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Ren Y, Li Z, Li X, Su J, Li Y, Gao Y, Zhou J, Ji C, Zhu S, Yu M. The Influence of Thermal Parameters on the Self-Nucleation Behavior of Polyphenylene Sulfide (PPS) during Secondary Thermoforming. MATERIALS (BASEL, SWITZERLAND) 2024; 17:890. [PMID: 38399144 PMCID: PMC10890424 DOI: 10.3390/ma17040890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 02/04/2024] [Accepted: 02/07/2024] [Indexed: 02/25/2024]
Abstract
During the secondary thermoforming of carbon fiber-reinforced polyphenylene sulfide (CF/PPS) composites, a vital material for the aerospace field, varied thermal parameters profoundly influence the crystallization behavior of the PPS matrix. Notably, PPS exhibits a distinctive self-nucleation (SN) behavior during repeated thermal cycles. This behavior not only affects its crystallization but also impacts the processing and mechanical properties of PPS and CF/PPS composites. In this article, the effects of various parameters on the SN and non-isothermal crystallization behavior of PPS during two thermal cycles were systematically investigated by differential scanning calorimetry. It was found that the SN behavior was not affected by the cooling rate in the second thermal cycle. Furthermore, the lamellar annealing resulting from the heating process in both thermal cycles affected the temperature range for forming the special SN domain, because of the refined lamellar structure, and expelled various defects. Finally, this study indicated that to control the strong melt memory effect in the first thermal cycle, both the heating rate and processing melt temperature need to be controlled simultaneously. This work reveals that through collaborative control of these parameters, the crystalline morphology, crystallization temperature and crystallization rate in two thermal cycles are controlled. Furthermore, it presents a new perspective for controlling the crystallization behavior of the thermoplastic composite matrix during the secondary thermoforming process.
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Affiliation(s)
- Yi Ren
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Shanghai Collaborative Innovation Center of High-Performance Fibers and Composites (Province-Ministry Joint), Key Laboratory of High-Performance Fibers & Products, Ministry of Education, Center for Civil Aviation Composites, Donghua University, Shanghai 201620, China
- Key Laboratory of Shanghai City for Lightweight Composites, College of Materials Science and Engineering, Donghua University, Shanghai 201620, China
| | - Zhouyang Li
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Shanghai Collaborative Innovation Center of High-Performance Fibers and Composites (Province-Ministry Joint), Key Laboratory of High-Performance Fibers & Products, Ministry of Education, Center for Civil Aviation Composites, Donghua University, Shanghai 201620, China
| | - Xinguo Li
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Shanghai Collaborative Innovation Center of High-Performance Fibers and Composites (Province-Ministry Joint), Key Laboratory of High-Performance Fibers & Products, Ministry of Education, Center for Civil Aviation Composites, Donghua University, Shanghai 201620, China
- Key Laboratory of Shanghai City for Lightweight Composites, College of Materials Science and Engineering, Donghua University, Shanghai 201620, China
| | - Jiayu Su
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Shanghai Collaborative Innovation Center of High-Performance Fibers and Composites (Province-Ministry Joint), Key Laboratory of High-Performance Fibers & Products, Ministry of Education, Center for Civil Aviation Composites, Donghua University, Shanghai 201620, China
- Key Laboratory of Shanghai City for Lightweight Composites, College of Materials Science and Engineering, Donghua University, Shanghai 201620, China
| | - Yue Li
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University, Shanghai 201306, China
| | - Yu Gao
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Shanghai Collaborative Innovation Center of High-Performance Fibers and Composites (Province-Ministry Joint), Key Laboratory of High-Performance Fibers & Products, Ministry of Education, Center for Civil Aviation Composites, Donghua University, Shanghai 201620, China
- Key Laboratory of Shanghai City for Lightweight Composites, College of Materials Science and Engineering, Donghua University, Shanghai 201620, China
| | - Jianfeng Zhou
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Shanghai Collaborative Innovation Center of High-Performance Fibers and Composites (Province-Ministry Joint), Key Laboratory of High-Performance Fibers & Products, Ministry of Education, Center for Civil Aviation Composites, Donghua University, Shanghai 201620, China
| | - Chengchang Ji
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Shanghai Collaborative Innovation Center of High-Performance Fibers and Composites (Province-Ministry Joint), Key Laboratory of High-Performance Fibers & Products, Ministry of Education, Center for Civil Aviation Composites, Donghua University, Shanghai 201620, China
- Key Laboratory of Shanghai City for Lightweight Composites, College of Materials Science and Engineering, Donghua University, Shanghai 201620, China
| | - Shu Zhu
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Shanghai Collaborative Innovation Center of High-Performance Fibers and Composites (Province-Ministry Joint), Key Laboratory of High-Performance Fibers & Products, Ministry of Education, Center for Civil Aviation Composites, Donghua University, Shanghai 201620, China
- Key Laboratory of Shanghai City for Lightweight Composites, College of Materials Science and Engineering, Donghua University, Shanghai 201620, China
| | - Muhuo Yu
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Shanghai Collaborative Innovation Center of High-Performance Fibers and Composites (Province-Ministry Joint), Key Laboratory of High-Performance Fibers & Products, Ministry of Education, Center for Civil Aviation Composites, Donghua University, Shanghai 201620, China
- Key Laboratory of Shanghai City for Lightweight Composites, College of Materials Science and Engineering, Donghua University, Shanghai 201620, China
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Cui J, Yang SG, Zhang R, Cao Y, Wang Y, Zeng X, Liu F, Ungar G. Continuous Spectrum of Morphologies and Phase Behavior across the Contact Zone from Poly(l-lactide) to Poly(d-lactide): Stereocomplex, Homocrystal, and Between. Macromolecules 2023; 56:8754-8766. [PMID: 38024153 PMCID: PMC10653275 DOI: 10.1021/acs.macromol.3c01815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 10/10/2023] [Accepted: 10/12/2023] [Indexed: 12/01/2023]
Abstract
The enantiomeric ratio is a key factor affecting the crystallization behavior and morphology of poly-l-lactide/poly-d-lactide (PLLA/PDLA) blends. Despite a number of studies on crystallization of nonequimolar PLLA/PDLA blends, a full picture of the effect of the L/D ratio is still lacking. Here, we put the two enantiomers in contact and allow interdiffusion above the melting point of the stereocomplex crystal (SC) to prepare samples with a continuously changing L/D ratio from enantiopure PLLA (ratio 0/100) to enantiopure PDLA (100/0). Using polarized optical microscopy, atomic force microscopy, and microbeam X-ray diffraction, the continuous spectrum of morphologies and phase behaviors across the contact zone is investigated. The blend morphology shows clear evidence of "poisoning by purity" of SC crystallization at all blend compositions. The low birefringence of the 50/50 SC is found to be due to the meandering of broken edge-on lamellae. Its further decrease to near zero as L/D deviates further away from 50/50 is explained by transition from radial edge-on lamellae to fully random meandering lamellae, then to mixed flat-on lamellae, and finally to submicron-sized axialites. In comparison with the smooth and straight homocrystal (HC) lamellae of pure enantiomers, the lamellae in the blends often have serrated edges caused by pinning by rejected excess enantiomer acting as an impurity during lamellar growth. A feature of the binary phase diagram is pure enantiomers acting as an impurity to the SC and counter-enantiomer acting as an impurity to homocrystallization of the enantiomers. Crystallization was found to be most suppressed at 99% enantiomeric purity, where the amount of the counter-enantiomer is insufficient for creation of SC nuclei and HC growth is inhibited by the small amount of the enantio-impurity. These and other intriguing results are less likely to be noticed without the continuous composition gradient of the contact sample.
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Affiliation(s)
- Jiaming Cui
- Shaanxi
International Research Center for Soft Matter, State Key Laboratory
for Mechanical Behavior of Materials, Xi’an
Jiaotong University, Xi’an 710049, P. R. China
| | - Shu-Gui Yang
- Shaanxi
International Research Center for Soft Matter, State Key Laboratory
for Mechanical Behavior of Materials, Xi’an
Jiaotong University, Xi’an 710049, P. R. China
| | - Ruibin Zhang
- Department
of Materials Science and Engineering, Sheffield
University, Sheffield S1 3JD, U.K.
| | - Yu Cao
- Shaanxi
International Research Center for Soft Matter, State Key Laboratory
for Mechanical Behavior of Materials, Xi’an
Jiaotong University, Xi’an 710049, P. R. China
| | - Yubo Wang
- Shaanxi
International Research Center for Soft Matter, State Key Laboratory
for Mechanical Behavior of Materials, Xi’an
Jiaotong University, Xi’an 710049, P. R. China
| | - Xiangbing Zeng
- Department
of Materials Science and Engineering, Sheffield
University, Sheffield S1 3JD, U.K.
| | - Feng Liu
- Shaanxi
International Research Center for Soft Matter, State Key Laboratory
for Mechanical Behavior of Materials, Xi’an
Jiaotong University, Xi’an 710049, P. R. China
| | - Goran Ungar
- Shaanxi
International Research Center for Soft Matter, State Key Laboratory
for Mechanical Behavior of Materials, Xi’an
Jiaotong University, Xi’an 710049, P. R. China
- Department
of Materials Science and Engineering, Sheffield
University, Sheffield S1 3JD, U.K.
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Cui J, Yang SG, Zhang Q, Liu F, Ungar G. Poisoning by Purity: What Stops Stereocomplex Crystallization in Polylactide Racemate? Macromolecules 2023; 56:989-998. [PMID: 36818575 PMCID: PMC9933539 DOI: 10.1021/acs.macromol.2c02067] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 12/28/2022] [Indexed: 01/22/2023]
Abstract
Formation of stereocomplex crystals (SC) is an effective way to improve the heat resistance and mechanical performance of poly(lactic acid) products. However, at all but the slowest cooling rates, SC crystallization of a high-molecular-weight poly(l-lactic acid)/poly(d-lactic acid) (PLLA/PDLA) racemate stops at a high temperature or does not even start, leaving the remaining melt to crystallize into homochiral crystals (HC) or an SC-HC mixture on continuous cooling. To understand this intriguing phenomenon, we revisit the SC crystallization of both high- and low-molecular-weight PLLA/PDLA racemates. Based on differential scanning calorimetry (DSC), supplemented by optical microscopy and X-ray scattering, we concluded that what stops the growth of SC is the accumulation of the nearly pure enantiomer, either PDLA or PLLA, that is rejected from the SC ahead of its growth front. The excess enantiomer is a result of random compositional fluctuation present in the melt even if the average composition is 1:1. The situation is more favorable if the initial polymer is not fully molten or is brought up to just above the melting point where SC seeds remain, as proven by DSC and X-ray scattering. Moreover, we find that not only is SC growth poisoned by the locally pure enantiomer but also that at lower temperatures, the HC growth can be poisoned by the blend. This explains why SC growth, arrested at high temperatures, can resume at lower temperatures, along with the growth of HC. Furthermore, while some previous works attributed the incomplete SC crystallization to a problem of primary nucleation, we find that adding a specific SC-promoting nucleating agent does not help alleviate the problem of cessation of SC crystallization. This reinforces the conclusion that the main problem is in growth rather than in nucleation.
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Affiliation(s)
- Jiaming Cui
- Shaanxi
International Research Center for Soft Matter, State Key Laboratory
for Mechanical Behavior of Materials, Xi’an
Jiaotong University, Xi’an710049, China
| | - Shu-Gui Yang
- Shaanxi
International Research Center for Soft Matter, State Key Laboratory
for Mechanical Behavior of Materials, Xi’an
Jiaotong University, Xi’an710049, China,
| | - Qilu Zhang
- Shaanxi
International Research Center for Soft Matter, State Key Laboratory
for Mechanical Behavior of Materials, Xi’an
Jiaotong University, Xi’an710049, China
| | - Feng Liu
- Shaanxi
International Research Center for Soft Matter, State Key Laboratory
for Mechanical Behavior of Materials, Xi’an
Jiaotong University, Xi’an710049, China
| | - Goran Ungar
- Shaanxi
International Research Center for Soft Matter, State Key Laboratory
for Mechanical Behavior of Materials, Xi’an
Jiaotong University, Xi’an710049, China,Department
of Materials Science and Engineering, Sheffield
University, SheffieldS1 3JD, U.K.,,
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Affiliation(s)
- Leire Sangroniz
- POLYMAT and Polymer Science and Technology Department, Faculty of Chemistry, University of the Basque Country UPV/EHU, Paseo Manuel de Lardizábal, 3, 20018 Donostia-San Sebastián, Spain
| | - Dario Cavallo
- Department of Chemistry and Industrial Chemistry, University of Genova, via Dodecaneso, 31, 16146 Genova, Italy
| | - Alejandro J. Müller
- POLYMAT and Polymer Science and Technology Department, Faculty of Chemistry, University of the Basque Country UPV/EHU, Paseo Manuel de Lardizábal, 3, 20018 Donostia-San Sebastián, Spain
- IKERBASQUE - Basque Foundation for Science, Bilbao, Spain
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Mechanical properties and heat resistance of stereocomplex polylactide/copolyester blend films prepared by in situ melt blending followed with compression molding. Heliyon 2018; 4:e01082. [PMID: 30603714 PMCID: PMC6307044 DOI: 10.1016/j.heliyon.2018.e01082] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Revised: 10/26/2018] [Accepted: 12/18/2018] [Indexed: 11/26/2022] Open
Abstract
This work focuses on the process to obtain high heat-resistant stereocomplex polylactide (scPLA)/copolyester blend films by in situ melt blending of high molecular-weight poly(L-lactide) (PLLA), low molecular-weight poly(D-lactide) (PDLA) and copolyester followed with compression molding. A copolyester of poly(ε-caprolactone-co-L-lactide) was used as a film former. Stereocomplexation, mechanical properties and heat resistance of the scPLA/copolyester blend films were investigated by differential scanning calorimetry (DSC), tensile testing and dynamic mechanical analysis (DMA), respectively. The PDLA fractions enhanced stereocomplexation and heat resistance of the blend films while the copolyester fraction reduced film brittleness. Dimensional stability to heat of blend films was also determined and was accorded to their DMA results. It was concluded that the high heat-resistant and less brittle scPLA films could be prepared using 70/30 (w/w) PLLA/PDLA with 20 wt% copolyester through melt blending before compression molding. This film showed similar stress at break and heat resistance to those of polypropylene film but with lower strain at break.
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Yang B, Wang R, Ma HL, Li X, Brünig H, Dong Z, Qi Y, Zhang X. Structure Mediation and Properties of Poly( l-lactide)/Poly( d-lactide) Blend Fibers. Polymers (Basel) 2018; 10:E1353. [PMID: 30961279 PMCID: PMC6401892 DOI: 10.3390/polym10121353] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 11/30/2018] [Accepted: 12/01/2018] [Indexed: 12/02/2022] Open
Abstract
Poly(l-lactic acid) (PLLA) and poly(d-lactic acid) (PDLA) blend as-spun fibers (50/50, wt.%) were prepared by melt spinning. Structure mediation under temperature and stress and properties of poly(l-lactic acid)/poly(d-lactic acid)(PLLA/PDLA) as-spun fibers were investigated by wide-angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC). The results show that highly oriented stereocomplex (SC) crystals can be formed in PLLA/PDLA blend fibers drawn at 60 °C and annealed at 200 °C. However, at drawn temperature of 80 °C, only lower oriented SC crystals can be formed. For PLLA/PDLA blend fibers drawn twice at 60 °C (PLLA/PDLA-60-2), the crystallinity of SC crystals increases with annealing temperature in the range of 200 to 215 °C, while the degree of orientation decreases slightly. When the annealing temperature is 210 °C, the crystallinity and orientation of SC crystals in PLLA/PDLA-60-2 fibers reach 51% and -0.39, respectively. Moreover, PLLA/PDLA-60-2-210 fibers exhibit excellent heat-resistant property even at 200 °C. The results indicate that the oriented PLLA/PDLA blend fibers with high SC crystals content can be regulated in a short time.
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Affiliation(s)
- Bo Yang
- Beijing Key Laboratory of Clothing Materials R & D and Assessment, Beijing Engineering Research Center of Textile Nanofiber, School of Materials Science & Engineering, Beijing Institute of Fashion Technology, Beijing 100029, China.
| | - Rui Wang
- Beijing Key Laboratory of Clothing Materials R & D and Assessment, Beijing Engineering Research Center of Textile Nanofiber, School of Materials Science & Engineering, Beijing Institute of Fashion Technology, Beijing 100029, China.
| | - Hui-Ling Ma
- Beijing Key Laboratory of Clothing Materials R & D and Assessment, Beijing Engineering Research Center of Textile Nanofiber, School of Materials Science & Engineering, Beijing Institute of Fashion Technology, Beijing 100029, China.
| | - Xiaolu Li
- Beijing Key Laboratory of Clothing Materials R & D and Assessment, Beijing Engineering Research Center of Textile Nanofiber, School of Materials Science & Engineering, Beijing Institute of Fashion Technology, Beijing 100029, China.
| | - Harald Brünig
- Leibniz Institute of Polymer Research Dresden, Hohe Strasse 6, 01069 Dresden, Germany.
| | - Zhenfeng Dong
- Beijing Key Laboratory of Clothing Materials R & D and Assessment, Beijing Engineering Research Center of Textile Nanofiber, School of Materials Science & Engineering, Beijing Institute of Fashion Technology, Beijing 100029, China.
| | - Yue Qi
- Beijing Key Laboratory of Clothing Materials R & D and Assessment, Beijing Engineering Research Center of Textile Nanofiber, School of Materials Science & Engineering, Beijing Institute of Fashion Technology, Beijing 100029, China.
| | - Xiuqin Zhang
- Beijing Key Laboratory of Clothing Materials R & D and Assessment, Beijing Engineering Research Center of Textile Nanofiber, School of Materials Science & Engineering, Beijing Institute of Fashion Technology, Beijing 100029, China.
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