of Clacton should be the judges of my actions,” Farage said on Tuesday. “This will be a people vs the establishment by-election.”

Farage added: “I will fight to win.”

Other parties have already stated that they will not field candidates for a by-election Farage triggers.

The right-wing populist leader has been one of the loudest anti-immigration voices in the United Kingdom and was key to securing victory for the Brexit movement. His Reform party currently has just eight of 650 parliament seats but has been leading in opinion polls as anti-migrant sentiments flare in the UK. Last year, a YouGov poll found that Reform would likely win a general election were one to be held then.

In May, Labour lost massively to Reform in elections in Wales and Scotland and 136 local council elections in England. While Reform gained more than 1,450 seats, including in Labour strongholds, the governing party lost more than 1,460 seats, giving a strong indication of the surge in support for Reform across the country.

Here’s what we know:

What is the funding scandal surrounding Nigel Farage?

Farage is facing an investigation by parliament into donations, including allegations he received undeclared money for his campaign.

Receiving gifts is not against parliament’s code of conduct, but failing to declare them can be.

The main investigation is one conducted by the Parliamentary Commissioner for Standards into a 5-million-pound ($6.7m) undeclared donation Farage received from Thailand-based cryptocurrency billionaire Christopher Harborne before announcing his candidacy in the 2024 general election.

On Tuesday, The Guardian newspaper said bankers had reported the donation to the National Crime Agency as potentially laundered money.

Farage has claimed the money was a personal gift, he received it before being elected to parliament and, therefore, it does not breach parliamentary rules.

“I have done nothing wrong. I have not broken the law in any way at all. I have not misused public money,” Farage said on Tuesday.

Separately, an investigation by The Sunday Times this week found that Farage received donations from convicted fraudster, cryptocurrency entrepreneur and longtime ally George Cottrell for security and staffing before the 2024 elections.

Cottrell, who has served as Farage’s aide in the past, was arrested in the US in 2016 while travelling with Farage on charges that he had offered to launder money for undercover agents posing as drug traffickers. He served eight months in prison and was released in March 2017.

Responding to the allegations on Sunday, Farage said he had done “nothing wrong” and was considering legal action against The Sunday Times.

On Monday, United States President Donald Trump, an ally of Farage, appeared to back the politician in a post on his Truth Social platform by sharing a link to an article headlined: “They’re running the 2024 anti-Trump playbook on Nigel Farage.”

Why are other parties refusing to contest a by-election?

The ruling Labour Party and opposition Conservatives and Liberal Democrats have all accused Farage of “playing games” and said they will not put candidates forward in a by-election.

On Tuesday, Prime Minister Keir Starmer said Farage’s announcement was a “desperate stunt” because the Reform politician was “up to his neck in sleaze”. The Labour Party has already referred the Cottrell case to the Electoral Commission.

Foreign Secretary Yvette Cooper told the BBC: “Nobody is going to get drawn into what is a political stunt by Nigel Farage because he wants to duck and dive around the rules that apply to everyone.”

Kemi Badenoch, leader of the Conservatives, said her party “will not be standing a candidate in the fake by-election that Farage is causing to distract people from what is happening”.

While the parliamentary investigation into his affairs will be on hold for the duration of a by-election, it would resume if he regains his seat, which he is expected to do.

He comfortably secured more than 40 percent of the vote in Clacton in 2024 and will not face opposition from major parties in 2026.

If he’s re-elected, he could still be suspended and yet another election could be called in Clacton, this time without him as a candidate.

What has Reform UK said about all this?

Reform UK has sounded a defiant tone amid the scandal.

Deputy leader Richard Tice told UK media channel TALK that Farage will “receive a dramatically increased majority” in the by-election and the numbers will “prove to the rest of the electorate that more people want to vote for Nigel and Reform because they recognise that Britain is broken”.

In a post on X, the party said: “For too long the establishment in Westminster has passed judgement on Nigel Farage’s political integrity.”

“It’s time for the people of Clacton to decide,” it added.

Reform has also said it will pay for the by-election in Clacton in what critics say is an attempt to deflect claims it is wasting taxpayers’ money. %!s()