عنوان مقاله
تأثیر ذرات نانو الاستومری بر روی ویژگی‌های مکانیکی و رفتار کریستالی شدن پلی پروپیلن
فهرست مطالب
چکیده
مقدمه
قسمت آزمایشگاهی
نتایج و بحث
نتیجه گیری
بخشی از مقاله
اندازه‌گیری آزمایشگاهی
ویژگی‌های مکانیکی
آزمایشات کشش بر روی یک ماشین کشش AG-1 (50 میلی‌متر/ دقیقه) انجام شده‌اند. طول ضربه با استفاده از آزمایش ضربه ایزود بر روی میله‌های سوراخ شده به وسیله ضربه ماشینCEAST تعیین شده‌اند. آزمایشات طول و مدول موجی بر رویInstron-4466 انجام شده‌اند، HDT با استفاده از یک آزمایشگر انحراف گرماییHD-PC تست شده است.
کلمات کلیدی:
The effect of elastomeric nano-particles on the mechanical properties and crystallization behavior of polypropylene Manli Zhanga , Yiqun Liua , Xiaohong Zhanga , Jianming Gaoa , Fan Huanga , Zhihai Songa , Genshuan Weib , Jinliang Qiaoa,* a SINOPEC Beijing Research Institute of Chemical Industry, Beijing 100013, People’s Republic of China b Institute of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100080, People’s Republic of China Received 5 April 2002; received in revised form 25 May 2002; accepted 10 June 2002 Abstract Generally, toughness of polypropylene (PP) is an issue which has been investigated for many years to search for improvements. A traditional approach is to blend with rubber particles to enhance the toughness of PP yet modulus of PP decreases accordingly. Recently, we have achieved a good balance of toughness and stiffness of PP via blending PP with a small amount of elastomeric nano-particles (ENP). Based on our measurements, mechanical properties of the blends studied both the toughness of PP at room temperature and at 220 8C show substantial increase. On the other hand, the stiffness of the PP blends retains or even possesses a slight enhancement. One of the reasons for this improvement is due to the fact that the ENP is not only a toughening modifier but also a nucleation agent for the PP. The nucleation density of the blends increases, while the crystallization kinetics of the blends becomes faster compared with the pure PP samples. q 2002 Elsevier Science Ltd. All rights reserved. Keywords: Elastomeric nano-particles; Polypropylene; Crystallization, toughness and stiffness 1. Introduction Isotactic polypropylene (PP) is a semi-crystalline polymer with desired properties, its toughness, especially notched impact strength, however, is not generally sufficient for applications as engineering plastics. Various methods for toughening PP have been studied, among which blending is the most effective and convenient way which can be classified into non-elastomer toughening [1,2] and elastomer toughening [3,4], or the combination of the both [5–7]. Recently, emerging is the method of rigid nanoparticles toughening [8,9]. Toughen PP with some commonly used rubbers such as ethylene–propylene rubber (EPR), ethylene–propylene diene monomer (EPDM), and styrene–butadiene rubbers (SBR), can lead to fairly high toughness, but simultaneously the loss of stiffness cannot be neglected. While toughening PP with rigid particles, toughness cannot usually be improved effectively, although their tensile strength and stiffness increase. It is difficult to prepare a PP blend with good balance of toughness and stiffness. Recently, a new kind of highly cross-linked nano-particle rubbers, ultra-fine full-vulcanized rubber powders (UFRP), by irradiating rubber latex and spray drying has been developed [10]. The particle size of the UFRP is tunable between 30 and 2000 nm by controlling polymerization conditions of the rubber latex. When the particle size is below 100 nm, the UFRP can be also recognized as elastomeric nano-particle (ENP). It has been found that the UFPR could be used in many different plastics as a good toughening modifier [11,12]. In this study, SB-ENP is used to toughen PP. A good combination of toughness and stiffness is achieved by blending PP with ENP. According to the toughening theory [13,14], the formulation of dc ¼ tc=½kðp=6FrÞ 1=3 2 1 ð1Þ where dc is the critical rubber particle diameter and Fr the rubber volume fraction, k the geometric factor characterizing the spatial package of the particles, tc is the critical faceto-face inter-particle distance or critical thickness of matrix ligaments. The brittle–tough transition occurs at a very low rubber volume fraction if the particle size of rubber is small enough. Therefore, the loss in stiffness caused by introducing
