عوامل مؤثر بر فشردگی مولکولی و اثر آن بر خواص مکانیکی اپوکسی

نوع مقاله : گزارش

نویسندگان

1 دانشجو ارشد

2 مرکز تحقیقات علوم و تکنولوژی کامپوزیت

چکیده

اپوکسی پخت‌شده پلیمری گرماسخت با ساختار بی‌شکل است. ساختار فاز بی‌شکل، بازتابی از تاریخچه گرمایی مکانیکی پلیمر است. پارامترهای بسیاری در ساختار فاز بی‌شکل بر خواص فیزیکی و مکانیکی اثرگذارند. از پارامترهایی که کمتر مورد توجه قرار گرفته، فشردگی مولکولی است. هدف این مقاله، بررسی عوامل اثرگذار بر فشردگی مولکولی است که به تغییر خواص مکانیکی منجر می‌شود. اندازه‌گیری فشردگی مولکولی با پراش پرتو ایکس و تخمین تقریبی آن با استفاده از چگالی ماکروسکوپی و محاسبه جدایش بین‌زنجیری با استفاده از معادله براگ انجام می‌شود. همچنین، معادلات دیگری برای محاسبه میانگین جدایش بین‌زنجیری و اندازه بلور در سامانه‌های نیمه‌بلوری در این مقاله معرفی می‌شود. مطالعات نشان می‌دهند، وجود ساختارهای صلب در پیکره باعث افزایش تمایل به آرایش‌یافتگی می‌شود. افزون بر این، وجود شاخه کوچک‌تر از فضای آزاد بین‌زنجیری، افزایش فشردگی و خواص مکانیکی را به‌دنبال دارد. به‌طور کلی در اضافه‌کردن افزودنی به سامانه، با کاهش مقیاس اندازه ذره فشردگی سامانه بیشتر می‌شود. همچنین، وجود اصلاح‌کننده‌های سطحی روی ذرات، به‌ویژه نانوذرات، سبب آرایش ماتریس موجود در اطراف ذره می‌شود که افزایش فشردگی مولکولی و خواص مکانیکی را به‌دنبال دارد. افزودن نرم‌کننده به سامانه نیز در صورت جدایی فاز با بزرگ‌ترشدن مقدار فاز ناپیوسته، باعث کاهش فشردگی مولکولی می‌شود و پیک هاله بی‌شکل را به‌سمت زوایای کوچک‌تر جابه‌جا می‌کند.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Effective Factors on Molecular Packing and Its Effect on Mechanical Properties of Epoxy

نویسندگان [English]

  • Mehran Jahani 1
  • Mehrzad Mortezaei 2
1 master Student
2 Composite Science and Technology Research Center
چکیده [English]

Cured epoxy is a thermosetting polymer with amorphous structure. The amorphous
phase structure reflects the mechanical thermal history of a polymer. Many parameters
in the structure of the amorphous phase affect physical and mechanical properties. One of
the rarely considered parameters is molecular packing. The purpose of this study is to
investigate the factors affecting molecular packing, which leads to changes in mechanical
properties. The measurement of molecular packing by x-ray diffraction is carried out
using the Bragg equation and its approximate estimation is acquired using macroscopic
density. Other equations for calculating chain diffraction and crystal size are introduced
in semi-crystalline systems. Studies have shown that the presence of rigid structures in
the backbone increases the tendency for arrangement. In addition, the branch tends to
increased packing and mechanical properties when it is smaller than the free space between
the chains. Generally in adding additive, the effect increases on molecular packing by
reducing the particle scale. Also, the presence of surface modifiers on particles, especially
in nanoscale particles, results in a matrix arrangement around the particle, an increase in
molecular packing and mechanical properties. The addition of a plasticizer in the system in
the case of fuzzy separation, as the bubble phase becomes larger, there is a reduction in the amount of packing in the chain and displaces the amorphous halo towards smaller angles.

کلیدواژه‌ها [English]

  • X-ray diffraction
  • molecular packing
  • epoxy
  • mechanical properties
  • reinforcement

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