scholarly journals Thermal and Thermo-Mechanical Properties of Poly(L-Lactic Acid) Biocomposites Containing β-Cyclodextrin/d-Limonene Inclusion Complex

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2569
Author(s):  
Monika Dobrzyńska-Mizera ◽  
Monika Knitter ◽  
Salvatore Mallardo ◽  
Maria Cristina Del Barone ◽  
Gabriella Santagata ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Glass Transition ◽  
Inclusion Complex ◽  
Room Temperature ◽  
Morphological Analysis ◽  
Nucleating Agent ◽  
Thermomechanical Analysis ◽  
Constant Stiffness ◽  
High Temperature Processing

Bio-based composites made of poly(L-lactic acid) (PLLA) and β-cyclodextrin/d-limonene inclusion complex (CD-Lim) were prepared by melt extrusion. Encapsulation of volatile d-limonene molecules within β-cyclodextrin cages was proven to be a successful strategy to prevent evaporation during high-temperature processing. However, small amounts of limonene were released upon processing, resulting in the plasticization of the polymeric matrix. Morphological analysis revealed good dispersion of the filler, which acted as a nucleating agent, favoring the growth of PLLA crystals. The composites′ lowered glass transition temperature upon the addition of CD-Lim was also proved by thermomechanical analysis (DMA). Moreover, DMA revealed constant stiffness of modified materials at room temperature, which is crucial in PLLA-based formulations.

Improving the Toughness of Poly (L-lactic acid) by Interpenetrating Network Structure

2011 ◽  
Vol 239-242 ◽  
pp. 1919-1922
Author(s):  
Tun Galag Dong ◽  
Ye Jin ◽  
Xin Guo ◽  
Wen Xiu Sun ◽  
Meng Ting Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Glass Transition ◽  
Tensile Test ◽  
Room Temperature ◽  
Fracture Strain ◽  
Polymer Network ◽  
Interpenetrating Polymer Network ◽  
Interpenetrating Network ◽  
Composite Samples

An interpenetrating polymer network was formed by blending of PLLA and PEG cross-linked β-CD to improve the toughness of PLLA, and the mechanical properties of PLLA composites were studied using tensile test. The PLLA composite samples exhibited a single glass transition and their Tg values decreased with increasing PEG/β-CD content, indicating that PLLA and PEG/β-CD are miscible. The PLLA composite samples aged at room temperature achieved the highest fracture strain (about 235%), about 40 times that of the original PLLA sample, while the Young's modulus was not seriously hampered.

Study on the Crystallization Activation Energy of Poly (L-lactic acid) Nucleated with P-tert-butylcalix[8]arene

2018 ◽  
Vol 26 (2) ◽  
pp. 169-175
Author(s):  
Yaoqi Shi ◽  
Liang Wen ◽  
Zhong Xin
Keyword(s):  
Activation Energy ◽  
Lactic Acid ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Crystallization Temperature ◽  
Nucleating Agent ◽  
Crystallization Activation Energy ◽  
Temperature Range ◽  
Chain Mobility

The crystallization activation energy (Δ E) of a polymer comprises the nucleation activation energy Δ F and the transport activation energy Δ E*. In this paper, the Δ E of poly (L-lactic acid) (PLLA) nucleated with nucleating agent p- tert-butylcalix[8]arene (tBC8) was calculated. The results showed that the Δ E of nucleated PLLA was 165.97 kJ/mol, which is higher than that of pure PLLA. The reason why Δ E of PLLA increased when incorporating nucleating agent was studied. The increment of glass transition temperature ( Tg) for nucleated PLLA revealed that the polymer chain mobility was restricted by tBC8, which was considered as the reason for the increase of Δ E*. Further, polyethylene glycol (PEG) was added to improve the chain mobility, thus eliminated the variation of the transport activation energy Δ E* caused by tBC8. Then the effect of the increment of crystallization temperature range on the increase of Δ F was also taken into consideration. It was concluded that both decreasing the mobility of chain segments and increasing the crystallization temperature range caused an increase of Δ E for PLLA/tBC8.

Influence of Nucleating Agent on PLLA Crystalline and Mechanical Properties

2012 ◽  
Vol 624 ◽  
pp. 269-273 ◽  
Author(s):  
Gang Yang ◽  
Qun Gao ◽  
Chun Fa Ouyang ◽  
Kang Sheng Zheng ◽  
Yun Guo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Lactic Acid ◽  
Tensile Test ◽  
Nucleating Agent ◽  
Nucleating Agents ◽  
Maximum Value ◽  
Crystalline Property ◽  
Mechanical Performances ◽  
Sem Investigation

This paper mainly concerned the effect of nucleating agents CAV101 on PLLA crystalline property. CAV101 was mixed with poly (L-lactic acid) (PLLA) to make PLLA/CAV101 blends, with CAV101 contents of 0, 0.1%, 0.3%, 0.5%, 0.7%, respectively. Mechanical performances, morphology and crystalline properties were investigated by tensile test, WAXD, SEM. The results demonstrated that the tensile strength and elongation of PLLA increased with the increase of CAV101 content and the maximum value at CAV101 of 0.3% and 0.5%, respectively. The crystallinity of PLLA blends CAV101 of 0.1%, 0.3%, 0.5%, 0.7% were 86.58%, 82.43%, 49.01%, 64.00% respectively.The SEM investigation found that the agglomeration of PLLA with the increasing of nucleating agents CAV101 content.

Morphology, thermal and dynamic mechanical properties of poly(lactic acid)/expandable graphite (PLA/EG) flame retardant composites

2017 ◽  
Vol 32 (1) ◽  
pp. 89-107 ◽  
Author(s):  
Mfiso Emmanuel Mngomezulu ◽  
Adriaan Stephanus Luyt ◽  
Maya Jacob John
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Glass Transition ◽  
Flame Retardant ◽  
Dynamic Mechanical Properties ◽  
Poly Lactic Acid ◽  
Expandable Graphite ◽  
Damping Factor ◽  
Melt Mixing ◽  
Dynamic Mechanical

This work reports on the effect of expandable graphite (EG) on the morphology, thermal and dynamic mechanical properties of flame retardant poly(lactic acid) (PLA)/EG composites. The composites were prepared by melt-mixing and their structure, morphology, melting and crystallization behaviour, as well as their dynamic mechanical properties, were investigated. It was found that graphite layers still existed in an aggregate structure with poor filler dispersion resulting in a lack of interfacial adhesion between EG and the PLA matrix. The presence of EG did not favour the crystallization of PLA, increased the glass transition temperature and showed a reduction in the crystallinity of the composites. The composites with higher filler contents showed enhanced storage and loss moduli. The glass transition temperatures from the loss modulus and damping factor curves varied inconsistently with EG content. The use of commercial EG as filler in PLA can preserve the thermal properties of injection moulding grade Cereplast PLA.

scholarly journals Non-isothermal Crystallization, Thermal Stability, and Mechanical Performance of Poly(L-lactic acid)/Barium Phenylphosphonate Systems

2017 ◽  
Vol 15 (1) ◽  
pp. 248-254 ◽  
Author(s):  
Yan-Hua Cai ◽  
Li-Sha Zhao
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Lactic Acid ◽  
Isothermal Crystallization ◽  
Mechanical Performance ◽  
Nucleating Agent ◽  
Crystal Form ◽  
Decomposition Temperature ◽  
Scanning Calorimetry ◽  
Crystallization Peak

AbstractThe introduction of a nucleating agent in semi-crystalline polymers is a frequently utilized way to improve the crystallization performance, and the use of a nucleating agent has a very great effect on the performance of the polymer in other areas including thermal stability and mechanical properties. In this investigation, barium phenylphosphonate (BaP) was prepared as a crystallization accelerator for Poly(L-lactic acid) (PLLA), and the non-isothermal crystallization behavior, thermal stability, and mechanical properties of PLLA modified by BaP were investigated using differential scanning calorimetry (DSC), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and electronic tensile testing. Non-isothermal crystallization analysis showed that the BaP could significantly accelerate the crystallization of PLLA, and the non-isothermal crystallization peak shifted to a higher temperature with increasing concentration of BaP, however, the corresponding crystallization peak became wider. XRD results after non-isothermal crystallization confirmed the non-isothermal crystallization DSC results. Additionally, the addition of BaP did not change the crystal form of PLLA. A comparative study on thermal stability indicated that BaP decreased the onset decomposition temperature of PLLA, resulting from the formation of more tiny and imperfect crystals. Whereas the influence of BaP on the thermal decomposition profile of PLLA was negligible. In terms of mechanical properties, the tensile strength and elastic modulus of PLLA/BaP increased compared to the virgin PLLA, unfortunately, the elongation at break decreased.

Polyamide 6 and high molecular weight phenol novolac blend having excellent mechanical properties in humid conditions

2018 ◽  
Vol 32 (6) ◽  
pp. 778-794 ◽  
Author(s):  
Takayuki Hirai ◽  
Kenzo Fukumori ◽  
Taiji Ikawa ◽  
Tetsuya Oda
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Glass Transition ◽  
High Molecular Weight ◽  
Room Temperature ◽  
Glassy State ◽  
Physical And Mechanical Properties ◽  
Polyamide 6 ◽  
Low Molecular Weight ◽  
Melt Mixing

Polymer blends of polyamide 6 (PA6) and phenol novolac (PN) were prepared by melt mixing. Up to 30 wt% of high molecular weight PN (HPN) or low molecular weight PN (LPN) was blended with PA6, and the physical and mechanical properties were examined. The water absorption of PA6 is inhibited by PN, and this effect is independent of the molecular weight of PN. PA6 and PN are miscible, and their blends show a single glass transition temperature ( T g) that is higher than that of PA6. HPN can enhance the T g of PA6 more efficiently than LPN because of its high T g. PA6 and the PA6/LPN blend after immersion in water had lower-than-room-temperature T gs transitioning to rubbery states. In contrast, the PA6/HPN blend after immersion in water had a higher-than-room-temperature T g. The PA6/HPN blend in water has excellent mechanical properties in its glassy state compared to those of PA6 in the dry state. Thus, the PA6/HPN blend can be used to broaden the applications of PA6, especially in humid conditions.

scholarly journals Biocomposites based on poly(lactic acid) and kenaf fibers: Effect of micro-fibrillated cellulose

2013 ◽  
Vol 32 (1) ◽  
pp. 331 ◽  
Author(s):  
Gordana Bogoeva-Gaceva ◽  
Dimko Dimeski ◽  
Vineta Srebrenkoska
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Flexural Strength ◽  
Microfibrillated Cellulose ◽  
Poly Lactic Acid ◽  
Kenaf Fiber ◽  
Kenaf Fibers

In this work, the influence of microfibrillated cellulose (MFC) on the basic mechanical properties of PLA/kenaf fiber biocomposites has been studied. The addition of 5–15 % microfibrillated cellulose to a biocomposite premix has resulted in an increased glass transition temperature of the final product, produced by compression molding of previously melt-mixed composite components. The presence of MFC has influenced the interface-sensitive properties of the PLA/kenaf composite: at an optimal loading of 10 %, the interfacial energy release rate was increased by about 20 %. Moreover, flexural strength and modulus of the composites were also improved (from 34.8 MPa to 57.1 MPa and from 4.9 GPa to 5.8 GPa, respectively).   

scholarly journals Insight on the effect of a piperonylic acid derivative on the crystallization process, melting behavior, thermal stability, optical and mechanical properties of poly(l-lactic acid)

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 203-213
Author(s):  
Li-Sha Zhao ◽  
Yan-Hua Cai
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Lactic Acid ◽  
Cooling Rate ◽  
Acid Derivative ◽  
Melting Process ◽  
Nucleating Agent ◽  
Cold Crystallization ◽  
Melt Crystallization ◽  
Optical And Mechanical Properties

AbstractA new piperonylic acid derivative (BPASD) was synthesized and evaluated as an organic nucleating agent for poly(l-lactic acid) (PLLA) via melt-crystallization; the other behaviors including cold-crystallization, melting process after crystallization, thermal stability in air atmosphere, and optical and mechanical properties of PLLA/BPASD samples were also investigated. The results of the melt-crystallization investigation showed that, in comparison to virgin PLLA, the BPASD could induce PLLA to crystallize in higher temperature region or at a faster cooling rate, suggesting that the BPASD as a heterogeneous nucleating agent could promote the crystallization of PLLA, but the melt-crystallization depended on the cooling rate, BPASD concentration, and the final melting temperature. With increasing of BPASD concentration, a shift to the lower temperature of cold-crystallization peak and decrease of crystallization enthalpy indicated that BPASD had an inhibition for the cold-crystallization of PLLA to some extent. The heating rate, crystallization temperature, the BPASD, and its concentration were critical factors to the melting process, and double-melting peaks appeared in heating were assigned to melting–recrystallization. Thermal decomposition behavior revealed that the addition of BPASD reduced the thermal stability of PLLA, but the interaction of PLLA and BPASD could prevent the decrease of the onset decomposition temperature. Further, the BPASD also decreased the light transmittance and elongation at the break of PLLA, but the tensile modulus and tensile strength of PLLA were enhanced.

Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C

1976 ◽  
Vol 34 ◽  
pp. 592-593
Author(s):  
Ernest L. Hall ◽  
J. B. Vander Sande
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Dislocation Structure ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Optical Devices ◽  
Semiconductor Compound ◽  
Wide Range ◽  
Sample Orientation

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.

Sign in / Sign up

Export Citation Format

Share Document