بررسی عملکرد چوب راش اصلاح‌شده با دی‌متیلول دی‌هیدروکسی اتیلن اوره (DMDHEU) در مقابل هوازدگی تسریع‌شده

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه علوم و صنایع چوب و کاغذ، دانشکدۀ منابع طبیعی، دانشکدگان کشاورزی و منابع طبیعی، دانشگاه تهران،کرج، ایران.

2 گروه مهندسی صنایع چوب، دانشکدة مهندسی مواد و علوم میان‌رشته‌ای، دانشگاه تربیت دبیر شهید رجائی، تهران. ایران.

10.22059/jfwp.2024.381075.1309

چکیده

عملکرد چوب راش اصلاح‌شده با دی‌متیلول دی‌هیدروکسی اتیلن اوره اصلاح‌شده (mDMDHEU) در مقابل هوازدگی بررسی شد. از رزین دی‌متیلول دی‌هیدروکسی اتیلن اوره اصلاح‌شده با غلظت 30 درصد و منیزیم کلراید به‌عنوان کاتالیزور به‌میزان 5 درصد وزنی استفاده شد. پس از اشباع نمونه­ ها به روش خلاء-فشار، پخت رزین در شرایط بخار فوق داغ (دمای 100 درجه به‌مدت 36 ساعت) و آون ( دمای 120 درجه به‌مدت 24 ساعت) انجام شد. مقاومت به هوازدگی نمونه­ ها تحت شرایط هوازدگی تسریع شده به‌مدت 750 ساعت اندازه­ گیری شد. نتایج نشان داد درصد افزایش وزن در شرایط پخت در آون به‌دلیل دمای بالای تیمار بیشتر بود ولی پخت به روش بخار فوق داغ عملکرد مطلوب ­تری در مقابل هوازدگی نشان داد. بیشترین میزان جذب آب و واکشیدگی برای نمونة شاهد و کمترین آن برای تیمار پخت در آون بود. نتایج حاکی از آن است که دمای بالاتر تیمار منجر به کاهش بیشتر جذب آب و افزایش ثبات ابعادی شده است. بررسی طیف‌سنجی مادون قرمز پس از هوازدگی نشان داد که ارتفاع پیک مربوط به حلقه ­های آروماتیک در نمونه­ های اصلاح‌شده نسبت به نمونه­ های اصلاح‌نشده به یک میزان کاهش یافته که نشان‌دهندة عدم حفاظت از لیگنین در هیچ یک از تیمارها، در برابر هوازدگی است. در مقایسه با پخت به روش آون، پخت با بخار فوق داغ موجب آب‌گریزی بیشتر سطح و کاهش تغییرات رنگی و مورفولوژی سطح ناشی از هوازدگی شد.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Performance of beech wood modified with dimethylol dihydroxyethylene urea (DMDHEU) against accelerated weathering

نویسندگان [English]

  • Zahra Rezaei 1
  • Asghar Tarmian 1
  • Aisona Talaei 2
1 Department of Wood and Paper Science and Technology, Faculty of Natural Resources, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.
2 Department of Wood Science Engineering, Faculty of Materials Engineering and Interdisciplinary Science, Shahid Rajaee Teacher Training University, Tehran, Iran.
چکیده [English]

The performance of beech wood modified with methylolated dimethylol dihydroxyethylene urea (mDMDHEU), with low formaldehyde emission, against weathering was investigated. Methylolated dimethylol dihydroxyethylene urea, at a concentration of 30%, and MgCl₂ as a catalyst at 5% by weight were used. After impregnation of the wood samples via the vacuum-pressure process, the samples were cured under superheated steam conditions (100°C for 36 hours) and in an oven (120°C for 24 hours). The weathering resistance of the samples was evaluated under accelerated weathering conditions for 750 hours. The results showed that the weight percent gain (%WPG) was higher in the oven curing method due to the higher treatment temperature; however, the superheated steam curing method showed better performance against weathering. The highest water absorption and swelling occurred in the control sample, while the lowest was observed in the oven-cured sample. The results indicated that the higher treatment temperature led to a further decrease in water absorption and an increase in dimensional stability. FTIR spectroscopy after weathering showed a reduction in the peak of aromatic rings in the modified samples, indicating that lignin was not effectively protected against weathering in any of the treatments. Compared to oven curing, curing with superheated steam resulted in greater water repellency of the surface and reduced changes in color and surface morphology caused by weathering.

کلیدواژه‌ها [English]

  • FTIR spectroscopy
  • mDMDHEU
  • Water repellency
  • Weathering
  • Wood modification

مراجع

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نشریه جنگل و فرآورده های چوب
دوره 77، شماره 3
آذر 1403
صفحه 313-326

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