Crystal structures and their effects on the properties of polyamide 12/clay and polyamide 6–polyamide 66/clay nanocomposites

2006 ◽  
Vol 100 (6) ◽  
pp. 4782-4794 ◽  
Author(s):  
Y. Zhang ◽  
J. H. Yang ◽  
T. S. Ellis ◽  
J. Shi

2009 ◽  
Vol 62 (6) ◽  
pp. 791-800 ◽  
Author(s):  
D. García-López ◽  
I. Gobernado-Mitre ◽  
J. F. Fernández ◽  
J. C. Merino ◽  
J. M. Pastor


2021 ◽  
Vol 63 (4) ◽  
pp. 311-316
Author(s):  
Simon Backens ◽  
Jan Siering ◽  
Stefan Schmidt ◽  
Nikolai Glück ◽  
Wilko Flügge

Abstract Lightweight pressure vessels of type IV for hydrogen storage consist of a thermoplastic inner liner, commonly from polyethylene or polyamide. The liner is the permeation barrier against the compressed gas and must prevent the formation of cracks, also after temperature changes, for example after refueling processes. In the present work high-density polyethylene, cross-linked polyethylene, polyamide 6 and polyamide 12 were characterized by tensile tests, single notch impact tests and permeations measurements before and after a cyclic thermal aging process. The aging only lead to slight changes of mechanical properties due to post-crystallization, but to a significant decrease of permeation properties. This decrease was contributed to weakened, amorphous regions where chain splitting occurred. Considerable differences in properties resulted from different peroxide cross-linking times of polyethylene at the same temperature. A longer holding time at 200 °C led to an improvement in impact strength by a factor of more than three. However, the permeation properties decreased by about 50 %, indicating that peroxide cross-linking in the melt inhibited the formation of crystalline regions.



2006 ◽  
Vol 13 (8-9) ◽  
pp. 773-782 ◽  
Author(s):  
J. S. Choi ◽  
S. T. Lim ◽  
H. J. Choi ◽  
A. Pozsgay ◽  
L. Százdi




Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5285
Author(s):  
Babette Goetzendorfer ◽  
Thomas Mohr ◽  
Ralf Hellmann

We introduced a new approach in selective laser sintering for hybrid multicomponent systems by fabricating the sintered polyamide 12 (PA12) part directly onto a similar (PA12) or dissimilar (polyamide 6 (PA6) and tool steel 1.2709) joining partner. Thus, the need for adhesive substances or joining pressure was completely circumvented, leading to the possibility of pure hybrid lightweight bi-polymer or metal–polymer systems. By taking advantage of the heating capabilities of the sinter laser regarding the substrate surface, different exposure strategies circumvented the lack of overlapping melting temperatures of dissimilar polymers. Therefore, even sintering on non-PA12 polymers was made possible. Finally, the transfer on metallic substrates—made up by selective laser melting (SLM)—was successfully performed, closing the gap between two powder-based additive processes, selective laser sintering (SLS) and SLM.



2019 ◽  
Vol 30 (6) ◽  
pp. 2833-2843 ◽  
Author(s):  
Adam Gnatowski ◽  
Agnieszka Kijo-Kleczkowska ◽  
Rafał Gołębski ◽  
Kamil Mirek

Purpose The issues concerning the prediction of changes in properties of polymer materials as a result of adding reinforcing fibers are currently widely discussed in the field of polymer material processing. This paper aims to present strengths and weaknesses of composites based on polymer materials strengthened with fibers. It touches upon composite cracking at the junction of a matrix and its reinforcement. It also discusses the analysis of changes in properties of chosen materials as a result of adding reinforcing fibers. The paper shows improvement in the strength of polymer materials with fiber addition, which is extremely important, because these types of composites are used in the aerospace, automotive and electrical engineering industries. Design/methodology/approach Comparing the properties of matrix strength with fiber properties is practically impossible. Thus, fiber tensile strength and composite tensile strength shall be compared (González et al., 2011): tensile (glass fiber GF) = 900 [MPa], elongation ΔL≈ 0; yield point (polyamide 66) = 70−90 [MPa], elongation Δ[%] = 3,5-18; tensile (polyamide 66 + 15% GF) = 80-125 [MPa], elongation Δ[%] ≈ 0; tensile (polyamide 66 + 30% GF) = 190 [MPa], elongation Δ[%] ≈ 0; yield point (polyamide 6) = 45-85 [MPa], elongation Δ[%] = 4-15; tensile (polyamide 6 + 15% GF) = 80-125 [MPa], elongation Δ[%] ≈ 0; tensile (polyamide 6 + 30% GF) = 95-130 [MPa] elongation Δ[%] ≈ 0. Comparison of properties of selected polymers and composites is presented in Tables 1−10 and Figures 1 and 2. The measurement methodology is presented in detail in the paper Kula et al. (2018). The increase in fiber content (to the extent discussed) leads to the increase in yield strength stresses and hardness. The value of yield strength for polyamide with the addition of fiberglass grows gradually with the increase in fiber content. The hardness of the composite of polyamide with glass balls increases together with the increase in reinforcement content. The changes of these values do not occur linearly. The increase in fiber content has a slight impact on density change (the increase of about 1 g/mm3 per 10 per cent). Findings The use of polymers as a matrix allows to give composites features such as: lightness, corrosion resistance, damping ability, good electrical insulation and thermal and easy shaping. Polymers used as a matrix perform the following functions in composites: give the desired shape to the products, allow transferring loads to fibers, shape thermal, chemical and flammable properties of composites and increase the possibilities of making composites. Fiber-reinforced polymer composites are the effect of searching for new construction materials. Glass fibers show tensile strength, stiffness and brittleness, while the polymer matrix has viscoelastic properties. Glass fibers have a uniform shape and dimensions. Fiber-reinforced composites are therefore used to increase strength and stiffness of materials. Polymers have low tensile strength, exhibit high deformability. Polymers reinforced by glass fiber have a high modulus of elasticity and therefore provide better the mechanical properties of the material. Composites with glass fibers do not exhibit deformations in front of cracking. An increase in the content of glass fiber in composites increases the tensile strength of the material. Polymers reinforced by glass fiber are currently one of the most important construction materials and are widely used in the aerospace, automotive and electro-technical industries. Originality/value The paper presents the test results for polyethylene composites with 25 per cent and 50 per cent filler coming from recycled car carpets of various car makes. The tests included using differential scanning calorimetry, testing material hardness, material tensile strength and their dynamic mechanical properties.



2004 ◽  
Vol 95 (3) ◽  
pp. 756-763 ◽  
Author(s):  
Xin Kang ◽  
Suqin He ◽  
Chengshen Zhu ◽  
Liuyang Wang ◽  
Liyun Lüˇ ◽  
...  


2009 ◽  
Vol 97 (2) ◽  
pp. 577-580 ◽  
Author(s):  
A. M. D. Leite ◽  
L. F. Maia ◽  
R. A. Paz ◽  
E. M. Araújo ◽  
H. L. Lira


Polymer ◽  
2005 ◽  
Vol 46 (10) ◽  
pp. 3264-3274 ◽  
Author(s):  
Bok Nam Jang ◽  
Charles A. Wilkie


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